Статті в журналах з теми "Clay soils Moisture Australia Measurement"
Щоб переглянути інші типи публікацій з цієї теми, перейдіть за посиланням: Clay soils Moisture Australia Measurement.
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-50 статей у журналах для дослідження на тему "Clay soils Moisture Australia Measurement".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте статті в журналах для різних дисциплін та оформлюйте правильно вашу бібліографію.
1
Brockwell, J., Catherine M. Evans, Alison M. Bowman, and Alison McInnes. "Distribution, frequency of occurrence and symbiotic properties of the Australian native legume Trigonella suavissima Lindl. and its associated root-nodule bacteria." Rangeland Journal 32, no. 4 (2010): 395. http://dx.doi.org/10.1071/rj09080.
Повний текст джерелаАнотація:
Trigonella suavissima Lindl. is an Australian native legume belonging to the tribe Trifolieae. It is an ephemeral species that is widely distributed in the arid interior of the continent where it occurs, following periodic inundation, on clay soils of the watercourse country of the Channel Country (far-western Queensland, north-east South Australia and north-western New South Wales). T. suavissima is the only member of its tribe that is endemic to Australia. Likewise, its root-nodule bacteria (Sinorhizobium sp.) may be the only member of its taxonomic group (S. meliloti, S. medicae) that is an Australian native. The distribution and frequency of occurrence of T. suavissima and the size of soil populations (density) of Sinorhizobium were monitored at 64 locations along inland river systems of the Channel Country. Measurements were made of (i) the nitrogen-fixing effectiveness of the symbioses between T. suavissima and strains of its homologous Sinorhizobium and (ii) the nitrogen-fixing effectiveness of the symbioses between legumes symbiotically related to T. suavissima and diverse strains of Sinorhizobium. It was concluded that the distribution and frequency of occurrence of T. suavissima is soil related. The species is most widespread on fine-textured clay soils with deep, self-mulching surfaces and high moisture-holding capacity. By contrast, the occurrence of T. suavissima is sporadic in the upper reaches of the inland river systems where the soils are poorly structured clays with lower moisture-holding capacity. Sinorhizobium is most abundant where the plant is most common. The nitrogen-fixing symbioses between T. suavissima and strains of Sinorhizobium isolated from soils across the region were consistently effective and often highly effective. Some of these strains fixed a little nitrogen with lucerne (Medicago sativa L.). T. suavissima also had some symbiotic (nitrogen-fixing) affinity with an exotic Trigonella (T. arabica Del.). The economic value of T. suavissima (and its symbiosis with Sinorhizobium) to the beef industry in the Channel Country is discussed.
2
Stanley, John N., David W. Lamb, Gregory Falzon, and Derek A. Schneider. "Apparent electrical conductivity (ECa) as a surrogate for neutron probe counts to measure soil moisture content in heavy clay soils (Vertosols)." Soil Research 52, no. 4 (2014): 373. http://dx.doi.org/10.1071/sr13142.
Повний текст джерелаАнотація:
Site-specific measurements of the apparent electrical conductivity (ECa) of soil using the EM38 were correlated with near-simultaneous neutron probe readings over periods of moisture extraction by an irrigated cotton crop. Thirty sites were monitored from three ECa zones within a 96-ha field of grey Vertosol soil 30 km west of Moree, New South Wales, Australia. This study differs from previous approaches by reporting the effect on ECa of a wetting front (irrigation) reaching a single ECa measurement point in a field and by using polyethylene neutron probe access tubes so that the EM38 could be operated directly over the same site measured by a neutron probe. We report strong correlations (r = 0.94) between neutron probe counts (CRR) averaged to a depth of 40 or 60 cm and ECa from an EM38 held in the vertical mode 20 cm above the soil surface. All combinations of EM sensor height (0–1.2 m) to neutron probe measurement depth (0.2–1.4 m) returned correlations >0.85. The relationship between CCR and ECa was linear for the purposes of estimating water content over a range of background ECa levels. More critical modelling suggested a slight curve (logarithmic model) fitted best. The range of surface-surveyed ECa from the start of irrigation (refill point) to fully irrigated (full point) was ~27 mS m–1 for this Vertosol, where surface ECa readings typically ranged from 50 to 200 mS m–1. We suggest that the calibration of ECa to CRR might be effected by a two-point measurement of the soil, namely at both upper (field capacity) and lower (wilting point) ECa values, and a site-specific calibration template generated by extending these point measures to whole-field surveys.
3
Liu, Y. Y., J. P. Evans, M. F. McCabe, R. A. M. de Jeu, A. I. J. M. van Dijk, and H. Su. "Influence of cracking clays on satellite estimated and model simulated soil moisture." Hydrology and Earth System Sciences 14, no. 6 (June 18, 2010): 979–90. http://dx.doi.org/10.5194/hess-14-979-2010.
Повний текст джерелаАнотація:
Abstract. Vertisols are clay soils that are common in the monsoonal and dry warm regions of the world. One of the characteristics of these soil types is to form deep cracks during periods of extended dry, resulting in significant variation of the soil and hydrologic properties. Understanding the influence of these varying soil properties on the hydrological behavior of the system is of considerable interest, particularly in the retrieval or simulation of soil moisture. In this study we compare surface soil moisture (θ in m3 m−3) retrievals from AMSR-E using the VUA-NASA (Vrije Universiteit Amsterdam in collaboration with NASA) algorithm with simulations from the Community Land Model (CLM) over vertisol regions of mainland Australia. For the three-year period examined here (2003–2005), both products display reasonable agreement during wet periods. During dry periods however, AMSR-E retrieved near surface soil moisture falls below values for surrounding non-clay soils, while CLM simulations are higher. CLM θ are also higher than AMSR-E and their difference keeps increasing throughout these dry periods. To identify the possible causes for these discrepancies, the impacts of land use, topography, soil properties and surface temperature used in the AMSR-E algorithm, together with vegetation density and rainfall patterns, were investigated. However these do not explain the observed θ responses. Qualitative analysis of the retrieval model suggests that the most likely reason for the low AMSR-E θ is the increase in soil porosity and surface roughness resulting from cracking of the soil. To quantitatively identify the role of each factor, more in situ measurements of soil properties that can represent different stages of cracking need to be collected. CLM does not simulate the behavior of cracking soils, including the additional loss of moisture from the soil continuum during drying and the infiltration into cracks during rainfall events, which results in overestimated θ when cracks are present. The hydrological influence of soil physical changes are expected to propagate through the modeled system, such that modeled infiltration, evaporation, surface temperature, surface runoff and groundwater recharge should be interpreted with caution over these soil types when cracks might be present. Introducing temporally dynamic roughness and soil porosity into retrieval algorithms and adding a "cracking clay" module into models are expected to improve the representation of vertisol hydrology.
4
Grant, CD, and AV Blackmore. "Self mulching behavior in clay soils - Its definition and measurement." Soil Research 29, no. 2 (1991): 155. http://dx.doi.org/10.1071/sr9910155.
Повний текст джерелаАнотація:
The history of the self-mulching concept is reviewed and from this a definition is proposed. Observation of the phenomenon to date has been quite subjective and qualitative, and the causes and mechanisms are little understood. A numerical index is developed to help redress these deficiencies. The self-mulching property embodies the ability of a soil to re-aggregate its clay in the course of wetting and air drying after the natural structure has been disrupted by puddling. A comparison of the clay released by such puddling with the clay released by shaking after drying and slaking of the puddle, forms the basis of the components for the numerical index. Suitable parameters for these components were extracted from experiments using typical Australian self-mulching soils. These soils also displayed a degree of subplasticity in at least part of their aggregated clay fraction. The numerical index values were compared with field structure ratings, made by pedologists, for 47 (mostly surface) soils from Australia and other parts of the world, and good agreement was found. The index is relevant to further work on mechanisms and modifications in self-mulching or potentially self-mulching soils.
5
Keramatikerman, Mahdi, Amin Chegenizadeh, Hamid Nikraz, and Yuksel Yilmaz. "Mechanical Behaviour of Atrazine-Contaminated Clay." Applied Sciences 10, no. 7 (April 3, 2020): 2457. http://dx.doi.org/10.3390/app10072457.
Повний текст джерелаАнотація:
Atrazine (ATZ) is one of the most heavily used types of herbicide that is currently applied in the agricultural industry all around the world, especially Australia and the United States. This study investigates the effect of atrazine contamination on the mechanical characteristics of two Western Australian natural clays and one commercial type of clay. A series of the Atterberg limit, compaction, and torsional ring shear tests were performed on the clays contaminated with 2, 4, and 6% atrazine content. The results showed that increasing the atrazine content led to a reduction in both liquid limit (LL) and plastic (PL) of the tested soils. Similarly, the optimum moisture content (OMC) and maximum dry density (MDD) decreased by increasing the atrazine in all tested clays. The ring shear results showed that the peak shear strength and residual stress ratio of the clays decreased by increasing the contamination. Also, the results showed that atrazine contamination caused an increase in cohesion and a decrease in the friction angle of the tested soils. Also, longer periods of contamination caused a reduction in strength characteristics of the tested soils.
6
Banu, Nargis A., Balwant Singh, and Les Copeland. "Microbial biomass and microbial biodiversity in some soils from New South Wales, Australia." Soil Research 42, no. 7 (2004): 777. http://dx.doi.org/10.1071/sr03132.
Повний текст джерелаАнотація:
Eight surface soils (0–15 cm) including 1 Ferrosol, 2 Tenosols, 2 Kurosols, 1 Sodosol, 1 Chromosol, and 1 Kandosol were collected from mainly pasture sites in New South Wales. The soils had different physico-chemical properties and there were some differences between the sites in climatic conditions. Soil microbial biomass carbon (MBC) was estimated by the chloroform-fumigation extraction method, and substrate utilisation patterns determined by the Biolog method were used to assess the amount, functional diversity, substrate richness and evenness, and community structure of the microorganisms in these soils. The amount of MBC (585 µg C/g) and the microbial diversity (H´ = 3.24) were high in soils that had high clay (33%), organic C (5.96%), total N (0.45%), free iron (7.06%), moisture content (50%), and cation exchange capacitiy (133.5 mmolc/kg). These soil properties, e.g. soil moisture (r2 = 0.72), organic C (r2 = 0.58), total N (r2 = 0.63), free iron (r2 = 0.44), and EC (r2 = 0.53), were positively correlated with MBC and microbial diversity index, whereas pH and sand and silt content showed negative correlations. The climatic factors (temperature and rainfall) had no significant influence on either MBC or diversity.
7
Shamir, O., N. Goldshleger, U. Basson, and M. Reshef. "MAPPING SPATIAL MOISTURE CONTENT OF UNSATURATED AGRICULTURAL SOILS WITH GROUND-PENETRATING RADAR." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B8 (June 24, 2016): 1279–85. http://dx.doi.org/10.5194/isprs-archives-xli-b8-1279-2016.
