Journal articles on the topic 'Texture contrast soil'
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1
Laffan, M. D., and T. J. Kingston. "Earthworms in some Tasmanian forest soils in relation to bioturbation and soil texture profile." Soil Research 35, no. 6 (1997): 1231. http://dx.doi.org/10.1071/s96076.
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Soil properties and earthworm population density were examined for 5 forest soils derived from Silurian-Devonian sandstones (Mathinna Beds) in north-eastern Tasmania. The soils occur along gradients of altitude, rainfall, and forest type; they include 2 with texture-contrast and 3 with gradational soil profile types. The density and biomass of the most abundant earthworm species Megascolex montisarthuri, and of all earthworm species combined, were found to be greater in gradational than in texture-contrast soils. A greater proportion of the earthworms in gradational soils than in texture-contrast soils was found to occur at soil depths exceeding 10 cm. The contrast was most pronounced between the 2 texture-contrast soils and the single gradational soil that occur under dry eucalypt forest. This paper explores the hypothesis that bioturbation of surface and subsurface layers by earthworms is an important mixing process that in gradational soils outweighs the counter tendency for soil particles to sort and thus form texture-contrast profiles.
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Hardie, Marcus A., Richard B. Doyle, William E. Cotching, and Shaun Lisson. "Subsurface Lateral Flow in Texture-Contrast (Duplex) Soils and Catchments with Shallow Bedrock." Applied and Environmental Soil Science 2012 (2012): 1–10. http://dx.doi.org/10.1155/2012/861358.
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Development-perched watertables and subsurface lateral flows in texture-contrast soils (duplex) are commonly believed to occur as a consequence of the hydraulic discontinuity between the A and B soil horizons. However, in catchments containing shallow bedrock, subsurface lateral flows result from a combination of preferential flow from the soil surface to the soil—bedrock interface, undulations in the bedrock topography, lateral flow through macropore networks at the soil—bedrock interface, and the influence of antecedent soil moisture on macropore connectivity. Review of literature indicates that some of these processes may also be involved in the development of subsurface lateral flow in texture contrast soils. However, the extent to which these mechanisms can be applied to texture contrast soils requires further field studies. Improved process understanding is required for modelling subsurface lateral flows in order to improve the management of waterlogging, drainage, salinity, and offsite agrochemicals movement.
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Minasny, Budiman, Alex B. McBratney, Damien J. Field, Grant Tranter, Neil J. McKenzie, and Daniel M. Brough. "Relationships between field texture and particle-size distribution in Australia and their implications." Soil Research 45, no. 6 (2007): 428. http://dx.doi.org/10.1071/sr07051.
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This paper aims to establish the means and ranges of clay, silt, and sand contents from field texture classes, and to investigate the differences in the field texture classes and texture determined from particle-size analysis. The results of this paper have 2 practical applications: (1) to estimate the particle size distribution and its uncertainty from field texture as input to pedotransfer functions, and (2) to examine the criteria of texture contrast soils in the Australian Soil Classification system. Estimates of clay, silt, and sand content for each field texture class are given and this allows the field texture classes to be plotted in the texture triangle. There are considerable differences between field texture classes and particle-size classes. Based on the uncertainties in determining the clay content from field texture, we establish the probability of the occurrence of a texture contrast soil according to the Australian Soil Classification system, given the texture of the B2 horizon and its overlying A horizon. I enjoy doing the soil-texture feel test with my fingers or kneading a clay soil, which is a short step from ceramics or sculpture. Hans Jenny (1984)
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Cotching, W. E., G. Oliver, M. Downie, R. Corkrey, and R. B. Doyle. "Land use and management influences on surface soil organic carbon in Tasmania." Soil Research 51, no. 8 (2013): 615. http://dx.doi.org/10.1071/sr12251.
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The effects of environmental parameters, land-use history, and management practices on soil organic carbon (SOC) concentrations, nitrogen, and bulk density were determined in agricultural soils of four soil types in Tasmania. The sites sampled were Dermosols, Vertosols, Ferrosols, and a group of texture-contrast soils (Chromosol and Sodosol) each with a 10-year management history ranging from permanent perennial pasture to continuous cropping. Rainfall, Soil Order, and land use were all strong explanatory variables for differences in SOC, soil carbon stock, total nitrogen, and bulk density. Cropping sites had 29–35% less SOC in surface soils (0–0.1 m) than pasture sites as well as greater bulk densities. Clay-rich soils contained the greatest carbon stocks to 0.3 m depth under pasture, with Ferrosols containing a mean of 158 Mg C ha–1, Vertosols 112 Mg C ha–1, and Dermosols 107 Mg C ha–1. Texture-contrast soils with sandier textured topsoils under pasture had a mean of 69 Mg C ha–1. The range of values in soil carbon stocks indicates considerable uncertainty in baseline values for use in soil carbon accounting. Farmers can influence SOC more by their choice of land use than their day-to-day soil management. Although the influence of management is not as great as other inherent site variables, farmers can still select practices for their ability to retain more SOC.
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Hardie, Marcus A., William E. Cotching, Richard B. Doyle, Greg Holz, Shaun Lisson, and Kathrin Mattern. "Effect of antecedent soil moisture on preferential flow in a texture-contrast soil." Journal of Hydrology 398, no. 3-4 (February 2011): 191–201. http://dx.doi.org/10.1016/j.jhydrol.2010.12.008.
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Hardie, Marcus, Richard Doyle, William Cotching, Greg Holz, and Shaun Lisson. "Hydropedology and Preferential Flow in the Tasmanian Texture-Contrast Soils." Vadose Zone Journal 12, no. 4 (October 18, 2013): vzj2013.03.0051. http://dx.doi.org/10.2136/vzj2013.03.0051.
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Zhao, Yue, Zhuopeng Zhang, Honglei Zhu, and Jianhua Ren. "Quantitative Response of Gray-Level Co-Occurrence Matrix Texture Features to the Salinity of Cracked Soda Saline–Alkali Soil." International Journal of Environmental Research and Public Health 19, no. 11 (May 27, 2022): 6556. http://dx.doi.org/10.3390/ijerph19116556.
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Desiccation cracking during water evaporation is a common phenomenon in soda saline–alkali soils and is mainly determined by soil salinity. Therefore, quantitative measurement of the surface cracking status of soda saline–alkali soils is highly significant in different applications. Texture features can help to determine the mechanical properties of soda saline–alkali soils, thus improving the understanding of the mechanism of desiccation cracking in saline–alkali soils. This study aims to provide a new standard describing the surface cracking conditions of soda saline–alkali soil on the basis of gray-level co-occurrence matrix (GLCM) texture analysis and to quantitatively study the responses of GLCM texture features to soil salinity. To achieve this, images of 200 field soil samples with different surface cracks were processed and calculated for GLCMs under different parameters, including directions, gray levels, and step sizes. Subsequently, correlation analysis was then conducted between texture features and electrical conductivity (EC) values. The results indicated that direction had little effect on the GLCM texture features, and that four selected texture features, contrast (CON), angular second moment (ASM), entropy (ENT), and homogeneity (HOM), were the most correlated with EC under a gray level of 2 and step size of 1 pixel. The results also showed that logarithmic models can be used to accurately describe the relationships between EC values and GLCM texture features of soda saline–alkali soils in the Songnen Plain of China, with calibration R2 ranging from 0.88 to 0.92, and RMSE from 2.12 × 10−4 to 9.68 × 10−3, respectively. This study can therefore enhance the understanding of desiccation cracking of salt-affected soil to a certain extent and can also help to improve the detection accuracy of soil salinity.
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Blackwell, PS, TW Green, and KA Olsson. "The size and horizon of origin of fragments produced by deep ripping texture contrast soils." Soil Research 25, no. 2 (1987): 211. http://dx.doi.org/10.1071/sr9870211.
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Two texture contrast soils were cultivated by deep ripping when they were drier than their lower plastic limits. The size distribution and soil horizon-of-origin of the resulting fragments were measured. One soil, a transitional red-brown earth, had either been previously uncultivated below the A horizon or had been deep ploughed and gypsum added two years previously. There was much fragmentation and mixing of soil from both of the horizons. Fine soil (<2 mm diam.) from the A horizon reached the lower depths of the trough made by the ripping and coarse soil from the B horizon (>50 mm) was brought to near the surface. The fragment size distributions were characteristically bimodal. Fragments of the fine mode (<2 mm) came mainly from the A horizon, fragments of the coarse mode (11-25 mm or larger) came mainly from the B horizon. In the laboratory, clods from the deep ripped soil were crushed at the same low water potential (air dry). The crushing energy per unit mass (specific crushing energy) was inversely proportional to the normalized geometric mean diameter of the fragments produced. Suggestions are made for modelling the effects of deep ripping.
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Cruz, D. R., L. F. S. Leandro, D. A. Mayfield, Y. Meng, and G. P. Munkvold. "Effects of Soil Conditions on Root Rot of Soybean Caused by Fusarium graminearum." Phytopathology® 110, no. 10 (October 2020): 1693–703. http://dx.doi.org/10.1094/phyto-02-20-0052-r.
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Fusarium graminearum is an important soybean pathogen that causes seedling disease, root rot, and pre- and postemergence damping-off. However, effects of soil conditions on the disease are not well understood. The objective of this greenhouse study was to determine the impacts of soil texture, pH, and soil moisture on seedling root rot symptoms and detrimental effects on seedling development caused by F. graminearum. F. graminearum-infested millet was added (10%, vol/vol) to soil with four different textures (sand, loamy sand, sandy loam, and loam). Soil moisture was maintained at saturation, field capacity or permanent wilting point at soil pH levels of 6 or 8. Seedlings were evaluated 4 weeks after planting for root rot, root length, root and shoot dry weights, leaf area, and F. graminearum colonization (by qPCR). There was a significant interaction between soil moisture and soil texture for root rot assessed visually (P < 0.0001). Highest severity (67%) and amount of F. graminearum DNA were observed at pH 6 and permanent wilting point in sandy loam soils. Pot saturation resulted in the lowest levels of disease in sandy loam and loam soils (11.6 and 10.8%, respectively). Reductions in seedling growth parameters, including root length, foliar area, shoot and root dry weights, and root tips, relative to the noninfested control, were significantly greater in sandy loam soils. In contrast, there were no significant growth reductions in sand. This study showed that levels of root rot increased under moisture-limiting conditions, producing detrimental effects on plant development.
