Hu Jiang, Yong Li, Qiang Zou, Jun Zhang, Junfang Cui, Jianyi Cheng, Bin Zhou, Siyu Chen, Wentao Zhou, Hongkun Yao
The quantification of soil strength parameters is a crucial prerequisite for constructing physical models related to hydro-geophysical processes. However, due to ignoring soil spatial variability at different scales, traditional parameter assignment strategies, such as assigning values depending on land use classification or other classification systems, as well as those extrapolation and interpolation methods, are insufficient for physical process modelling. This work addressed this deficiency by proposing a method to derive stochastic soil strength parameters under hybrid machine learning (ML) models, taking into account the grain-size distribution (GSD) of soil with scaling invariance. The nonlinear connection between GSD parameters (derived from GSD curves, such as μ and Dc), moisture content, and soil shear strength parameters was fitted by the suggested hybrid ML model. An analysis of a case study revealed that: (i) the Multi-layer Perceptron optimized by the African Vulture Optimization Algorithm (AVOA) algorithm performs the best and can estimate the shear strength parameters of soil mass on vegetated slopes; (ii) all the selected ML models showed significant improvements in predictive performance after optimization with the AVOA, with R2 scores increasing by 24.72% for Support Vector Regressor, 34.04% for eXtreme Gradient Boosting, and 35.53% for Multi-layer Perceptron; and (iii) soil cohesion has an increasing relationship with the GSD parameter μ, while soil internal friction angle has a negative correlation with the grain-size parameter Dc. The proposed methodology can give predictions of soil shear strength distribution parameters, providing parameter support for the physical modelling of surface process dynamics.
土壤强度参数的量化是构建与水文地球物理过程相关的物理模型的重要前提。然而,由于忽略了不同尺度的土壤空间变异性,传统的参数赋值策略,如根据土地利用分类或其他分类系统赋值,以及那些外推法和内插法,都不足以用于物理过程建模。本研究针对这一不足,提出了一种在混合机器学习(ML)模型下推导随机土壤强度参数的方法,其中考虑到了具有比例不变性的土壤粒度分布(GSD)。建议的混合 ML 模型拟合了 GSD 参数(从 GSD 曲线得出,如 μ 和 Dc)、含水量和土壤抗剪强度参数之间的非线性联系。案例研究分析表明(i) 经非洲秃鹫优化算法(AVOA)优化的多层感知器性能最佳,可以估算植被边坡土体的剪切强度参数;(ii) 经 AVOA 优化后,所有选定的 ML 模型的预测性能都有显著提高,R2 分数提高了 24.(iii) 土壤内聚力与 GSD 参数 μ 呈递增关系,而土壤内摩擦角与粒度参数 Dc 呈负相关关系。所提出的方法可预测土壤剪切强度分布参数,为地表过程动力学物理建模提供参数支持。
{"title":"A GSD-driven approach to deriving stochastic soil strength parameters under hybrid machine learning models","authors":"Hu Jiang, Yong Li, Qiang Zou, Jun Zhang, Junfang Cui, Jianyi Cheng, Bin Zhou, Siyu Chen, Wentao Zhou, Hongkun Yao","doi":"10.1111/ejss.70009","DOIUrl":"10.1111/ejss.70009","url":null,"abstract":"<p>The quantification of soil strength parameters is a crucial prerequisite for constructing physical models related to hydro-geophysical processes. However, due to ignoring soil spatial variability at different scales, traditional parameter assignment strategies, such as assigning values depending on land use classification or other classification systems, as well as those extrapolation and interpolation methods, are insufficient for physical process modelling. This work addressed this deficiency by proposing a method to derive stochastic soil strength parameters under hybrid machine learning (ML) models, taking into account the grain-size distribution (GSD) of soil with scaling invariance. The nonlinear connection between GSD parameters (derived from GSD curves, such as <i>μ</i> and <i>D</i><sub>c</sub>), moisture content, and soil shear strength parameters was fitted by the suggested hybrid ML model. An analysis of a case study revealed that: (i) the Multi-layer Perceptron optimized by the African Vulture Optimization Algorithm (AVOA) algorithm performs the best and can estimate the shear strength parameters of soil mass on vegetated slopes; (ii) all the selected ML models showed significant improvements in predictive performance after optimization with the AVOA, with <i>R</i><sup>2</sup> scores increasing by 24.72% for Support Vector Regressor, 34.04% for eXtreme Gradient Boosting, and 35.53% for Multi-layer Perceptron; and (iii) soil cohesion has an increasing relationship with the GSD parameter <i>μ</i>, while soil internal friction angle has a negative correlation with the grain-size parameter <i>D</i><sub>c</sub>. The proposed methodology can give predictions of soil shear strength distribution parameters, providing parameter support for the physical modelling of surface process dynamics.</p>","PeriodicalId":12043,"journal":{"name":"European Journal of Soil Science","volume":"75 6","pages":""},"PeriodicalIF":4.0,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142597702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mélody Rousseau, Andjin Siegenthaler, Andrew K. Skidmore, G. Arjen de Groot, Ivo Laros
Despite a decrease in industrial nitrogen and sulfur deposition over recent decades, soil acidification remains a persistent challenge to European forest health, especially in regions of intense agriculture and urbanisation. Using topsoil eDNA metabarcoding and functional annotations from a sample of 49 plots (each 30 × 30 m) located in The Netherlands and Germany, we investigated the effect of severe acidification on bacterial taxonomic diversity under different forest types and explored potential functional implications for nutrient cycling. Furthermore, we assessed which soil parameters known to influence soil bacterial communities affect these acidophilic communities. Here, we are the first to demonstrate under natural conditions that soil bacterial diversity in extremely acidic soils (pH <4.5) continues to decline similarly across forest types as pH further decreases under intensifying human activity. Our results confirmed pH as the key driver of soil bacterial communities, even in extremely acidic soils. Ongoing severe acidification continues to reduce bacterial communities, favouring taxa adapted to extreme acidity and primarily involved in recalcitrant carbon-degradation compounds (e.g. cellulolysis potential = 0.78%–9.99%) while simultaneously diminishing taxa associated with nitrogen cycling (e.g. fixation potential = 6.72%–0.00%). Altogether, our findings indicate a further decline in bacterial diversity in already extremely acidic soils, likely disrupting nutrient cycling through changes in immobilisation and mineralisation processes. Our study highlights the continuous acidification of European temperate forests to extremely low pH levels, further disrupting forest ecosystem functioning. The significant reduction in bacterial diversity under such a severe acidification gradient, as demonstrated here, underscores the necessity to include severely acidified forests in conservation programmes and monitoring to prevent further degradation of European soils beyond repair.
