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Fei, Wang, Xu Yilu, Yang Xiaodong, Liu Yanju, Lv Guang-Hui und Yang Shengtian. „Soil water potential determines the presence of hydraulic lift of Populus euphratica Olivier across growing seasons in an arid desert region“. Journal of Forest Science 64, No. 7 (01.08.2018): 319–29. http://dx.doi.org/10.17221/49/2018-jfs.
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Hydraulic lift (HL) of deep-rooted plants is a water adaptation phenomenon to extreme drought conditions which would subsequently improve the survival of shallow-rooted plants in an arid desert area. There is an ongoing debate on whether the difference in water potential between plant roots and soils determine the presence of HL, thus considerable research efforts are needed to improve our understanding. In this study, we used the Ryel model and comparative analysis to determine the changes in soil water potential (SWP), the soil layer of obtaining water from plant roots (SLOW), the amount water released from plant roots into soils, and the total amount of release water of HL (H<sub>T</sub>) of five stratified soil layers at different depths (i.e. 0–10, 10–40, 40–70, 70–100 and 100–150 cm) across plant growing season (i.e. June, August and October). The results showed that SLOW always appeared in the lowest SWP soil layer, and that lowest SWP differed among soil layers. The lowest SWP soil layer and SLOW shifted from shallow to deep soil layers across the growing seasons. Additionally, H<sub>T</sub> decreased across the growing seasons. Fine root biomass decreased in shallow whereas increased in deep soil layers across growing seasons. Our results proved the water potential difference among soil layers determined the presence of HL in an arid desert region. The changes in water potential difference among soil layers might shift the lowest SWP soil layer from shallow to deep soil layers, and as a consequent decrease H<sub>T</sub> across plant growing seasons.
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S. P., Pogorilyy, Prysyazhnyi V. G. und Shkarivskyi G. V. „Research of the reasons of excessing the air and underground soil layers of the deep blocked soils of black earth“. Mehanization and electrification of agricultural, Nr. 15(114) (2022): 124–30. http://dx.doi.org/10.37204/0131-2189-2022-15-15.
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Purpose. Investigation of the causes of compaction of arable and subsoil soil layers of deep podzolic chernozems. Methods. Experimental studies of the density of arable and subsoil soil layers of deep podzolic chernozems with subsequent processing of the results on a PC. Results. The results of experimental researches of formation of the overcompacted layers of chernozems of deep podzolic depending on ways and means of influence on them are stated. Conclusions. As a result of research it is established that on deep chernozem chernozems the maximum depth of overcompacted layers formed by self-compaction for virgin soil does not exceed 30 cm, and man-made impact on these soils leads to overcompaction of layers up to 40 cm deep. Possible areas of further research on this issue are the study of technical and technological aspects of ensuring acceptable for optimal plant development density. Keywords: overcompaction, arable and subsoil layers of soil, division of chernozems deep podzolic, running systems, soil density.
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Zhang, Shu-Wen, Xubin Zeng, Weidong Zhang und Michael Barlage. „Revising the Ensemble-Based Kalman Filter Covariance for the Retrieval of Deep-Layer Soil Moisture“. Journal of Hydrometeorology 11, Nr. 1 (01.02.2010): 219–27. http://dx.doi.org/10.1175/2009jhm1146.1.
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Abstract Previous studies have demonstrated that soil moisture in the top layers (e.g., within the top 1-m depth) can be retrieved by assimilating near-surface soil moisture observations into a land surface model using ensemble-based data assimilation algorithms. However, it remains a challenging issue to provide good estimates of soil moisture in the deep layers, because the error correlation between the surface and deep layers is low and hence is easily influenced by the physically limited range of soil moisture, probably resulting in a large noise-to-signal ratio. Furthermore, the temporally correlated errors between the surface and deep layers and the nonlinearity of the system make the retrieval even more difficult. To tackle these problems, a revised ensemble-based Kalman filter covariance method is proposed by constraining error covariance estimates in deep layers in two ways: 1) explicitly using the error covariance at the previous time step and 2) limiting the increase of the soil moisture error correlation with the increase of the vertical distance between the two layers. This method is then tested at three separate point locations representing different precipitation regimes. It is found that the proposed method can effectively control the abrupt changes of error covariance estimates between the surface layer and two deep layers. It significantly improves the estimates of soil moisture in the two deep layers with daily updating. For example, relative to the initial background error, after 150 daily updates, the error in the deepest layer reduces to 11.4%, 32.3%, and 27.1% at the wet, dry, and medium wetness locations, only reducing to 62.3%, 80.8%, and 47.5% with the original method, respectively. However, the improvement of deep-layer soil moisture retrieval is very slight when the updating frequency is reduced to once every three days.
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Xie, Haixia, Shuai He, Chuanqin Huang und Wenfeng Tan. „Origin of Smectite in Salinized Soil of Junggar Basin in Xinjiang of China“. Minerals 9, Nr. 2 (10.02.2019): 100. http://dx.doi.org/10.3390/min9020100.
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In this paper, salinized soils with different degrees of salinity are sampled in Junggar Basin of Xinjiang of China. The X-ray diffraction, transmission electron microscopy, and inductively coupled plasma mass spectrometry are employed to investigate the morphology and distribution characteristics of smectite in salinized soil profiles. In the salinized soil profiles of this region, crystals of smectite are poor where lattice fringes are not parallel. In all soil layers, the content of smectite in the soil increases with the decrease in content of illite, which has demonstrated significant negative correlation (r = 0.79, n = 50, p < 0.01) between illite and smectite. This phenomenon has demonstrated that illite may be transformed into smectite in salinized soils of studied regions. In general, the transformation process of illite to smectite is affected by climate condition. The δ18O values of secondary carbonate in the 0–10 cm soil layers is higher than that in deep soil layers, which indicates that δ18O concentrates in surface soil and reflects temperature rise during soil layer formation. The δ13C values of secondary carbonate and soil organic matter in 0-10cm soil layers are higher than that in deep soil layers. It indicates that C4 plants were the main plants, which reflects that the climate was relatively dry during the formation of the surface soil. Thus, the climate during the surface soil formation is arid, which is not conducive for leaching K+ from illite of the 0–10 cm soil to form smectite. As a result, the content of the smectite becomes lowest in the soil surface. In the relative humid condition of deep soil layers, the K+ of the illite of the soil would be relative easily leached and more smectite may be formed. Furthermore, the presence of salt in the salinized soil would promote the formation of smectite in Junggar Basin of Xinjiang. A lot of Ca2+, Na + and Mg2+ in the soil solution of salinized soils would enter into the illite and occupy K+ positions. The studied result shows that the amount of smectite would increase with the increase of salt below 10cm of the soil layer, where the amount of smectite would be significantly correlated with soil electrical conductivity (r = 0.64, n = 39, p < 0.01). In the Junggar Basin in Xinjiang, therefore, the salinized soil below 10 cm would have the necessary water conditions and chemical components for illite transformation to smectite.
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Juraev, Fazliddin U., Umeda X. Umedova, Shuxrat B. Shodiyev, Amrillo A. Fayziyev und Abrorjon A. ugli Savriddinov. „Deep tillage using bioselvent preparation before soil washing“. BIO Web of Conferences 82 (2024): 01016. http://dx.doi.org/10.1051/bioconf/20248201016.
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The article presents a new tool for deep soil tillage, as well as design, operation principles and parameters of two-tier deep tillage device used in the process of deconsolidation of gypsum and dense soil layers according to a special technology with active rotating working bodies and the technology of its application, while improving the ameliorative state of saline soils using the biosolvent chemical composition with spraying on the soil surface and inner layer, before the autumn washing with salt, and washes out harmful salts from the soil. The developed tools and the parameters of their device for deep tillage of the soil and the technology of its application, the results of theoretical and experimental studies are presented.
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Wang, Shaofei, Xiaodong Gao, Min Yang, Gaopeng Huo, Xiaolin Song, Kadambot H. M. Siddique, Pute Wu und Xining Zhao. „The natural abundance of stable water isotopes method may overestimate deep-layer soil water use by trees“. Hydrology and Earth System Sciences 27, Nr. 1 (04.01.2023): 123–37. http://dx.doi.org/10.5194/hess-27-123-2023.
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Abstract. Stable water isotopes have been used extensively to study the water use strategy of plants in various ecosystems. In deep vadose zone (DVZ) regions, the rooting depth of trees can reach several meters to tens of meters. However, the existence of roots in deep soils does not necessarily mean the occurrence of root water uptake, which usually occurs at a particular time during the growing season. Therefore, quantifying the contribution of deep-layer soil water (DLSW) in DVZ regions using the natural abundance of stable water isotopes may not be accurate because this method assumes that trees always extract shallow- and deep-layer soil water. We propose a multi-step method for addressing this issue. First, isotopic labeling in deep layers identifies whether trees absorb DLSW and determines the soil layer depths from which trees derive their water source. Next, we calculate water sources based on the natural abundance of stable isotopes in the soil layer determined above to quantify the water use strategy of trees. We also compared the results with the natural abundance of stable water isotopes method. The 11- and 17-year-old apple trees were taken as examples for analyses on China's Loess Plateau. Isotopic labeling showed that the water uptake depth of 11-year-old apple trees reached 300 cm in the blossom and young fruit (BYF) stage and only 100 cm in the fruit swelling (FSW) stage, whereas 17-year-old trees always consumed water from the 0–320 cm soil layer. Overall, apple trees absorbed the most water from deep soils (>140 cm) during the BYF stage, and 17-year-old trees consumed more water in these layers than 11-year-old trees throughout the growing season. In addition, the natural abundance of stable water isotopes method overestimated the contribution of DLSW, especially in the 320–500 cm soil layer. Our findings highlight that determining the occurrence of root water uptake in deep soils helps to quantify the water use strategy of trees in DVZ regions.
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Shi, Ming, Lianjin Tao und Zhigang Wang. „Study on the Influence of Deep Soil Liquefaction on the Seismic Response of Subway Stations“. Applied Sciences 14, Nr. 6 (09.03.2024): 2307. http://dx.doi.org/10.3390/app14062307.