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Chittleborough, DJ. "Formation and pedology of duplex soils." Australian Journal of Experimental Agriculture 32, no. 7 (1992): 815. http://dx.doi.org/10.1071/ea9920815.
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The term 'duplex' was first used by Northcote (1960) in his classification 'A Factual Key for the Recognition of Australian Soils' to describe soils which have an abrupt textural contrast between the surface soil horizons and the subsurface. Chemical, mineralogical and physical properties other than the textural contrast are not diagnostic. It is not surprising therefore, that duplex soils exhibit great diversity in their properties, particularly their genesis and mode of development. Many theories-chemical, physical, biological-have been proposed to explain the origin of duplex soils and the processes responsible for the development of their dominant morphological characteristic, the texture contrast. These theories, and some of the implications for an understanding of soil development, are reviewed.
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Phillips, Jonathan D. "Contingency and generalization in pedology, as exemplified by texture-contrast soils." Geoderma 102, no. 3-4 (August 2001): 347–70. http://dx.doi.org/10.1016/s0016-7061(01)00041-6.
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Kirkby, C. A., L. J. Smythe, J. W. Cox, and D. J. Chittleborough. "Phosphorus movement down a toposequence from a landscape with texture contrast soils." Soil Research 35, no. 2 (1997): 399. http://dx.doi.org/10.1071/s96045.
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Pedological processes culminating in physical and chemical differences to the soil profile down a toposequence also changed the migrating potential of phosphorus (P) within the landscape. Considerable erosion had occurred resulting in a large movement of soil from the upper to the lower slopes. This, in turn, had led to a decrease in profile depths on the upper slopes and an increase on the lower slopes. We found that in the upper parts of the toposequence there was enhanced macropore or bypassing flow resulting in a greater and deeper leaching of P compared with the lower slopes. The P that moved was almost entirely in the dissolved form and clearly originated from commercial phosphate fertiliser that had been added to the soil surface immediately prior to the start of irrigation. We could find no evidence to support the commonly held view that P often moves through soil in association with very fine clay-sized particles. When considering land management options for reducing phosphate movement in catchment areas, our results suggest that the upper parts of the landscape need to be given special consideration.
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Gupta, Surya, Sara Bonetti, Peter Lehmann, and Dani Or. "Limited role of soil texture in mediating natural vegetation response to rainfall anomalies." Environmental Research Letters 17, no. 3 (February 22, 2022): 034012. http://dx.doi.org/10.1088/1748-9326/ac5206.
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Abstract Evidence suggests that the response of rainfed crops to dry or wet years is modulated by soil texture. This is a central tenet for certain agronomic operations in water-limited regions that rely on spatial distribution of soil texture for guiding precision agriculture. In contrast, natural vegetation in climatic equilibrium evolves to form a dynamic assemblage of traits and species adapted to local climatic conditions, primarily precipitation in water-limited regions. For undisturbed landscapes, we hypothesize that natural vegetation responds to rainfall anomalies irrespectively of local soil texture whereas rainfed crops are expected to respond to texture-mediated plant available water. Earth system models (ESMs) often quantify vegetation response to drought and water stress based on traditional agronomic concepts despite fundamental differences in composition and traits of natural vegetation and crops. We seek to test the hypothesis above at local and regional scales to differentiate natural vegetation and rainfed crops response to rainfall anomalies across soil types and better link them to water and carbon cycles. We employed field observations and remote sensing data to systematically examine the response of natural and rainfed cropped vegetation across biomes and scales. At local scales (field to ∼0.1 km), we used crop yields from literature data and natural vegetation productivity as gross primary productivity (GPP) from adjacent FLUXNET sites. At regional scales (∼102 km), we rely exclusively on remote-sensing-based GPP. Results confirm a lack of response of natural vegetation productivity to soil texture across biomes and rainfall anomalies at all scales. In contrast, crop yields at field scale exhibit correlation with soil texture in dry years (in agreement with conventional agronomic practices). These results support the hypothesis that natural vegetation is decoupled from soil texture, whereas rainfed crops retain dependency on soil texture in dry years. However, the observed correlation of crops with soil texture becomes obscured at larger scales by spatial variation of topography, rainfall, and uncertainty in soil texture and GPP values. The study provides new insights into what natural vegetation’s climatic equilibrium might mean and reveals the role of scale in expressing such sensitivities in ESMs.
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Banks, Robert, Laura Wendling, Kaye Basford, Anthony Ringrose-Voase, and Vera Banks. "Beneficial soil profile differences associated with tropical grass pastures on sodic texture contrast soils in Northern New South Wales." Soil Research 58, no. 2 (2020): 207. http://dx.doi.org/10.1071/sr19140.
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Volunteer native pastures on widespread sodic texture contrast soils in northern New South Wales slopes and plains are known for their limited agricultural production. Fertilised tropical grass pastures on these soils are reported to have much increased pasture production, deeper, more abundant root mass and greater soil profile moisture storage. The subsoil physical differences between native and tropical grass pastures are not well understood. This observational study compared root abundance, soil structure and soil physical parameters (dispersion, bulk density, porosity and pore distribution) in sodic texture contrast soils under native and adjacent, well established and fertilised tropical pastures in a 14-year chronosequence. The physical differences observed may have contributed to improved soil water storage reported by other authors. Fourteen years after establishment, mean root abundance was significantly lower in soils under native pasture and greater in the tropical grass pasture system with 4600 and 8400 m of roots m–3 respectively. Dispersion values were high in native pastures but soils under tropical pastures had to be physically worked to cause dispersion. Bulk density under native pasture was significantly higher than in tropical grass pastures by 0.08 g cm–3 at 0–10 cm and by 0.2 g cm–3 in the upper B horizons. Total soil porosity of topsoils and upper B horizons was consequently lower in native than in tropical grass pasture. Tropical grass pasture upper B horizons had a three-fold greater macroporosity (pores > 30 µm), than under native pastures. This is equivalent to significantly greater potential water flow through stable macropores in dense sodic B horizons in tropical pastures. These findings indicate that pasture system selection and management positively affects deep soil structural properties which promote pasture productivity. The study contributes to a better understanding of mechanisms of published deeper water storage in tropical grass pasture systems on these normally low production soils.
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Delbari, M., P. Afrasiab, and W. Loiskandl. "Geostatistical analysis of soil texture fractions on the field scale." Soil and Water Research 6, No. 4 (November 28, 2011): 173–89. http://dx.doi.org/10.17221/9/2010-swr.
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Geostatistical estimation methods including ordinary kriging (OK), lognormal ordinary kriging (LOK), cokriging (COK), and indicator kriging (IK) are compared for the purposes of prediction and, in particular, uncertainty assessment of the soil texture fractions, i.e. sand, silt, and clay proportions, in an erosion experimental field in Lower Austria. The soil samples were taken on 136 sites, about 30-m apart. The validation technique was cross-validation, and the comparison criteria were the mean bias error (MBE) and root mean squared error (RMSE). Statistical analysis revealed that the sand content is positively skewed, thus persuading us to use LOK for the estimation. COK was also used due to a good negative correlation seen between the texture fractions. The autocorrelation analysis showed that the soil texture fractions in the study area are strongly to moderately correlated in space. Cross-validation indicated that COK is the most accurate method for estimating the silt and clay contents; RMSE equalling to 3.17% and 1.85%, respectively. For the sand content, IK with RMSE (12%) slightly smaller than COK (RMSE = 14%) was the best estimation method. However, COK maps presented the true variability of the soil texture fractions much better than the other approaches, i.e. they achieved the smallest smoothness. Regarding the local uncertainty, the estimation variance maps produced by OK, LOK, and COK methods similarly indicated that the lowest uncertainty occurred near the data locations, and that the highest uncertainty was seen in the areas of sparse sampling. The uncertainty, however, varied much less across the study area compared to conditional variance for IK. The IK conditional variance maps showed, in contrast, some relations to the data values. The estimation uncertainty needs to be evaluated for the incorporation into the risk analysis in the soil management.
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Ren, Jianhua, Xiaojie Li, Sijia Li, Honglei Zhu, and Kai Zhao. "Quantitative Analysis of Spectral Response to Soda Saline-AlkaliSoil after Cracking Process: A Laboratory Procedure to Improve Soil Property Estimation." Remote Sensing 11, no. 12 (June 13, 2019): 1406. http://dx.doi.org/10.3390/rs11121406.
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Cracking on the surface of soda saline-alkali soil is very common. In most previous studies, spectral prediction models of soil salinity were less accurate since spectral measurements were usually performed on 2 mm soil samples which cannot represent true soil surface condition very well. The objective of our research is to provide a procedure to improve soil property estimation of soda saline-alkali soil based on spectral measurement considering the texture feature of the soil surface with cracks. To achieve this objective, a cracking test was performed with 57 soil samples from Songnen Plain of China, the contrast (CON) texture feature of crack images of soil samples was then extracted from grey level co-occurrence matrix (GLCM). The original reflectance was then measured and the mixed reflectance considering the CON texture feature was also calculated from both the block soil samples (soil blocks separated by crack regions) and the comparison soil samples (soil powders with 2 mm particle size). The results of analysis between spectra and the main soil properties indicate that surface cracks can reduce the overall reflectivity of the soda saline-alkali soil and thus increasing the spectral difference among the block soil samples with different salinity levels. The results also show that both univariate and multivariate linear regression models considering the CON texture feature can greatly improve the prediction accuracy of main soil properties of soda saline-alkali soils, such as Na+, EC and salinity, which also can reduce the intensity of field spectral measurements under natural condition.
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Xu, G. Q., and Y. Li. "Rooting depth and leaf hydraulic conductance in the xeric tree Haloxyolon ammodendron growing at sites of contrasting soil texture." Functional Plant Biology 35, no. 12 (2008): 1234. http://dx.doi.org/10.1071/fp08175.