{"title":"Further reduction in soil bacterial diversity under severe acidification in European temperate forests","authors":"Mélody Rousseau, Andjin Siegenthaler, Andrew K. Skidmore, G. Arjen de Groot, Ivo Laros","doi":"10.1111/ejss.70005","DOIUrl":"10.1111/ejss.70005","url":null,"abstract":"<p>Despite a decrease in industrial nitrogen and sulfur deposition over recent decades, soil acidification remains a persistent challenge to European forest health, especially in regions of intense agriculture and urbanisation. Using topsoil eDNA metabarcoding and functional annotations from a sample of 49 plots (each 30 × 30 m) located in The Netherlands and Germany, we investigated the effect of severe acidification on bacterial taxonomic diversity under different forest types and explored potential functional implications for nutrient cycling. Furthermore, we assessed which soil parameters known to influence soil bacterial communities affect these acidophilic communities. Here, we are the first to demonstrate under natural conditions that soil bacterial diversity in extremely acidic soils (pH <4.5) continues to decline similarly across forest types as pH further decreases under intensifying human activity. Our results confirmed pH as the key driver of soil bacterial communities, even in extremely acidic soils. Ongoing severe acidification continues to reduce bacterial communities, favouring taxa adapted to extreme acidity and primarily involved in recalcitrant carbon-degradation compounds (e.g. cellulolysis potential = 0.78%–9.99%) while simultaneously diminishing taxa associated with nitrogen cycling (e.g. fixation potential = 6.72%–0.00%). Altogether, our findings indicate a further decline in bacterial diversity in already extremely acidic soils, likely disrupting nutrient cycling through changes in immobilisation and mineralisation processes. Our study highlights the continuous acidification of European temperate forests to extremely low pH levels, further disrupting forest ecosystem functioning. The significant reduction in bacterial diversity under such a severe acidification gradient, as demonstrated here, underscores the necessity to include severely acidified forests in conservation programmes and monitoring to prevent further degradation of European soils beyond repair.</p>","PeriodicalId":12043,"journal":{"name":"European Journal of Soil Science","volume":"75 6","pages":""},"PeriodicalIF":4.0,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/ejss.70005","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142597706","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Coastal wetland soils are frequently underlain by sulfidic materials. Sea level fluctuations can lead to oxidation of sulfidic materials in acid sulfate soils (ASS) and increased acidity which mobilises trace metals when water levels are low, and inundation of coastal wetland soils and reformation of sulfidic materials when water levels are high. We measured the effect of surface water level fluctuations in soils from coastal wetland sites under four different vegetation types: Apium gravedens (AG), Leptospermum lanigerum (LL), Phragmites australis (PA) and Paspalum distichum (PD) on an estuarine floodplain in southern Australia. We assessed effects of fluctuating water levels on reduced inorganic sulfur (RIS) in terms of acid volatile sulfide (AVS), chromium reducible sulfur (CRS) and trace metals (Fe, Al, Mn, Zn, Ni). Intact soil cores were incubated under dry, flooded and wet–dry cycle treatments of 14 days for a total of 56 days. The flooded treatment increased RIS concentrations in most depths in the AG, PA and PD sites. Lower CRS concentrations occurred in all sites in the dry treatment due to oxidation of sulfidic materials when the surface layer was exposed to lower water levels. CRS was positively correlated with SOC in all treatments. The highest net acidity occurred in the dry treatment and lowest occurred in the flooded treatment in most sites. Inundation with seawater caused SO42− reduction and decreased soluble Fe in the PA and PD sites. General decreases in Al, Zn and Ni concentrations in flooded treatments may have been due to adsorption onto colloids or co-precipitation with slight increases in pH. SO42− concentrations decreased in the LL, PA and PD sites in the flooded treatment due to reformation of pyrite. In general, accumulation of RIS in soils under different vegetation types following brackish water inundation varied according to vegetation type, which may be linked to differences in organic material input and particle size distribution. Geochemical characteristics reflected whether oxidation or reduction processes dominated at each site in the wet–dry cycle treatments, with oxidation dominating in the LL and PA sites and reduction dominating in the AG and PD sites. This is likely due to more readily decomposable organic matter forming sulfidic materials during short periods of inundation.