Повний текст джерелаАнотація:
Soil subsurface moisture content, especially in the root zone, is important for evaluation the influence of soil moisture to agricultural crops. Conservative monitoring by point-measurement methods is time-consuming and expensive. In this paper we represent an active remote-sensing tool for subsurface spatial imaging and analysis of electromagnetic physical properties, mostly water content, by ground-penetrating radar (GPR) reflection. Combined with laboratory methods, this technique enables real-time and highly accurate evaluations of soils' physical qualities in the field. To calculate subsurface moisture content, a model based on the soil texture, porosity, saturation, organic matter and effective electrical conductivity is required. We developed an innovative method that make it possible measures spatial subsurface moisture content up to a depth of 1.5 m in agricultural soils and applied it to two different unsaturated soil types from agricultural fields in Israel: loess soil type (Calcic haploxeralf), common in rural areas of southern Israel with about 30% clay, 30% silt and 40% sand, and hamra soil type (Typic rhodoxeralf), common in rural areas of central Israel with about 10% clay, 5% silt and 85% sand. Combined field and laboratory measurements and model development gave efficient determinations of spatial moisture content in these fields. The environmentally friendly GPR system enabled non-destructive testing. The developed method for measuring moisture content in the laboratory enabled highly accurate interpretation and physical computing. Spatial soil moisture content to 1.5 m depth was determined with 1–5% accuracy, making our method useful for the design of irrigation plans for different interfaces.
8
Shamir, O., N. Goldshleger, U. Basson, and M. Reshef. "MAPPING SPATIAL MOISTURE CONTENT OF UNSATURATED AGRICULTURAL SOILS WITH GROUND-PENETRATING RADAR." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B8 (June 24, 2016): 1279–85. http://dx.doi.org/10.5194/isprsarchives-xli-b8-1279-2016.
Повний текст джерелаАнотація:
Soil subsurface moisture content, especially in the root zone, is important for evaluation the influence of soil moisture to agricultural crops. Conservative monitoring by point-measurement methods is time-consuming and expensive. In this paper we represent an active remote-sensing tool for subsurface spatial imaging and analysis of electromagnetic physical properties, mostly water content, by ground-penetrating radar (GPR) reflection. Combined with laboratory methods, this technique enables real-time and highly accurate evaluations of soils' physical qualities in the field. To calculate subsurface moisture content, a model based on the soil texture, porosity, saturation, organic matter and effective electrical conductivity is required. We developed an innovative method that make it possible measures spatial subsurface moisture content up to a depth of 1.5 m in agricultural soils and applied it to two different unsaturated soil types from agricultural fields in Israel: loess soil type (Calcic haploxeralf), common in rural areas of southern Israel with about 30% clay, 30% silt and 40% sand, and hamra soil type (Typic rhodoxeralf), common in rural areas of central Israel with about 10% clay, 5% silt and 85% sand. Combined field and laboratory measurements and model development gave efficient determinations of spatial moisture content in these fields. The environmentally friendly GPR system enabled non-destructive testing. The developed method for measuring moisture content in the laboratory enabled highly accurate interpretation and physical computing. Spatial soil moisture content to 1.5 m depth was determined with 1–5% accuracy, making our method useful for the design of irrigation plans for different interfaces.
9
Parvin, Nargish, and Aurore Degré. "Soil-specific calibration of capacitance sensors considering clay content and bulk density." Soil Research 54, no. 1 (2016): 111. http://dx.doi.org/10.1071/sr15036.
Повний текст джерелаАнотація:
Soil hydrology research requires the accurate measurement of soil water content. Recently, less expensive capacitance sensors (CS) have become popular for the measurement of soil moisture across soil profiles, but these sensors need to be calibrated for precise results. The purpose of the present study was to determine the effect of clay content and bulk density (ρb) on the calibration of CS. Two different CS (10HS and 5TM) were considered for the study. Clay content and ρb of the soils were determined from two different sites and from three different depths (0–5, 25–30 and 50–60 cm) of an experimental field in Gembloux, Belgium. Custom calibration (CC) equations were developed using packed soil columns following the same ρb at sequential volumetric water content (θ) levels. The factory-supplied calibration (FSC) showed an overestimation of θ (0.04–0.07 m3 m–3) with the 10HS sensor, and an underestimation of θ (0.06–0.077 m3 m–3) with the 5TM sensor for the entire calibration range. The variance in raw sensor outputs for different ρb and clay content of soil depths was not highly significant because the soil had limited range of variability in ρb and clay content. However, the CC is recommended in parallel with FSC for the precise measurement of soil moisture with CS.
10
Spratt, DM, and GR Singleton. "Experimental Embryonation and Survival of Eggs of Capillaria-Hepatica (Nematoda) Under Mouse Burrow Conditions in Cereal-Growing Soils." Australian Journal of Zoology 35, no. 4 (1987): 337. http://dx.doi.org/10.1071/zo9870337.
Повний текст джерелаАнотація:
The apparent absence of the nematode Capillaria hepatica in mice from regions of south-eastern Australia where plagues occur may be due to constraints on embryonation and survival of eggs in the mouse burrow, where C. hepatica is thought to be transmitted. Excavation of mouse burrows in the mallee wheatlands indicated that nest chambers generally were at depths of 200-400 mm. At these depths minimum and maximum weekly soil temperatures during the main period of mouse breeding ranged from 15 to 36.5�C and soil moisture contents were 14.5-32.8%. Embryonation and survival of C. hepatica eggs were assessed in the laboratory in three types of soil over these ranges of soil temperature and soil moisture content, emulating conditions of the mouse burrow. Two of the soil types, Walpeup sandy loan and Deniliquin riverine clay, are representative of the light and heavy soils, respectively, where mouse plagues occur in south-eastern Australia. The third type of soil was a potting mixture previously used experimentally and known to support a high rate of transmission of C. hepatica. Eggs were able to embryonate, and embryonated eggs to survive for 30 days, in each type of soil across the ranges of temperature and moisture content. The results further support the potential of C. hepatica to be used tactically in suppressing mouse numbers in the cereal-growing regions of south-eastern Australia.
11
Liu, Y. Y., M. F. McCabe, J. P. Evans, A. I. J. M. van Dijk, R. A. M. de Jeu, and H. Su. "Influence of cracking clays on satellite observed and model simulated soil moisture." Hydrology and Earth System Sciences Discussions 7, no. 1 (February 4, 2010): 907–27. http://dx.doi.org/10.5194/hessd-7-907-2010.
Повний текст джерелаАнотація:
Abstract. Vertisols are clay soils that are common in the monsoonal and dry warm regions of the world. A defining feature of these soils is the development of shrinking cracks during dry periods, the effects of which are not described in land surface models nor considered in the surface soil moisture estimation from passive microwave satellite observations. To investigate the influence of this process we compared the soil moisture (θ in m3 m−3) from AMSR-E observations and the Community Land Model (CLM) simulations over vertisols across mainland Australia. Both products agree reasonably well during wet seasons. However, during dry periods, AMSR-E θ falls below values for surrounding non-clays, while CLM simulations are higher. The impacts of soil property used in the AMSR-E algorithm, vegetation density and rainfall patterns were investigated, but do not explain the observed θ patterns. Analysis of the retrieval model suggests that the most likely reason for the low AMSR-E θ is the increase in soil porosity and surface roughness through cracking. CLM does not consider the behavior of cracking clay, including the further loss of moisture from soil and extremely high infiltration rates that would occur when cracks develop. Analyses show that the corresponding water fluxes can be different when cracks occur and therefore modeled evaporation, surface temperature, surface runoff and groundwater recharge should be interpreted with caution. Introducing temporally dynamic roughness and soil porosity into retrieval algorithms and adding a "cracking clay" module into models, respectively, may improve the representation of vertisol hydrology.
12
Bertrand, I., L. J. Janik, R. E. Holloway, R. D. Armstrong, and M. J. McLaughlin. "The rapid assessment of concentrations and solid phase associations of macro- and micronutrients in alkaline soils by mid-infrared diffuse reflectance spectroscopy." Soil Research 40, no. 8 (2002): 1339. http://dx.doi.org/10.1071/sr01104.
Повний текст джерелаАнотація:
Chemical analysis is a crucial but often expensive and time consuming step in the characterisation of soils. Mid-infrared diffuse reflectance (MIR-DRIFT) spectroscopy coupled with partial least square (PLS) analysis was used to determine macro- and micronutrient concentrations of a range of alkaline soils from southern Australia. Solid phase associations of macro- and micronutrients were also investigated using the mineralogical information contained in the infrared spectra of soil samples. Results showed that MIR-PLS analysis is a powerful and rapid technique for the accurate prediction of more than 15 chemical properties from each soil sample spectrum. Correlation coefficients for MIR derived concentration versus laboratory determined values were greater than R2 = 0.80 for soil moisture, calcium carbonate concentration, total concentration of Mg, K, S, Fe, Al, Mn, Zn, Cu, and oxalate- extractable Al, Fe, Mn, and Si. In calcareous soils, sulfur was associated with carbonate and conversely Mg was more related to the clay concentration of soils. Micronutrients such as Fe, Zn, Mn, and Cu were positively associated with smectite/illite in the clay fraction and negatively with kaolinite. The potential use of these results in partitioning model to assess plant available micronutrients pools is discussed.
13
Nelson, P. N., J. A. Baldock, and J. M. Oades. "Changes in dispersible clay content, organic carbon content, and electrolyte composition following incubation of sodic soil." Soil Research 36, no. 6 (1998): 883. http://dx.doi.org/10.1071/s98024.
Повний текст джерелаАнотація:
Measurement of dispersible clay is important for the diagnosis of structural stability problems in soil. However, clay dispersibility is known to change with water content and time. The purpose of the present study was to determine how incubation of sodic soil under different water content regimes influences clay dispersibility. Two topsoils (depth 0-0·1 m), one sodic [exchangeable sodium percentage (ESP) 9 · 7] and the other non-sodic (ESP 3·8), were collected from an experimental pasture at Kyabram, Victoria, and 2 soils, a sodic topsoil (depth 0-0·1 m, ESP 6·9) and the corresponding subsoil (depth 0·2-0 m, ESP 25·7), were collected from a cropped field at Two Wells, South Australia. The soils were incubated for 264 days in a split-plot design. The main treatments were soil type and incubation water content: continuously air-dry, continuously wet (-50 kPa), or with wet/dry cycles. The subtreatment was water content at analysis: air dry or wet (-50 kPa). Clay dispersion was greater when measured on wet soils than dry soils, irrespective of water contents during the prior incubation. Electrical conductivity increased, and sodium adsorption ratio (SAR), pH, and organic carbon content decreased as a function of the time for which the soils were wet. In the Kyabram soils that were wet when analysed, easily dispersible clay content increased with SAR. Decreases in moderately dispersible clay under the wetting/drying regime were not related to electrolyte composition, and were attributed to particle rearrangement and cementation. The decreases in clay dispersibility with time occurred despite net losses of carbohydrate and aliphatic materials. An implication of the work is that the decomposition of soil organic matter, even in the absence of fresh additions, may reduce clay dispersion in sodic soils by altering electrolyte concentration and composition.