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An experiment was conducted on Haloxylon ammodendron C.A. Mey, a small xeric tree. Soil water content, soil evaporation, leaf water potential, leaf transpiration rate and stomatal conductance were measured at the two sites that contrast in soil texture: sandy and heavy textured, 8 km apart on the southern periphery of Gurbantonggut Desert, Central Asia, during the 2005 and 2006 growing seasons. Leaf specific hydraulic conductance was calculated from the measurements, and root distributions of plants grown at the two sites were quantified by whole-root system excavation. In general, plants grown in sandy soil experienced better water status than in heavy textured soil. Low soil evaporation loss is not the main reason for this better plant water status at sandy site. Plants in sandy soil developed much deeper root systems, larger root surface areas and higher root: leaf surface area ratio than in heavy textured soil, which facilitated plants acquiring more water and surviving the prolonged drought period. Plants growing at light textured sites should have an advantage in acclimatising to the changed water conditions of the future. Plants at the more sandy sites have a larger buffering capacity to excessive variation in ambient conditions.
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Redding, Todd, and Kevin Devito. "Aspect and soil textural controls on snowmelt runoff on forested Boreal Plain hillslopes." Hydrology Research 42, no. 4 (August 1, 2011): 250–67. http://dx.doi.org/10.2166/nh.2011.162.
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Plot studies were conducted on a jack pine forest with sandy soil and aspen forests with sandy and loam soils to examine the controls of slope aspect, soil texture and fall soil moisture content on near-surface snowmelt runoff and infiltration. It was hypothesized that near-surface runoff would be greater from north-facing slopes on loam soils with increased fall soil moisture content. Fall soil moisture had no measurable effect on spring snowmelt runoff. Infiltration of snowmelt dominated (drainage coefficients 53–100%, median 87%) over near-surface runoff (runoff coefficients 1–65%, median 7%) for most plots. Runoff was related to concrete frost at the mineral soil surface. In contrast to the processes hypothesized, south-facing hillslopes with sandy soils generated greater runoff than north-facing slopes or sites with finer-textured soils. These results were due to greater concrete frost development resulting from periodic spring snowmelt and re-freezing in the upper soil. South-facing hillslopes with sandy soils featured lower canopy cover, allowing greater solar radiation to reach the snow surface which led to the formation of concrete frost and faster melt rates resulting in near-surface runoff. Where hillslopes are connected to receiving surface waters by continuous concrete frost, snowmelt runoff at the watershed scale may be enhanced.
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Spohn, Marie, and Johan Stendahl. "Carbon, nitrogen, and phosphorus stoichiometry of organic matter in Swedish forest soils and its relationship with climate, tree species, and soil texture." Biogeosciences 19, no. 8 (April 22, 2022): 2171–86. http://dx.doi.org/10.5194/bg-19-2171-2022.
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Abstract. While the carbon (C) content of temperate and boreal forest soils is relatively well studied, much less is known about the ratios of C, nitrogen (N), and phosphorus (P) of the soil organic matter, as well as the abiotic and biotic factors that shape them. Therefore, the aim of this study was to explore carbon, nitrogen, and organic phosphorus (OP) contents and element ratios in temperate and boreal forest soils and their relationships with climate, dominant tree species, and soil texture. For this purpose, we studied 309 forest soils located all over Sweden between 56 and 68∘ N. The soils are a representative subsample of Swedish forest soils with a stand age >60 years that were sampled for the Swedish Forest Soil Inventory. We found that the N stock of the organic layer increased by a factor of 7.5 from −2.0 to 7.5 ∘C mean annual temperature (MAT), which is almost twice as much as the increase in the organic layer stock along the MAT gradient. The increase in the N stock went along with an increase in the N:P ratio of the organic layer by a factor of 2.1 from −2.0 to 7.5 ∘C MAT (R2=0.36, p<0.001). Forests dominated by pine had higher C:N ratios in the organic layer and mineral soil down to a depth of 65 cm than forests dominated by spruce. Further, also the C:P ratio was increased in the pine-dominated forests compared to forests dominated by other tree species in the organic layer, while the C:OP ratio in the mineral soil was not elevated in pine forests. C, N, and OP contents in the mineral soil were higher in fine-textured soils than in coarse-textured soils by a factor of 2.3, 3.5, and 4.6, respectively. Thus, the effect of texture was stronger on OP than on N and C likely because OP adsorbs very rigidly to mineral surfaces. Further, we found that the P and K concentrations of the organic layer were inversely related to the organic layer stock, while the N:P ratio was positively related to the organic layer stock. Taken together, the results show that the N:P ratio of the organic layer was most strongly related to MAT. Further, the C:N ratio was most strongly related to dominant tree species even in the mineral subsoil. In contrast, the C:P ratio was only affected by dominant tree species in the organic layer, but the C:OP ratio in the mineral soil was hardly affected by tree species due to the strong effect of soil texture on the OP concentration.
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Coonan, Elizabeth C., Alan E. Richardson, Clive A. Kirkby, Lynne M. Macdonald, Martin R. Amidy, Craig L. Strong, and John A. Kirkegaard. "Carbon stability in a texture contrast soil in response to depth and long-term phosphorus fertilisation of grazed pasture." Soil Research 58, no. 1 (2020): 21. http://dx.doi.org/10.1071/sr19065.
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It is important to understand the stability of soil organic matter (SOM) sequestered through land management changes. In this study we assessed differences in carbon (C) stability of pasture soils that had high and low C content (2.35% vs 1.73% whole soil C in the 0–10 cm layer) resulting from long-term phosphorus fertilisation. We used soil size fractionation (fine fraction, coarse fraction and winnowing) to assess the amount of stable C and indicators of microbial decomposition capacity (catabolic profiles, metabolic quotient) to assess C stability. As a main effect throughout the 60-cm profile, C concentrations were higher in the fine fraction soil in the high (excess P fertiliser; P2) than low (no P fertiliser; P0) treatments, demonstrating a larger stable C fraction. For both P2 and P0, there was a strong correlation between C measured in the fine fraction and winnowed fraction in the 0–30 cm layer (R = 0.985, P < 0.001), but no correlation was observed for the 30–60 cm layer (R = 0.121, P > 0.05). In addition, we conducted two incubation experiments to assess C stability in the treatments with depth and to assess C stability in the physical soil fractions. For the surface soils (0–10 cm), the highest respiration occurred in fractions containing plant material, including roots (coarse fraction, 0.65 g CO2-C kg–1 soil; whole soil, 1.48 g CO2-C kg–1 soil), which shows that the plant material was less stable than the fine and winnowed soil fractions (0.43 and 0.40 g CO2-C kg–1 soil respectively). Soil respiration, microbial metabolic quotient and substrate utilisation were similar in P0 and P2. Collectively, the data show that the increased C in P2 was associated with increased C concentrations in the more stable fine soil fraction, but with no change in the stability of the C within the fractions.
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Hardie, Marcus A., Richard B. Doyle, William E. Cotching, Kathrin Mattern, and Shaun Lisson. "Influence of antecedent soil moisture on hydraulic conductivity in a series of texture-contrast soils." Hydrological Processes 26, no. 20 (January 9, 2012): 3079–91. http://dx.doi.org/10.1002/hyp.8325.
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von Fromm, Sophie F., Alison M. Hoyt, Markus Lange, Gifty E. Acquah, Ermias Aynekulu, Asmeret Asefaw Berhe, Stephan M. Haefele, et al. "Continental-scale controls on soil organic carbon across sub-Saharan Africa." SOIL 7, no. 1 (June 29, 2021): 305–32. http://dx.doi.org/10.5194/soil-7-305-2021.
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Abstract. Soil organic carbon (SOC) stabilization and destabilization has been studied intensively. Yet, the factors which control SOC content across scales remain unclear. Earlier studies demonstrated that soil texture and geochemistry strongly affect SOC content. However, those findings primarily rely on data from temperate regions where soil mineralogy, weathering status and climatic conditions generally differ from tropical and subtropical regions. We investigated soil properties and climate variables influencing SOC concentrations across sub-Saharan Africa. A total of 1601 samples were analyzed, collected from two depths (0–20 and 20–50 cm) from 17 countries as part of the Africa Soil Information Service project (AfSIS). The data set spans arid to humid climates and includes soils with a wide range of pH values, weathering status, soil texture, exchangeable cations, extractable metals and land cover types. The most important SOC predictors were identified by linear mixed-effects models, regression trees and random forest models. Our results indicate that geochemical properties, mainly oxalate-extractable metals (Al and Fe) and exchangeable Ca, are equally important compared to climatic variables (mean annual temperature and aridity index). Together, they explain approximately two-thirds of SOC variation across sub-Saharan Africa. Oxalate-extractable metals were most important in wet regions with acidic and highly weathered soils, whereas exchangeable Ca was more important in alkaline and less weathered soils in drier regions. In contrast, land cover and soil texture were not significant SOC predictors on this large scale. Our findings indicate that key factors controlling SOC across sub-Saharan Africa are broadly similar to those in temperate regions, despite differences in soil development history.
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Ben-Hur, M., G. Yolcu, H. Uysal, M. Lado, and A. Paz. "Soil structure changes: aggregate size and soil texture effects on hydraulic conductivity under different saline and sodic conditions." Soil Research 47, no. 7 (2009): 688. http://dx.doi.org/10.1071/sr09009.
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Hydraulic conductivity of soil is strongly dependent on soil structure, which can be degraded during wetting and leaching. It was hypothesised that this structural degradation is dependent on initial aggregate size distribution and soil texture. The general aim of this study was to investigate the effects of aggregate sizes and soil textures, and their interactions, on the structural degradation and saturated hydraulic conductivity (Ks) of smectitic soils under different saline and sodic conditions. The studied soils were clay and loamy sand soils with low (~4.5) or high (~10) exchangeable sodium percentages (ESP), and with aggregate sizes in the ranges: (i) <1 mm (small aggregates); or (ii) 2–4 mm (large aggregates). The Ks values of the samples in a column after slow or fast pre-wetting were determined by means of a constant head device. Different wetting rates and leaching under various saline and sodic conditions had no effect on the Ks of the loamy sand; however, the Ks values of this soil with large aggregates were an order of magnitude greater than those of the soil with small aggregates. In contrast, in the clay soil with large aggregates, the Ks values after fast pre-wetting were significantly smaller than those after slow pre-wetting, probably because of aggregate slaking. No significant effects of the wetting rates on Ks were found in clay soil with small aggregates. An increase in the ESP in the clay soil decreased the Ks by a factor of 1.5 for the large aggregates and by an order of magnitude for the small aggregates, mainly as a result of increased clay swelling. Leaching the clay soil with deionised water significantly decreased the Ks values, partly because of clay dispersion. Although significant structural degradation of the clay soil occurred during leaching, the Ks values were smaller in the soils with small aggregates than in those with large aggregates, indicating the importance of the initial aggregate size on Ks even in soils that are prone to structural damage.