{"title":"Effect of brackish water inundation on temperate coastal acid sulfate soils under different vegetation types","authors":"Chang Xu, Rahul Ram, Vanessa N. L. Wong","doi":"10.1111/ejss.70008","DOIUrl":"https://doi.org/10.1111/ejss.70008","url":null,"abstract":"<p>Coastal wetland soils are frequently underlain by sulfidic materials. Sea level fluctuations can lead to oxidation of sulfidic materials in acid sulfate soils (ASS) and increased acidity which mobilises trace metals when water levels are low, and inundation of coastal wetland soils and reformation of sulfidic materials when water levels are high. We measured the effect of surface water level fluctuations in soils from coastal wetland sites under four different vegetation types: <i>Apium gravedens</i> (AG), <i>Leptospermum lanigerum</i> (LL), <i>Phragmites australis</i> (PA) and <i>Paspalum distichum</i> (PD) on an estuarine floodplain in southern Australia. We assessed effects of fluctuating water levels on reduced inorganic sulfur (RIS) in terms of acid volatile sulfide (AVS), chromium reducible sulfur (CRS) and trace metals (Fe, Al, Mn, Zn, Ni). Intact soil cores were incubated under dry, flooded and wet–dry cycle treatments of 14 days for a total of 56 days. The flooded treatment increased RIS concentrations in most depths in the AG, PA and PD sites. Lower CRS concentrations occurred in all sites in the dry treatment due to oxidation of sulfidic materials when the surface layer was exposed to lower water levels. CRS was positively correlated with SOC in all treatments. The highest net acidity occurred in the dry treatment and lowest occurred in the flooded treatment in most sites. Inundation with seawater caused SO<sub>4</sub><sup>2−</sup> reduction and decreased soluble Fe in the PA and PD sites. General decreases in Al, Zn and Ni concentrations in flooded treatments may have been due to adsorption onto colloids or co-precipitation with slight increases in pH. SO<sub>4</sub><sup>2−</sup> concentrations decreased in the LL, PA and PD sites in the flooded treatment due to reformation of pyrite. In general, accumulation of RIS in soils under different vegetation types following brackish water inundation varied according to vegetation type, which may be linked to differences in organic material input and particle size distribution. Geochemical characteristics reflected whether oxidation or reduction processes dominated at each site in the wet–dry cycle treatments, with oxidation dominating in the LL and PA sites and reduction dominating in the AG and PD sites. This is likely due to more readily decomposable organic matter forming sulfidic materials during short periods of inundation.</p>","PeriodicalId":12043,"journal":{"name":"European Journal of Soil Science","volume":"75 6","pages":""},"PeriodicalIF":4.0,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142588144","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Haimei Lei, Nisha Bao, Sihan Peng, Xiaoyan Yang, Zhiwei Lu
The non-Lambertian surface features varying particle size and discrete distribution, resulting in reflectance to be unevenly distributed in different directions. Mine soil with a high content of coarse particles and non-uniform particle distribution exhibits significant non-Lambertian properties on its surface. Consequently, not only vertical observation of the reflectance spectra but also multi-angle reflectance spectra are related to the physical and chemical properties (e.g. soil organic carbon, moisture content and particle size) of mine soil. Understanding the bidirectional reflectance distribution of mine soil with various particle sizes is essential for accurately estimating soil properties using spectroscopy. Current estimations of soil properties using spectroscopy mainly focus on vertical observations, overlooking the bidirectional reflectance characteristics. This study reports the bidirectional reflectance distribution of mine soil with various particle sizes. Furthermore, the performance of different bidirectional reflectance distribution function (BRDF) models in simulating the bidirectional reflectance of mine soil with various particle sizes was evaluated. Soil samples from three typical mine areas were collected and sieved into seven particle sizes ranging from 25 to 3500 μm. The bidirectional reflectance in the Vis–NIR wavelength region was measured in a laboratory using the Northeastern University bidirectional reflectance measurement system. The performance of five BRDF models (isotropic multiple scattering approximation, anisotropic multiple scattering approximation, H2008, H2012 and SOILSPECT) in modelling the bidirectional reflectance distribution of mine soil with different particle sizes was compared. Sobol's sensitivity indices were used to quantify the contributions of the parameters in the BRDF models. The results showed that (1) small mine soil particles (25 μm) exhibited greater reflectance than large particles (3500 μm). Large particles (3500 μm) exhibited backward scattering, whereas small particles (25 μm) exhibited extremely forward scattering characteristics because of the high silicon dioxide content; (2) the SOILSPECT model outperformed the other BRDF models in simulating the bidirectional reflectance of mine soil and had the smallest root mean square error (0.004–0.04); (3) the single-scattering albedo (ɷ) parameter had the greatest contribution in the SOILSPECT model. Four parameters in the phase function (b, b′, c and c′) effectively indicated the scattering behaviour of mine soil with different particle sizes. These findings improve our understanding of the scattering characteristics of mine soil with various particle sizes and can be used to improve the accuracy of extracting particle size and other soil properties from mine soil.
{"title":"Quantitative characterization of bidirectional reflectance distribution of mine soil using physical models","authors":"Haimei Lei, Nisha Bao, Sihan Peng, Xiaoyan Yang, Zhiwei Lu","doi":"10.1111/ejss.70003","DOIUrl":"10.1111/ejss.70003","url":null,"abstract":"<p>The non-Lambertian surface features varying particle size and discrete distribution, resulting in reflectance to be unevenly distributed in different directions. Mine soil with a high content of coarse particles and non-uniform particle distribution exhibits significant non-Lambertian properties on its surface. Consequently, not only vertical observation of the reflectance spectra but also multi-angle reflectance spectra are related to the physical and chemical properties (e.g. soil organic carbon, moisture content and particle size) of mine soil. Understanding the bidirectional reflectance distribution of mine soil with various particle sizes is essential for accurately estimating soil properties using spectroscopy. Current estimations of soil properties using spectroscopy mainly focus on vertical observations, overlooking the bidirectional reflectance characteristics. This study reports the bidirectional reflectance distribution of mine soil with various particle sizes. Furthermore, the performance of different bidirectional reflectance distribution function (BRDF) models in simulating the bidirectional reflectance of mine soil with various particle sizes was evaluated. Soil samples from three typical mine areas were collected and sieved into seven particle sizes ranging from 25 to 3500 μm. The bidirectional reflectance in the Vis–NIR wavelength region was measured in a laboratory using the Northeastern University bidirectional reflectance measurement system. The performance of five BRDF models (isotropic multiple scattering approximation, anisotropic multiple scattering approximation, H2008, H2012 and SOILSPECT) in modelling the bidirectional reflectance distribution of mine soil with different particle sizes was compared. Sobol's sensitivity indices were used to quantify the contributions of the parameters in the BRDF models. The results showed that (1) small mine soil particles (25 μm) exhibited greater reflectance than large particles (3500 μm). Large particles (3500 μm) exhibited backward scattering, whereas small particles (25 μm) exhibited extremely forward scattering characteristics because of the high silicon dioxide content; (2) the SOILSPECT model outperformed the other BRDF models in simulating the bidirectional reflectance of mine soil and had the smallest root mean square error (0.004–0.04); (3) the single-scattering albedo (<i>ɷ</i>) parameter had the greatest contribution in the SOILSPECT model. Four parameters in the phase function (<i>b</i>, <i>b</i>′, <i>c</i> and <i>c</i>′) effectively indicated the scattering behaviour of mine soil with different particle sizes. These findings improve our understanding of the scattering characteristics of mine soil with various particle sizes and can be used to improve the accuracy of extracting particle size and other soil properties from mine soil.</p>","PeriodicalId":12043,"journal":{"name":"European Journal of Soil Science","volume":"75 6","pages":""},"PeriodicalIF":4.0,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142594755","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Biocrusts are a critical surface cover in global drylands, but knowledge about their influences on surface soil thermal properties are still lacking because it is quite challenging to make accurate thermal property measurements for biocrust layers, which are only millimetres thick. In this study, we repacked biocrust layers (moss- and cyanobacteria-dominated, respectively) that had the same material as the original intact biocrusts but was more homogeneous and thicker. The thermal conductivity (λ), heat capacity (C) and thermal diffusivity (k) of the repacked and intact biocrusts were measured by the heat pulse (HP) technique at different mass water contents (θm) and mass ratios (Wt), and the differences between repacked and intact biocrusts were analysed. Our results show that biocrusts substantially alter the thermal properties of the soil surface. The average λ of moss (0.37 W m−1 K−1) and cyanobacteria biocrusts (0.90 W m−1 K−1) were reduced by 63.0% and 10.3% compared with bare soil (1.00 W m−1 K−1), respectively. Edge effects including heat loss and water evaporation caused the λ and k of the biocrusts to be underestimated, but the C to be overestimated. The differences in thermal properties were significant (p <0.001), except for the differences in thermal conductivity between repacked and intact cyanobacteria biocrusts, which were not significant (p = 0.379). Specifically, in the volumetric water content (θv) range of 0 to 20%, the λ and k of the repacked moss biocrusts were underestimated by 59.1% and 61.8%, respectively, and the C was overestimated by 23.9% compared with the intact moss biocrusts. The λ and k of the repacked cyanobacteria biocrusts were underestimated by 15.8% and 79.2%, respectively, and the C was overestimated by 34.8% compared with the intact cyanobacteria biocrusts at the θv range of 0 to 30%. Typically, this difference increased as the θv rises between repacked and intact biocrusts. Our new measurements provide evidence that the thermal properties of biocrusts were previously misjudged due to the measurement limitations imposed by their limited thickness when measured in situ. Biocrusts are likely more significant in regulating soil heat and temperature in drylands than was previously assumed.