14
Jayawardane, NS, and WS Meyer. "Measuring air-filled porosity changes in an irrigated swelling clay soil." Soil Research 23, no. 1 (1985): 15. http://dx.doi.org/10.1071/sr9850015.
Повний текст джерелаАнотація:
An in-situ method for measuring air filled porosity (�a) of soils using a neutron meter was developed and evaluated for a layered, swelling clay soil. Bulk density-volumetric moisture content relationships of soil layers were used to calculate the regressions of volumetric moisture content on �a. These regressions were combined with calibration equations of the neutron meter to obtain relationships between �a and neutron counts. The �a values predicted from measured neutron count ratios show good agreement with �a values calculated from the measured bulk densities and moisture contents in a transitional red-brown earth. The method provides a rapid and non-destructive measurement of �a. Soil aeration in a transitional red-brown earth under two irrigation treatments was assessed using neutron counts to monitor the changes in �a profiles. Large soil cores which were flooded had lower profile �a values than did cores which were not flooded. However, differences were small, owing apparently to the very low rates of infiltration and redistribution. The potential use of this method to continuously monitor changes in �a profiles allows frequent calculation of aeration stress indices, which may be used to predict crop responses and yield losses due to poor aeration.
15
te Brake, B., M. J. van der Ploeg, and G. H. de Rooij. "Water storage change estimation from in situ shrinkage measurements of clay soils." Hydrology and Earth System Sciences Discussions 9, no. 11 (November 21, 2012): 13117–54. http://dx.doi.org/10.5194/hessd-9-13117-2012.
Повний текст джерелаАнотація:
Abstract. Water storage in the unsaturated zone is a major determinant of the hydrological behaviour of the soil, but methods to quantify soil water storage are limited. The objective of this study is to assess the applicability of clay soil surface elevation change measurements to estimate soil water storage changes. We measured moisture contents in soil aggregates by EC-5 sensors, and in volumes comprising multiple aggregates and intra-aggregates spaces by CS616 sensors. In a prolonged drying period, aggregate-scale storage change measurements revealed normal shrinkage for layers ≥ 30 cm depth, indicating volume loss equalled water loss. Shrinkage in a soil volume including multiple aggregates and voids was slightly less than normal, due to soil moisture variations in the profile and delayed drying of deeper soil layers upon lowering of the groundwater level. This resulted in shrinkage curve slopes of 0.89, 0.90 and 0.79 for the layers 0–60, 0–100 and 0–150 cm. Under a dynamic drying and wetting regime, shrinkage curve slopes ranged from 0.29 to 0.69 (EC-5) and 0.27 to 0.51 (CS616). Alternation of shrinkage and incomplete swelling resulted in an underestimation of volume change relatively to water storage change, due to hysteresis between swelling and shrinkage. Since the slope of the shrinkage relation depends on the drying regime, measurement scale and combined effect of different soil layers, shrinkage curves from laboratory tests on clay aggregates require suitable modifications for application to soil profiles. Then, the linear portion of the curve can help soil water storage estimation from soil surface elevation changes. These elevation changes might be measurable over larger extents by remote sensing.
16
te Brake, B., M. J. van der Ploeg, and G. H. de Rooij. "Water storage change estimation from in situ shrinkage measurements of clay soils." Hydrology and Earth System Sciences 17, no. 5 (May 23, 2013): 1933–49. http://dx.doi.org/10.5194/hess-17-1933-2013.
Повний текст джерелаАнотація:
Abstract. The objective of this study is to assess the applicability of clay soil elevation change measurements to estimate soil water storage changes, using a simplified approach. We measured moisture contents in aggregates by EC-5 sensors, and in multiple aggregate and inter-aggregate spaces (bulk soil) by CS616 sensors. In a long dry period, the assumption of constant isotropic shrinkage proved invalid and a soil moisture dependant geometry factor was applied. The relative overestimation made by assuming constant isotropic shrinkage in the linear (basic) shrinkage phase was 26.4% (17.5 mm) for the actively shrinking layer between 0 and 60 cm. Aggregate-scale water storage and volume change revealed a linear relation for layers ≥ 30 cm depth. The range of basic shrinkage in the bulk soil was limited by delayed drying of deep soil layers, and maximum water loss in the structural shrinkage phase was 40% of total water loss in the 0–60 cm layer, and over 60% in deeper layers. In the dry period, fitted slopes of the ΔV–ΔW relationship ranged from 0.41 to 0.56 (EC-5) and 0.42 to 0.55 (CS616). Under a dynamic drying and wetting regime, slopes ranged from 0.21 to 0.38 (EC-5) and 0.22 to 0.36 (CS616). Alternating shrinkage and incomplete swelling resulted in limited volume change relative to water storage change. The slope of the ΔV–ΔW relationship depended on the drying regime, measurement scale and combined effect of different soil layers. Therefore, solely relying on surface level elevation changes to infer soil water storage changes will lead to large underestimations. Recent and future developments might provide a basis for application of shrinkage relations to field situations, but in situ observations will be required to do so.
17
Gupta, Surya, Tomislav Hengl, Peter Lehmann, Sara Bonetti, and Dani Or. "SoilKsatDB: global database of soil saturated hydraulic conductivity measurements for geoscience applications." Earth System Science Data 13, no. 4 (April 15, 2021): 1593–612. http://dx.doi.org/10.5194/essd-13-1593-2021.
Повний текст джерелаАнотація:
Abstract. The saturated soil hydraulic conductivity (Ksat) is a key parameter in many hydrological and climate models. Ksat values are primarily determined from basic soil properties and may vary over several orders of magnitude. Despite the availability of Ksat datasets in the literature, significant efforts are required to combine the data before they can be used for specific applications. In this work, a total of 13 258 Ksat measurements from 1908 sites were assembled from the published literature and other sources, standardized (i.e., units made identical), and quality checked in order to obtain a global database of soil saturated hydraulic conductivity (SoilKsatDB). The SoilKsatDB covers most regions across the globe, with the highest number of Ksat measurements from North America, followed by Europe, Asia, South America, Africa, and Australia. In addition to Ksat, other soil variables such as soil texture (11 584 measurements), bulk density (11 262 measurements), soil organic carbon (9787 measurements), moisture content at field capacity (7382), and wilting point (7411) are also included in the dataset. To show an application of SoilKsatDB, we derived Ksat pedotransfer functions (PTFs) for temperate regions and laboratory-based soil properties (sand and clay content, bulk density). Accurate models can be fitted using a random forest machine learning algorithm (best concordance correlation coefficient (CCC) equal to 0.74 and 0.72 for temperate area and laboratory measurements, respectively). However, when these Ksat PTFs are applied to soil samples obtained from tropical climates and field measurements, respectively, the model performance is significantly lower (CCC = 0.49 for tropical and CCC = 0.10 for field measurements). These results indicate that there are significant differences between Ksat data collected in temperate and tropical regions and Ksat measured in the laboratory or field. The SoilKsatDB dataset is available at https://doi.org/10.5281/zenodo.3752721 (Gupta et al., 2020) and the code used to extract the data from the literature and the applied random forest machine learning approach are publicly available under an open data license.
18
Bousbih, Safa, Mehrez Zribi, Charlotte Pelletier, Azza Gorrab, Zohra Lili-Chabaane, Nicolas Baghdadi, Nadhira Ben Aissa, and Bernard Mougenot. "Soil Texture Estimation Using Radar and Optical Data from Sentinel-1 and Sentinel-2." Remote Sensing 11, no. 13 (June 27, 2019): 1520. http://dx.doi.org/10.3390/rs11131520.
Повний текст джерелаАнотація:
This paper discusses the combined use of remotely sensed optical and radar data for the estimation and mapping of soil texture. The study is based on Sentinel-1 (S-1) and Sentinel-2 (S-2) data acquired between July and early December 2017, on a semi-arid area about 3000 km2 in central Tunisia. In addition to satellite acquisitions, texture measurement samples were taken in several agricultural fields, characterized by a large range of clay contents (between 13% and 60%). For the period between July and August, various optical indicators of clay content Short-Wave Infrared (SWIR) bands and soil indices) were tested over bare soils. Satellite moisture products, derived from combined S-1 and S-2 data, were also tested as an indicator of soil texture. Algorithms based on the support vector machine (SVM) and random forest (RF) methods are proposed for the classification and mapping of clay content and a three-fold cross-validation is used to evaluate both approaches. The classifications with the best performance are achieved using the soil moisture indicator derived from combined S-1 and S-2 data, with overall accuracy (OA) of 63% and 65% for the SVM and RF classifications, respectively.
19
Pan, Weinan, R. P. Boyles, J. G. White, and J. L. Heitman. "Characterizing Soil Physical Properties for Soil Moisture Monitoring with the North Carolina Environment and Climate Observing Network." Journal of Atmospheric and Oceanic Technology 29, no. 7 (July 1, 2012): 933–43. http://dx.doi.org/10.1175/jtech-d-11-00104.1.
Повний текст джерелаАнотація:
Abstract Soil moisture has important implications for meteorology, climatology, hydrology, and agriculture. This has led to growing interest in development of in situ soil moisture monitoring networks. Measurement interpretation is severely limited without soil property data. In North Carolina, soil moisture has been monitored since 1999 as a routine parameter in the statewide Environment and Climate Observing Network (ECONet), but with little soils information available for ECONet sites. The objective of this paper is to provide soils data for ECONet development. The authors studied soil physical properties at 27 ECONet sites and generated a database with 13 soil physical parameters, including sand, silt, and clay contents; bulk density; total porosity; saturated hydraulic conductivity; air-dried water content; and water retention at six pressures. Soil properties were highly variable among individual ECONet sites [coefficients of variation (CVs) ranging from 12% to 80%]. This wide range of properties suggests very different behavior among sites with respect to soil moisture. A principal component analysis indicated parameter groupings associated primarily with soil texture, bulk density, and air-dried water content accounted for 80% of the total variance in the dataset. These results suggested that a few specific soil properties could be measured to provide an understanding of differences in sites with respect to major soil properties. The authors also illustrate how the measured soil properties have been used to develop new soil moisture products and data screening for the North Carolina ECONet. The methods, analysis, and results presented here have applications to North Carolina and for other regions with heterogeneous soils where soil moisture monitoring is valuable.
20
Schapel, Amanda, David Davenport, and Petra Marschner. "Increases in organic carbon concentration and stock after clay addition to sands: validation of sampling methodology and effects of modification method." Soil Research 55, no. 2 (2017): 124. http://dx.doi.org/10.1071/sr15206.