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Betti, Giacomo, Cameron Grant, Gordon Churchman, and Robert Murray. "Increased profile wettability in texture-contrast soils from clay delving: case studies in South Australia." Soil Research 53, no. 2 (2015): 125. http://dx.doi.org/10.1071/sr14133.
Full textAbstract:
Clay delving is becoming a popular practice to increase productivity of texture-contrast soils in southern Australia. The practice brings subsoil clay to the surface to be mixed with the sandy topsoil, and unlike clay spreading, it combines the addition of hydrophilic material with a ripping effect that disrupts the sharp boundary between the sandy topsoil and clayey subsoil. Our objective was to evaluate the magnitude of effects caused by delving on the spatial distribution of water through the profile for three Sodosols (Stagnic Solonetz soils) in the south-east of South Australia. We also wished to evaluate the extent to which clay delving might reduce water ponding at the A–B horizon interface. We wetted both delved and undelved texture-contrast soils with a Brilliant Blue dye solution under initially dry and wet conditions (to evaluate the effect of antecedent water content), and then took digital images of the stained profiles for quantitative comparison of the wetted areas. The stained soil profiles indicated that clay delving reduced preferential water flow (finger flow) and resulted in deeper and more uniform wetting of the A horizon, particularly under initially dry conditions. Under wet conditions (where water repellence was largely overcome), finger flow was significantly reduced regardless of delving but it still occurred to varying degrees depending on site characteristics. Delving significantly reduced ponding of water at the A–B horizon boundary and allowed greater penetration into the B horizon. At all sites, greater effects occurred directly on the delving lines and diminished with distance, implying that closer spacing of delving tines would increase uniformity of wetting throughout the profile. The effectiveness of delving on profile wetting was highly variable across the three sites, indicating that the outcome depends inter alia on the intrinsic soil characteristics and the delving equipment used in the field.
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Nascimento, Alexandre Ferreira do, Sheila Aparecida Correia Furquim, Eduardo Guimarães Couto, Raphael Moreira Beirigo, Jairo Calderari de Oliveira Júnior, Plínio Barbosa de Camargo, and Pablo Vidal-Torrado. "Genesis of textural contrasts in subsurface soil horizons in the Northern Pantanal-Brazil." Revista Brasileira de Ciência do Solo 37, no. 5 (October 2013): 1113–27. http://dx.doi.org/10.1590/s0100-06832013000500001.
Full textAbstract:
The Pantanal region can be characterized as a quaternary floodplain with predominant sedimentation in the form of alluvial fans. In the geomorphologic and sedimentary evolution, the avulsion process is inherent to this depositional system and its dynamics, together with surface water floods, influence soil sedimentation on this plain. The knowledge and differentiation of these two events can contribute to a better understanding of the variability of soil properties and distribution under the influence of these sedimentation processes. Therefore, this study investigated the genesis of soils in the Northern Pantanal with textural contrasts in deeper horizons and their relationship with the depositional system dynamics. We analyzed four soil profiles in the region of Barão de Melgaço, Mato Grosso State, Brazil (RPPN SESC Pantanal). Two profiles were sampled near the Rio Cuiabá (AP1 and AP4) and two near the Rio São Lourenço (AP10 and AP11). In AP11, the horizons contrast in particle size between the profile basis and the surface. In AP1, AP4 and AP10, the horizons overlaying the sand layer have similar particle size properties, mainly in terms of sand distribution. In the first case, floods (surface water) seem to have originated the horizons and layers with contrasting texture. In the second case, avulsion is the most pronounced process. Therefore, the two modes can form soils with contrasting texture that are discriminable by soil morphology, based on the distinct features associated to the specific sedimentation processes.
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Cox, J. W., D. J. Chittleborough, H. J. Brown, A. Pitman, and J. C. R. Varcoe. "Seasonal changes in hydrochemistry along a toposequence of texture-contrast soils." Soil Research 40, no. 4 (2002): 581. http://dx.doi.org/10.1071/sr01042.
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Ameliorative strategies are urgently required in some agricultural catchments in southern Australia to reduce the loss of potential contaminants to streams. However, a better understanding of where the contaminants are generated on hillslopes, their forms, and the pathways through which they are transported were required. Thus, seasonal changes in the quantities and forms of several chemical species were measured in both vertical and lateral flow pathways at 4 sites along a toposequence in the Mt Lofty Ranges, South Australia. Instrumentation was installed to measure and quantify overland flow and throughflow, and porous-wick samplers were installed at 2 depths to study the chemistry of leachate. Neutron moisture meter access tubes were installed to measure seasonal changes in soil water content with depth as this influences chemical concentrations and mobility. In years of average to below average annual rainfall, throughflow was the most important transport pathway for contaminants. However, it was expected that overland flow will be the dominant transport pathway when annual rainfall is above about 550 mm. Changes in water content of the texture-contrast soils was caused by seasonal rainfall causing periodic saturation, by waterlogging, groundwater, or both. This affected the type and form of contaminant. For example, Na and Cl concentrations were generally only large (800 and 1500 mg/L, respectively) on the lower slopes but in the wettest seasons their concentrations increased at depth on mid-slopes due to the influence of shallow saline groundwater. These chemicals then leached when groundwater levels subsided. The results suggest that ameliorative strategies to reduce agricultural contaminants should target the transport pathways specific to each chemical species, at the point (or points) in the landscape where they are generated.
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Gibson, G., BJ Radford, and RGH Nielsen. "Fallow management, soil water, plant-available soil nitrogen and grain sorghum production in south west Queensland." Australian Journal of Experimental Agriculture 32, no. 4 (1992): 473. http://dx.doi.org/10.1071/ea9920473.
Full textAbstract:
The effects of tillage frequency (conventional, reduced and zero), primary tillage implement (disc, blade and chisel plough), stubble management (retention and removal), gypsum application, and paraplowing were examined with respect to soil water storage, soil nitrate accumulation, crop establishment, crop growth, grain yield and grain nitrogen content for 4 successive sorghum crops on a sodic, texture-contrast soil in south west Queensland. Retention of sorghum stubble (v. removal) produced an increase in mean yield of sorghum grain of 393 kg/ha, due to increased soil water extraction and increased water use efficiency by the following crop. The highest mean yield occurred after reduced blade tillage with stubble retained. Zero tillage with stubble removed gave the lowest mean grain yield. Zero tillage always had the lowest quantity of soil nitrate-nitrogen at sowing. In one fallow, increased aggressiveness of primary tillage (disc v. blade plough) increased the quantity of nitrate-nitrogen in the top 60 cm of soil at sowing. These effects on available soil nitrogen did not result in corresponding differences in grain nitrogen content. Results indicate that for optimum fallow management on this texture-contrast soil in south west Queensland, sorghum residues should be retained, tillage frequency should be reduced, but not to zero, blade ploughing should be preferred to discing, and gypsum application should not be practised.
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Nikolova, Radina, Michaella Petkova, Nikolai Dinev, Anelia Kenarova, Silvena Boteva, Dimitar Berov, and Galina Radeva. "Correlation between bacterial abundance, soil properties and heavy metal contamination in the area of non-ferrous metal processing plant, Southern Bulgaria." BioRisk 17 (April 21, 2022): 19–30. http://dx.doi.org/10.3897/biorisk.17.77458.
Full textAbstract:
In the present study, the correlation between bacterial abundance and soil physicochemical properties along the heavy metal contamination gradient in the area of non-ferrous metal processing plant was assessed. Our results showed that bacterial abundance (number of heterotrophic bacteria and number of 16S rRNA gene copies) decreased with 45–56% (CFU) and 54–87% (16S rRNA gene) along the Zn, Pb and Cd contamination gradient. The total bacterial abundance (16S rRNA gene) increased exponentially in contrast to the abundance of heterotrophic bacteria. The reduction of bacterial abundance in heavily contaminated soil indicated that the soil properties (soil pH, total organic carbon, inorganic ions, soil texture) could modify the effects of heavy metals and the response of microorganisms to that stress in long-term contaminated soils.
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Hamilton, G. J., J. Sheppard, R. Bowey, and P. Fisher. "Blade loosening creates a deeper and near-stable rooting zone that raises the productivity of a structurally unstable texture contrast soil." Soil Research 55, no. 2 (2017): 101. http://dx.doi.org/10.1071/sr15364.
Full textAbstract:
Improving the workability and raising the productivity of structurally weak and/or dispersive texture contrast soils has been the objective of many research projects. These have used applications of gypsum, with and without ripping the top 300–400mm depth of soil, and responses have been moderate and short lived. The approach taken in the present study was to ameliorate the soil by a combination of subtle soil disturbance to a depth of approximately 300mm using a specially designed blade loosener, with controlled traffic and no-tillage crop establishment practices. The aim was to use the roots of the stimulated plant growth to stabilise a loosened and deepened root zone. Comparative conditions in the 0–500mm depth of soil in blade-loosened and normal seedbeds were monitored over three very different growing seasons (2001, 2002 and 2003) using chemical analyses, bulk density (BD), penetration resistance (PR) and soil moisture content measurements. Productivity was monitored by dry matter and grain yield, and profitability by gross margin analyses. Structural stability of the rooting zone soil, or the lack of it, was shown to be a consequence of how the seasonal dynamics of the profile moisture content affected the probability of waterlogged surface soil conditions. In the normal seedbed (control) the surface soil quickly reconsolidated (BD ≥1500kgm–3), and subsoil BD (BD ≈ 1800kgm–3), PR (≥1.8MPa) and percentage saturation (≥95%) remained at levels restrictive of root growth. Conversely, the same properties in the surface and subsoil of the blade-loosened seedbed remained at levels conducive to unrestricted root growth (BD ≤1400kgm–3, PR ≤1.1MPa, saturation ≤70%). The blade-loosened treatment was substantially more productive (average grain yield increase 35%; P<0.05) and profitable (average gross margin increase 56%).