生物簇是全球旱地的重要表层覆盖物,但由于生物簇层只有几毫米厚,要对其进行精确的热属性测量非常困难,因此有关生物簇对表层土壤热属性影响的知识仍然缺乏。在本研究中,我们对生物簇层(分别以苔藓和蓝藻为主)进行了重新包装,其材料与原始完整生物簇层相同,但更均匀、更厚。通过热脉冲(HP)技术测量了不同质量含水量(θm)和质量比(Wt)下重新包装的生物簇和完整生物簇的导热系数(λ)、热容量(C)和热扩散率(k),并分析了重新包装的生物簇和完整生物簇之间的差异。结果表明,生物簇极大地改变了土壤表面的热特性。与裸土(1.00 W m-1 K-1)相比,苔藓(0.37 W m-1 K-1)和蓝藻生物簇(0.90 W m-1 K-1)的平均λ分别降低了 63.0% 和 10.3%。热量损失和水分蒸发等边缘效应导致生物簇的λ和k被低估,但C被高估。除了重新包装的蓝藻生物簇与完整蓝藻生物簇之间的导热系数差异不显著(p = 0.379)外,其他热特性差异均显著(p <0.001)。具体而言,在体积含水量(θv)为0-20%的范围内,与完整的苔藓生物簇相比,重新包装的苔藓生物簇的λ和k分别被低估了59.1%和61.8%,C被高估了23.9%。与完整的蓝藻生物簇相比,在 θv 为 0 至 30% 的范围内,重新组合的蓝藻生物簇的λ 和 k 分别被低估了 15.8% 和 79.2%,C 被高估了 34.8%。通常情况下,随着重新包装的生物簇与完整生物簇之间 θv 值的增加,这一差异也会增大。我们的新测量结果提供了证据,证明生物簇的热特性以前曾被误判,这是因为在原位测量时,生物簇的厚度有限,测量受到限制。生物簇在调节旱地土壤热量和温度方面的作用可能比以前认为的更大。
{"title":"Overlooked biocrust impacts on surface soil thermal properties: Evidence from heat-pulse sensing on large volume samples","authors":"Junru Chen, Bo Xiao, Joshua Heitman","doi":"10.1111/ejss.70004","DOIUrl":"10.1111/ejss.70004","url":null,"abstract":"<p>Biocrusts are a critical surface cover in global drylands, but knowledge about their influences on surface soil thermal properties are still lacking because it is quite challenging to make accurate thermal property measurements for biocrust layers, which are only millimetres thick. In this study, we repacked biocrust layers (moss- and cyanobacteria-dominated, respectively) that had the same material as the original intact biocrusts but was more homogeneous and thicker. The thermal conductivity (<i>λ</i>), heat capacity (<i>C</i>) and thermal diffusivity (<i>k</i>) of the repacked and intact biocrusts were measured by the heat pulse (HP) technique at different mass water contents (<i>θ</i><sub>m</sub>) and mass ratios (<i>W</i><sub>t</sub>), and the differences between repacked and intact biocrusts were analysed. Our results show that biocrusts substantially alter the thermal properties of the soil surface. The average <i>λ</i> of moss (0.37 W m<sup>−1</sup> K<sup>−1</sup>) and cyanobacteria biocrusts (0.90 W m<sup>−1</sup> K<sup>−1</sup>) were reduced by 63.0% and 10.3% compared with bare soil (1.00 W m<sup>−1</sup> K<sup>−1</sup>), respectively. Edge effects including heat loss and water evaporation caused the <i>λ</i> and <i>k</i> of the biocrusts to be underestimated, but the <i>C</i> to be overestimated. The differences in thermal properties were significant (<i>p</i> <0.001), except for the differences in thermal conductivity between repacked and intact cyanobacteria biocrusts, which were not significant (<i>p</i> = 0.379). Specifically, in the volumetric water content (<i>θ</i><sub>v</sub>) range of 0 to 20%, the <i>λ</i> and <i>k</i> of the repacked moss biocrusts were underestimated by 59.1% and 61.8%, respectively, and the <i>C</i> was overestimated by 23.9% compared with the intact moss biocrusts. The <i>λ</i> and <i>k</i> of the repacked cyanobacteria biocrusts were underestimated by 15.8% and 79.2%, respectively, and the <i>C</i> was overestimated by 34.8% compared with the intact cyanobacteria biocrusts at the <i>θ</i><sub>v</sub> range of 0 to 30%. Typically, this difference increased as the <i>θ</i><sub>v</sub> rises between repacked and intact biocrusts. Our new measurements provide evidence that the thermal properties of biocrusts were previously misjudged due to the measurement limitations imposed by their limited thickness when measured in situ. Biocrusts are likely more significant in regulating soil heat and temperature in drylands than was previously assumed.</p>","PeriodicalId":12043,"journal":{"name":"European Journal of Soil Science","volume":"75 6","pages":""},"PeriodicalIF":4.0,"publicationDate":"2024-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142574530","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Suwei Xu, Yuhei Nakayama, Maia G. Rothman, Andrew J. Margenot
Agricultural management practices can profoundly influence soil phosphorus (P), with effects accumulating over time. To test the overarching hypothesis that soil P pools estimated by sequential fractionation would be altered by long-term agricultural practices, we used an experiment established in 1876 in the north-central US to quantify 145-year impacts of crop rotation (continuous maize [Zea mays L.], maize-soybean [Glycine max L. Merr.] and maize-oat [Avena sativa L.]-alfalfa [Medicago sativa L.]) and 117-year impacts of fertilization (unfertilized and fertilized) with rock phosphate, manure or synthetic fertilizer on soil P fractions at 15 cm intervals across 0–90 cm depth. Fertilization impacts on soil P were mostly limited to the surface (0–30 cm) depth, but extended to 90 cm depth under diverse rotations. Under fertilization, soil total P concentration increased by 51% at 0-30 cm while concomitantly decreasing by 30% at 60–90 cm compared to no fertilization, indicating that vertically stratified surface soil P accumulation and subsoil P depletion can co-occur even under positive P balances. Positive P balances (1222–1494 kg/ha) induced by fertilization enriched inorganic P (Pi) (+39% to 358%) and labile organic P (Po) fractions (+11%) while depleting non-labile Po fractions (−31%), with depletion increasing with the degree of crop diversification. Fertilization had minor impacts on P fractions beyond 30 cm depth, except for acid extractable Pi (HCl-Pi) depletion under continuous maize and maize-soybean rotations (−16% to −78%) and accumulation under maize-oat-alfalfa rotation (+41% to +84%) at 60–90 cm. In contrast, without fertilization, diversifying maize rotations with oat and alfalfa decreased HCl-Pi and residual P (−21% to −57%) but increased non-labile Po fractions (+54%), suggesting potential mining of non-labile Pi pools by deep-rooted legumes under nutrient limitation. The 1–2 orders of magnitude greater changes in stocks of P fractions than stocks of total P emphasize the importance of distinguishing P pools even with operational fractionation to fully capture changes in P cycling beyond total P stocks. Our study revealed that a positive P balance under 117 years of fertilization (i) enriched Pi and labile Po pools but (ii) depleted non-labile Po pools, (iii) largely at 0–30 cm, and (iv) non-labile Po depletion increased with crop diversification under 145-year rotation treatments.
农业管理方法会对土壤中的磷(P)产生深远的影响,这种影响会随着时间的推移而不断累积。为了验证通过顺序分馏法估算的土壤磷库会因长期农业实践而改变这一重要假设,我们使用了 1876 年在美国中北部进行的一项实验,以量化轮作(连作玉米[Zea mays L. ]、玉米-大豆[Glybine max L. Merr. ]和玉米-山羊[Avena mays L. ])145 年的影响。玉米-大豆[Glycine max L. Merr.]和玉米-山羊[Avena sativa L.]-紫花苜蓿[Medicago sativa L.])145 年的轮作影响,以及用磷矿石、粪肥或合成肥料施肥(未施肥和施肥)117 年对 0-90 厘米深度每隔 15 厘米土壤 P 分量的影响。施肥对土壤钾的影响主要局限于表层(0-30 厘米),但在不同的轮作条件下,施肥对土壤钾的影响扩展到 90 厘米深。与不施肥相比,施肥后 0-30 厘米处的土壤总磷浓度增加了 51%,而 60-90 厘米处的土壤总磷浓度同时减少了 30%,这表明即使在正磷平衡的情况下,垂直分层的表层土壤磷积累和底层土壤磷耗竭也会同时发生。施肥引起的正钾平衡(1222-1494 千克/公顷)富集了无机钾(Pi)(+39%-358%)和可溶性有机钾(Po)组分(+11%),同时消耗了非可溶性有机钾组分(-31%),消耗量随作物多样化程度而增加。施肥对 30 厘米深度以外的钾组分影响较小,但在连续玉米和玉米-大豆轮作下,酸提取钾(HCl-Pi)消耗(-16% 至 -78%),而在玉米-山羊-紫花苜蓿轮作下,钾在 60-90 厘米处积累(+41% 至 +84%)。相比之下,在不施肥的情况下,玉米与燕麦和苜蓿的多样化轮作减少了 HCl-Pi 和残余 P(-21% 至 -57%),但增加了非可吸收的 Po 部分(+54%),这表明在养分限制条件下,深根豆科植物可能会开采非可吸收的 Pi 池。钾馏分储量的变化比总钾储量的变化大 1-2 个数量级,这强调了即使进行操作分馏也要区分钾池的重要性,以全面捕捉总钾量以外的钾循环变化。我们的研究表明,在 117 年的施肥条件下,正 P 平衡(i)富集了 Pi 和可溶性 Po 池,但(ii)消耗了非可溶性 Po 池;(iii)主要在 0-30 厘米处;(iv)在 145 年的轮作处理下,非可溶性 Po 的消耗随着作物多样化而增加。
{"title":"Depth-dependent soil phosphorus alteration is independent of 145-year phosphorus balances","authors":"Suwei Xu, Yuhei Nakayama, Maia G. Rothman, Andrew J. Margenot","doi":"10.1111/ejss.70006","DOIUrl":"https://doi.org/10.1111/ejss.70006","url":null,"abstract":"<p>Agricultural management practices can profoundly influence soil phosphorus (P), with effects accumulating over time. To test the overarching hypothesis that soil P pools estimated by sequential fractionation would be altered by long-term agricultural practices, we used an experiment established in 1876 in the north-central US to quantify 145-year impacts of crop rotation (continuous maize [<i>Zea mays</i> L.], maize-soybean [<i>Glycine max</i> L. Merr.] and maize-oat [<i>Avena sativa</i> L.]-alfalfa [<i>Medicago sativa</i> L.]) and 117-year impacts of fertilization (unfertilized and fertilized) with rock phosphate, manure or synthetic fertilizer on soil P fractions at 15 cm intervals across 0–90 cm depth. Fertilization impacts on soil P were mostly limited to the surface (0–30 cm) depth, but extended to 90 cm depth under diverse rotations. Under fertilization, soil total P concentration increased by 51% at 0-30 cm while concomitantly decreasing by 30% at 60–90 cm compared to no fertilization, indicating that vertically stratified surface soil P accumulation and subsoil P depletion can co-occur even under positive P balances. Positive P balances (1222–1494 kg/ha) induced by fertilization enriched inorganic P (P<sub>i</sub>) (+39% to 358%) and labile organic P (P<sub>o</sub>) fractions (+11%) while depleting non-labile P<sub>o</sub> fractions (−31%), with depletion increasing with the degree of crop diversification. Fertilization had minor impacts on P fractions beyond 30 cm depth, except for acid extractable P<sub>i</sub> (HCl-P<sub>i</sub>) depletion under continuous maize and maize-soybean rotations (−16% to −78%) and accumulation under maize-oat-alfalfa rotation (+41% to +84%) at 60–90 cm. In contrast, without fertilization, diversifying maize rotations with oat and alfalfa decreased HCl-P<sub>i</sub> and residual P (−21% to −57%) but increased non-labile P<sub>o</sub> fractions (+54%), suggesting potential mining of non-labile P<sub>i</sub> pools by deep-rooted legumes under nutrient limitation. The 1–2 orders of magnitude greater changes in stocks of P fractions than stocks of total P emphasize the importance of distinguishing P pools even with operational fractionation to fully capture changes in P cycling beyond total P stocks. Our study revealed that a positive P balance under 117 years of fertilization (i) enriched P<sub>i</sub> and labile P<sub>o</sub> pools but (ii) depleted non-labile P<sub>o</sub> pools, (iii) largely at 0–30 cm, and (iv) non-labile P<sub>o</sub> depletion increased with crop diversification under 145-year rotation treatments.</p>","PeriodicalId":12043,"journal":{"name":"European Journal of Soil Science","volume":"75 6","pages":""},"PeriodicalIF":4.0,"publicationDate":"2024-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/ejss.70006","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142561737","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Chunping Zhang, Qi Li, Runqiu Feng, Ping Li, Jie Liu, Yunfeng Yang