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Subway systems are a crucial component of urban public transportation, especially in terms of safety during seismic events. Soil liquefaction triggered by earthquakes is one of the key factors that can lead to underground structural damage. This study investigates the impact of deep soil liquefaction on the response of subway station structures during seismic activity, aiming to provide evidence and suggestions for earthquake-resistant measures in underground constructions. The advanced finite element software PLAXIS was utilized for dynamic numerical simulations. Non-linear dynamic analysis methods were employed to construct models of subway stations and the surrounding soil layers, including soil–structure interactions. The UBC3D-PLM liquefaction constitutive model was applied to describe the liquefaction behavior of soil layers, while the HS constitutive model was used to depict the dynamic characteristics of non-liquefied soil layers. The study examined the influence of deep soil liquefaction on the dynamic response of subway station structures under different seismic waves. The findings indicate that deep soil liquefaction significantly increases the vertical displacement and acceleration responses of subway stations compared to non-liquefied conditions. The liquefaction behavior of deep soil layers leads to increased horizontal effective stress on both sides of the structure, thereby increasing the horizontal deformation of the structure and posing a potential threat to the safety and functionality of subway stations. This research employed detailed numerical simulation methods, incorporating the non-linear characteristics of deep soil layer liquefaction, providing an analytical framework based on regulatory standards for evaluating the impact of deep soil liquefaction on the seismic responses of subway stations. Compared to traditional studies, this paper significantly enhances simulation precision and practical applicability. Results from this research indicate that deep soil layer liquefaction poses a non-negligible risk to the structural safety of subway stations during earthquakes. Therefore, the issue of deep soil liquefaction should receive increased attention in engineering design and construction, with effective prevention and mitigation measures being implemented.
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Na, Li, Risu Na, Yongbin Bao und Jiquan Zhang. „Time-Lagged Correlation between Soil Moisture and Intra-Annual Dynamics of Vegetation on the Mongolian Plateau“. Remote Sensing 13, Nr. 8 (15.04.2021): 1527. http://dx.doi.org/10.3390/rs13081527.
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Soil moisture is a reliable water resource for plant growth in arid and semi-arid regions. Characterizing the interaction between soil moisture and vegetation is important for assessing the sustainability of terrestrial ecosystems. This study explores the spatiotemporal characteristics of four soil moisture layers (layer 1: 0–7 cm, layer 2: 7–28 cm, layer 3: 28–100 cm, and layer 4: 100–289 cm) and the time-lagged correlation with the normalized difference vegetation index (NDVI) for different vegetation types on an intra-annual scale on the Mongolian Plateau (MP). The most significant results indicated that: (1) the four layers of soil moisture can be roughly divided into rapid change (layers 1 and 2), active (layer 3), and stable (layer 4) layers. The soil moisture content in the different vegetation regions was forest > grassland > desert vegetation. (2) The soil moisture in layer 1 showed the strongest positive correlation with NDVI in the whole area; meanwhile, the soil moisture of layers 2 and 3 showed the strongest negative correlation with the NDVI mainly in grassland and desert, and layer 4 showed the strongest negative correlation with the NDVI in the forest. (3) Mutual responses of NDVI and deep layer soil moisture required a longer time compared with the shallow layer. In the annual time scale, the NDVI was affected by the change in soil moisture in most of the study area, except for coniferous forest and desert vegetation regions. (4) Under the different stages of vegetation change, the soil moisture changes advance than NDVI about 3 months during the greening stage, while the NDVI changes advance than soil moisture by 0.5 months during the browning stage. Regardless of the stage, changes in soil moisture are initiated from the shallow layer and advance to the deep layer. The results of this study provide deep insight into the relationship between soil moisture and vegetation in arid and semi-arid regions.
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Wei, Di, Yang Zhang, Yiwen Li, Yun Zhang und Bo Wang. „Hydrothermal Conditions in Deep Soil Layer Regulate the Interannual Change in Gross Primary Productivity in the Qilian Mountains Area, China“. Forests 14, Nr. 12 (12.12.2023): 2422. http://dx.doi.org/10.3390/f14122422.
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The variability in soil hydrothermal conditions generally contributes to the diverse distribution of vegetation cover types and growth characteristics. Previous research primarily focused on soil moisture alone or the average values of soil hydrothermal conditions in the crop root zone (0–100 cm). However, it is still unclear whether changes in gross primary productivity (GPP) depend on the hydrothermal conditions at different depths of soil layers within the root zone. In this study, the soil hydrothermal conditions from three different layers, surface layer 0–7 cm (Level 1, L1), shallow layer 7–28 cm (Level 2, L2), and deep layer 28–100 cm (Level 3, L3) in the Qilian Mountains area, northwestern China, are obtained based on ERA5-Land reanalysis data. The Sen-MK trend test, Pearson correlation analysis, and machine learning algorithm were used to explore the influence of these three soil hydrothermal layers on GPP. The results show that soil moisture values increase with soil depth, while the soil temperature values do not exhibit a stratified pattern. Furthermore, the strong correlation between GPP and deep soil hydrothermal conditions was proved, particularly in terms of soil moisture. The Random Forest feature importance extraction revealed that deep soil moisture (SM-L3) and surface soil temperature (ST-L1) are the most influential variables. It suggests that regulations of soil hydrothermal conditions on GPP may involve both linear and nonlinear effects. This study can obtain the temporal and spatial dynamics of soil hydrothermal conditions across different soil layers and explore their regulations on GPP, providing a basis for clarifying the relationship between soil and vegetation in arid mountain systems.
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Jamshed, Muhammad Ammar. „Analyze Soil Fertility using Deep Learning Convolutional Neural Networks“. Shanlax International Journal of Arts, Science and Humanities 10, Nr. 3 (01.01.2023): 1–5. http://dx.doi.org/10.34293/sijash.v10i3.5281.
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This research revolves around how plant soil potential can be further discovered and used for farming through detection of relevant nutrients and chemicals within the soil landscapes within areas and even desert climates and how we can improve land soil fertility of the purpose of farming both using Convolutional neural networks which process of imagery in layers and predictive detections of objects within image backgrounds and frontal lobes. When we view layers for farming beneath the surface to understand suitability of farming done on top. The general model applied can be summarized as follows: As shown In Appendix 1a, we can see the various layers soil has to assess the possibility of nutrient provision for farming [2]. The Objective is to examine availability of plant nutrients using convolution of Nueral networks to classify open farmlands through image analysis and layering. Convolution Nueral networks is divided into four steps starting with input of images, drafting a convolution layer, creating a pooling layer and flattening the Nueral network. It can be performed as a machine learning Algorithmic procedure with Python as well as R programming. CNN divides the images into pixels, edges, frontal lobes and shading through the support of power machine learning libraries and packages like Tensorflow and Keras.
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Sun, Yiming, Xunlong Chen, Anna Zhong, Shijie Guo und Houxi Zhang. „Variations in Microbial Residue and Its Contribution to SOC between Organic and Mineral Soil Layers along an Altitude Gradient in the Wuyi Mountains“. Forests 14, Nr. 8 (18.08.2023): 1678. http://dx.doi.org/10.3390/f14081678.
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Microbes are crucial components of soil, and their residue carbon plays a significant role in the formation and stabilization of soil carbon pools. However, current research on microbial residue carbon has predominantly focused on surface soils, with limited studies on deep soils. The patterns of variation along soil profiles and their controlling factors remain unclear. Therefore, this study aimed to investigate the soils from different elevations in the Wuyi Mountains, specifically focusing on the organic layers (0–10 cm) and mineral layers (30–40 cm). Amino sugars were utilized as biomarkers for the microbial residue, and the RDA (redundancy analysis) method was employed to analyze the patterns of microbial residue carbon in different soil layers and to identify the factors that control them. The results indicate that there are significant differences in the microbial residue carbon content and its contribution to soil organic carbon (SOC) between the different soil layers. Specifically, between the organic layer and the mineral layer, the microbial residue carbon content exhibited an increasing trend, whereas its contribution to SOC decreased. This finding suggests that soil layer type has a notable impact on microbial residue carbon content and its contribution to SOC. Moreover, fungal residue carbon content was found to be higher than bacterial residue carbon content in both soil layers. However, the ratio of fungal residue carbon to bacterial residue carbon gradually decreased between the organic layer and the mineral layer. This implies that although fungal residue carbon remains dominant, the contribution of bacterial residue carbon to the soil carbon pool increases as the soil transitions to the mineral layer. The total soil carbon content, elevation, and C/N ratio exhibited positive correlations with fungal and bacterial residue carbon, indicating their significant roles in the accumulation of microbial residue carbon in soils. Notably, elevation emerged as a key regulating factor in the accumulation of microbial residue carbon, explaining 85.8% and 67.9% of the variations observed in the organic layer and the mineral layer respectively. These research findings contribute to a better understanding of the soil carbon cycling process and its mechanisms, providing a scientific basis for developing strategies to enhance soil carbon sequestration by manipulating micro-organisms.
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Liu, Dongwei, Shanlong Li, Weixing Zhu, Yongyang Wang, Shasha Zhang und Yunting Fang. „Storage and Stability of Soil Organic Carbon in Two Temperate Forests in Northeastern China“. Land 12, Nr. 5 (06.05.2023): 1019. http://dx.doi.org/10.3390/land12051019.