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Dhawale, Nandkishor M., Viacheslav I. Adamchuk, Shiv O. Prasher, Raphael A. Viscarra Rossel, and Ashraf A. Ismail. "Evaluation of Two Portable Hyperspectral-Sensor-Based Instruments to Predict Key Soil Properties in Canadian Soils." Sensors 22, no. 7 (March 26, 2022): 2556. http://dx.doi.org/10.3390/s22072556.
Full textAbstract:
In contrast with classic bench-top hyperspectral (multispectral)-sensor-based instruments (spectrophotometers), the portable ones are rugged, relatively inexpensive, and simple to use; therefore, they are suitable for field implementation to more closely examine various soil properties on the spot. The purpose of this study was to evaluate two portable spectrophotometers to predict key soil properties such as texture and soil organic carbon (SOC) in 282 soil samples collected from proportional fields in four Canadian provinces. Of the two instruments, one was the first of its kind (prototype) and was a mid-infrared (mid-IR) spectrophotometer operating between ~5500 and ~11,000 nm. The other instrument was a readily available dual-type spectrophotometer having a spectral range in both visible (vis) and near-infrared (NIR) regions with wavelengths ranging between ~400 and ~2220 nm. A large number of soil samples (n = 282) were used to represent a wide variety of soil textures, from clay loam to sandy soils, with a considerable range of SOC. These samples were subjected to routine laboratory soil analysis before both spectrophotometers were used to collect diffuse reflectance spectroscopy (DRS) measurements. After data collection, the mid-IR and vis-NIR spectra were randomly divided into calibration (70%) and validation (30%) sets. Partial least squares regression (PLSR) was used with leave one out cross-validation techniques to derive the spectral calibrations to predict SOC, sand, and clay content. The performances of the calibration models were reevaluated on the validation set. It was found that sand content can be predicted more accurately using the portable mid-IR spectrophotometer and clay content is better predicted using the readily available dual-type vis-NIR spectrophotometer. The coefficients of determination (R2) and root mean squared error (RMSE) were determined to be most favorable for clay (0.82 and 78 g kg−1) and sand (0.82 and 103 g kg−1), respectively. The ability to predict SOC content precisely was not particularly good for the dataset of soils used in this study with an R2 and RMSE of 0.54 and 4.1 g kg−1. The tested method demonstrated that both portable mid-IR and vis-NIR spectrophotometers were comparable in predicting soil texture on a large soil dataset collected from agricultural fields in four Canadian provinces.
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Salem, Abouelnadar El, Hongchang Wang, Yuan Gao, Xiantao Zha, Mohamed Anwer Abdeen, and Guozhong Zhang. "Effect of Biomimetic Surface Geometry, Soil Texture, and Soil Moisture Content on the Drag Force of Soil-Touching Parts." Applied Sciences 11, no. 19 (September 25, 2021): 8927. http://dx.doi.org/10.3390/app11198927.
Full textAbstract:
Soil adhesion is a major problem for agricultural machinery, especially in sticky soils within the plastic range. One promising and practical way to minimize soil–tool adhesion is to modify the surface geometry to one inspired by soil-burrowing animals. In this study, 27 domed discs were fabricated according to an L27 (33) Taguchi orthogonal array and tested to determine the optimal dimensions of domed surfaces to reduce drag force. The optimized domed disc was tested in a soil bin under different soil conditions (soil texture: silty loam and sandy clay loam; soil moisture content: 23%, 30%, and 37%). All trials included a flat disc (without a dome pattern) as a control. The optimal dimensions of domed surfaces to generate the lowest possible drag force under the present experimental conditions were explored based on signal-to-noise ratio analysis. The optimal levels of control parameters were found at a surface coverage ratio of 60%, dome height of 5 mm, and dome base diameter of 20 mm. Statistics revealed that the dome height-to-diameter ratio and disc coverage ratio are crucial factors that influence the drag force of domed surfaces. In contrast, the dome base diameter had a limited influence on drag force. In all treatments, the drag force of the optimized domed disc was less than that of the flat disc (by about 9% to 25%, according to soil conditions). Accordingly, it can be concluded that adequately designed domed surfaces could significantly reduce the drag force in sticky soil compared to their flat counterparts.
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He, Y., D. Chen, B. G. Li, Y. F. Huang, K. L. Hu, Y. Li, and I. R. Willett. "Sequential indicator simulation and indicator kriging estimation of 3-dimensional soil textures." Soil Research 47, no. 6 (2009): 622. http://dx.doi.org/10.1071/sr08218.
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The complex distribution characteristics of soil textures at a large or regional scale are difficult to understand with the current state of knowledge and limited soil profile data. In this study, an indicator variogram was used to describe the spatial structural characteristics of soil textures of 139 soil profiles. The profiles were 2 m deep with sampling intervals of 0.05 m, from an area of 15 km2 in the North China Plain. The ratios of nugget-to-sill values (SH) of experimental variograms of the soil profiles in the vertical direction were equal to 0, showing strong spatial auto-correlation. In contrast, SH ratios of 0.48–0.81 in the horizontal direction, with sampling distances of ~300 m, showed weaker spatial auto-correlation. Sequential indicator simulation (SIS) and indicator kriging (IK) methods were then used to simulate and estimate the 3D spatial distribution of soil textures. The outcomes of the 2 methods were evaluated by the reproduction of the histogram and variogram, and by mean absolute error of predictions. Simulated results conducted on dense and sparse datasets showed that when denser sample data are used, complex patterns of soil textures can be captured and simulated realisations can reproduce variograms with reasonable fluctuations. When data are sparse, a general pattern of major soil textures still can be captured, with minor textures being poorly simulated or estimated. The results also showed that when data are sufficient, the reproduction of the histogram and variogram by SIS was significantly better than by the IK method for the predominant texture (clay). However, when data are sparse, there is little difference between the 2 methods.
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Mirzaeitalarposhti, Reza, Hossein Shafizadeh-Moghadam, Ruhollah Taghizadeh-Mehrjardi, and Michael Scott Demyan. "Digital Soil Texture Mapping and Spatial Transferability of Machine Learning Models Using Sentinel-1, Sentinel-2, and Terrain-Derived Covariates." Remote Sensing 14, no. 23 (November 22, 2022): 5909. http://dx.doi.org/10.3390/rs14235909.
Full textAbstract:
Soil texture is an important property that controls the mobility of the water and nutrients in soil. This study examined the capability of machine learning (ML) models in estimating soil texture fractions using different combinations of remotely sensed data from Sentinel-1 (S1), Sentinel-2 (S2), and terrain-derived covariates (TDC) across two contrasting agroecological regions in Southwest Germany, Kraichgau and the Swabian Alb. Importantly, we tested the predictive power of three different ML models: the random forest (RF), the support vector machine (SVM), and extreme gradient boosting (XGB) coupled with the remote sensing data covariates. As expected, ML model performance was not consistent regarding the input covariates, soil texture fractions, and study regions. For example, in the Swabian Alb, the SVM model performed the best for the sand content with S2 + TDC (RMSE = 3.63%, R2 = 0.42), and XGB best predicted the clay content with S1 + S2 + TDC (RMSE = 6.84%, R2 = 0.64). In Kraichgau, the best models for sand (RMSE = 7.54%, R2 = 0.79) and clay contents (RMSE = 6.14%, R2 = 0.48) were obtained using XGB and SVM, respectively. Moreover, the results indicated that TDC were critical in estimating soil texture fractions, especially in Kraichgau, which indicated that topography plays an important role in defining the spatial distribution of soil properties. In contrast, the contribution of remote sensing data better predicted the silt and clay content in the Swabian Alb. The transferability of a region-specific model to the other region was low as indicated by poor predictive performance. The resulting soil-texture-fraction maps could be a significant source of information for efficient land resource management and environmental monitoring. Nonetheless, further research to evaluate the added value of the Sentinel imagery and to better analyze the spatial transferability of machine learning models is highly recommended.
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Smutný, V., and J. Křen. "Improvement of an elutriation method for estimation of weed seedbank in the soil." Plant, Soil and Environment 48, No. 6 (December 11, 2011): 271–78. http://dx.doi.org/10.17221/4242-pse.
Full textAbstract:
A model experiment was conducted to compare hand extraction (elutriation) under running water and elutriation using the device Analysette 3, the two methods for estimation of weed seedbank in the soil. Technical parameters have been assessed for efficient operating of the device. We studied the time required for elutriation of soil samples and the time for collecting, counting and identifying the separated seeds. No significant difference in the effect of the used elutriation method on results of qualitative and quantitative estimation of weed seedbank densities has been found at any of the three locations differing in soil texture (silty loam, loam and clay loam soil). The time necessary for elutriation of soil samples was highly significantly shorter if the device was used, by 35.5 to 42.9% depending on soil texture vs. hand elutriation. The shortest time was assessed for silty loam soil. By contrast, the time needed for selecting, counting and identifying seeds was shortest for clay loam soil. This time was 46 and 92% longer for loam and silty loam soil, respectively. These differences were statistically highly significant. Comparing the seedbank in the soil, a significantly lower number of weed seeds as well as species was found on silty loam soil vs. the two locations with heavier soils. Amaranthus retroflexus was a dominating species at all locations, and on silty loam soil also Chenopodium album. Of a total number of 32 weed species detected in our experiment, 28 were annual and only four perennial (Cirsium arvense, Elytrigia repens, Rumex obtusifolius and Sonchus arvensis).
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Kargas, George, Nikolaos Ntoulas, and Panayiotis A. Nektarios. "Soil texture and salinity effects on calibration of TDR300 dielectric moisture sensor." Soil Research 51, no. 4 (2013): 330. http://dx.doi.org/10.1071/sr13009.
