Is macroporosity controlled by complexed clay and soil organic carbon?
Is macroporosity controlled by complexed clay and soil organic carbon?
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DOI：
10.1016/j.geoderma.2023.116565
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发表时间：
2023-09
期刊：
影响因子：
6.1
通讯作者：
A. Koop;D. Hirmas;S. Billings;Li Li-Li;Alejandro Cueva;Xi Zhang;H. Wen;A. Nemes;Ligia F. T. de Souza-Lig
中科院分区：
文献类型：
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作者：
A. Koop;D. Hirmas;S. Billings;Li Li-Li;Alejandro Cueva;Xi Zhang;H. Wen;A. Nemes;Ligia F. T. de Souza-Lig
在每年到十年的时间尺度上，气候引起的土壤结构快速变化的多尺度证据越来越多。因此，确定控制土壤结构和相关大孔隙发育和维持的性质和机制变得越来越重要。这是特别相关的，因为大孔隙度对饱和导水率（K sat）有不成比例的影响，这强烈影响水储存和通量，从而影响水循环。在这项研究中，我们使用决策树和分段线性回归来评估土壤和气候特性对有效孔隙度（EP;大孔隙度的代理）的影响，在不同的土地利用和管理措施下，在地表和地下的视野。数据来自1，491 pedons（3，679个视野），跨越五个代表生物气候的生态区（如潜在植被）表明，在大陆尺度上，表层（A）和次表层（B）的EP强烈依赖于土壤有机碳（SOC）和粘粒总质量的复合分数;我们称之为复合有机碳和粘土（COCC）的组合部分。在A层，EP对COCC的响应呈轻微的正响应，而在B层，EP随COCC的增加而急剧增加。这是因为在B层中COCC的较小值反映了较大的粘土池，该粘土池具有更大的容纳潜力，并且SOC的复杂添加促进了更强的有机-矿物键以及这些层中土壤结构的伴随发展和维持。与此相反，较大的COCC值在A层反映的条件下，所有或大部分的粘土组分有效地与SOC复合，导致在一个较大的池的非复合土壤有机质与不同的对比效果的大孔隙度，最终静音的响应EP增加COCC。在表层，年平均降水量和土地利用等间接因子是EP的重要预测因子，而COCC在控制下层EP方面更有影响力。EP-COCC关系也适用于生态区域，但其影响被土壤和气候的相互作用所缓解，这表明气候对这种关系的影响是间接和复杂的。犁耕表面的视野和视野下犁耕层表现出更大的均匀性（由于干扰效应降低土壤的异质性），以及减少的幅度和速度的变化EP作为COCC的功能相比，未受干扰的视野。我们的研究结果表明，粘土和SOC的复杂部分是重要的控制大孔隙度和K sat在生态区域尺度和EP-COCC关系可能是一个重要的框架，了解和预测未来的土地利用和气候引起的土壤水力特性的变化。
Multi-scale evidence of rapid, climate-induced soil structural changes occurring at yearly to decadal timescales is mounting. As a result, it has become increasingly important to identify the properties and mechanisms controlling the development and maintenance of soil structure and associated macroporosity. This is especially relevant since macroporosity has disproportionate effects on saturated hydraulic conductivity (K sat) which strongly influences water storage and flux, thus, affecting the water cycle. In this study, we use decision trees and piecewise linear regression to assess the influence of soil and climate properties on effective porosity (EP; a proxy of macroporosity) in both surface and subsurface horizons under varying land-use and management practices. Data from 1,491 pedons (3,679 horizons) spanning five ecoregions representing bioclimate (eg, potential vegetation) across the conterminous US demonstrate that, at a continental scale, EP in surface (A) and subsurface (B) horizons is strongly dependent on the complexed fraction of the total mass of soil organic carbon (SOC) and clay; a combined fraction that we refer to as complexed organic carbon and clay (COCC). EP showed a slight positive response to COCC in A horizons but increased steeply with increasing COCC in B horizons. This is because the smaller values of COCC in B horizons reflect a larger pool of clay that has a greater potential to accommodate and complex additions of SOC promoting stronger organo-mineral bonds and the concomitant development and maintenance of soil structure in these horizons. In contrast, larger values of COCC in A horizons reflect conditions where all or most of the clay fraction is effectively complexed with SOC resulting in a larger pool of non-complexed soil organic matter with varying contrasting effects on macroporosity that ultimately mute the response of EP to increases in COCC. In surface horizons, indirect factors such as mean annual precipitation and land use were important predictors of EP, whereas COCC was more influential in controlling EP within the subsoil. The EP-COCC relationship also holds within ecoregions but its effect is mitigated by soil and climate interactions suggesting that the effect of climate on this relationship is indirect and complex. Plowed surface horizons and horizons underlying plowed layers showed greater homogenization (due to disturbance effects reducing heterogeneity in the soil) as well as a reduction in the magnitude and rate of change of EP as a function of COCC compared to undisturbed horizons. Our findings suggest that the complexed fraction of clay and SOC is important for controlling macroporosity and K sat at ecoregion scales and that the EP-COCC relationship may be an important framework for understanding and predicting future land use-and climate-induced changes in soil hydraulic properties.