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Forests worldwide store large quantities of carbon (C), particularly in soils as soil organic C (SOC). In northeastern China, two dominant forest types, secondary mixed forest (MF) and larch plantation forest (LF), cover extensive areas. However, we lack an understanding of the patterns and the mechanisms of SOC storage and stabilization in MF and LF, especially in deep soil layers. This research aims to illustrate the vertical distribution and mineral protection of SOC over soil depth; we also used δ13C values of soil fractions to evaluate SOC stability. Samples from the surface litter (Oi), organic layer (Oa+e), and 0–40 cm mineral soils were collected from both MF and LF plots. We used two different methods to separate bulk soils into distinguished fractions: (1) macro- and micro-aggregates and the non-aggregated fraction, and (2) particulate organic matter (POM) and mineral-associated organic matter (MAOM). The C concentrations, C stocks, and δ13C of all soil fractions were determined. Our findings were as follows: (1) SOC was mainly stored in mineral soils and was 13.6% lower in LF (8609 ± 1180 g C m−2) than MF (9969 ± 2084 g C m−2). (2) In both MF and LF, the SOC stock was mainly stored in aggregates (averaged 92.7%); macroaggregates dominated in the surface layers (Oa+e layer and 0–10 cm) but microaggregates dominated in the deep layers (10–20 cm and 20–40 cm). In mineral soils, MAOM was the dominant fraction of the C stock (averaged 81.6%). (3) The proportion of C distributed in microaggregates and MAOM increased from Oa+e to the 20–40 cm layer. (4) The C/N ratios and δ13C values of MAOM were smaller and heavier compared to those of POM. Our study demonstrated that in both forests, aggregate formation and mineral association predominantly contributed to SOC storage, and large stocks of SOC were distributed in the deep soil. The increasing proportion of SOC in microaggregates and MAOM along the soil depth, most likely derived from microbial turnover and microbial necromass, influenced SOC stability in both forest types.
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Marasca, Indiamara, Stella Vannucci Lemos, Reginaldo Barbosa Silva, Saulo Philipe Sebastião Guerra und Kleber Pereira Lanças. „Soil Compaction Curve of an Oxisol Under Sugarcane Planted After In-row Deep Tillage“. Revista Brasileira de Ciência do Solo 39, Nr. 5 (Oktober 2015): 1490–97. http://dx.doi.org/10.1590/01000683rbcs20140559.
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ABSTRACT Soil tillage that maintains the productivity of sugarcane plantations, providing an area for the root development and without traffic on crop rows, has given rise to new technologies in rural areas. The purpose of this study was to evaluate the soil physical properties in two sugarcane plantations, one of which was prepared with deep tilling and the other with conventional tillage. The experiment was conducted in Lençóis Paulista, São Paulo State. Soil penetration resistance and relative density were analyzed. The cone index was lower in deep-tilled soil without traffic in all layers, than in deep-tilled soil with traffic and in conventional tillage. In both tillage treatments, the relative density values were acceptable in the 0.00-0.15 m soil layer, but considered detrimental for sugarcane development in the 0.15-0.30 and 0.30-0.45 m layers.
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Sarto, Marcos Vinicius Mansano, Wander Luis Barbosa Borges, Doglas Bassegio, Márcio Renato Nunes, Charles W. Rice und Ciro Antonio Rosolem. „Deep Soil Water Content and Forage Production in a Tropical Agroforestry System“. Agriculture 12, Nr. 3 (03.03.2022): 359. http://dx.doi.org/10.3390/agriculture12030359.
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Agroforestry systems integrating tree and forage growth are important for maintaining soil health but may change the soil’s physical-hydric properties. Our goal was to investigate the impact of introducing Eucalyptus trees into a pasture on the soil water content throughout the soil profile. The study was conducted in a 6-year-old agroforestry system where two species of Eucalyptus were introduced into a palisade grass pasture. Soil moisture was sampled at 0.0 (planting row), 2.0, 4.0, and 6.0 m (midpoint between tree rows) from the Eucalyptus tree rows. A monoculture palisade grass pasture was used as a control. The soil water content down to a depth of 50 cm was lowest in the tree row and increased with distance from the trees. In the Eucalyptus row, the soil water content in the 0–50 cm layer was lower than in the monoculture pasture. Agroforestry systems decreased the water content in the superficial layers of the soil in the rainy months; in the dry season, the soil water contents in all layers were similar between the Eucalyptus inter-rows. In most seasons, the agroforest systems reduced the forage production close to the Eucalyptus tree rows, up to 2 m from the trees, likely due to the soil water content decrease. Overall, this study showed that in tropical regions with sandy soils, the grass and trees’ competition must be considered when establishing integrated agroforestry systems in order to maximize the advantages and benefits of the diversified agroecosystem.
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Condon, Jason, Helen Burns und Guangdi Li. „The extent, significance and amelioration of subsurface acidity in southern New South Wales, Australia“. Soil Research 59, Nr. 1 (2021): 1. http://dx.doi.org/10.1071/sr20079.
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Soil pH is seldom uniform with depth, rather it is stratified in layers. The soil surface (0–0.02 m) commonly exhibits relatively high pH and overlies a layer of acidic soil of 0.05–0.15 m deep, termed an acidic subsurface layer. Commercial and research sampling methods that rely on depth increments of 0.1 m either fail to detect or under report the presence or magnitude of pH stratification. The occurrence of pH stratification and the presence of acidic subsurface layers may cause the extent of acidity in NSW agricultural land to be underestimated. Though the cause of pH stratification in agricultural systems is well understood, the effect on agricultural production is poorly quantified due in part to inadequate sampling depth intervals resulting in poor identification of acidic subsurface layers. Although liming remains the best method to manage acidic soil, current practices of low pH targets (pHCa 5), inadequate application rates and no or ineffective incorporation have resulted in the continued formation of acidic subsurface layers. Regular monitoring in smaller depth increments (0.05 m), higher pH targets (pHCa > 5.5) and calculation of lime rate requirements that account for application method are required to slow or halt soil degradation by subsurface acidification. If higher pH is not maintained in the topsoil, the acidification of subsurface soils will extend further into the profile and require more expensive operations that mechanically place amendments deep in the soil. Although the use of organic amendments has shown promise to enhance soil acidity amelioration with depth, the longevity of their effect is questionable. Consequently, proactive, preventative management of topsoil pH with lime addition remains the most cost-effective solution for growers.
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Bell, M. J., B. J. Bridge, G. R. Harch und D. N. Orange. „Rapid internal drainage rates in Ferrosols“. Soil Research 43, Nr. 4 (2005): 443. http://dx.doi.org/10.1071/sr04063.
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Adoption of conservation tillage practices on Red Ferrosol soils in the inland Burnett area of south-east Queensland has been shown to reduce runoff and subsequent soil erosion. However, improved infiltration resulting from these measures has not improved crop performance and there are suggestions of increased loss of soil water via deep drainage. This paper reports data monitoring soil water under real and artificial rainfall events in commercial fields and long-term tillage experiments, and uses the data to explore the rate and mechanisms of deep drainage in this soil type. Soils were characterised by large drainable porosities (≥0.10 m3/m3) in all parts of the profile to depths of 1.50 m, with drainable porosity similar to available water content (AWC) at 0.25 and 0.75 m, but >60% higher than AWC at 1.50 m. Hydraulic conductivity immediately below the tilled layer in both continuously cropped soils and those after a ley pasture phase was shown to decline with increasing soil moisture content, although the rate of decline was much greater in continuously cropped soil. At moisture contents approaching the drained upper limit (pore water pressure = –100 cm H2O), estimates of saturated hydraulic conductivity after a ley pasture were 3–5 times greater than in continuously cropped soil, suggesting much greater rates of deep drainage in the former when soils are moist. Hydraulic tensiometers and fringe capacitance sensors monitored during real and artificial rainfall events showed evidence of soils approaching saturation in the surface layers (top 0.30–0.40 m), but there was no evidence of soil moistures exceeding the drained upper limit (i.e. pore water pressures ≤ –100 cm H2O) in deeper layers. Recovery of applied soil water within the top 1.00–1.20 m of the profile during or immediately after rainfall events declined as the starting profile moisture content increased. These effects were consistent with very rapid rates of internal drainage. Sensors deeper in the profile were unable to detect this drainage due to either non-uniformity of conducting macropores (ie. bypass flow) or unsaturated conductivities in deeper layers that far exceed the saturated hydraulic conductivity of the infiltration throttle at the bottom of the cultivated layer. Large increases in unsaturated hydraulic conductivities are likely with only small increases in water content above the drained upper limit. Further studies with drainage lysimeters and large banks of hydraulic tensiometers are planned to quantify drainage risk in these soil types.
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Henckel, Thilo, Udo Jäckel, Sylvia Schnell und Ralf Conrad. „Molecular Analyses of Novel Methanotrophic Communities in Forest Soil That Oxidize Atmospheric Methane“. Applied and Environmental Microbiology 66, Nr. 5 (01.05.2000): 1801–8. http://dx.doi.org/10.1128/aem.66.5.1801-1808.2000.
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ABSTRACT Forest and other upland soils are important sinks for atmospheric CH4, consuming 20 to 60 Tg of CH4 per year. Consumption of atmospheric CH4 by soil is a microbiological process. However, little is known about the methanotrophic bacterial community in forest soils. We measured vertical profiles of atmospheric CH4 oxidation rates in a German forest soil and characterized the methanotrophic populations by PCR and denaturing gradient gel electrophoresis (DGGE) with primer sets targeting thepmoA gene, coding for the α subunit of the particulate methane monooxygenase, and the small-subunit rRNA gene (SSU rDNA) of all life. The forest soil was a sink for atmospheric CH4 in situ and in vitro at all times. In winter, atmospheric CH4was oxidized in a well-defined subsurface soil layer (6 to 14 cm deep), whereas in summer, the complete soil core was active (0 cm to 26 cm deep). The content of total extractable DNA was about 10-fold higher in summer than in winter. It decreased with soil depth (0 to 28 cm deep) from about 40 to 1 μg DNA per g (dry weight) of soil. The PCR product concentration of SSU rDNA of all life was constant both in winter and in summer. However, the PCR product concentration of pmoAchanged with depth and season. pmoA was detected only in soil layers with active CH4 oxidation, i.e., 6 to 16 cm deep in winter and throughout the soil core in summer. The same methanotrophic populations were present in winter and summer. Layers with high CH4 consumption rates also exhibited more bands of pmoA in DGGE, indicating that high CH4oxidation activity was positively correlated with the number of methanotrophic populations present. The pmoA sequences derived from excised DGGE bands were only distantly related to those of known methanotrophs, indicating the existence of unknown methanotrophs involved in atmospheric CH4 consumption.
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Maximenko, Vladimir, Tatyana Volchkova und Snezana Menshikova. „Directed formation of fertility of soils in Non-Chernozem region, taking into account the potential capabilities of arable crops“. Melioration and Water Management, Nr. 5 (06.02.2020): 48–53. http://dx.doi.org/10.32962/0235-2524-2019-5-48-53.