In terrestrial ecosystems, resource availability and soil microbial biomass are substantially changed with ecological recovery. However, the shifts in resource stoichiometry and microbial biomass stoichiometry often do not align, leading to stoichiometric imbalance that constrains microbial growth and, consequently, affects plant community succession. The mechanisms by which soil microbes acclimate to these imbalances and how such adjustments influence plant community dynamics remain largely unexplored in alpine grasslands. To address these processes, we examined ecological stoichiometry during the secondary succession of zokor-disturbed grassland on the Qinghai–Tibet Plateau, China, utilizing a space-for-time substitution approach. Carbon (C), nitrogen (N) and phosphorus (P) contents across plant–soil–microbe and soil ecoenzymatic activities involved in soil microbial nutrient acquisition were measured. The results indicated that C:P and N:P imbalances between microbes and their plant resources intensified with the recovery of zokor-disturbed grassland. This led to phosphorus limitation in microbial growth, as indicated by the mean vector angles exceeding 45° and decreased threshold element ratio of C:P. In response, soil microbes increased their production of P-acquiring enzymes to mitigate P limitation. Through structural equation modelling (SEM), we found that the C:N:P ratios within the plant–soil–microbe systems explained 74.5% of the total variance in plant aboveground biomass. We concluded that maintaining balanced C:N:P stoichiometric ratios in plant–soil–microbe systems, facilitated by soil ecoenzymatic activities, enhances plant diversity and net primary productivity during the recovery of zokor-disturbed grassland.
{"title":"Ecosystem compartment stoichiometry drives the secondary succession processes of zokor-disturbed grassland","authors":"Chunping Zhang, Qi Li, Runqiu Feng, Ping Li, Jie Liu, Yunfeng Yang","doi":"10.1111/ejss.70000","DOIUrl":"10.1111/ejss.70000","url":null,"abstract":"<p>In terrestrial ecosystems, resource availability and soil microbial biomass are substantially changed with ecological recovery. However, the shifts in resource stoichiometry and microbial biomass stoichiometry often do not align, leading to stoichiometric imbalance that constrains microbial growth and, consequently, affects plant community succession. The mechanisms by which soil microbes acclimate to these imbalances and how such adjustments influence plant community dynamics remain largely unexplored in alpine grasslands. To address these processes, we examined ecological stoichiometry during the secondary succession of zokor-disturbed grassland on the Qinghai–Tibet Plateau, China, utilizing a space-for-time substitution approach. Carbon (C), nitrogen (N) and phosphorus (P) contents across plant–soil–microbe and soil ecoenzymatic activities involved in soil microbial nutrient acquisition were measured. The results indicated that C:P and N:P imbalances between microbes and their plant resources intensified with the recovery of zokor-disturbed grassland. This led to phosphorus limitation in microbial growth, as indicated by the mean vector angles exceeding 45° and decreased threshold element ratio of C:P. In response, soil microbes increased their production of P-acquiring enzymes to mitigate P limitation. Through structural equation modelling (SEM), we found that the C:N:P ratios within the plant–soil–microbe systems explained 74.5% of the total variance in plant aboveground biomass. We concluded that maintaining balanced C:N:P stoichiometric ratios in plant–soil–microbe systems, facilitated by soil ecoenzymatic activities, enhances plant diversity and net primary productivity during the recovery of zokor-disturbed grassland.</p>","PeriodicalId":12043,"journal":{"name":"European Journal of Soil Science","volume":"75 5","pages":""},"PeriodicalIF":4.0,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142519613","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dispersive soils, characterized by their poor resistance to water erosion and high sodium ion concentrations, pose a significant threat to both engineering and agricultural activities. Thus, the identification and improvement of dispersive soils are of paramount importance. There are several theories regarding the causes of soil dispersion, with the prevailing view attributing it to the expansion of the electrical double layer induced by sodium ions, which subsequently reduces the cohesion between soil particles. As a result, sodium indicators such as exchangeable sodium percentage (ESP), percentage sodium (PS), and sodium adsorption rate (SAR) are commonly employed in the identification of dispersive soils. Currently, in efforts to improve dispersive soils for both engineering and agricultural purposes, chemical and biological agents are being added to enhance the soil's erosion resistance and regulate the concentration of sodium ions. Although numerous reviews have been conducted on the identification and improvement of dispersive soils, they tend to focus on the identification methods and the types of improvers, often overlooking the applicability of identification methods, the economic costs and environmental impacts of improvers. In practical improvement, the accuracy of soil identification must be ensured first and foremost. The selection of improvers should not only prioritise efficacy but also undergo thorough analysis and evaluation from multiple perspectives. This paper, therefore, reviews the advantages and disadvantages of various identification methods and assesses the differences among improvers from economic and environmental standpoints, providing a comprehensive theoretical basis for the improvement of dispersive soils.