Full textAbstract:
Newly developed sensors have simplified real-time determination of soil water content (θm). Although the TDR300 is one of the most recent dielectric sensors, little is known with regard to the accuracy and dependency of its measurements of soil type and other environmental factors. In this study, the performance of TDR300 was investigated using liquids of known dielectric properties and a set of porous media with textures ranging from sandy to clayey. The experiments were conducted in the laboratory by mixing different amounts of water with each soil to obtain a sufficient range of soil water contents. For sand, the calculated permittivity values (εr) correlated adequately with Topp’s equation derived for time domain reflectometry. However, for the remaining inorganic porous media, εr values were overestimated compared with those resulting from Topp’s equation, especially for water contents exceeding 0.2 cm3/cm3. The results suggested that the relationship between θm and √εr was strongly linear (0.953< r2 <0.998). The most accurate results were provided by soil-specific calibration equations, which were obtained by the multi-point calibration equation. However, two-point calibration equations determined water content in all tested soils reasonably well, except for clay soil. A linear regression equation was developed that correlated the slope of the relationship θm–√εr with bulk soil electrical conductivity (EC). The regression slope was influenced more by soil EC than by soil texture. Also, TDR300 response was investigated in bi-layered systems (liquid–air and saturated porous media–air). In a bi-layered sensing volume characterised by strongly contrasting dielectric values, the appropriate bulk permittivity values for water and loam soil were determined by arithmetic rather than refractive index averaging, while for butanol and sand these values remained somewhere between the two averaging schemes, indicating that the upward infiltration calibration technique is inappropriate for the TDR300 sensor. Soil solute EC, as determined by measurements conducted in liquids and sand, significantly affected permittivity values at much lower levels than the limit of EC <2 dS/m, as suggested by the manufacturer. However, the relationship θm–√εr remained linear up to EC 2 dS/m, which corresponded to a bulk soil EC value of 0.6 dS/m. By contrast, for EC values >2 dS/m, the relationship θm–√εr was not linear, and, thus the TDR300 device calibration became increasingly difficult. Therefore, rather than operating as a time domain device, TDR300 operates as a water content reflectometer type device.
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Colquhoun, Jed B., Daniel J. Heider, and Richard A. Rittmeyer. "Potato injury risk and weed control from reduced rates of PPO-inhibiting herbicides." Weed Technology 35, no. 4 (June 8, 2021): 632–37. http://dx.doi.org/10.1017/wet.2021.38.
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AbstractThe ability to use the protoporphyrinogen oxidase (PPO)-inhibiting herbicides fomesafen, flumioxazin, and sulfentrazone in potato is limited regionally or by soil texture, largely because of crop injury noted in research in the 1990s. With that in mind, we evaluated whether reducing the herbicide rates could maintain weed control while providing more consistent crop safety. Studies were conducted on a silt loam and a coarse-textured loamy sand soil. Soil texture played a greater than anticipated role in PPO-inhibitor herbicide injury risk as it relates to high-precipitation events. For example, in 2020 at the silt loam location, there were five precipitation events across the season that exceeded 2.5 cm, including one 6 d after treatment (DAT), and a seasonal total precipitation that was over 10 cm greater than the previous year. Despite excessive moisture and initial potato injury as high as 27% where flumioxazin was applied at the high rate with S-metolachlor, by 29 DAT injury was less than 10% in all treatments, and marketable tuber yield was similar among treatments. In contrast, in 2020 at the loamy sand location, there were four precipitation events across the season that exceeded 2.5 cm, and potato injury was as much as 60%. In 2020 the high amount of injury from flumioxazin was hypothesized to be caused by precipitation before herbicide application and not after, suggesting a need for more research in this area. This work documents the fine line between yield reduction presumably caused by reduced weed control and yield reduction assumed to be related to herbicide injury. This delineation between adequate weed control and consistent crop safety may differ by soil texture and environmental conditions, supporting the notion that custom-tailored weed management may become more necessary as high-precipitation events become more common in upper midwestern U.S. agricultural systems.
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Holland, J. E., R. E. White, and R. Edis. "The relation between soil structure and solute transport under raised bed cropping and conventional cultivation in south-western Victoria." Soil Research 45, no. 8 (2007): 577. http://dx.doi.org/10.1071/sr07068.
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This study examined the relationship between soil structure and solute transport in a texture contrast soil under 2 different tillage treatments—raised beds and conventional cultivation—in south-western Victoria. Undisturbed soil samples were collected for resin-impregnation and image analysis. This enabled several descriptive parameters of macropore structure to be calculated. Large, undisturbed soil samples were also collected for a solute transport experiment using a KCl solution. A convective log-normal transfer function was used to model Cl– movement. The assessment of soil structure showed that the raised beds contained a better connected pore network than the conventionally cultivated soil. Solute transport was faster through the raised bed soil when close to saturation (at –5 mm tension). Under these conditions, the solute transport parameters showed a smaller ratio of transport volume to soil water volume in the raised bed than the conventionally cultivated soil. Together, these data strongly indicate that the raised beds had greater pore connectivity and were able to transmit solute faster and more efficiently than the conventionally cultivated soil. It is concluded that raised bed soils are better structured and provide less risk from waterlogging than conventionally cultivated soils. However, there is greater potential for preferential flow of pesticides and solutes in raised bed soils.
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Walsh, Peter G., and Geoff S. Humphreys. "Inheritance and formation of smectite in a texture contrast soil in the Pilliga State Forests, New South Wales." Soil Research 48, no. 1 (2010): 88. http://dx.doi.org/10.1071/sr09059.
Full textAbstract:
Smectite genesis is generally considered to require an alkaline environment, for in acid environments it is reportedly unstable. This study shows that smectite is forming in an acid, texture-contrast soil in the Pilliga State Forests in north-western New South Wales. Three modes of smectite genesis in the study soil are presented. The first mode involves direct inheritance from the underlying parent rock. The second and third modes involve precipitation of smectite from solution and its deposition from suspension, respectively. While the bulk of the smectite in the study soil is inherited from the transformation of labile primary minerals and rock fragments in the parent rock, restricted drainage coupled with a parent material capable of supplying the elemental constituents of smectite are also important factors in its genesis.
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Morand, David T. "The World Reference Base for Soils (WRB) and Soil Taxonomy: an appraisal of their application to the soils of the Northern Rivers of New South Wales." Soil Research 51, no. 3 (2013): 167. http://dx.doi.org/10.1071/sr12144.
Full textAbstract:
Few soil surveys in New South Wales have utilised international soil classifications. Extensive morphological and laboratory data collected during soil surveys in the Northern Rivers region provided a strong basis for correlation with the World Reference Base for Soil Resources (WRB), Soil Taxonomy (ST), and the Australian Soil Classification (ASC). Of the 32 reference soil groups comprising the WRB, 20 were present locally; nine of the 12 ST orders were present. After re-classification of soils, correlation of the ASC with the WRB and ST was undertaken. Soils not requiring extensive laboratory analysis for classification and sharing similar central concepts were the more straightforward to correlate. Several ASC orders have unique central concepts and were therefore difficult to correlate with any one WRB reference soil group or ST order/suborder. Other soils were difficult to correlate due to differences in definitions of similar diagnostic criteria. This is most applicable to soils with strong texture-contrast and those with natric conditions. Such soils are not adequately differentiated to suit the Northern Rivers conditions. Of the two international schemes, the WRB was easier to apply locally due to the relative simplicity of the scheme. Considering certain aspects of Australian soils would improve the applicability of the WRB as a truly international framework for soil classification and correlation. Amendments to both the ASC and WRB are suggested.
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Kaur, Ravinder, Sanjeev Kumar, and H. P. Gurung. "A pedo-transfer function (PTF) for estimating soil bulk density from basic soil data and its comparison with existing PTFs." Soil Research 40, no. 5 (2002): 847. http://dx.doi.org/10.1071/sr01023.
Full textAbstract:
Collection of non-destructive soil core samples for determination of bulk densities is costly, difficult, time- consuming, and often impractical. To overcome this difficulty, several attempts have been made in the past to estimate soil bulk densities through pedo-transfer functions (PTFs), requiring soil texture and organic carbon (OC) content data. Although many studies have shown that both organic carbon and texture predominantly determine soil bulk density, a majority of the PTFs developed so far are a function only of organic matter (OM)/OC. In addition, no attempts have been made to test and compare the applicability of these PTFs on an independent soil data set. Thus, through this study efforts have been made not only to develop a robust soil bulk density estimating PTF, based on both soil texture and organic carbon content data, but also to compare its predictive potential with the existing PTFs on an independent soil data set from 4 ecologically diverse micro-watersheds in Almora district of Uttaranchal State in India. Effects of varying levels of soil particle size distributions and/or OC/OM contents on the absolute relative errors associated with these PTFs were also analysed for assessing their applicability to the independent soil data set. Amongst the existing PTFs, Curtis and Post, Adams, Federer, and Huntington-A methods were found to be associated with positive bias or mean errors (ME) and root mean square prediction differences (RMSPD) ranging between 0.10 and 0.38, and between 0.23 and 0.45, respectively, whereas Alexander-A, Alexander-B, Manrique and Jones-A, Manrique and Jones-B, and Rawls methods were found to be associated with negative ME and RMSPD values ranging between -0.08 and -0.15, and 0.18 and 0.23, respectively. In contrast, Bernoux, Huntington-B, and Tomasella and Hodnett-PTFs, with RMSPD values ranging between 0.18 and 0.20, were the only methods associated with little or no bias. However, on comparing the predictive potential of the existing PTFs, in terms of their 1 : 1 relationships between the observed and predicted soil bulk densities and ME and RMSPD values, only Manrique and Jones-B (ME: -0.08; RMSPD: 0.18), Alexander-A (ME: -0.08; RMSPD: 0.19), and Rawls (ME: -0.11; RMSPD: 0.22) methods were observed to give somewhat more realistic soil bulk density estimations. The study revealed very limited predictive potential of the existing PTFs, due to their development on specific soils and/or ecosystems, use of an indirectly computed organic matter (instead of directly measured organic carbon) content as a predictor variable, poor predictive potential of developed regression model(s), and/or subjective errors. In contrast to this, the new soil bulk density estimating PTF was found to be associated with far better 1 : 1 relationship between the observed and predicted soil bulk densities and zero ME (or bias) and lowest (0.15 g/cm3) RMSPD values. The absolute relative errors associated with both the new and the existing soil OC/OM and texture-dependent PTFs were observed to be almost insensitive to the varying levels of silt and clay. However, compared with the existing PTFs, these errors associated with the new PTF were observed to be much more insensitive to the varying levels of OC/OM, thereby indicating the applicability of the new PTF to a wide range of soil types.