Повний текст джерелаАнотація:
Plant growth on sands is often constrained by water repellence, low fertility and low water-holding capacity (WHC). These soils also have low organic carbon (OC) concentration, particularly in a bleached A2 horizon. Addition of subsoil clay to sands (clay modification) can overcome these constraints and increase WHC; however, little is known about the effect on OC concentration. Clay addition is predicted to increase OC storage via increased OC input from improved plant growth and increased stabilisation of OC by binding to clays. The objectives of this study were (i) to validate the number of soil samples required within a 25-m grid for accurate OC and bulk density measurement in clay-modified soils and (ii) to determine OC concentration, bulk density and OC stocks in clay-modified compared with unmodified soil. The study was carried out on two agricultural properties in South Australia, where unmodified controls (sands with 1–3% clay) were compared with three methods of modification using clay (clay spread, delved and spaded). Soil cores to 50cm depth were collected after harvest within a 25-m grid. The study showed that clay modification could increase OC stocks (0–30cm) by up to 14tha–1 in the South East and 22tha–1 in the Eyre Peninsula. However, the magnitude of the OC stock increase was influenced by the modification method and depended on concentration and depth of incorporation of the added clay and organic matter.
21
Foley, J. L., P. E. Tolmie, and D. M. Silburn. "Improved measurement of conductivity on swelling clay soils using a modified disc permeameter method." Soil Research 44, no. 7 (2006): 701. http://dx.doi.org/10.1071/sr05195.
Повний текст джерелаАнотація:
Disc permeameters are the preferred method for measuring unsaturated hydraulic conductivity (Kψ) in situ. However, in swelling clays, Kψ measured using 3-D measurement and analysis methods are often several orders of magnitude too high and are of no value for modelling internal drainage. During a series of experiments, the causes of inflated Kψ values were identified and a modified method developed to accurately measure Kψ. On a Black Vertosol, Kψ was strongly correlated with water content and measurement period, with higher flow rates occurring until the soil profile had fully wet up. Near-saturated Kψ measured under permeameters was up to 2 orders of magnitude higher than field-saturated conductivity (KFS) measured in ponded rings. This discrepancy was caused by residual capillarity and unrestricted swelling at the wetting front in unsaturated soils. In addition, lateral flow was common and surface depressions around permeameters filled with water, erroneously contributing to measured infiltration and invalidating assumptions in the 3-D analysis. To prevent this, permeameters were confined within rings to restrict flow to 1D, and measured Kψ (confined) was then compared with Kψ (unconfined) and KFS (ponded rings). Confining flow to 1D reduced Kψ by up to 2 orders of magnitude for a Black Vertosol and by a factor of 3 for a Red Ferrosol. Near-saturated Kψ from confined permeameters agreed well with KFS after similar short measurement durations (e.g. 0.5 h), but Kψ was still overestimated until steady-state flow was established. Therefore, to derive estimates of Kψ that reflect natural flow during internal drainage, we recommend (i) pre-wetting the soil and extending measurement time to attain steady-state flow, and (ii) confining permeameters within rings to restrict flow to 1 dimension. This method was used to compare lucerne ley and annual cropping treatments on 2 Black Vertosols (Bongeen and Waco). Kψ was similar between cropping treatments, suggesting that initial differences in structure and porosity were transient and related to soil moisture content. The Bongeen soil had a significantly lower Kψ (K–1 cm of 0.8 mm/h) than the Waco soil (2.0 mm/h).
22
Silburn, DM, and JL Foley. "Evaluation of some methods for measuring transient hydraulic properties of rain-induced surface seals on two clay soils." Soil Research 32, no. 3 (1994): 471. http://dx.doi.org/10.1071/sr9940471.
Повний текст джерелаАнотація:
Surface sealing of soils can markedly affect infiltration under rain. Robust infiltration models and methods for measuring hydraulic properties are needed. A review of methods of measuring seal hydraulic properties indicated that methods differ greatly in the hydraulic boundary conditions used and this may affect results and make a systematic analysis difficult. Two methods ('post-rain' suction permeameter and rainfall in situ) of measuring seal flux and conductivity under appropriate hydraulic boundary conditions were tested in a laboratory for two clay soils under simulated rain. The suction permeameter tests showed that conductivity of surface seal samples is altered by the suction applied during the measurement. This occurred in the absence of rain and appears to be more general than previously reported. Transient infiltration and conductivity measured by the two methods were in close agreement from ponding time onwards, provided suction equal to that measured under the seal was applied in the suction permeameter. The suction permeameter can provide conductivity data under a wider range of conditions than the rainfall in situ method, including prior to ponding, but requires measured subseal suction data. The two methods are seen to be complementary. The transient conductivity behaviour of the two soils was markedly different-the well aggregated, swelling clay exhibited an exponential decay, similar to commonly used models; the less aggregated, non-swelling clay did not. Desorption moisture characteristic curves (MCC) and measured subseal moisture content gave useful estimates of subseal suction after commencement of surface ponding, provided: (a) a correction from desorption to adsorption is not made, as desorption occurs in the subseal soil after time of ponding; and (b) MCC are measured using appropriate pre-treatment (rainfall wetting of sample in 10-20 mm depth in a soil bed).
23
Kodikara, J., P. Rajeev, D. Chan, and C. Gallage. "Soil moisture monitoring at the field scale using neutron probe." Canadian Geotechnical Journal 51, no. 3 (March 2014): 332–45. http://dx.doi.org/10.1139/cgj-2012-0113.
Повний текст джерелаАнотація:
Measurement of the moisture variation in soils is required for geotechnical design and research because soil properties and behavior can vary as moisture content changes. The neutron probe, which was developed more than 40 years ago, is commonly used to monitor soil moisture variation in the field. This study reports a full-scale field monitoring of soil moisture using a neutron moisture probe for a period of more than 2 years in the Melbourne (Australia) region. On the basis of soil types available in the Melbourne region, 23 sites were chosen for moisture monitoring down to a depth of 1500 mm. The field calibration method was used to develop correlations relating the volumetric moisture content and neutron counts. Observed results showed that the deepest “wetting front” during the wet season was limited to the top 800 to 1000 mm of soil whilst the top soil layer down to about 550 mm responded almost immediately to the rainfall events. At greater depths (550 to 800 mm and below 800 mm), the moisture variations were relatively low and displayed predominantly periodic fluctuations. This periodic nature was captured with Fourier analysis to develop a cyclic moisture model on the basis of an analytical solution of a one-dimensional moisture flow equation for homogeneous soils. It is argued that the model developed can be used to predict the soil moisture variations as applicable to buried structures such as pipes.
24
Mendham, D. S., A. M. O'Connell, and T. S. Grove. "Organic matter characteristics under native forest, long-term pasture, and recent conversion to Eucalyptus plantations in Western Australia: microbial biomass, soil respiration, and permanganate oxidation." Soil Research 40, no. 5 (2002): 859. http://dx.doi.org/10.1071/sr01092.
Повний текст джерелаАнотація:
The influence of land-use management on Walkley-Black soil carbon (C) concentration, 3 concentrations of permanganate oxidisable C (33, 167, and 333 mm), microbial biomass, and soil respiration in a laboratory incubation was tested in surface soil from 10 sites in south-western Australia. The sites ranged in total C concentration from 1.9 to 8.3%, and represented a broad climatic and soil-type distribution across south-western Australia. At each of the sites, 0-10 cm soil was collected from plots in pasture (20-71 years old), Eucalyptus globulus plantation (7-10 years old, established on ex-pasture), and native vegetation. Soil profiles and position in the landscape for each of the land-use types were matched as closely as possible at each site to minimise influences other than land use. Total C was highly correlated with clay content. Land use caused no significant change in the relationship between total C and soil texture, and land use had little effect on total C concentration. Permanganate-oxidisable C was highly correlated with Walkley-Black organic C (R2�>�0.90) for all 3 concentrations that were investigated. Only the most dilute concentration of permanganate-oxidisable C (33 mm) was sensitive enough to detect small changes in soil organic matter with land use (P = 0.045). Microbial biomass and respiration at 25 kPa matric potential moisture content and 35°C temperature were used as biological indicators of soil organic matter lability. Cumulative respired C was more sensitive to land use than Walkley-Black organic C, with lower respiration in native soils compared with managed soils with low C concentrations, but higher than the managed soils at sites with high C concentrations. Microbial biomass was not significantly affected by land use. Microbial biomass and cumulative respired C were strongly influenced by soil texture, with the microbial quotient (proportion of microbial biomass in total carbon) and the proportion of total C respired significantly lower in soils with higher silt and clay contents. Land use had no significant effect on these relationships. Overall, land use caused only minor differences in the biological and chemical indicators of organic matter quality across a broad range of sites in south-western Australia.
25
AL-Rawas, A. A. "State-of-the-Art-Review of Collapsible Soils." Sultan Qaboos University Journal for Science [SQUJS] 5 (December 1, 2000): 115. http://dx.doi.org/10.24200/squjs.vol5iss0pp115-135.
Повний текст джерелаАнотація:
Collapsible soils are encountered in arid and semi-arid regions. Such soils cause potential construction problems due to their collapse upon wetting. The collapse phenomenon is primarily related to the open structure of the soil. Several soil collapse classifications based on parameters such as moisture content, dry density, Atterberg limits and clay content have been proposed in the literature as indicators of the soil collapse potential. Direct measurement of the magnitude of collapse, using laboratory and/or field tests, is essential once a soil showed indications of collapse potential. Treatment methods such as soil replacement, compaction control and chemical stabilization showed significant reduction in the settlement of collapsible soils. The design of foundations on collapsible soils depends on the depth of the soil, magnitude of collapse and economics of the design. Strip foundations are commonly used when collapsing soil extends to a shallow depth while piles and drilled piers are recommended in cases where the soil extends to several meters. This paper provides a comprehensive review of collapsible soils. These include the different types of collapsible soils, mechanisms of collapse, identification and classification methods, laboratory and field testing, treatment methods and guidelines for foundation design.
26
Rossel, R. A. Viscarra, Y. S. Jeon, I. O. A. Odeh, and A. B. McBratney. "Using a legacy soil sample to develop a mid-IR spectral library." Soil Research 46, no. 1 (2008): 1. http://dx.doi.org/10.1071/sr07099.
Повний текст джерелаАнотація:
This paper describes the development of a diffuse reflectance spectral library from a legacy soil sample. When developing a soil spectral library, it is important to consider the number of samples that are needed to adequately describe the soil variability in the region in which the library is to be used; the manner in which the soil is sampled, handled, prepared, stored, and scanned; and the reference analytical procedures used. As with any type of modelling, the dictum is ‘garbage in = garbage out’ and hopefully the converse ‘quality in = quality out’. The aims of this paper are to: (i) develop a soil mid infrared (mid-IR) diffuse reflectance spectral library for cotton-growing regions of eastern Australia from a legacy soil sample, (ii) derive soil spectral calibrations for the prediction of soil properties with uncertainty, and (iii) assess the accuracy of the predictions and populate the legacy soil database with good quality information. A scheme for the construction and use of this spectral library is presented. A total of 1878 soil samples from different layers were scanned. They originated from the Upper Namoi, Namoi, and Gwydir Valley catchments of north-western New South Wales (NSW) and the McIntyre region of southern Queensland (Qld). A conditioned Latin hypercube sampling (cLHS) scheme was used to sample the spectral data space and select 213 representative samples for laboratory soil analyses. Using these data, partial least-squares regression (PLSR) was used to construct the calibration models, which were validated internally using cross validation and externally using an independent test dataset. Models for organic C (OC), cation exchange capacity (CEC), clay content, exchangeable Ca, total N (TN), total C (TC), gravimetric moisture content θg, total sand and exchangeable Mg were robust and produced accurate results (R2adj. > 0.75 for both cross and test set validations). The root mean squared error (RMSE) of mid-IR-PLSR predictions was compared to those from (blind) duplicate laboratory measurements. Mid-IR-PLSR produced lower RMSE values for soil OC, clay content, and θg. Finally, bootstrap aggregation-PLSR (bagging-PLSR) was used to predict soil properties with uncertainty for the entire library, thus repopulating the legacy soil database with good quality soil information.