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The article considers the possibility of directed formation of soil fertility in the conditions of crop production by increasing the efficiency of accumulation of incoming solar energy by crops. The effect is provided by deep volumetric loosening with one-time intra-soil introduction of meliorant, cultivation of crop-meliorant and subsequent treatment of different depths of the reclaimed soil layer for agricultural crops rotation. Given that the root system of plants affects the physical and chemical properties of the soil, its deeper placement contributes to the enrichment of deep layers soil of nutrients. Directed formation of the root system in the likeness of its natural development in favorable conditions of structural addition provides natural deposition in its layers of elements available for subsequent crops.
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Yang, L., W. Wei, L. Chen, F. Jia und B. Mo. „Spatial variations of shallow and deep soil moisture in the semi-arid Loess Plateau, China“. Hydrology and Earth System Sciences 16, Nr. 9 (10.09.2012): 3199–217. http://dx.doi.org/10.5194/hess-16-3199-2012.
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Abstract. Soil moisture in deep soil layers is an important relatively stable water resource for vegetation growth in the semi-arid Loess Plateau of China. Characterizing the spatial variations of deep soil moisture with respect to the topographic conditions has significant importance for vegetation restoration. In this study, we focused on analyzing the spatial variations and factors influencing soil moisture content (SMC) in shallow (0–2 m) and deep (2–8 m) soil layers, based on soil moisture observations in the Longtan watershed, Dingxi, Gansu province. The vegetation type of each sampling site for each comparison is same and varies by different positions, gradients, or aspects. The following discoveries were captured: (1) in comparison with shallow SMC, slope position and slope aspect may affect shallow soil moisture more than deep layers, while slope gradient affects both shallow and deep soil moisture significantly. This indicates that a great difference in deep soil hydrological processes between shallow and deep soil moisture remains that can be attributed to the introduced vegetation and topography. (2) A clear negative relationship exists between vegetation growth condition and deep soil moisture, which indicates that plants under different growing conditions may differ in consuming soil moisture, thus causing higher spatial variations in deep soil moisture. (3) The dynamic role of slope position and slope aspect on deep soil moisture has been changed due to large-scale plantation in semi-arid environment. Consequently, vegetation growth conditions and slope gradients may become the key factors dominating the spatial variations in deep soil moisture.
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Zhao, Zhuangjun, Margaret Mukami Gitau, Tao Hu, Yan Xie, Longxing Hu und Jinmin Fu. „Investigation of Growth, Free Amino Acids, and Carbohydrate Concentration in the Roots of Perennial Ryegrass in Response to Soil Salinity at Subsurface Soil Depths“. Journal of the American Society for Horticultural Science 141, Nr. 6 (November 2016): 539–47. http://dx.doi.org/10.21273/jashs03793-16.
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Plants growing in salt-affected soils may have retarded growth and inhibited or altered metabolic processes. This study aims at investigating the impact of subsurface soil salinity on root growth and metabolic processes in perennial ryegrass (Lolium perenne). The seeds of perennial ryegrass (cv. Quick Start II) were planted in polyvinyl chloride (PVC) tubes (10 cm diameter × 42 cm long) for 2 months. The experiment consisted of three treatments: 1) control, 40 cm filled with sand–peat mixture (7 sand : 3 peat wt/wt); 2) T20, a 20-cm-deep layer of saline soil covered with a 20-cm-deep layer of sand–peat mixture; and 3) T30, a 30-cm-deep layer of saline soil covered with a 10-cm-deep layer of sand–peat mixture. Our study showed that soil salinity at the subsurface inhibited the growth of perennial ryegrass roots. Compared with the control, the root activity in saline soil layer decreased, whereas it remained high in the mixture-soil zone. The content of amino acids in the roots obtained from the surface soil (0–10 cm) in T30 was greater than that in both the T20 and the control regimes. The content of soluble sugars in the roots went up with the decrease of the depth of sand–peat mixture. The increased root activity and free amino acids content in the roots sampled from the upper soil layers coupled with the increased soluble sugars in the roots subjected to soil salinity stress in the bottom soil layer represents some adaptive responses and regulative mechanisms in perennial ryegrass.
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Yang, L., W. Wei, L. Chen, F. Jia und B. Mo. „Spatial variation of shallow and deep soil moisture in the semi-arid loess hilly area, China“. Hydrology and Earth System Sciences Discussions 9, Nr. 4 (05.04.2012): 4553–86. http://dx.doi.org/10.5194/hessd-9-4553-2012.
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Abstract. Soil moisture in deep soil layers is the only relatively stable water resource for introduced vegetation in the semi-arid Loess Plateau of China. Characterizing the spatial variation of deep soil moisture is significant for vegetation restoration with respect to the topographic conditions. In this study, we focused on analyzing the spatial variations and influencing factors of soil moisture content (SMC) in shallow (0–2 m) and deep (2–8 m) soil layers based on soil moisture observation in the Longtan watershed. The vegetation type of each sampling site for each comparison is same, while varies with slope position, slope gradient, or slope aspect. The following results are found: (1) compared with shallow SMC, slope position and slope aspect may affect shallow soil moisture more, rather than deep layers. Slope gradient however, affect both shallow and deep soil moisture significantly. It indicates that high difference of deep soil hydrological processes between shallow and deep soil moisture remains, which can be attributed to the introduced vegetation and topography. (2) The vegetation growth condition has significant negative relation with deep soil moisture. This result indicates that plants under different growth conditions may consume soil moisture differently, thus causing higher spatial variation of deep soil moisture. (3) The dynamic role of slope position and slope aspect on deep SMC has been changed by introduced vegetation in semi-arid environment. Consequently, vegetation growth condition and slope gradient may be the major factor contributing to the spatial variation of deep soil moisture.
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Azevedo, Raphael Passaglia, Lucas de Castro Moreira da Silva, Fernandes Antonio Costa Pereira, Pedro Maranha Peche, Leila Aparecida Salles Pio, Marcelo Mancini, Nilton Curi und Bruno Montoani Silva. „Interactions between Intrinsic Soil Properties and Deep Tillage in the Sustainable Management of Perennial Crops“. Sustainability 15, Nr. 1 (31.12.2022): 760. http://dx.doi.org/10.3390/su15010760.
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Choosing the appropriate management system is essential for sustainable agricultural practices. Yet, soil-specific properties at the subsurface are seldom considered when choosing the appropriate tillage system. This study assessed the effect of tillage depth on physical–hydraulic properties in three contrasting soil classes in the establishment of perennial crops. Tillage practices were evaluated in soils with natural dense layers (Inceptisols and Ultisols), and soils with very small and stable granular structure (Oxisols). From least to most aggressive, tested tillage systems included surface furrowing + plant holes (MT); plowing followed by two diskings + furrowing (CT); plowing followed by two diskings + subsoiling (SB); and plowing followed by two diskings + rotary hoeing (DM). Physical indicators with the greatest explanatory power were relative field capacity (RFC, 97%), aeration capacity (AC, 95%), macroporosity (Pmac, 95%), the S index (Sgi, 89%), and bulk density (Bd, 81%). DM caused the greatest modification in soil structure, especially at the surface. It increased values of AC, Pmac, and Sgi, and reduced Bd values. Only deep tillage systems (DM and SB) improved soil structure in deeper layers. Highest Bd values were observed for MT (1.47 g cm−3), and lowest for DM (1.21 g cm−3). Soil classes responded differently to soil tillage systems. DM was most effective in soils with densified layers (Inceptisol and Ultisol). Effects were less expressive in the studied Oxisol. Comparing MT and DM, Pmac increased by more than 100% in the studied Ultisol, but by less than 20% in the Oxisol. No tillage system affected the Oxisol’s soil structure in deeper layers, due to its small and stable granular structure. The choice of optimal tillage strategies should consider soil-specific properties, especially at greater depths, to guarantee more productive and sustainable crop systems.
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Wen, Linsheng, Yun Peng, Wenping Deng, Yuanqiu Liu, Tianjun Bai, Qin Zou, Xiaojun Liu, Ling Zhang und Guodong Jia. „Variation in Water Uptake Dynamics of Dominant Wood Plants of Pinus taiwanensis Hayata Communities Based on Stable Isotopes“. Forests 13, Nr. 8 (22.08.2022): 1336. http://dx.doi.org/10.3390/f13081336.
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Plant community formation is determined by plant competition, while the water uptake depth of vegetation is regarded as a critical factor in maintaining species coexistence under competition. However, the source variation of montane plant water uptake remains poorly understood, especially under the condition of climate change. We introduced stable hydrogen and oxygen isotopes to investigate the water uptake pattern of the trees and shrubs in a Pinus taiwanensis Hayata community in subtropical mountains. The results showed that the main sources of water uptake in plants varied with soil water content, due to variations in annual precipitation distribution. In July and September, under extremely wet conditions, the evergreen conifer species P. taiwanensis and the shrub Eurya muricata mainly absorbed water from the deep soil layer (40–80 cm, more than 70%). By contrast, the deciduous shrub Rhododendron dilatatum largely relied on upper soil water (0–40 cm, 75.4%) in July but the same deep water source in September. In August and the non-growing season (January), when soil moisture content was low, plants preferred surface layer soil water (0–20 cm, above 50%). In October, the soil water in the middle (20–40 cm) and deep layers (40–80 cm) were the main water source of the three plants. However, the plant water sources showed great difference between P. taiwanensis and shrubs in November: P. taiwanensis absorbed more water from the soil surface layers (89.5%), while R. dilatatum mainly took up surface soil water (54.2%) and E. muricata predominantly obtained water from surface soil water (49.6%) and the deep soil layer (39.3%). These findings suggest that the water uptake of dominant woody plants in a P. taiwanensis community has great plasticity, and its water uptake depth varies with soil water content. In addition, these co-existing species generally absorbed water from similar soil layers in the P. taiwanensis community and exhibited a hydrological niche overlap, indicating a very possible competition between species in future water-limited conditions caused by climate change.