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Meinecke, Annabell, Andreas Hermann, and Andreas Westphal. "Using a selective fast turn-around bioassay for population density determination of Heterodera schachtii." Nematology 15, no. 7 (2013): 809–19. http://dx.doi.org/10.1163/15685411-00002720.
Full textAbstract:
In Central Europe, Heterodera schachtii is kept below threshold levels by cover-cropping with resistant crucifers and crop rotation with non-hosts. Determining population densities of H. schachtii in soil is critical when implementing resistant and tolerant sugar beet cultivars in integrated pest management (IPM) programmes. Soil extraction of the cysts followed by egg counts or extraction of the second-stage juveniles (J2) facilitated by the chemical stimulant acetox can be unsatisfactory in mixed field populations of cyst nematodes. In contrast to H. schachtii, nematodes typically present in sugar beet soils, e.g., Globodera pallida, G. rostochiensis, H. avenae, H. filipjevi, Meloidogyne hapla, M. incognita and Pratylenchus penetrans, rarely penetrated radish roots. In this bioassay, equivalents of 50 g of soil dry weight were adjusted to 10-20% moisture, seeded with Raphanus sativus cv. Saxa 3, and incubated at a day-night (16:8 h) cycle of 28/23°C for 4 days before J2 in radish roots were enumerated. In different soil types, penetration by H. schachtii reflected the inoculation levels. When inoculated with mixes of H. schachtii with H. avenae or H. filipjevi, counts of H. schachtii were similar to those in soils with H. schachtii only. When comparing three methods in three soils spiked with H. schachtii cysts, the bioassay and the extraction method were lightly impacted by the soil texture but results of the acetox method varied with texture. When implemented for field samples from Franconia, the radish bioassay and the acetox method provided results related to cyst and egg extraction data. The radish bioassay provided a quick and easy method for quantifying H. schachtii in the presence of other nematode species in a wide range of soil types. Including this assay in IPM programmes may serve as an alternative to standard methods and will improve the decision making in sustainable production systems.
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MacEwan, R. J., D. M. Crawford, P. J. Newton, and T. S. Clune. "High clay contents, dense soils, and spatial variability are the principal subsoil constraints to cropping the higher rainfall land in south-eastern Australia." Soil Research 48, no. 2 (2010): 150. http://dx.doi.org/10.1071/sr09076.
Full textAbstract:
Available soil information and unpublished data from soil survey indicate that high clay contents and high bulk density are the major subsoil constraints to crop growth in the high rainfall zone (HRZ) of south-eastern Australia. Seven high rainfall agroecological zones are proposed as sub-divisions of the region to focus future research and development. The HRZ is dominated by texture-contrast soils (69.9%) and soils with clay subsoil (89.4%) and high bulk density (mean 1.6 t/m3). Sodicity and acidity are also significant constraints to crop production in the HRZ. The physical limitations to root growth in the HRZ subsoils are best appreciated through the least-limiting water range concept and growth-limiting bulk densities. Management options and results of past research and intervention in soil loosening, drainage, raised beds, liming, and gypsum are reviewed. Climatic uncertainty raises questions about the future relevance of waterlogging as a constraint in the HRZ and confounds the development of reliable recommendations for engineering intervention.
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Abeysinghe, A. M. S. N., M. M. T. Lakshani, U. D. H. N. Amarasinghe, Yuan Li, T. K. K. Chamindu Deepagoda, Wei Fu, Jun Fan, et al. "Soil-Gas Diffusivity-Based Characterization of Variably Saturated Agricultural Topsoils." Water 14, no. 18 (September 16, 2022): 2900. http://dx.doi.org/10.3390/w14182900.
Full textAbstract:
Soil-gas diffusivity and its variation with soil moisture plays a fundamental role in diffusion-controlled migration of climate-impact gases from different terrestrial agroecosystems including cultivated soils and managed pasture systems. The wide contrast in soil texture and structure (e.g., density, soil aggregation) in agriculture topsoils (0–10 cm) makes it challenging for soil-gas diffusivity predictive models to make accurate predictions across different moisture conditions. This study characterized gas diffusivity and gas-phase tortuosity in soils sampled from managed pasture and cultivated sites in Sri Lanka at 0–10 cm depth, together with selected soil-gas diffusivity data from the literature. Soil-gas diffusivity was measured using a one-chamber diffusion apparatus using N2 and O2 as experimental gases. The measured diffusivity, together with literature data representing both intact and repacked soils, were tested against five existing widely known gas diffusivity predictive models. The tested models tended to mischaracterize the two-region behavior in some of the aggregated soils, suggesting the need of soil-specific diffusivity models to better describe gas diffusivity in agricultural soils. We suggested a new parametric two-region model, developed in line with literature-based models, to represent both unimodal and bimodal/two-region behavior of selected soils. The new model statistically outperformed the existing predictive models for both intact and repacked soils and, hence, demonstrated its applicability to better characterize site-specific greenhouse gas emissions under different soil water regimes.
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Battsetseg, Dugersuren, Choijinjav Lkhagvasuren, Ochirbat Batkhishig, and Khavtgai Zoljargal. "Soils of Buyant River Basin: Types, Properties, and Relation to Other Environmental Parameters." UNIVERSITY NEWS. NORTH-CAUCASIAN REGION. NATURAL SCIENCES SERIES, no. 1 (205) (March 31, 2020): 26–35. http://dx.doi.org/10.18522/1026-2237-2020-1-26-35.
Full textAbstract:
Buyant river basin is one of the most elevated river basins of Mongolia. Its total area is 8488.7 km2, and the basin, administratively, occupy the territories of 33 bags belonging to 5 soums of Khovd (Duut, Jargalant, Buyant, and Khovd) and Bayan-Ulgi (Deluun) aimags. For the past 300 years, bottoms of the basin used for agriculture while majority of rest land exploited by traditional nomadic livestock breeding. The soils in the basin is contrast due to its altitudinal differences. There are 35 types of soils belonging to 18 soil groups of 9 orders are distributed in the Buyant river basin. The purpose of this paper is to define quantitative analysis for soil and it properties and identify external linkages with other natural factors and socio-economic indicators. The research is employed basic soil laboratory analysis following traditional methods. For the factor analysis, the multiple linear regression analysis is used. According to the results, the soils in the Buyant river basin are generally low fertile with sandy and sandy clay texture. The soil physical properties largely dependent on climate change, aridity, and land use. Besides, abovementioned natural factors and their impacts of soil properties the soil itself define social processes going on in at the basin level.
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Samaritani, E., J. Shrestha, B. Fournier, E. Frossard, F. Gillet, C. Guenat, P. A. Niklaus, et al. "Heterogeneity of soil carbon pools and fluxes in a channelized and a restored floodplain section (Thur River, Switzerland)." Hydrology and Earth System Sciences 15, no. 6 (June 6, 2011): 1757–69. http://dx.doi.org/10.5194/hess-15-1757-2011.
Full textAbstract:
Abstract. Due to their spatial complexity and dynamic nature, floodplains provide a wide range of ecosystem functions. However, because of flow regulation, many riverine floodplains have lost their characteristic heterogeneity. Restoration of floodplain habitats and the rehabilitation of key ecosystem functions, many of them linked to organic carbon (C) dynamics in riparian soils, has therefore become a major goal of environmental policy. The fundamental understanding of the factors that drive the processes involved in C cycling in heterogeneous and dynamic systems such as floodplains is however only fragmentary. We quantified soil organic C pools (microbial C and water extractable organic C) and fluxes (soil respiration and net methane production) in functional process zones of adjacent channelized and widened sections of the Thur River, NE Switzerland, on a seasonal basis. The objective was to assess how spatial heterogeneity and temporal variability of these pools and fluxes relate to physicochemical soil properties on one hand, and to soil environmental conditions and flood disturbance on the other hand. Overall, factors related to seasonality and flooding (temperature, water content, organic matter input) affected soil C dynamics more than soil properties did. Coarse-textured soils on gravel bars in the restored section were characterized by low base-levels of organic C pools due to low TOC contents. However, frequent disturbance by flood pulses led to high heterogeneity with temporarily and locally increased C pools and soil respiration. By contrast, in stable riparian forests, the finer texture of the soils and corresponding higher TOC contents and water retention capacity led to high base-levels of C pools. Spatial heterogeneity was low, but major floods and seasonal differences in temperature had additional impacts on both pools and fluxes. Soil properties and base levels of C pools in the dam foreland of the channelized section were similar to the gravel bars of the restored section. By contrast, spatial heterogeneity, seasonal effects and flood disturbance were similar to the forests, except for indications of high CH4 production that are explained by long travel times of infiltrating water favoring reducing conditions. Overall, the restored section exhibited both a larger range and a higher heterogeneity of organic C pools and fluxes as well as a higher plant biodiversity than the channelized section. This suggests that restoration has indeed led to an increase in functional diversity.
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Samaritani, E., J. Shrestha, B. Fournier, E. Frossard, F. Gillet, C. Guenat, P. A. Niklaus, K. Tockner, E. A. D. Mitchell, and J. Luster. "Heterogeneity of soil carbon pools and fluxes in a channelized and a restored floodplain section (Thur River, Switzerland)." Hydrology and Earth System Sciences Discussions 8, no. 1 (January 24, 2011): 1059–91. http://dx.doi.org/10.5194/hessd-8-1059-2011.