27
Yamaguchi, T., T. Takei, Y. Yazawa, M. T. F. Wong, R. J. Gilkes, and R. S. Swift. "Effect of humic acid, sodium, and calcium additions on the formation of water-stable aggregates in Western Australian wheatbelt soils." Soil Research 42, no. 4 (2004): 435. http://dx.doi.org/10.1071/sr03053.
Повний текст джерелаАнотація:
The effect of humic acids extracted from coal waste and peat on the formation of water-stable aggregates in kaolinitic soils from the wheatbelt of Western Australia and a prepared kaolinite–quartz mix were assessed. This effect was compared with that produced by adding calcium to the soils. In the case of kaolinite–quartz mix, the treated samples were measured for micro-aggregation since macro-aggregates were not formed under the experimental conditions. The wheatbelt soils were already aggregated and the measurement was of the further macro-aggregation of these aggregates. In kaolinite–quartz, calcium additions alone enhanced the formation of stable micro-aggregates. This effect was amplified with additions of humic acids when up to 30% of the clay-sized particles were aggregated into larger aggregates. This humic acid effect was not observed in the sodium dominated mineral system.In contrast to the kaolinite-quartz samples, the selection of wheatbelt soils used in this study responded little to calcium additions alone. Humic acid increased the size of aggregates in the sodium-treated soils presumably due to the presence of aluminium in the system studied at pH 4.5. The aluminium ions can be expected to act as the bridging cations between the negatively charged clay-sized particles and the anionic groups present in the organic matter. The ineffectiveness of calcium in these soils allowed the positive effect of the humic acids to be expressed clearly. These findings provide another management option for improving the soil structure of salt-affected land because some of these soils are unlikely to respond to gypsum application.
28
Huth, Neil I., Michael J. Robertson, and Perry L. Poulton. "Regional differences in tree - crop competition due to soil, climate and management." Crop and Pasture Science 61, no. 9 (2010): 763. http://dx.doi.org/10.1071/cp09254.
Повний текст джерелаАнотація:
Large areas of trees are being planted in Australian agricultural lands for a range of environmental, ecological and economic reasons. In the medium to low rainfall zones, these plantings can negatively impact upon adjacent agricultural production through competition for soil moisture. The nature of the tree–crop competition zone and the means of managing it have been studied in the main southern cropping zones. However, the differences in soil, climate and agronomic systems in Australia’s northern dryland cropping zones could lead to differences in the competition processes and the management options needed to minimise them. In this study, the competition for soil moisture and resultant impacts on crop production were studied for a Eucalyptus argophloia windbreak on a farm near Warra, Queensland (26.93°S, 150.93°E). The results indicate well defined inner and outer competition zones, the extents of which agree with those found elsewhere in Australia and overseas. However, while the extent of the competition is comparable with other regions, local agronomic practices developed for variable climatic conditions and deep clay soils allow trees to extract soil water stored during fallow periods resulting in relatively higher production losses.
29
Holford, I. C. R., B. E. Schweitzer, and G. J. Crocker. "Comparative effects of subterranean clover, medic, lucerne, and chickpea in wheat rotations, on nitrogen, organic carbon, and moisture in two contrasting soils." Soil Research 36, no. 1 (1998): 57. http://dx.doi.org/10.1071/s97036.
Повний текст джерелаАнотація:
The effects of subterranean clover, medic, and lucerne, grown simultaneously from 1988 to 1990, followed by wheat from 1991 to 1993, and of chickpea and long fallow in alternate years with wheat, on soil total nitrogen (N), nitrate-N (NO-3-N), organic carbon (C), and moisture were measured over 6 years in 2 long-term experiments on a black earth (pellic vertisol) and red clay (chromic vertisol) in northern New South Wales. The accretion of soil total N in the black earth and NO-3-N in both soils was higher after lucerne than after other legumes, and NO-3 in the black earth remained high after lucerne to the full depth (120 cm) of measurement during the following 3 years of wheat growing. Clover had the next largest effect on total N and NO-3 accretion, and chickpea had the smallest effect except in the red clay where chickpea increased NO-3 more than medic in 1990. However, none of the annual legumes had much effect on NO-3 after the first year of cropping and their small residual effects, if any, were confined to the top 30 cm of soil. Levels of total N accretion after lucerne were higher than previously measured, because of the greater depth of measurement, but were similar on a per unit depth basis. High levels of NO-3 -N after long fallow, especially in the black earth, which tended to be higher than after medic or chickpea, were probably caused by accelerated mineralisation of organic N which has declined more in this rotation than in any other. There was no accumulation of organic C during the legume growing period in any rotation, and C tended to be lower after chickpea than after other legumes. Organic C was almost always lowest in the long fallow treatment. Summer-growing grasses, which occurred in all treatments to varying degrees, may have caused the organic C accumulation during the 3 years of cropping. In the first year of wheat growing, soil water was lower after lucerne than after other treatments and highest after long fallow, continuous wheat, and chickpea. It was replenished in the red clay to field capacity in all treatments by high rainfall during the fallow before the first wheat crop but not in the black earth, which failed to reach field capacity in any treatment even 2.5 years after the pasture legume phase.
30
Walker, SR, and WM Blacklow. "Adsorption and degradation of triazine herbicides in soils used for lupin production in Western-Australia - Laboratory studies and a simulation model." Soil Research 32, no. 6 (1994): 1189. http://dx.doi.org/10.1071/sr9941189.
Повний текст джерелаАнотація:
Most lupins (Lupinus angustifolius L. and L. albus L.) grown in Western Australia are sown with simazine, and some with atrazine, to give persistent control of a broad spectrum of weeds. Rates of application are adjusted for soil types yet there can be ineffective weed control and crop damage. The kinetics of degradation in four soils was studied in the laboratory to determine how it varied between soils and was modified by soil temperature, pH, moisture and gamma irradiation. The time for half the herbicide to be lost from the soils (HL) varied from 42 to 110 days at 20�C and -0.08 MPa water potential. Loss was rapid in the first day of incubation and subsequent losses were described precisely by first-order functions. However, the first-order half-lives (t1/2) were 3-21 days greater than the corresponding HLs, because the first-day losses were unaccounted for by the first-order functions. Gamma irradiation had no influence on degradation kinetics which supported chemical hydrolysis as the mechanism of degradation. The t1/2 values were correlated positively with the proportion of applied herbicide that was adsorbed by the soils (PAd). Atrazine was more persistent than simazine and had higher PAd values. The PAd values increased with soil pH, organic matter and clay content. The t1/2 values decreased exponentially with temperatures from 28 to 9-degrees-C, and decreased with soil water potentials from -0.08 to -1.50 MPa for a loamy sand at a near-neutral pH. A computer simulation model gave good agreement with observed residue decays and showed that the initially rapid losses from the soils could be explained by high rates of hydrolysis when all the applied herbicide was in the soil solution and, consequently, herbicide concentrations were high (87-100 mM). Rapid losses of the triazines in the field are likely in warm, acidic soils-particularly if the herbicide concentrations in the soil solution are high for reasons of limited vertical distribution of the applied herbicides through the soil profile.
31
Walker, SR, and WM Blacklow. "Corrigenda - Adsorption and degradation of triazine herbicides in soils used for lupin production in Western-Australia - Laboratory studies and a simulation model." Soil Research 32, no. 6 (1994): 1189. http://dx.doi.org/10.1071/sr9941189c.
Повний текст джерелаАнотація:
Most lupins (Lupinus angustifolius L. and L. albus L.) grown in Western Australia are sown with simazine, and some with atrazine, to give persistent control of a broad spectrum of weeds. Rates of application are adjusted for soil types yet there can be ineffective weed control and crop damage. The kinetics of degradation in four soils was studied in the laboratory to determine how it varied between soils and was modified by soil temperature, pH, moisture and gamma irradiation. The time for half the herbicide to be lost from the soils (HL) varied from 42 to 110 days at 20�C and -0.08 MPa water potential. Loss was rapid in the first day of incubation and subsequent losses were described precisely by first-order functions. However, the first-order half-lives (t1/2) were 3-21 days greater than the corresponding HLs, because the first-day losses were unaccounted for by the first-order functions. Gamma irradiation had no influence on degradation kinetics which supported chemical hydrolysis as the mechanism of degradation. The t1/2 values were correlated positively with the proportion of applied herbicide that was adsorbed by the soils (PAd). Atrazine was more persistent than simazine and had higher PAd values. The PAd values increased with soil pH, organic matter and clay content. The t1/2 values decreased exponentially with temperatures from 28 to 9-degrees-C, and decreased with soil water potentials from -0.08 to -1.50 MPa for a loamy sand at a near-neutral pH. A computer simulation model gave good agreement with observed residue decays and showed that the initially rapid losses from the soils could be explained by high rates of hydrolysis when all the applied herbicide was in the soil solution and, consequently, herbicide concentrations were high (87-100 mM). Rapid losses of the triazines in the field are likely in warm, acidic soils-particularly if the herbicide concentrations in the soil solution are high for reasons of limited vertical distribution of the applied herbicides through the soil profile.
32
Daniells, Ian G. "Hardsetting soils: a review." Soil Research 50, no. 5 (2012): 349. http://dx.doi.org/10.1071/sr11102.
Повний текст джерелаАнотація:
Hardsetting soils have been defined as soils that set to a hard, structureless mass during drying and are thereafter difficult or impossible to cultivate until the profile is rewetted. Soil strength increases rapidly as the soil dries, and so seedlings must grow quickly before soil strength becomes too high for root growth or shoot emergence. Recent work on the mechanisms of hardsetting confirms that aggregate disruption through slaking and dispersion on wetting leads to coalescence. Bridging by dispersed particles under matric potential makes a soil hardset. Failure to recover from a coalesced state as the soil dries leaves it with a massive structure. This paper reviews the worldwide occurrence of hardsetting soils, the evolution of definitions of hardsetting, and the use of those definitions in soil classification with particular emphasis on Australia. Measurement of hardsetting includes methods such as visual score of slaking and dispersion, penetration resistance, fall-cone penetration, dispersion, fractions of soil organic matter, friability index, modulus of rupture, and a particular use of the soil water retention curve. Overcoming problems associated with hardsetting soils and their ongoing management is difficult. Further work is needed on the reasons for variable responses to tillage, no tillage, and pasture. Modifying soil texture has limited application, and increasing soil organic matter under cropping is difficult in low-rainfall areas. Polymers have been shown to be beneficial. Mulching maintains higher soil moisture and therefore a softer surface, while biochar shows inconsistent effects. Controlled traffic is a key to reducing recompaction. Management of a hardsetting soil must include the whole rotation, including when to till, when to crop, and when to graze or not.