{"title":"Progress towards the identification and improvement of dispersive soils: A review","authors":"Xudong Zhang, Zhongxu Liu, Yan Han","doi":"10.1111/ejss.70002","DOIUrl":"10.1111/ejss.70002","url":null,"abstract":"<p>Dispersive soils, characterized by their poor resistance to water erosion and high sodium ion concentrations, pose a significant threat to both engineering and agricultural activities. Thus, the identification and improvement of dispersive soils are of paramount importance. There are several theories regarding the causes of soil dispersion, with the prevailing view attributing it to the expansion of the electrical double layer induced by sodium ions, which subsequently reduces the cohesion between soil particles. As a result, sodium indicators such as exchangeable sodium percentage (ESP), percentage sodium (PS), and sodium adsorption rate (SAR) are commonly employed in the identification of dispersive soils. Currently, in efforts to improve dispersive soils for both engineering and agricultural purposes, chemical and biological agents are being added to enhance the soil's erosion resistance and regulate the concentration of sodium ions. Although numerous reviews have been conducted on the identification and improvement of dispersive soils, they tend to focus on the identification methods and the types of improvers, often overlooking the applicability of identification methods, the economic costs and environmental impacts of improvers. In practical improvement, the accuracy of soil identification must be ensured first and foremost. The selection of improvers should not only prioritise efficacy but also undergo thorough analysis and evaluation from multiple perspectives. This paper, therefore, reviews the advantages and disadvantages of various identification methods and assesses the differences among improvers from economic and environmental standpoints, providing a comprehensive theoretical basis for the improvement of dispersive soils.</p>","PeriodicalId":12043,"journal":{"name":"European Journal of Soil Science","volume":"75 5","pages":""},"PeriodicalIF":4.0,"publicationDate":"2024-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142519611","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Arid and semi-arid lands are exceptionally sensitive to climate change. However, the application of phytolith analysis to these environments is hindered by the potential for lateral migration of phytoliths during wind erosion, which may affect the reliability of phytolith-based paleoenvironmental reconstructions. Moreover, there is a lack of quantitative studies of the dispersion and deposition of phytoliths by wind erosion. Here we apply Sutton's equation and theoretical models from the field of blown sand physics and engineering to quantify the lateral migration of various phytolith morphotypes in the surface soil of sand dunes in the Horqin Sandy Land in China. Phytolith morphotypes and concentrations were determined in addition to sedimentary organic matter content and grain size. Combined with the analysis of plant communities, these measurements were used to quantify the lateral migration of phytolith morphotypes, and the results were compared with theoretical models. We found that phytolith concentrations decreased exponentially under an annual average wind speed with distance from the surface source; specifically, a large proportion of lateral phytolith migration occurred within the distance of ~3–5 m. There were significant linear correlations between the phytolith concentration and other environmental factors. A comprehensive form of Sutton's equation was used to estimate that a relatively large proportion (8.35%) of short-cell phytoliths may migrate laterally on dunes that are vulnerable to wind erosion. However, large phytoliths are deposited almost in situ, and relatively limited lateral migration of wind-transported phytoliths occurs in the Horqin Sandy Land overall. Our results provide a theoretical model and practice template for the application of phytolith analysis to soil and sediments, especially as a proxy of past vegetation and ecological change in the Horqin Sandy Land, and other areas affected by wind erosion. Additionally, short-cell phytoliths in palaeoenvironmental contexts satisfy the criteria necessary to investigate the extent with frequent aeolian activity.
{"title":"Lateral migration differs between phytolith morphotypes on sand dune surfaces","authors":"Guihua Zhang, Dongmei Jie, Guizai Gao, Dehui Li, Nannan Li, Jiangyong Wang, Honghao Niu, Meng Meng, Ying Liu","doi":"10.1111/ejss.13579","DOIUrl":"10.1111/ejss.13579","url":null,"abstract":"<p>Arid and semi-arid lands are exceptionally sensitive to climate change. However, the application of phytolith analysis to these environments is hindered by the potential for lateral migration of phytoliths during wind erosion, which may affect the reliability of phytolith-based paleoenvironmental reconstructions. Moreover, there is a lack of quantitative studies of the dispersion and deposition of phytoliths by wind erosion. Here we apply Sutton's equation and theoretical models from the field of blown sand physics and engineering to quantify the lateral migration of various phytolith morphotypes in the surface soil of sand dunes in the Horqin Sandy Land in China. Phytolith morphotypes and concentrations were determined in addition to sedimentary organic matter content and grain size. Combined with the analysis of plant communities, these measurements were used to quantify the lateral migration of phytolith morphotypes, and the results were compared with theoretical models. We found that phytolith concentrations decreased exponentially under an annual average wind speed with distance from the surface source; specifically, a large proportion of lateral phytolith migration occurred within the distance of ~3–5 m. There were significant linear correlations between the phytolith concentration and other environmental factors. A comprehensive form of Sutton's equation was used to estimate that a relatively large proportion (8.35%) of short-cell phytoliths may migrate laterally on dunes that are vulnerable to wind erosion. However, large phytoliths are deposited almost in situ, and relatively limited lateral migration of wind-transported phytoliths occurs in the Horqin Sandy Land overall. Our results provide a theoretical model and practice template for the application of phytolith analysis to soil and sediments, especially as a proxy of past vegetation and ecological change in the Horqin Sandy Land, and other areas affected by wind erosion. Additionally, short-cell phytoliths in palaeoenvironmental contexts satisfy the criteria necessary to investigate the extent with frequent aeolian activity.</p>","PeriodicalId":12043,"journal":{"name":"European Journal of Soil Science","volume":"75 5","pages":""},"PeriodicalIF":4.0,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142490645","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Wenbin Zhu, Hongmeng Zhao, Yu Wang, Clayton R. Butterly, Hao Chen, Jiahui Yuan, Mingqing Liu, Qiuhui Chen, Longjiang Zhang, Lei Wang