Full textAbstract:
Abstract. Due to their spatial complexity and dynamic nature, floodplains provide a wide range of ecosystem functions. However, because of flow regulation, many riverine floodplains have lost their characteristic heterogeneity. Restoration of floodplain habitats and the rehabilitation of key ecosystem functions has therefore become a major goal of environmental policy. Many important ecosystem functions are linked to organic carbon (C) dynamics in riparian soils. The fundamental understanding of the factors that drive the processes involved in C cycling in heterogeneous and dynamic systems such as floodplains is however only fragmentary. We quantified soil organic C pools (microbial C and water extractable organic C) and fluxes (soil respiration and net methane production) in functional process zones of adjacent channelized and widened sections of the Thur River, NE Switzerland, on a seasonal basis. The objective was to assess how spatial heterogeneity and temporal variability of these pools and fluxes relate to physicochemical soil properties on one hand, and to soil environmental conditions and flood disturbance on the other hand. Overall, factors related to seasonality and flooding (temperature, water content, organic matter input) affected soil C dynamics more than soil properties did. Coarse-textured soils on gravel bars in the restored section were characterized by low base-levels of organic C pools due to low TOC contents. However, frequent disturbance by flood pulses led to high heterogeneity with temporarily and locally increased pools and soil respiration. By contrast, in stable riparian forests, the finer texture of the soils and corresponding higher TOC contents and water retention capacity led to high base-levels of C pools. Spatial heterogeneity was low, but major floods and seasonal differences in temperature had additional impacts on both pools and fluxes. Soil properties and base levels of C pools in the dam foreland of the channelized section were similar to the gravel bars of the restored section. By contrast, spatial heterogeneity, seasonal effects and flood disturbance were similar to the forests, except for indications of high CH4 production that are explained by long travel times of infiltrating water favouring reducing conditions. Overall, the restored section exhibited both a larger range and a higher heterogeneity of organic C pools and fluxes as well as a higher plant biodiversity than the channelized section. This suggests that restoration has indeed led to an increase in functional diversity.
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Gong, Sitong, Hu Wang, Fei Lou, Ran Qin, and Tianling Fu. "Calcareous Materials Effectively Reduce the Accumulation of Cd in Potatoes in Acidic Cadmium-Contaminated Farmland Soils in Mining Areas." International Journal of Environmental Research and Public Health 19, no. 18 (September 17, 2022): 11736. http://dx.doi.org/10.3390/ijerph191811736.
Full textAbstract:
The in situ chemical immobilization method reduces the activity of heavy metals in soil by adding chemical amendments. It is widely used in farmland soil with moderate and mild heavy metal pollution due to its high efficiency and economy. However, the effects of different materials depend heavily on environmental factors such as soil texture, properties, and pollution levels. Under the influence of lead–zinc ore smelting and soil acidification, Cd is enriched and highly activated in the soils of northwestern Guizhou, China. Potato is an important economic crop in this region, and its absorption of Cd depends on the availability of Cd in the soil and the distribution of Cd within the plant. In this study, pot experiments were used to compare the effects of lime (LM), apatite (AP), calcite (CA), sepiolite (SP), bentonite (BN), and biochar (BC) on Cd accumulation in potatoes. The results showed that the application of LM (0.4%), AP (1.4%), and CA (0.4%) had a positive effect on soil pH and cations, and that they effectively reduced the availability of Cd in the soil. In contrast, the application of SP, BN, and BC had no significant effect on the soil properties and Cd availability. LM, AP, and CA treatment strongly reduced Cd accumulation in the potato tubers by controlling the total ‘flux’ of Cd into the potato plants. In contrast, the application of SP and BN promoted the migration of Cd from the root to the shoot, while the effect of BC varied by potato genotype. Overall, calcareous materials (LM, CA, and AP) were more applicable in the remediation of Cd-contaminated soils in the study area.
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Li, Qing, Fenlan Gu, Yong Zhou, Tao Xu, Li Wang, Qian Zuo, Liang Xiao, Jingyi Liu, and Yang Tian. "Changes in the Impacts of Topographic Factors, Soil Texture, and Cropping Systems on Topsoil Chemical Properties in the Mountainous Areas of the Subtropical Monsoon Region from 2007 to 2017: A Case Study in Hefeng, China." International Journal of Environmental Research and Public Health 18, no. 2 (January 19, 2021): 832. http://dx.doi.org/10.3390/ijerph18020832.
Full textAbstract:
Understanding the spatial pattern of soil chemical properties (SCPs) together with topological factors and soil management practices is essential for land management. This study examines the spatial changes in soil chemical properties and their impact on China’s subtropical mountainous areas. In 2007 and 2017, 290 and 200 soil samples, respectively, were collected in Hefeng County, a mountainous county in central China. We used descriptive statistics and geostatistical methods, including ANOVA, semivariance, Moran’s I, and fractal dimensions, to analyze the characteristics and spatial autocorrelation changes in soil organic matter (OM), available phosphorus (AP), available potassium (AK), and pH value from 2007 to 2017. We explored the relationship between each SCP and the relationship between SCPs with topographic parameters, soil texture, and cropping systems. The results show that the mean value of soil OM, AP, AK, and pH in Hefeng increased from 2007 to 2017. The spatial variation and spatial dependency of each SCP in 2007, excluding AP and AK in 2007, were higher than in 2017. The soil in areas with high topographic relief, profile curvature, and planform curvature had less AP, AK, and pH. Soil at higher elevation had lower OM (r = −0.197, p < 0.01; r = −0.334, p < 0.01) and AP (r = −0.043, p < 0.05; r = −0.121, p < 0.05) and higher AK (r = −0.305, p < 0.01; r = 0.408, p < 0.01) in 2007 and 2017. Soil OM and AK in 2007 were significantly (p < 0.05) correlated with soil texture (p < 0.05). In contrast, oil AP and soil pH in 2007 and all SCPs in 2017 were poorly correlated with soil texture. The cropping systems played an important role in affecting all SCPs in 2007 (p < 0.01), while they only significantly affected AK in 2017 (p < 0.05). Our findings demonstrate that both topological factors, that is, the changes in cropping management and the changes in acid rain, impact soil chemical properties. The local government should place more focus on reducing soil acid amounts, soil AP content, and soil erosion by improving water conservancy facilities.
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Debruyn, LAL, and AJ Conacher. "The bioturbation activity of ants in agricultural and naturally vegetated habitats in semiarid environments." Soil Research 32, no. 3 (1994): 555. http://dx.doi.org/10.1071/sr9940555.
Full textAbstract:
The effect of ant activity on bioturbation rates was assessed in the central wheatbelt of Western Australia in naturally vegetated and farmland sites, by bimonthly measurements of soil fauna activity and periodic measurements of ant nest dimensions. The percentage soil surface affected by soil fauna (%SSASF) was on average 0.5%, with the lowest activity in cropped areas and the highest %SSASF recorded in pasture sites (>2%). Overall %SSASF was greater on yellow sand in comparison with grey sandy loam. The estimated bioturbation rates of ant communities in naturally vegetated and farmland habitats on both soils ranged from 10 to 37 g m-2 yr-1. On average, the amount of soil excavated by ants to build a nest was 20 to 25 g. Aphaenogaster sp. D49 was identified as a significant contributor to soil turnover based on the frequency of excavation, nest density and mass of soil removed to build the nest (134 g). Aphaenogaster sp. D49 brought to the soil surface 465 g m-2 yr-1 on grey sandy loam and 223 g m-2 yr-1 on yellow sand. The activity period for the majority of ant nests was around 3 months, but some species such as Rhytidoponera spp. and Meranoplus spp. had nests active for up to 2 years. While other ant species such as Iridomyrmex sp. D13 have a high turnover of nests (<3 months). There was no clear seasonal trend in the number of active nest openings, although they appeared to be greatest in May, and lowest in January. Ant nest density was higher in yellow sand than in grey sandy loam, regardless of land use. Particle size distribution of ant spoils (soil brought to the surface during nest construction) and ant-affected soil at 26 cm was compared to the control soil at comparable depths, and found to be similar. Three instances where the ant spoil had a higher proportion of clay-sized particles in comparison with the control soil, and this was attributed to ants excavating into the clay subsoil or being size-selective in the material they excavated. The control soil had a texture-contrast between 2 and 26 cm, while all the ant nests examined had similiar texture between these two depths. This supports the hypothesis that ant activity homogenizes the soil texture profile.
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Leuther, Frederic, and Steffen Schlüter. "Impact of freeze–thaw cycles on soil structure and soil hydraulic properties." SOIL 7, no. 1 (June 11, 2021): 179–91. http://dx.doi.org/10.5194/soil-7-179-2021.
Full textAbstract:
Abstract. The ploughing of soils in autumn drastically loosens the soil structure and, at the same time, reduces its stability against external stresses. A fragmentation of these artificially produced soil clods during wintertime is often observed in areas with air temperatures fluctuating around the freezing point. From the pore perspective, it is still unclear (i) under which conditions frost action has a measurable effect on soil structure, (ii) what the impact on soil hydraulic properties is, and (iii) how many freeze–thaw cycles (FTCs) are necessary to induce soil structure changes. The aim of this study was to analyse the cumulative effects of multiple FTC on soil structure and soil hydraulic properties for two different textures and two different initial structures. A silt clay with a substantial amount of swelling clay minerals and a silty loam with fewer swell/shrink dynamics were either kept intact in undisturbed soil cores taken from the topsoil from a grassland or repacked with soil clods taken from a ploughed field nearby. FTCs were simulated under controlled conditions and changes in pore structure ≥ 48 µm were regularly recorded using X-ray µCT. After 19 FTCs, the impact on hydraulic properties were measured, and the resolution of structural characteristics were enhanced towards narrow macropores with subsamples scanned at 10 µm. The impact of FTC on soil structure was dependent on the initial structure, soil texture, and the number of FTCs. Frost action induced a consolidation of repacked soil clods, resulting in a systematic reduction in pore sizes and macropore connectivity. In contrast, the macropore systems of the undisturbed soils were only slightly affected. Independent of the initial structure, a fragmentation of soil clods and macro-aggregates larger than 0.8 to 1.2 mm increased the connectivity of pores smaller than 0.5 to 0.8 mm. The fragmentation increased the unsaturated hydraulic conductivity of all treatments by a factor of 3 in by a factor of 3 in a matrix potential range of −100 to −350 hPa, while water retention was only slightly affected for the silt clay soil. Already 2 to 5 FTCs enforced a well-connected pore system of narrow macropores in all treatments, but it was steadily improved by further FTCs. The implications of fewer FTCs during milder winters caused by global warming are twofold. In ploughed soils, the beneficial seedbed consolidation will be less intense. In grassland soils, which have reached a soil structure in dynamic equilibrium that has experienced many FTCs in the making, there is still a beneficial increase in water supply through increasing unsaturated hydraulic conductivity by continued FTCs that might also be less efficient in the future.