33
Jiang, Qianjing, Ming Cao, Yongwei Wang, Jun Wang, and Zhuoliang He. "Estimation of Soil Shear Strength Indicators Using Soil Physical Properties of Paddy Soils in the Plastic State." Applied Sciences 11, no. 12 (June 17, 2021): 5609. http://dx.doi.org/10.3390/app11125609.
Повний текст джерелаАнотація:
Saturated soil shear strength is a primary factor that reflects the driving resistance of agricultural machinery in paddy soils. The determination of soil shear strength indicators, such as cohesion and internal frictional angle, is crucial to improve the walking efficiency of agricultural machinery in paddy soils. However, the measurement of these indicators is often costly and time-consuming. Soil moisture content, density, and clay content are crucial factors that affect the cohesion and internal friction angle, while very limited studies have been performed to assess the interactive effects of the three factors on soil shear characteristics, especially on paddy soils. In this study, eight soil samples were taken from eight paddy fields in Southeastern China, and the central composition rotatable design was used to classify the soil samples into five levels based on different clay content (X1), moisture content (X2), and density (X3). The direct shear tests were carried out indoors on the remolded paddy soil using a self-made shear characteristic measuring device. Then, both individual and interactive effects of X1, X2, and X3 on soil cohesion and internal friction angles on paddy soils were systematically investigated and analyzed using the regression analysis method in the data processing software Design-Expert. Our results indicated that the effects of the three environmental factors on soil cohesion were in the order of X1 > X2 > X3, while the order was X2 > X3 > X1 for the impact on internal friction angle. The interactive effects were in the order of X1X2 > X1X3 > X2X3 for cohesion and X1X2 > X2X3 > X1X3 for internal friction angle. Two prediction models were successfully established to quantify the soil cohesion and internal friction angle as affected by soil physical properties, and the coefficient of determination (R2) was 0.91 and 0.89 for the two equations, respectively. The model validations using new soil samples suggested that the models were capable of predicting the shear characteristic parameters under different physical parameters effectively, with errors between predicted and measured soil shear strength indicators within 15% and relative root mean square error less than 11%.
34
Dang, Y. P., R. C. Dalal, M. J. Pringle, A. J. W. Biggs, S. Darr, B. Sauer, J. Moss, J. Payne, and D. Orange. "Electromagnetic induction sensing of soil identifies constraints to the crop yields of north-eastern Australia." Soil Research 49, no. 7 (2011): 559. http://dx.doi.org/10.1071/sr11199.
Повний текст джерелаАнотація:
Salinity, sodicity, acidity, and phytotoxic concentrations of chloride (Cl–) in soil are major constraints to crop production in many soils of north-eastern Australia. Soil constraints vary both spatially across the landscape and vertically within the soil profile. Identification of the spatial variability of these constraints will allow farmers to tune management to the potential of the land, which will, in turn, bring economic benefit. For three cropping fields in Australia’s northern grains region, we used electromagnetic induction with an EM38, which measures apparent electrical conductivity of the soil (ECa) and soil sampling to identify potential management classes. Soil Cl– and soluble Na+ concentrations, EC of the saturated extract (ECse), and soil moisture were the principal determinants of the variation of ECa, measured both at the drained upper limit of moisture (UL) and at the lower limit (LL) of moisture extracted by the crop. Grain yield showed a strong negative relation with ECa at both UL and LL, although it was stronger for the latter. We arrive at a framework to estimate the monetary value of site-specific management options, through: (i) identification of potential management classes formed from ECa at LL; (ii) measurement of soil attributes generally associated with soil constraints in the region; (iii) grain yield monitoring; and (iv) simple on-farm experiments. Simple on-farm experiments suggested that, for constrained areas, matching fertiliser application to realistic yield potential, coupled to gypsum amelioration, could potentially benefit growers by AU$14–46/ha.year (fertiliser) and $207/ha.3 years (gypsum).
35
Smiarowski, Adam, James Macnae, and Glen Bann. "Inversion of low-induction number conductivity meter data to predict seasonal saturation variation." GEOPHYSICS 76, no. 6 (November 2011): F395—F406. http://dx.doi.org/10.1190/geo2010-0378.1.
Повний текст джерелаАнотація:
Our research introduced a method to monitor saturation in the near surface. In agricultural settings, methods measuring electrical conductivity can provide useful information about soil type, moisture content, and salinity extent. Electrical conductivity meters have been used in a number of studies to determine soil properties in a qualitative sense. We examined the range of structures in which the use of low-induction number instruments can be used successfully to determine layered-earth electrical conductivity. We used an inversion routine which employs a Bayesian modification to the ridge-regression technique with a priori conductivity assumptions typical of agricultural areas. We performed joint inversion of horizontal and vertical dipole configurations at two coil separations for layer over half-space models with electrical properties of silt, loam, clay, and saline waters. Generally, the inversion code resolved layer thickness to better than 25% and electrical conductivity to better than 20% if the layer is less than 3-m thick. We then inverted field measurements acquired in salt-scalded areas in the Yass River Valley, New South Wales, Australia, to determine a layer over a half-space. With Kennedy’s formulation concerning the relationship between porosity, water saturation and electrical conductivity, we used the field results to predict autumn water saturation for the top layer to be 13% and the bottom layer to be 15%. In the spring, we used the field results to predict saturation of 50% for the top layer and 51% for the bottom layer, leading to a seasonal variation in soil saturation of approximately 36%. Predicted saturation was spatially consistent across the traverse line, suggesting that the developed methodology was successful.
36
Fang, Qian, Hanlie Hong, Lulu Zhao, Stephanie Kukolich, Ke Yin, and Chaowen Wang. "Visible and Near-Infrared Reflectance Spectroscopy for Investigating Soil Mineralogy: A Review." Journal of Spectroscopy 2018 (2018): 1–14. http://dx.doi.org/10.1155/2018/3168974.
Повний текст джерелаАнотація:
Clay minerals are the most reactive and important inorganic components in soils, but soil mineralogy classifies as a minor topic in soil sciences. Revisiting soil mineralogy has been gradually required. Clay minerals in soils are more complex and less well crystallized than those in sedimentary rocks, and thus, they display more complicated X-ray diffraction (XRD) patterns. Traditional characterization methods such as XRD are usually expensive and time-consuming, and they are therefore inappropriate for large datasets, whereas visible and near-infrared reflectance spectroscopy (VNIR) is a quick, cost-efficient, and nondestructive technique for analyzing soil mineralogic properties of large datasets. The main objectives of this review are to bring readers up to date with information and understanding of VNIR as it relates to soil mineralogy and attracts more attention from a wide variety of readers to revisit soil mineralogy. We begin our review with a description of fundamentals of VNIR. We then review common methods to process soil VNIR spectra and summary spectral features of soil minerals with particular attention to those <2 μm fractions. We further critically review applications of chemometric methods and related model building in spectroscopic soil mineral studies. We then compare spectral measurement with multivariate calibration methods, and we suggest that they both produce excellent results depending on the situation. Finally, we suggest a few avenues of future research, including the development of theoretical calibrations of VNIR more suitable for various soil samples worldwide, better elucidation of clay mineral-soil organic carbon (SOC) interactions, and building the concept of integrated soil mapping through combined information (e.g., mineral composition, soil organic matter-SOM, SOC, pH, and moisture).
37
Wong, M. T. F., and K. Wittwer. "Positive charge discovered across Western Australian wheatbelt soils challenges key soil and nitrogen management assumptions." Soil Research 47, no. 1 (2009): 127. http://dx.doi.org/10.1071/sr08098.
Повний текст джерелаАнотація:
Nitrogen management in Western Australia (WA) and in cropping areas elsewhere in Australia assumes that soil contains negligible or no positive charge and is therefore unable to retain nitrate against leaching. The amount of water needed to displace nitrate is thus assumed to be the drainable volume of water held by the soil (1 pore volume), and in sandy soils about 100 mm drainage is assumed to be required to displace nitrate by 1 m. The clay mineralogy of the highly weathered soils of the WA wheatbelt is dominated by kaolinite and iron and aluminium oxides. This mineralogy suggests likely occurrence of positive charge and anion exchange capacity (AEC), since these minerals can carry positive charge under normal acidic field situations. We measured AEC of soils sampled widely across the WA wheatbelt by independent leaching and batch equilibration methods of charge measurement. This showed widespread occurrence of positive charge and AEC in these soils. AEC ranged from 0 to 2.47 mmolc/kg and is linearly correlated with the potassium chloride or monocalcium phosphate extractable sulfate content of the soil. This correlation provides a rapid screening method to identify soils with positive charge. Application of ion-chromatographic theory showed that AEC has a large effect in delaying nitrate leaching by up to 12.5 pore volumes. The most highly charged soil (2.47 mmolc/kg) thus needed 12.5 times more water to displace nitrate than currently assumed. This potentially large delay in nitrate leaching affects the optimum amount and time of fertiliser application, rates of soil acidification attributed to nitrate leaching and the benefit of ameliorating subsoils to allow roots access to subsoil water and leached nitrate. It also calls into question the use of anions such as bromide to trace water flow and estimate recharge in these soils.
38
Henderson, C., A. Levett, and D. Lisle. "The effects of soil water content and bulk density on the compactibility and soil penetration resistance of some Western Australian sandy soils." Soil Research 26, no. 2 (1988): 391. http://dx.doi.org/10.1071/sr9880391.
Повний текст джерелаАнотація:
Quantitative models to predict the effects of soil compaction on wheat yields are being developed for the northern sandplains of Western Australia. An understanding of the relationships between soil water content (W), bulk density (p), compactibility and soil penetration resistance (P) is required. Thirteen subsoils from W.A. sandplain soils were tested for compactibility. As the amounts of very coarse sand or clay in the soil increased, the maximum density (�max.) achieved with a standard compactive effort also increased, while the critical soil water content (Wcrit,.) for maximum compactibility declined. The effects of p and W on P were investigated for five of the soils. The value of P was only slightly affected as W was reduced to less than 70% of the field capacity water content. As the soils were dried further, P increased exponentially. At all water contents, an increase in p was found to markedly increase P. Particle size distribution could be used to predict �max. and Wcrit., but could not be related to the effects of changes in p and W on P. The implications for the measurement and effects of soil compaction in the field are discussed.
39
Gorban, V. A. "To the method of studying the permittivity of soils (on an example of soils of ravine forests of the northern variant of the steppe zone of Ukraine)." Fundamental and Applied Soil Science 17, no. 3-4 (November 8, 2016): 90–97. http://dx.doi.org/10.15421/041616.