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Panitskiy, Andrey, Yelena Syssoeva, Symbat Baigazy, Assiya Kunduzbayeva, Laura Kenzhina, Yelena Polivkina, Natalya Larionova, Pavel Krivitskiy und Almira Aidarkhanova. „Vertical distribution of radionuclides in soil at the Semipalatinsk Test Site beyond its test locations“. PLOS ONE 18, Nr. 1 (06.01.2023): e0278581. http://dx.doi.org/10.1371/journal.pone.0278581.
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Data on the vertical distribution of radionuclides in the soil is necessary to fully understand the radioecological situation around ecosystems, give predictive estimates to how safe crop products are and justify a rehabilitation strategy for radioactively contaminated areas. A study was conducted to investigate the vertical distribution of radionuclides in soils of the former Semipalatinsk Test Site (STS) territory beyond its testing sites, that is, in areas in which no nuclear weapons or nuclear effects of radiological warfare agents were tested. Soil was sampled layerwise all over the Semipalatinsk Test Site down to 30 cm deep at a 5-cm spacing. Most of high activity concentrations of radionuclides all over the study area were detected in the 0–5 cm soil layer. Activity concentrations of the major man-made radionuclides were determined in soil samples collected by γ-, β and α-spectrometry. As a result, ranges of activity concentrations of 137Cs, 241Am, 90Sr and 239+240Pu were determined in 0–5, 5–10, 10–15, 15–20, 20–25, 25–30 cm soil layers. In the conventionally ‘background’ area, the 0–5 cm soil layer, on average, contains (the percentage of total activity concentration across the soil profile depth): 137Cs– 83%, 239+240Pu– 87% and 90Sr– 38%. For the 1953 plume, these values were 92%, 83% and 73%, respectively. Values for the 1951 plume in the 0–5 cm soil layer were: 137Cs– 93%, 239+240Pu– 93% and 90Sr– 59%. The minimum concentration of radionuclides are observed 20–30 cm deep in all areas studied. 90Sr is the most mobile radionuclide from the perspective of its ability to travel deep down the soil. The study found out that the nuclide vertical migration rates downward in soils based on detected activity were as follows (in descending order): 90Sr– 137Cs– 239+240Pu– 241Am. Coefficients that determine the ratio of the activity concentration of the radionuclide in the 0–20 and 0–30 cm soil cover layers to that of this radionuclide in the 0–5 cm topsoil were calculated. These coefficients enable to estimate the radionuclide inventory at each soil sampling point from their activity concentration in the 0–5 cm soil layer.
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Gautam, Tilak Prasad, und Tej Narayan Mandal. „Soil Characteristics in Moist Tropical Forest of Sunsari District, Nepal“. Nepal Journal of Science and Technology 14, Nr. 1 (10.10.2013): 35–40. http://dx.doi.org/10.3126/njst.v14i1.8876.
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The physico-chemical properties of soils of tropical moist forest (Charkoshe jungle) in Sunsari district of eastern Nepal were analyzed. The samples were collected during summer season from three depths: upper (0-15 cm), middle (15-30 cm) and deep (30-45 cm). They were analyzed for texture, pH, moisture, water holding capacity, organic carbon, total nitrogen, organic matter and microbial biomass carbon and nitrogen. The forest soil of upper and middle layers was loamy whereas that of deep layer was sandy loam. The pH value was lower (5.6) in upper layer than in the deep layer (6.6). The moisture content, water holding capacity, organic carbon, total nitrogen and organic matter were higher in upper layer and decreased with increasing depth. The higher level of soil nutrients in upper layer was due partly to reduction in the loss of top soil and partly to the increased supply of nutrients from the decomposed form of litter and fine roots of the forest plants. The average value of microbial biomass carbon in the soil was 676.6 μg g-¹and microbial biomass nitrogen was 59.0 μg g-¹. Nepal Journal of Science and Technology Vol. 14, No. 1 (2013) 35-40 DOI: http://dx.doi.org/10.3126/njst.v14i1.8876
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Yokota, Mika, Yupeng Guan, Yi Fan, Ximei Zhang und Wei Yang. „Vertical and temporal variations of soil bacterial and archaeal communities in wheat-soybean rotation agroecosystem“. PeerJ 10 (10.02.2022): e12868. http://dx.doi.org/10.7717/peerj.12868.
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Soil microbes are an essential component of terrestrial ecosystems and drive many biogeochemical processes throughout the soil profile. Prior field studies mainly focused on the vertical patterns of soil microbial communities, meaning their temporal dynamics have been largely neglected. In the present study, we investigated the vertical and temporal patterns of soil bacterial and archaeal communities in a wheat-soybean rotation agroecosystem at a depth of millions of sequences per sample. Our results revealed different vertical bacterial and archaeal richness patterns: bacterial richness was lowest in the deep soil layer and peaked in the surface or middle soil layer. In contrast, archaeal richness did not differ among soil layers. PERMANOVA analysis indicated that both bacterial and archaeal community compositions were significantly impacted by soil depth but unaffected by sampling time. Notably, the proportion of rare bacteria gradually decreased along with the soil profile. The rare bacterial community composition was the most important indicator for soil nutrient fertility index, as determined by random forest analysis. The soil prokaryotic co-occurrence networks of the surface and middle soil layers are more connected and harbored fewer negative links than that of the deep soil layer. Overall, our results highlighted soil depth as a more important determinant than temporal variation in shaping the soil prokaryotic community and interspecific interactions and revealed a potential role of rare taxa in soil biogeochemical function.
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Nurcholis, Mohammad, Susila Herlambang, Sri Aminah Suwartikaningsih, Dian Fiantis und Dwi Fitri Yudiantoro. „Soil Layers Properties of a Profile Developed on the Past Depositional Series on Merbabu Volcano Central Java Indonesia“. JOURNAL OF TROPICAL SOILS 24, Nr. 2 (30.10.2019): 53. http://dx.doi.org/10.5400/jts.2019.v24i2.53-63.
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A wide and deep soil profile (around 1200 cm) was observed at Ketep Park West Slope of Merbabu volcano Central Java, Indonesia to identify the soil morphology, physical and, chemical and mineralogical properties. Results showed that several soil development processes occurred in each volcanic deposits with different characteristics. Most soil layers met some of andic soil properties criteria such bulk density <0.9 g.cm-3, P retention of >85%, and (Alo + ½ Feo) >2.0%. A thin melanic material showing black color layer was found at the lower part of the soil profile, i.e. in depth from 726 to 798 cm. The dominant material in most soil layers is an allophane. Minerals in the sand fraction were dominated by labradorite and augite, with some layers were hypersthene and green hornblende.
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Boikov, Vasily Mikhailovich, Sergey Viktorovich Startsev, Andrey Vladimirovich Pavlov und Evgeniy Sergeevich Nesterov. „Results of studies on the sealing of crop residues of leguminous crops with ploughshares“. Agrarian Scientific Journal, Nr. 6 (26.06.2023): 122–27. http://dx.doi.org/10.28983/asj.y2023i6pp122-127.
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The article presents the results of experimental studies of the sealing of crop residues and their distribution over the depth of the cultivated soil layer by known general-purpose ploughshares without ploughshares. The research was carried out in fields with agrophones of winter wheat, chickpeas and winter rapeseed. The plowing of dark chestnut soils located in the steppe soil-climatic zone of the Left-Bank district of the Saratov region was carried out by aggregates K-701+PNL-8-40, K-701+PSK-8 and T-150K+PLN-5-35. As a result of field experiments, it was found out that straw, pollen and stubble are embedded in the soil in accordance with established agrotechnical requirements, more than 80%. Crop and plant residues are located in the bulk in the deep layers of the cultivated soil. Part of the stubble in an inclined position is located in the places where the layers of adjacent passages of the plow hulls meet. The design of the ploughshare-dump surface of the housing does not allow managing the upper organic-enriched soil layer.
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Pingping, Liu, Ren Huarui, Zhang Yiling, Wu Tiantian, Zheng Chunli und Zhang Tiancheng. „Impact of vegetation zones on soil phosphorus distribution in Northwest China“. Plant, Soil and Environment 65, No. 2 (01.02.2019): 71–77. http://dx.doi.org/10.17221/631/2018-pse.
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Soil phosphorus (P) fraction distribution and correlation at different soil depths along vegetation succession in wetland next to a lake in the Hongjiannao National Nature Reserve, China were studied using the Hedley fraction method. The overall trend for soil P content was calcium-bound P (Ca-P) > organic P (O-P) > aluminum/iron-bound P (Al/Fe-P) > labile-P (L-P). Ca-P and O-P were the predominant P forms in all the soil layers, representing on average 53.8‒84.9% and 12.9‒45.2% of the total P, respectively, whereas L-P (ranging from 0.5 to 1.5 mg/kg) was less than 1%. The soil in the Bassia dasyphylla and Carex duriuscula vegetation zones had the largest P contents. In these two vegetation zones, soil L-P was greatest in the surface soil layer; Al/Fe-P was most abundant in the deep layer; O-P was highest in the middle layer. Ca-P levels were generally similar across all soil layers. Regression analysis showed that distribution of P was highly correlated with organic carbon, total nitrogen and plant biomass. Results showed that the soils under Bassia dasyphylla and Carex duriuscula have considerable carbon input potentials, which would facilitate P mineralization as compared to other plants.
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Xu, Manlin, Qiqi Sun, Qiangbo Liu, Guo He, Congpeng Wang und Kang He. „Biochar Decreases Fertilizer Leaching and Promotes Miscanthus Growth in Saline-Alkaline Soil“. Plants 12, Nr. 20 (23.10.2023): 3649. http://dx.doi.org/10.3390/plants12203649.
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Biochar has been widely reported to improve soil conditions and affect plant growth. However, its effectiveness is limited by soil type and production technology. Considering the application effect of biochar in saline alkali soil, there is currently a lack of in-depth mechanism explanations in the research. Therefore, we designed an experiment to explore the effect of biochar on plant growth in saline alkali soil and conducted soil column experiments in a greenhouse environment using composite inorganic fertilizer (NPK). The results showed that biochar significantly affected the distribution of soil nutrient content at different depths, with a significant increase in fertility levels in the surface and middle layers and a decrease in fertility levels in deep soils. Compared to using fertilizers alone, the combined use of biochar and fertilizers further expands the enrichment effect and significantly reduces the leaching of fertilizers into deeper layers. At the same time, the application of biochar also improved soil properties, including an increase in electrical conductivity and organic matter content, as well as an increase in soil enzyme activity. On the other hand, the application of biochar also increases the activity of antioxidant enzymes and the content of osmoregulation substances in plants, reducing the environmental stress that plants are subjected to. Therefore, our results indicate that biochar can reduce the leaching of fertilizers into deep soil layers, improve soil properties, and promotes the growth of Miscanthus in saline alkali soils.