Organic fertilization is considered an effective approach in promoting agricultural green development, dramatically affecting soil phosphorus (P) availability. Nonetheless, limited information is available on the comprehensive impact of full substitution of organic fertilizer for chemical fertilizer on P speciation, phytoavailability, and apparent balance throughout different rice-growth stages. To address this gap, a 5-year field experiment was conducted, implementing five organic P gradients ranging from 0 (P0), 70 (P70), 140 (P140), 210 (P210) to 280 (P280) kg P2O5 ha−1 of organic fertilizer. To assess P phytoavailability in the root zone with submillimetre spatial resolutions, this study employed techniques such as the one- and two-dimensional diffusive gradients in thin films (DGT) technique and the high-resolution soil solution sampling technology (HR-Peeper). The findings revealed that increasing P rates enhanced soil Olsen-P and biological-based P fractions across rice-growth stages, primarily driven by variation in mineral-associated P. Notably, the P140 treatment demonstrated the highest P uptake efficiency among the different rice-growth stages, with a significant increase in soil DGT-P, particularly in the 0–60 mm soil layer (p <0.05), providing tangible evidence for enhanced P uptake. Moreover, compared with higher P treatments (P210 and P280), the P140 treatment markedly increased P use efficiency by 31.7% and 99.0%, respectively (p <0.05). Further, with a high ratio of DGT-P to Peeper-P and a low apparent balance of P, organic fertilization at the rate of 140 kg P2O5 ha−1 effectively struck a balance between ensuring adequate P supply for yield stability and mitigating potential P loss risks. These results underscore the significance of optimal organic fertilization in enhancing agronomic benefits while reducing environmental risks. They offer valuable insights to support field P management strategies and government decision-making processes.
有机施肥被认为是促进农业绿色发展的有效方法,能显著影响土壤中磷(P)的供应。然而,关于有机肥完全替代化肥对水稻不同生长阶段磷的种类、植物可利用性和表观平衡的综合影响的信息还很有限。为了填补这一空白,我们开展了一项为期 5 年的田间试验,实施了五种有机钾梯度,有机肥从 0(P0)、70(P70)、140(P140)、210(P210)到 280(P280)千克 P2O5 ha-1。为了以亚毫米空间分辨率评估根区的钾植物利用率,本研究采用了一维和二维薄膜扩散梯度(DGT)技术以及高分辨率土壤溶液取样技术(HR-Peeper)。研究结果表明,在不同的水稻生长阶段,增加钾的比率会提高土壤中的奥尔森钾和生物钾组分,这主要是由矿质钾的变化驱动的。值得注意的是,在不同的水稻生长阶段,P140 处理的钾吸收效率最高,土壤中的 DGT-P 显著增加,尤其是在 0-60 毫米的土层中(p <0.05),为钾吸收的提高提供了切实的证据。此外,与高磷处理(P210 和 P280)相比,P140 处理明显提高了磷的利用率,分别提高了 31.7% 和 99.0% (p <0.05)。此外,由于 DGT-P 与 Peeper-P 的比率较高,而 P 的表观平衡较低,以 140 kg P2O5 ha-1 的施肥量进行有机施肥可有效地在确保充足的 P 供给以保证产量稳定与降低潜在的 P 损失风险之间取得平衡。这些结果凸显了优化有机施肥在提高农艺效益和降低环境风险方面的重要意义。它们为支持田间钾肥管理战略和政府决策过程提供了宝贵的见解。
{"title":"Optimal organic fertilization enhances the phytoavailability of phosphorus in the root zone of rice","authors":"Wenbin Zhu, Hongmeng Zhao, Yu Wang, Clayton R. Butterly, Hao Chen, Jiahui Yuan, Mingqing Liu, Qiuhui Chen, Longjiang Zhang, Lei Wang","doi":"10.1111/ejss.13588","DOIUrl":"10.1111/ejss.13588","url":null,"abstract":"<p>Organic fertilization is considered an effective approach in promoting agricultural green development, dramatically affecting soil phosphorus (P) availability. Nonetheless, limited information is available on the comprehensive impact of full substitution of organic fertilizer for chemical fertilizer on P speciation, phytoavailability, and apparent balance throughout different rice-growth stages. To address this gap, a 5-year field experiment was conducted, implementing five organic P gradients ranging from 0 (P<sub>0</sub>), 70 (P<sub>70</sub>), 140 (P<sub>140</sub>), 210 (P<sub>210</sub>) to 280 (P<sub>280</sub>) kg P<sub>2</sub>O<sub>5</sub> ha<sup>−1</sup> of organic fertilizer. To assess P phytoavailability in the root zone with submillimetre spatial resolutions, this study employed techniques such as the one- and two-dimensional diffusive gradients in thin films (DGT) technique and the high-resolution soil solution sampling technology (HR-Peeper). The findings revealed that increasing P rates enhanced soil Olsen-P and biological-based P fractions across rice-growth stages, primarily driven by variation in mineral-associated P. Notably, the P<sub>140</sub> treatment demonstrated the highest P uptake efficiency among the different rice-growth stages, with a significant increase in soil DGT-P, particularly in the 0–60 mm soil layer (<i>p</i> <0.05), providing tangible evidence for enhanced P uptake. Moreover, compared with higher P treatments (P<sub>210</sub> and P<sub>280</sub>), the P<sub>140</sub> treatment markedly increased P use efficiency by 31.7% and 99.0%, respectively (<i>p</i> <0.05). Further, with a high ratio of DGT-P to Peeper-P and a low apparent balance of P, organic fertilization at the rate of 140 kg P<sub>2</sub>O<sub>5</sub> ha<sup>−1</sup> effectively struck a balance between ensuring adequate P supply for yield stability and mitigating potential P loss risks. These results underscore the significance of optimal organic fertilization in enhancing agronomic benefits while reducing environmental risks. They offer valuable insights to support field P management strategies and government decision-making processes.</p>","PeriodicalId":12043,"journal":{"name":"European Journal of Soil Science","volume":"75 5","pages":""},"PeriodicalIF":4.0,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142489475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}