Повний текст джерелаАнотація:
The article is devoted to the establishment of the peculiarities of the method for studying the dielectric permittivity of soils, which is its important electrophysical characteristic. The dielectric permittivity of the soil, which is a complex multiphase medium, depends on the dielectric properties of the mineral composition of its solid phase, the chemical composition, structure and composition of soil particles, their shape and size, and also the dielectric features of inter-porous air and moisture. Now it is possible to greatly simplify the technique of measuring the dielectric permittivity of soils due to the wide dissemination of compact digital instruments that provide high accuracy in measuring the capacitive characteristics of various media. For the approbation of the method, samples of soils of ravine forests of the northern variant of the steppe zone of Ukraine were used, as well as individual soil fractions of 2–3, 1–2 and 0.5–1 mm. All samples were studied in an air-dry state to level out the effect of moisture on the dielectric permittivity of soils, as described in many scientific papers. For measurements, a cylindrical condenser made of organic glass was manufactured, which does not conduct an electric current. The diameter of the capacitor plates was 20 mm, the distance between them was 0.7 mm. After placing the sample in the condenser, it was sealed by pressure from above the weight of about 0.3 kg to create a better contact with the covers of the capacitor. The measurements were carried out using a digital capacitance meter CM-9601A in the range of 0.1–200 picofarads at a test frequency of 800 Hz. At the end of the measurement, the soil sample was weighed to calculate its density. All measurements were performed three times. As a result of using this technique, it was found that the permittivity of a general soil sample is generally higher than that of individual soil fractions. This is explained by the more compact placement of soil particles in the soil sample and its greater density, while in studies of individual fractions, due to their shape, there remain pores between the aggregates that are not filled with soil material, which cause a decrease in sample density. As a result, the maximum density is typical for the soil fraction 0.5–1 mm, and the minimum for the fraction 2–3 mm. This is due to the fact that the maximum permittivity, as a rule, is characteristic for the fraction 0.5–1 mm, and the minimum for the fraction 2–3 mm. This assertion was proved by the measurements carried out. It was also found that the value of dielectric permittivity is significantly affected by soil enrichment of the clay fraction, the increased content of which causes an increase in the dielectric permittivity. Thus, as a result of the research, a method for measuring the dielectric permittivity of soils was tested using a modern digital capacitive meter. An increase in the dielectric permittivity of soils with an increase in their density and an increase in the content of the clay fraction was established. Soils, in general, have an increased permittivity in comparison with soil fractions of 2–3, 1–2 and 0.5–1 mm. There was a need to develop and approbate a technique for measuring the dielectric permittivity of soils in the field using undisturbed addition samples. In the future, in complex studies of soils, it is also desirable to perform a measurement of their dielectric permeability.
40
McKissock, I., R. J. Gilkes, and W. van Bronswijk. "The relationship of soil water repellency to aliphatic C and kaolin measured using DRIFT." Soil Research 41, no. 2 (2003): 251. http://dx.doi.org/10.1071/sr01091.
Повний текст джерелаАнотація:
In general, water repellency by soil increases with the increase of total organic matter and decreases as the clay and silt contents of the soil increase. The prediction of water repellency from soil organic carbon (OC) content may be improved by examining the types of carbon associated with water repellency. This paper examines the hypothesis that measurement of aliphatic C can provide a better prediction of water repellency than measurement of total OC and also looks at the effects of soil texture on water repellency and the amount of aliphatic C in the soil. DRIFT (diffuse reflectance infrared fourier transform) spectra were measured on sandy soils from the West Midland Sandplains north of Perth in Western Australia. The areas of the aliphatic CH stretching signal (3000–2800/cm) and the OH stretching signal due to kaolin (3750–3570/cm) were used as relative measures of aliphatic carbon and kaolin contents. The relationships of aliphatic C and kaolin to water repellency have been examined and compared with the relationships of water repellency to total OC and clay contents of soil.Hydrophobic organic C as measured by DRIFT gave a better prediction of soil water repellency (r2 = 0.45) than did the total OC (r2 = 0.36). The specific hydrophobicity of organic matter (aliphatic C/OC ratio) increased as sand content increased. However, the direct influence of soil texture on water repellency was of more significance than its indirect influence on the amounts and forms of soil organic matter. A multivariate model including aliphatic C and clay + silt content was the best model for describing water repellency (r2 = 0.58). DRIFT is an effective, rapid method for screening soils for water repellent properties.For individual sand grains there was a weak positive relationship (r2 = 0.26) between the size of the aliphatic CH peak measured from surfaces of sand grains and the water repellency of the grains. A discontinuous aliphatic surface layer was present on the surface of individual sand grains.
41
Baldi, Elena, Maurizio Quartieri, Enrico Muzzi, Massimo Noferini, and Moreno Toselli. "Use of In Situ Soil Solution Electric Conductivity to Evaluate Mineral N in Commercial Orchards: Preliminary Results." Horticulturae 6, no. 3 (July 8, 2020): 39. http://dx.doi.org/10.3390/horticulturae6030039.
Повний текст джерелаАнотація:
The aim of the present experiment was to evaluate the effectiveness of soil electrical conductivity (EC) measurement as a fast tool to assess mineral nitrogen (N) in orchards, in order to define precise N inputs that can help farmers to reduce useless fertilizer application. During one vegetative season, seven orchards of different species, supplied with mineral or organic fertilization, were monitored. Nitrate soil concentration was measured monthly by laboratory analyses, while soil EC and moisture were recorded continuously by soil probes. Nitrate and EC were positively correlated, laying the foundation for the identification of a fast and reliable index. However, while some dates showed a high Pearson correlation coefficient, no correlation was found for others. The correlation was not affected by type of fertilizer, and was higher in silty-clay-loam than in loam soils. Pooling all of the data, a significant correlation with a Pearson coefficient of 0.75 was found. The soil optimal nitrate N availability was defined by an EC in the range of 0.3 to 0.6 mS cm−1. Although these are only preliminary results, our data are promising, showing a good suitability of soil EC measurement as a means to monitor soil mineral N availability.
42
Loch, RJ, and JL Foley. "Measurement of aggregate breakdown under rain - Comparison with tests of water stability and relationships with field measurements of infiltration." Soil Research 32, no. 4 (1994): 701. http://dx.doi.org/10.1071/sr9940701.
Повний текст джерелаАнотація:
This paper reports comparisons between aggregate breakdown on wetting by rainfall with breakdown measured by a range of alternative methods. It also reports correlations between measured breakdown and steady infiltration rates of simulated rain of high and low energy, and hydraulic conductivities of surface seal layers formed under high energy rain. A wide range of soils in eastern Australia were studied. Highly significant correlations were found between measurements of aggregate breakdown to < 125 �m caused by rainfall wetting and both steady infiltration rates and hydraulic conductivities. Significant, but poorer correlations were found between steady infiltration rates and breakdown resulting from immersion wetting. Deletion of swelling soils from the data set greatly improved correlations between steady infiltration rates of high energy rain and breakdown measured by both immersion and tension wetting, showing that these methods of wetting ace particularly inappropriate for swelling soils. No correlation was found between infiltration rates and measured clay dispersion. Different relationships between the proportion of particles (%) < 125 �m at the soil surface (P125) and steady infiltration rates of low and high energy rain indicated that compaction of the soil surface layer, rather than increased aggregate breakdown, is a major cause of surface sealing by raindrop impacts. Measurements of fall cone penetration confirmed that drop impacts had compacted the surface layer. Suctions across the surface seal were related to P125 in that layer, and the relationship obtained was used in calculating hydraulic conductivities. The results confirm that measurement of aggregate breakdown under rainfall wetting produces results of much greater relevance to soil behaviour under field conditions than do tests based on immersion and tension wetting.
43
Freebairn, D. M., G. H. Wockner, N. A. Hamilton, and P. Rowland. "Impact of soil conditions on hydrology and water quality for a brown clay in the north-eastern cereal zone of Australia." Soil Research 47, no. 4 (2009): 389. http://dx.doi.org/10.1071/sr07054.
Повний текст джерелаАнотація:
Hydrology and water quality impacts of alternative land management practices are poorly quantified for semi-arid environments in the northern Australia cropping zone, yet wide-scale changes in tillage practices and land use were being recommended based on experience from other environments. The objective of this study was to explore changes in soil profile and catchment hydrology and water quality associated with different soil surface conditions created by different tillage and grazing practices. Soil water, runoff, and suspended sediment concentrations were monitored on 4 contour bay catchments over an 18-year period. Soil conditions were described by soil moisture, soil cover, and surface roughness in order to explore functional relationships between management, hydrology, and water quality. The site was chosen to represent the drier margins of cropping in southern Queensland where clay soils with high water-holding capacity, in conjunction with fallowing to store water for later crop growth, are an essential risk management tool. Accumulation of soil water in fallows was inefficient, with fallow efficiencies ranging from –7 to 40% due to high evaporation and runoff losses. Runoff amount was determined by soil water content, which was strongly influenced by antecedent rainfall, water use, and evaporation patterns. Surface cover and roughness had subtle influences on runoff, and a greater effect on suspended sediment concentration. Runoff and suspended sediment losses were considerably lower under pasture than cropping. A participative approach between farmers and scientists was demonstrated to be an efficient method to carry out an extensive and long-term catchment study at a remote location. This study provides benchmark data for future hydrologic and water quality investigations.
44
Tury, Rita, Szilárd Tóth, Réka Láposi, and László Fodor. "Investigating the change of soil resistence and moisture content in the case of pre-crops and soil tillage systems." Analecta Technica Szegedinensia 14, no. 1 (June 8, 2020): 19–23. http://dx.doi.org/10.14232/analecta.2020.1.19-23.
Повний текст джерелаАнотація:
The experiments were set up in large parcels at the Fleischmann Rudolf Research Institute of Eszterházy Károly University located in Kompolt. We carried out measurements by using a Penetronik penetrometer (electrical soil cone penetrometer) at the experimental site, where brown grassland soil as well as clay washed brown forest soil are the typical soil types. The device used primarily serves to investigate the physical and water management properties of soils suitable for agricultural cultivation. The instrument is a hand-operated tool for registering soil mechanical resistance in Newtons (0-1000 N) and also the moisture content of the topsoil (%) at the same time. The recording of the location of the measurement is made by the built-in GPS, and the results of the measurements are saved to the SD card of the device. The device’s data acquisition unit allows direct reading of measurement results, serial measurements and computer processing of results (0-70 cm). Taking our objectives into consideration, we defined the location of measuring points with various numbers according to the properties of the examined fields. Besides designating measuring points at a distance of 0, 5, 10, 15, 20 and 30 m from the edge of the fields, we designated two more in the middle of each field in all cases. The examined crop species included sand oats (Avena strigosa), baltacim (Onobrychis viciifolia) as well as common vetch (Vicia sativa L.) with oats as a companion crop. Summing up the measurement results, we have made the following statements: Low soil resistance (127-131 N) was experienced after soil loosening and oat-vetch with higher, well-preserved soil moisture content observed at each level, where the 50% moisture content of the soil started at the layer of 27 cm depth. Moderate soil resistance values (150-168 N) were manifested in the case of soil tillage with loosening and ploughing after sand oats. In this case, the 50 % soil moisture content was observed at the layer of 38 cm depth. Higher soil resistance values were found (171-196 N) in the case of 2 and 3-year-old crops of baltacim, respectively, where the 50 % soil moisture content was recorded from the layer of 58 cm depth. Based on the results, we consider it important to develop and improve soil tillage systems
45
Abancó, Clàudia, Georgina L. Bennett, Adrian J. Matthews, Mark Anthony M. Matera, and Fibor J. Tan. "The role of geomorphology, rainfall and soil moisture in the occurrence of landslides triggered by 2018 Typhoon Mangkhut in the Philippines." Natural Hazards and Earth System Sciences 21, no. 5 (May 19, 2021): 1531–50. http://dx.doi.org/10.5194/nhess-21-1531-2021.