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James, Jason, Warren Devine, Rob Harrison und Thomas Terry. „Deep Soil Carbon: Quantification and Modeling in Subsurface Layers“. Soil Science Society of America Journal 78, S1 (2014): S1—S10. http://dx.doi.org/10.2136/sssaj2013.06.0245nafsc.
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Mo, Wei, Zhiliang Wang, You Li, Jianjun Guo und Runzhi Zhang. „Faunal communities of deep soil layers in suburban Beijing“. Biodiversity Science 26, Nr. 3 (2018): 248–57. http://dx.doi.org/10.17520/biods.2018027.
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Amenu, G. G., und P. Kumar. „A model for hydraulic redistribution incorporating coupled soil-root moisture transport“. Hydrology and Earth System Sciences Discussions 4, Nr. 5 (04.10.2007): 3719–69. http://dx.doi.org/10.5194/hessd-4-3719-2007.
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Abstract. One of the adaptive strategies of vegetation, particularly in water limited ecosystems, is the development of deep roots and the use of hydraulic redistribution which enables them to make optimal use of resources available throughout the soil column. Hydraulic redistribution refers to roots acting as a preferential pathway for the movement of water from wet to dry soil layers driven by the moisture gradient – be it from the shallow to deep layers or vice versa. This occurs during the nighttime while during the daytime moisture movement is driven to fulfill the transpiration demand at the canopy. In this study, we develop a model to investigate the effect of hydraulic redistribution by deep roots on the terrestrial climatology. Sierra Nevada eco-region is chosen as the study site which has wet winters and dry summers. Hydraulic redistribution enables the movement of moisture from the upper soil layers to deeper zones during the wet months and this moisture is then available to meet the transpiration demand during the late dry season. It results in significant alteration of the profiles of soil moisture and water uptake as well as increase in the canopy transpiration, carbon assimilation, and the associated water-use-efficiency during the dry summer season. This also makes the presence of roots in deeper soil layers much more important than their proportional abundance would otherwise dictate. Comparison with observations of latent heat from a flux tower demonstrates improved predictability and provides validation of the model results. Hydraulic redistribution serves as a mechanism for the interaction between the variability of deep layer soil-moisture and the land-surface climatology and could have significant implications for seasonal and sub-seasonal climate prediction.
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Amenu, G. G., und P. Kumar. „A model for hydraulic redistribution incorporating coupled soil-root moisture transport“. Hydrology and Earth System Sciences 12, Nr. 1 (24.01.2008): 55–74. http://dx.doi.org/10.5194/hess-12-55-2008.
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Abstract. One of the adaptive strategies of vegetation, particularly in water limited ecosystems, is the development of deep roots and the use of hydraulic redistribution which enables them to make optimal use of resources available throughout the soil column. Hydraulic redistribution refers to roots acting as a preferential pathway for the movement of water from wet to dry soil layers driven by the moisture gradient – be it from the shallow to deep layers or vice versa. This occurs during the nighttime while during the daytime moisture movement is driven to fulfill the transpiration demand at the canopy. In this study, we develop a model to investigate the effect of hydraulic redistribution by deep roots on the terrestrial climatology. Sierra Nevada eco-region is chosen as the study site which has wet winters and dry summers. Hydraulic redistribution enables the movement of moisture from the upper soil layers to deeper zones during the wet months and this moisture is then available to meet the transpiration demand during the late dry season. It results in significant alteration of the profiles of soil moisture and water uptake as well as increase in the canopy transpiration, carbon assimilation, and the associated water-use-efficiency during the dry summer season. This also makes the presence of roots in deeper soil layers much more important than their proportional abundance would otherwise dictate. Comparison with observations of latent heat from a flux tower demonstrates improved predictability and provides validation of the model results. Hydraulic redistribution serves as a mechanism for the interaction between the variability of deep layer soil-moisture and the land-surface climatology and could have significant implications for seasonal and sub-seasonal climate prediction.
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Tiecher, Tadeu Luis, Carlos Alberto Ceretta, Jucinei José Comin, Eduardo Girotto, Alcione Miotto, Marcel Pires de Moraes, Lucas Benedet et al. „Forms and accumulation of copper and zinc in a sandy typic hapludalf soil after long-term application of pig slurry and deep litter“. Revista Brasileira de Ciência do Solo 37, Nr. 3 (Juni 2013): 812–24. http://dx.doi.org/10.1590/s0100-06832013000300028.
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Successive applications of pig slurry and pig deep litter may lead to an accumulation of copper (Cu) and zinc (Zn) fractions in the soil profile. The objective of this study was to evaluate the Cu and Zn forms and accumulation in a Sandy Typic Hapludalf soil after long-term application of pig slurry and deep litter. In March 2010, eight years after initiating an experiment in Braço do Norte, Santa Catarina (SC), Brazil, on a Sandy Typic Hapludalf soil, soil samples were collected from the 0-2.5, 2.5-5.0, 5-10 and 10-15 cm layers in treatments consisting of no manure application (control) and with applications of pig slurry and deep litter at two levels: the single and double rate of N requirement for maize and black oat succession. The soil was dried, ground in an agate mortar and analyzed for Cu and Zn contents by 0.01 mol L-1 EDTA and chemically fractionated to determine Cu and Zn. The applications of Pig deep litter and slurry at doses equivalent to 90 kg ha-1 N increased the contents of available Cu and Zn in the surface soil layer, if the double of this dose was applied in pig deep litter or double this dose in pig slurry, Cu and Zn migrated to a depth of 15 cm. Copper is accumulated mainly in the organic and residual fractions, and zinc preferentially in the fraction linked to clay minerals, especially in the surface soil layers.
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Sun, Wei Feng, Li Ping Jing, Yan Zou, Ning Bo Yang und Yong Qiang Li. „Shaking Table Test to Underground Structures in Layered Foundation“. Applied Mechanics and Materials 353-356 (August 2013): 1461–65. http://dx.doi.org/10.4028/www.scientific.net/amm.353-356.1461.
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A three-story underground structure shaking table test had been carried on to study the earthquake damage mechanism of underground structure in layered foundation. The test model was similar to typical subway station according to a certain similarity ratio, and the soils were disturbed sandy soil and silty clay dug from the site of Harbin subway. Shaking table tests to this typical model in silty clay and alternating layers of clay and sand were performed to reveal the effect of different layered soils. Results show that the sandy soil layer can reduce the damage of the soil and underground structure, the damage of underground structure is mainly controlled by displacement of the surrounding soil, and the response of shallow buried underground structure is larger than deep buried.
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Zhao, Zhenyu, Guodong Tang, Jian Wang, Yanping Liu und Yong Gao. „Soil Moisture Distribution and Time Stability of Aerially Sown Shrubland in the Northeastern Margin of Tengger Desert (China)“. Water 15, Nr. 20 (12.10.2023): 3562. http://dx.doi.org/10.3390/w15203562.
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Considering the importance of soil moisture in hydrological processes, it is crucial to understand the water distribution and time stability of different aerial shrub soils. There are few studies on the soil moisture of aerial vegetation in the northeastern margin of the Tengger Desert. Based on long-term monitoring data from the aerial seeding area in the northeastern margin of the Tengger Desert, the distribution characteristics of soil moisture and the temporal stability of soil moisture were studied. From June to October 2022, the soil moisture monitoring instrument WatchDog was used to monitor the long-term soil moisture changes (0–200 cm) in the four aerial afforestation plots of Hedysarum scoparium, mixed forest land (Hedysarum scoparium dominant species), mixed forest land (Calligonum mongolicum dominant species), and Calligonum mongolicum. The Spearman rank correlation coefficient was used to study the temporal stability of soil moisture in the four plots. Rainfall data were collected through small weather stations. The results show that the average soil water storage of four kinds of aerial shrub land in the study area was the highest in August, and the average soil water storage of different forest lands was different. The soil water content of the surface layer (0–30 cm) fluctuated the most in different months. The variation in soil water content in the shallow layer (30–100 cm) was smaller than that in the surface layer. The fluctuation of soil water content in the middle layer (100–150 cm) and deep layer (150–200 cm) was relatively stable. There was no strong variability in soil moisture content, and the temporal variation coefficient of surface soil moisture was the highest (31.44–39.8%), which showed moderate variability. The temporal variation coefficient of soil moisture in the shallow, middle and deep layers of all kinds of plots was significantly reduced, and the soil moisture stability of different aerial shrub land was the same. Spearman rank correlation analysis showed that the spatial pattern of soil water content in the surface layer (0–30 cm) and deep layer (150–200 cm) was more stable over time, that is, the temporal stability of soil water content was higher, and the temporal stability of soil water content in the middle and shallow layers of different types of shrub land was different. The research results help us to understand the soil hydrological process in the aerial seeding afforestation area in the northeastern margin of Tengger Desert, rationally arrange soil moisture monitoring points, efficiently manage and utilize water resources in the aerial seeding area, and provide a theoretical basis for local vegetation restoration and the optimization of the ecological environment.
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Zheng, Ce, Yudong Lu, Xiuhua Liu, Jiří Šimůnek, Yijian Zeng, Changchun Shi und Huanhuan Li. „In-Situ Monitoring and Characteristic Analysis of Freezing-Thawing Cycles in a Deep Vadose Zone“. Water 12, Nr. 5 (29.04.2020): 1261. http://dx.doi.org/10.3390/w12051261.