Повний текст джерелаАнотація:
Abstract. In 2018 Typhoon Mangkhut (locally known as Typhoon Ompong) triggered thousands of landslides in the Itogon region of the Philippines. A landslide inventory of the affected region is compiled for the first time, comprising 1101 landslides over a 570 km2 area. The inventory is used to study the geomorphological characteristics and land cover more prone to landsliding as well as the hydrometeorological conditions that led to widespread failure. The results showed that landslides mostly occurred on grassland and wooded slopes of clay superficial geology, predominantly facing east-southeast. Rainfall (Integrated Multi-satellitE Retrievals for Global Precipitation Measurement, IMERG GPM) associated with Typhoon Mangkhut is compared with 33 high-intensity rainfall events that did not trigger regional landslide events in 2018. Results show that landslides occurred during high-intensity rainfall that coincided with the highest soil moisture values (estimated clays saturation point), according to Soil Moisture Active Passive level 4 (SMAP-L4) data. Our results demonstrate the potential of SMAP-L4 and GPM IMERG data for landslide hazard assessment and early warning where ground-based data are scarce. However, other rainfall events in the months leading up to Typhoon Mangkhut that had similar or higher rainfall intensities and also occurred when soils were saturated did not trigger widespread landsliding, highlighting the need for further research into the conditions that trigger landslides in typhoons.
46
Ahn, Jeonghyeon, Guiying Rao, Mustafa Mamun, and Eric P. Vejerano. "Soil–air partitioning of volatile organic compounds into soils with high water content." Environmental Chemistry 17, no. 8 (2020): 545. http://dx.doi.org/10.1071/en20032.
Повний текст джерелаАнотація:
Environmental contextAssessing environmental and human health impacts of chemical spills relies on information about how chemicals move across multiple environments. We measured volatile contaminants in the air above soil saturated with water to provide estimates of air concentrations of selected chemicals released to soil from an oil refinery in Texas during Hurricane Harvey. Estimated concentrations were below recommended exposure limits, even in a worst-case scenario. AbstractThe emission of volatile organic compounds (VOCs) from soil into air is affected by soil moisture dynamics, soil temperature, solar irradiance and carbon availability. The high amount of water in soil can modify its properties, which changes how VOCs interact. We conducted a comprehensive measurement of the soil–air partition coefficient (KSA) of VOCs into water-saturated soil with both low and high water contents for polar, weakly polar and nonpolar VOCs into a mineral soil (S-clay) and soil containing a high amount of organic matter (S-om) under a water-saturated condition. Partitioning of non-polar substituted aromatics (1,2-dichlorobenzene and toluene) was sensitive to the organic matter content in water-saturated soil. 1,2-Dichlorobenzene and toluene had higher affinities to S-om than to S-clay at all investigated water contents because of their strong interaction with the organic matter in soil. KSA decreased with elevated water content only for non-polar substituted aromatic VOCs. Less hydrophobic VOCs (benzene and trichloroethylene) exhibited similar partitioning into both soils by sorbing onto the air-water interface and dissolving in soil water, while the organic matter did not affect partitioning. The weakly polar and polar VOCs (methyl tert-butyl ether and 1-butanol) showed similar partitioning into both soils by dissolving in soil water while sorption to the organic matter was significant only at high soil water contents. KSA of VOCs on soil with high organic matter content correlated strongly with psat and Koa, but not on mineral soil. Estimates of the air concentrations for a subset of VOCs released from one refinery during Hurricane Harvey in 2017 in Harris County, Texas were lower than the recommended exposure limits, even under a worst-case scenario.
47
McBeath, T. M., C. D. Grant, R. S. Murray, and D. J. Chittleborough. "Effects of subsoil amendments on soil physical properties, crop response, and soil water quality in a dry year." Soil Research 48, no. 2 (2010): 140. http://dx.doi.org/10.1071/sr08254.
Повний текст джерелаАнотація:
In southern Australia the ability of field crops to extract soil moisture and nutrients from depth depends on the physical and chemical properties of the subsoil. In texture-contrast soils accumulation of water and nutrients in the E or A2 horizon, immediately above a clay B horizon of much lower hydraulic conductivity (herein called the interface), may generate lateral flows and enhanced nutrient and solute transfer to water bodies. Evidence that deep-ripping with addition of subsoil nutrients can increase crop productivity in regions having hostile, alkaline subsoils led to experiments to test whether this response was related to an increase in the use of water and nutrients in the subsoil. Our study measured the effects of deep-ripping with and without amendments on soil physical and chemical properties of the A and upper B horizons of 2 South Australian soils. Deep-ripping and deep-placement of nutrients increased grain harvest weight even in an exceptionally dry season. The greater yield was accompanied by significantly lower field-penetration resistance to 0.35–0.50 m depth, which we hypothesise enabled the crop to better access stored soil water and deep placed nutrients in the subsoil. Residual effects from deep-ripping were minimal after 4 growing seasons; therefore, ripping will need to be practiced at regular intervals to maintain treatment effects. The ripping and nutrient amendments had no significant effect on exchangeable sodium percentage, electrical conductivity, and readily extractable phosphorus and nitrate-nitrogen, despite changes in these soil properties between spring and harvest sampling.
48
McMurray, Larn S., Christopher Preston, Albert Vandenberg, Dili Mao, and Jeffrey G. Paull. "Soil and weather conditions associated with plant damage from post-emergent metribuzin in lentil (Lens culinaris) in southern Australia." Crop and Pasture Science 70, no. 11 (2019): 958. http://dx.doi.org/10.1071/cp19257.
Повний текст джерелаАнотація:
Multiple field experiments and a controlled-environment temperature study were conducted to investigate soil and weather conditions responsible for herbicide phytotoxicity in lentil (Lens culinaris Medik.) from post-emergent application of metribuzin. A linear relationship was observed between plant injury (% necrosis) and metribuzin rate in all 12 environments, but in only 11 environments for anthesis dry weight and nine environments for both plant density and grain yield. Grain-yield reduction from label metribuzin rates of 135 g a.i. ha–1 for sand and 285 g a.i. ha–1 for clay ranged from 0% to 32% and 0% to 67%, respectively, across all environments. Principal component analysis of soil and weather factors around the time of herbicide application suggested that metribuzin-induced plant damage in lentil was due to a combination of multiple soil and weather factors. However, heavy rainfall within 10 days of herbicide application, particularly on light-textured soils or where soil moisture was low, was most strongly linked to plant damage. Experiments targeting the impact of reductions in temperature post-metribuzin application showed no effect, and of light intensities pre- and post-metribuzin application showed low effects on plant-damage measures. Because rainfall in the 10 days after application is a major determinant of metribuzin damage in winter-grown lentil in southern Australia, a higher level of selective tolerance to metribuzin than that present in commercial cultivars is needed for its safe post-emergent use. Early and late measures of plant damage will be required to assess accurately plant tolerance to post-emergent metribuzin application in lentil.
49
Beecher, H. G., I. H. Hume, and B. W. Dunn. "Improved method for assessing rice soil suitability to restrict recharge." Australian Journal of Experimental Agriculture 42, no. 3 (2002): 297. http://dx.doi.org/10.1071/ea00123.
Повний текст джерелаАнотація:
Groundwater recharge below ponded rice fields is a significant contributor to rising groundwater levels and the threat of soil and water salinisation. Reduced groundwater recharge is essential for sustainable rice based, irrigated farming systems in southern Australia. Currently a soil is deemed as suitable for rice production if 1 soil profile per 4 ha contains 2 m or more of continuous medium or heavy clay textured material. However, this study showed clay content to be a poor predictor of groundwater recharge. Electromagnetic induction surveys of rice fields can show variation in soil physico–chemical properties across rice fields. This allows the delineation of distinctly different areas of a field based on EM readings and allows accurate targeting of soil sampling and measurements. This study used soil chemical and physical properties and groundwater recharge data to assess the adequacy of the current rice soil suitability classification method. A 3-stage classification scheme of rice land suitability is proposed including EM31 soil mapping and measurement of soil sodicity as key components. The proposed scheme is as follows: (i) include the soil as suitable if the EM31v measurement is equal to or greater than 150 mS/m; (ii) if EM31v <150, include the soil if the ESP of the top 60 cm of the soil is greater than 6, or the ESP of the depth interval between 60 and 150 cm is greater than 12; (iii) all other soils are excluded from ricegrowing. The proposed scheme's ability to correctly identify low permeability soil in rice fields as suitable for rice growing was confirmed by the recharge values measured in these fields.
50
Permana, Andrianto Muliawan, and Paulus Pramono Rahardjo. "The site characterization of central jakarta soft soil using CPTu and laboratory test." Indonesian Geotechnical Journal 1, no. 1 (April 30, 2022): 25–40. http://dx.doi.org/10.56144/igj.v1i1.6.
Повний текст джерелаАнотація:
Construction activities has been named as one of the contributing factors to Jakarta’s alarming rate of land subsidence, which ranges between 1 to 15 cm annually, and up to 28 cm in some locations. This problem is commonly known as settlement, and the affected soft soil is usually attributed to under-consolidating soil (UC). In regards to that matter, this study aims to characterize the soft soil layer in Central Jakarta using the Cone Penetration Test with pore pressure measurement (CPTu) and laboratory assessment. In addition, Undrained Shear Strength () and Pore Pressure Ratio (and ) methods were used to estimate the over-consolidation Ratio (OCR) values. The data collected from 94 boreholes and 30 CPTu showed the soft soil layers in Central Jakarta, which was dominated by high-plasticity silty clay (CH) and clayey silt (MH). The layers are detected between the depth of 0 – 25 m and are characterized by high natural moisture content, void ratio, liquidity index, and compression index values. Within this layer of under consolidated soils, the indication of relatively low dry unit weight was also present. Furthermore, the laboratory tests showed several correlations related to under-consolidating soil, i.e. void ratio to in-situ effective stress, void ratio to compression index, and compression index to natural moisture content. The CPTu test interpretations returned a number of under-consolidation soil layer samples in Central Jakarta. Moreover, the result also indicates the presence of under-consolidating properties, as well as normally consolidated and lightly over-consolidated.