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Freeze-thaw cycles play a critical role in affecting ecosystem services in arid regions. Monitoring studies of soil temperature and moisture during a freeze-thaw process can generate data for research on the coupled movement of water, vapor, and heat during the freezing-thawing period which can, in turn, provide theoretical guidance for rational irrigation practices and ecological protection. In this study, the soil temperature and moisture changes in the deep vadose zone were observed by in-situ monitoring from November 2017 to March 2018 in the Mu Us Desert. The results showed that changes in soil temperatures and temperature gradients were largest in soil layers above the 100-cm depth, and variations decreased with soil depth. The relationship between soil temperature and unfrozen water content can be depicted well by both theoretical and empirical models. Due to gradients of the matric potential and temperature, soil water flowed from deeper soil layers towards the frozen soil, increasing the total water content at the freezing front. The vapor flux, which was affected mainly by temperature, showed diurnal variations in the shallow 20-cm soil layer, and its rate and variations decreased gradually with increasing soil depths. The freeze-thaw process can be divided into three stages: the initial freezing stage, the downward freezing stage, and the thawing stage. The upward vapor flux contributed to the formation of the frozen layer during the freezing process.
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Zhong, Rong, Zhaolan Zi, Peiru Wang, Hafeez Noor, Aixia Ren, Yongkang Ren, Min Sun und Zhiqiang Gao. „Effects of Five Consecutive Years of Fallow Tillage on Soil Microbial Community Structure and Winter Wheat Yield“. Agronomy 13, Nr. 1 (11.01.2023): 224. http://dx.doi.org/10.3390/agronomy13010224.
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To evaluate the effects of long-term fallow tillage on soil microbial community structure in different soil layers and winter wheat yield, we conducted a 5-year long-term field experiment in the Loess Plateau, China, using three fallow tillage methods: no-tillage (NT), subsoiling tillage (ST), and deep plowing (DP). The soil physical and chemical properties, community structure, and composition of soil bacteria and fungi in the 0–20 cm and 20–40 cm soil layers, and winter wheat yield were analyzed. The results showed that, compared with DP, NT and ST significantly increased soil moisture content (SWC), soil organic carbon (SOC) content, and dissolved organic carbon (DOC) contents in 0–20 cm soil layer (p < 0.05), and significantly increased soil microbial community Shannon and Simpson index in 0–40 cm soil layer (p < 0.05). Compared with NT, ST and DP significantly increased SWC and SOC contents in 20–40 cm soil layer (p < 0.05). Actinobacteria and Ascomycota were the most abundant bacteria and fungi in the soil of the experimental site. Redundancy analysis further showed that soil physicochemical properties (SWC, SOC, DOC, and DON) were closely related to the microbial community. PICRUSt2 prediction results showed that DP increased the metabolic functional diversity of bacteria and fungi. ST and DP significantly increased the yield of winter wheat, and DP had the best effect. In conclusion, subsoiling tillage and deep plowing were beneficial to the accumulation and utilization of natural precipitation and the improvement of soil microbial community structure. Deep plowing was beneficial to the decomposition and metabolism of straw and organic fertilizer, and improved the catabolic ability of microbial community, thus increasing the yield of winter wheat.
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Fang, Xuening, Wenwu Zhao, Lixin Wang, Qiang Feng, Jingyi Ding, Yuanxin Liu und Xiao Zhang. „Variations of deep soil moisture under different vegetation types and influencing factors in a watershed of the Loess Plateau, China“. Hydrology and Earth System Sciences 20, Nr. 8 (12.08.2016): 3309–23. http://dx.doi.org/10.5194/hess-20-3309-2016.
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Abstract. Soil moisture in deep soil layers is a relatively stable water resource for vegetation growth in the semi-arid Loess Plateau of China. Characterizing the variations in deep soil moisture and its influencing factors at a moderate watershed scale is important to ensure the sustainability of vegetation restoration efforts. In this study, we focus on analyzing the variations and factors that influence the deep soil moisture (DSM) in 80–500 cm soil layers based on a soil moisture survey of the Ansai watershed in Yan'an in Shanxi Province. Our results can be divided into four main findings. (1) At the watershed scale, higher variations in the DSM occurred at 120–140 and 480–500 cm in the vertical direction. At the comparable depths, the variation in the DSM under native vegetation was much lower than that in human-managed vegetation and introduced vegetation. (2) The DSM in native vegetation and human-managed vegetation was significantly higher than that in introduced vegetation, and different degrees of soil desiccation occurred under all the introduced vegetation types. Caragana korshinskii and black locust caused the most serious desiccation. (3) Taking the DSM conditions of native vegetation as a reference, the DSM in this watershed could be divided into three layers: (i) a rainfall transpiration layer (80–220 cm); (ii) a transition layer (220–400 cm); and (iii) a stable layer (400–500 cm). (4) The factors influencing DSM at the watershed scale varied with vegetation types. The main local controls of the DSM variations were the soil particle composition and mean annual rainfall; human agricultural management measures can alter the soil bulk density, which contributes to higher DSM in farmland and apple orchards. The plant growth conditions, planting density, and litter water holding capacity of introduced vegetation showed significant relationships with the DSM. The results of this study are of practical significance for vegetation restoration strategies, especially for the choice of vegetation types, planting zones, and proper human management measures.
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Chen, Ji Hua, Ai Hong Zhou, Qiu Jun Wang und Ying Jiao Xu. „Study on the Influence of Seismic Wave Inputting Interface on the Earthquake Response of Deep Soft Sites“. Advanced Materials Research 243-249 (Mai 2011): 2523–28. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.2523.
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Earthquake effects of two typical deep soft sites selected from Tianjin(site 1)and Shanghai(site 2) are studied when the vertical inputting earthquake waves are located in different depth of sites. As far as the shear wave velocity of soil layers is concerned, seven kinds of soil layers in site 1 and eight soil layers in site 2 are selected as the vertical imputing interfaces of earthquake waves. Two acceleration waves recorded during Taft earthquake and Northbridge earthquake are selected, and the peak values of two waves are adjusted to be 0.35m/s2、0 70m /s2 and 0 98m /s2, respectively. The earthquake response of sites is calculated by SHAKE91 program. The results are compared to those of site when the input interfaces of earthquake waves are located in bedrock with shear wave velocity larger than 500m/s. The conclusion is as following: With the depth of input position (or shear wave velocity) increasing, the value of the ground acceleration response spectrum gradually closes to the actual data.; For the general building the soil layer with shear wave velocity for 400m/s or so can be chosen as the input interface, and the building with long natural vibration period should be treated seriously, and the soil layer whose shear wave velocity is above 500m/s can be chosen as the input interface.
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Jayawardane, NS, und SA Prathapar. „Effect of soil loosening on the hydraulic properties of a duplex soil“. Soil Research 30, Nr. 6 (1992): 959. http://dx.doi.org/10.1071/sr9920959.
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In a duplex, transitional red-brown earth, the relationships between hydraulic conductivity K, diffusivity D, soil water potential (�) and volumetric water content (�) in different soil layers were evaluated. Changes in these relationships and in the derived parameters; macroscopic capillary length and characteristic microscopic pore radius due to soil loosening were examined. Replicated large undisturbed and repacked cores of 0.75 m diameter and 1.35 m deep, located in a lysimeter, were used in this study. The K- � relationships were measured during steady upward flow from a watertable at different depths. The � � relationships were measured during a soil drying cycle. The undisturbed soil showed similar soil water characteristics (�-� curves) in all soil layers, at depths greater than 0.25 m. In contrast, K at high � was significantly lower in the upper subsoil, 'throttle' layer with high clay content, compared with the deeper soil layers. However, previous studies on a similar soil have also shown that factors other than pore size distribution, such as tortuosity and pore connectivity, markedly influence the hydraulic conductivity properties of clay soils. Coefficients in the log � on log� and in the log K(�) on log � relationships for all soil layers combined differed markedly from the coefficients for individual layers, indicating the need to measure these properties separately for different subsoil clay layers of this duplex soil. The repacking of the soil to a lower bulk density caused an increase in K at high � values. This was accompanied by a significant decrease in slope of the log � -log � relationship, from 17-21 to around 7, in the subsoil layers. The slope of the regression of log � - K(�) on log� changed from 24 in undisturbed soil to 9 in the repacked soil. This was mainly due to large changes in the � -�relationship, in combination with smaller changes in the K- � relationship. The decrease in diffusivity D with reduction in 0 was less marked in the repacked soil compared with the undisturbed soil. Thus, soil repacking shifted D(�) towards a constant value, for the range of � measured. This was mainly due to a slower rate of change in K with decrease in � on the repacked soil, combined with a compensating increase in d � /d� values. The calculated values of macroscopic capillary length decreased and characteristic pore radius increased, reflecting the changes in pore sizes and hydraulic conductivities due to soil loosening. However, at any given supply and antecedent �, the sorptivity was greater in the loosened soil due to larger changes in water content and hydraulic conductivities. The potential application of these soil properties in evaluating water flow in undisturbed or loosened soils is briefly discussed.
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Wang, Hong Bin, Lan Po Zhao und Wen Ju Liang. „Effect of Tillage Systems on Soil Profile Construction and Aggregate Stability in the Songliao Plain Cornbelt“. Applied Mechanics and Materials 130-134 (Oktober 2011): 3693–96. http://dx.doi.org/10.4028/www.scientific.net/amm.130-134.3693.
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In order to improve black soil productivity in the Songliao Plain Cornbelt, a new tillage technology “deep plowing with mulching” was established. The effects of different tillage systems (deep plowing with mulching, subsoiling tillage and conventional tillage) on soil profile construction and aggregate stability were studied in this paper. The results showed that different tillage systems led to different patterns of soil profile construction; the deep plowing with mulching, subsoiling tillage and conventional tillage formed “flat type”, “undulated type” and “groove type” in the interface between plow layer and plow pan, respectively. Compared with subsoiling tillage and conventional tillage, deep plowing with mulching significantly increased the contents of macroaggregates, and decreased the aggregate deterioration rate in the plow layers. This work demonstrates that the new tillage technology could promote soil aggregate stability and contribute to soil structure improvement in the Songliao Plain Cornbelt, China.
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Bao, Tiejun, Yunnuan Zheng, Ze Zhang, Heyang Sun, Ran Chao, Liqing Zhao, Hua Qing, Jie Yang und Frank Yonghong Li. „Divergent water sources of three dominant plant species following precipitation events in enclosed and mowing grassland steppes“. PeerJ 7 (10.10.2019): e7737. http://dx.doi.org/10.7717/peerj.7737.
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Understanding of the dynamic patterns of plant water use in a changing environment is one of foci in plant ecology, and can provide basis for the development of best practice in restoration and protection of ecosystem. We studied the water use sources of three coexisting dominant plant species Leymus chinensis, Stipa grandis and Cleistogenes squarrosa growing in both enclosed and mowing grassland in a typical steppe. The oxygen stable isotope ratios (δ18O) of soil water and stem water of these three species were determined, along with soil moisture, before and after precipitation events. The results showed that (1) mowing had no significant effect on the soil moisture and its δ18O, whereas precipitation significantly changed the soil moisture though no significant effect detected on its δ18O. (2) C. squarrosa took up water majorly from top soil layer due to its shaollow root system; L. chinensis took up relative more water from deep soil layer, and S. grandis took up water from the middle to deep soil layers. (3) L. chinensis and S. grandis in mowing grassland tended to take up more water from the upper soil layers following precipitation events, but showed no sensitive change in water source from soil profile following the precipitation in the enclosed grassland, indicating a more sensitive change of soil water sources for the two species in mowing than enclosed grassland. The differences in root morphology and precipitation distribution may partly explain the differences in their water uptake from different soil layers. Our results have important theoretical values for understanding the water competition among plants in fluctuating environment and under different land use in the typical steppe.
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Voron, V. P., V. H. Borysenko, I. O. Barabash, V. K. Muntian, O. M. Tkach, S. H. Sydorenko und Ye Ye Melnyk. „INFLUENCE OF THERMAL RADIATION ON FOREST SOILS“. Forestry and Forest Melioration, Nr. 132 (05.02.2018): 105–14. http://dx.doi.org/10.33220/1026-3365.132.2018.105.
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Forest fires are a powerful environmental factor that breaks the balance between the individual components of forest ecosystems. Thermal radiation is one type of the heat distribution during surface fires in forests. The objects of the study were forest soils, the monoliths of which were radiated with heat in specially created laboratory equipment. The facility allows detecting heat flux distribution in soils under laboratory conditions. The peculiarities of the processes for the typical soils for pine and oak stands were revealed. The highest temperature was observed on the surface of the soil. As the depth increased the temperature dropped. The most noticeable decrease was observed in a surface layer from 0 to 4 cm. The difference between the temperatures on the surface and at a depth of 10 cm could be 240–300°С for sandy soils and 260–400°С for gray forest soils. The temperature of deep soil layers increased even after stopping the heat radiation. The heating of dry sandy soils deep in to the profile occurs more strongly than in the moist sample. The sandy soil was found to warm deeper and more intensively as compared to loamy soils.
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Amenu, Geremew G., Praveen Kumar und Xin-Zhong Liang. „Interannual Variability of Deep-Layer Hydrologic Memory and Mechanisms of Its Influence on Surface Energy Fluxes“. Journal of Climate 18, Nr. 23 (01.12.2005): 5024–45. http://dx.doi.org/10.1175/jcli3590.1.
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Abstract The characteristics of deep-layer terrestrial memory are explored using observed soil moisture data and simulated soil temperature from the Illinois Climate Network stations. Both soil moisture and soil temperature are characterized by exponential decay in amplitude, linear lag in phase, and increasing persistence with depth. Using spectral analysis, four dominant low-frequency modes are identified in the soil moisture variability. These signals have periods of about 12, 17, 34, and 60 months, which correspond to annual cycle, (4/3) ENSO, quasi-biennial (QB) ENSO, and quasi-quadrennial (QQ) ENSO signals, respectively. For deep layers, the interannual modes are dominant over the annual cycle, and vice versa for the near-surface layer. There are inherently two mechanisms by which deep-layer moisture impacts the surface fluxes. First, its temporal variability sets the lower boundary condition for the transfer of moisture and heat fluxes from the surface. Second, this temporal variability influences the uptake of moisture by plant roots, resulting in the variability of the transpiration and, therefore, the entire energy balance. Initial results suggest that this second mechanism may be more predominant.
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Achat, D. L., M. R. Bakker, L. Augusto, D. Derrien, N. Gallegos, N. Lashchinskiy, S. Milin et al. „Phosphorus status of soils from contrasting forested ecosystems in southwestern Siberia: effects of microbiological and physicochemical properties“. Biogeosciences 10, Nr. 2 (04.02.2013): 733–52. http://dx.doi.org/10.5194/bg-10-733-2013.
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Abstract. The Siberian forest is a tremendous repository of terrestrial organic carbon (C), which may increase owing to climate change, potential increases in ecosystem productivity and hence C sequestration. Phosphorus (P) availability could limit the C sequestration potential, but tree roots may mine the soil deep to increase access to mineral P. Improved understanding and quantification of the processes controlling P availability in surface and deep soil layers of Siberian forest ecosystems are thus required. The objectives of the present study were to (1) evaluate P status of surface and deep soil horizons from different forest plots in southwestern Siberia and (2) assess the effects of physicochemical soil properties, microbiological activity and decomposition processes on soil P fractions and availability. Results revealed high concentrations of total P (879–1042 mg kg−1 in the surface mineral soils) and plant-available phosphate ions. In addition, plant-available phosphate ions accumulated in the subsoil, suggesting that deeper root systems may mine sufficient available P for the trees and the potentially enhanced growth and C sequestration, may not be P-limited. Because the proportions of total organic P were large in the surface soil layers (47–56% of total P), we concluded that decomposition processes may play a significant role in P availability. However, microbiological activity and decomposition processes varied between the study plots and higher microbiological activity resulted in smaller organic P fractions and consequently larger available inorganic P fractions. In the studied Siberian soils, P availability was also controlled by the physicochemical soil properties, namely Al and Fe oxides and soil pH.
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Cao, Zhiwei, Xi Fang, Wenhua Xiang, Pifeng Lei und Changhui Peng. „The Vertical Differences in the Change Rates and Controlling Factors of Soil Organic Carbon and Total Nitrogen along Vegetation Restoration in a Subtropical Area of China“. Sustainability 12, Nr. 16 (10.08.2020): 6443. http://dx.doi.org/10.3390/su12166443.
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The study was to investigate the change patterns of soil organic carbon (SOC), total nitrogen (TN), and soil C/N (C/N) in each soil sublayer along vegetation restoration in subtropical China. We collected soil samples in four typical plant communities along a restoration chronosequence. The soil physicochemical properties, fine root, and litter biomass were measured. Our results showed the proportion of SOC stocks (Cs) and TN stocks (Ns) in 20–30 and 30–40 cm soil layers increased, whereas that in 0–10 and 10–20 cm soil layers decreased. Different but well-constrained C/N was found among four restoration stages in each soil sublayer. The effect of soil factors was greater on the deep soil than the surface soil, while the effect of vegetation factors was just the opposite. Our study indicated that vegetation restoration promoted the uniform distribution of SOC and TN on the soil profile. The C/N was relatively stable along vegetation restoration in each soil layer. The accumulation of SOC and TN in the surface soil layer was controlled more by vegetation factors, while that in the lower layer was controlled by both vegetation factors and soil factors.
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Wang, Xuezhen, Hao Zhou und Jiangtao Ji. „Effect of Mounting Angle on Bending Subsoiling Tool–Soil Interactions Using DEM Simulations“. Agriculture 12, Nr. 11 (01.11.2022): 1830. http://dx.doi.org/10.3390/agriculture12111830.
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Mechanical subsoiling is an effective practice to promote better water infiltration and crop root development. The bending subsoiling tool (BST) is a primary subsoiling tool and is used to remove soil compaction and restore soil productivity. In this study, a discrete element model was developed and validated using laboratory soil bin tests to investigate the effects of the mounting angle of the BST (5°–33°) on soil disturbance behaviors and draft forces. The results show that the upheaval, failure and fragmentation of soil was achieved by successive shearing, uplifting, extrusion, tension and turning actions from the cutting share and cambered shank of the BST. Increasing soil depths gave smaller soil disturbance ranges in lateral, forward and upward directions. With an increase in mounting angle, both the draft force and soil rupture distance ratio initially decreased and then increased, whereas the soil loosening efficiency initially increased and then decreased. Overall, increasing the mounting angle of the BST from 5° to 33° gave a greater soil surface flatness that increased rapidly when the mounting angle increased from 26° to 33°. Appropriately increasing mounting angle of the BST from 5° to 26° could lift more moist soil from the deep seed and middle layers (5.0–15.5% increase) into the shallow seed layer (depth of <50 mm) without seriously affecting the mixing of the deep layer and other layers. Considering both the soil disturbance characteristics and draft forces, a mounting angle of 26° appeared to outperform the other angles.
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Padarian, José, Budiman Minasny und Alex B. McBratney. „Using deep learning for digital soil mapping“. SOIL 5, Nr. 1 (26.02.2019): 79–89. http://dx.doi.org/10.5194/soil-5-79-2019.
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Abstract. Digital soil mapping (DSM) has been widely used as a cost-effective method for generating soil maps. However, current DSM data representation rarely incorporates contextual information of the landscape. DSM models are usually calibrated using point observations intersected with spatially corresponding point covariates. Here, we demonstrate the use of the convolutional neural network (CNN) model that incorporates contextual information surrounding an observation to significantly improve the prediction accuracy over conventional DSM models. We describe a CNN model that takes inputs as images of covariates and explores spatial contextual information by finding non-linear local spatial relationships of neighbouring pixels. Unique features of the proposed model include input represented as a 3-D stack of images, data augmentation to reduce overfitting, and the simultaneous prediction of multiple outputs. Using a soil mapping example in Chile, the CNN model was trained to simultaneously predict soil organic carbon at multiples depths across the country. The results showed that, in this study, the CNN model reduced the error by 30 % compared with conventional techniques that only used point information of covariates. In the example of country-wide mapping at 100 m resolution, the neighbourhood size from 3 to 9 pixels is more effective than at a point location and larger neighbourhood sizes. In addition, the CNN model produces less prediction uncertainty and it is able to predict soil carbon at deeper soil layers more accurately. Because the CNN model takes the covariate represented as images, it offers a simple and effective framework for future DSM models.