The effects of long-term fertilizations on soil hydraulic properties vary with scales.
The effects of long-term fertilizations on soil hydraulic properties vary with scales.
复制标题
长期施肥对土壤水力特性的影响因尺度而异。
DOI：
10.1016/j.jhydrol.2020.125890
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发表时间：
2021-03
影响因子：
6.4
通讯作者：
Rickard W
中科院分区：
文献类型：
--
作者：
Zhang X;Neal AL;Crawford JW;Bacq-Labreuil A;Akkari E;Rickard W
从经过175年不同施肥处理的田间采集土壤样本。
利用X射线断层扫描和孔隙尺度模拟计算土壤渗透率。
在团聚体尺度上，土壤比在土芯尺度上更具各向同性和均匀性。
土芯尺度的土壤渗透率随土壤碳含量呈指数增长。
团聚体尺度的土壤渗透率随土壤碳含量渐近增长。
土壤结构是土壤质量的一个指标，其在种植制度转变或施肥变化后的改变是缓慢的。这种改变如何随尺度变化仍不清楚。我们基于英国洛桑试验站（始于1843年）的长期小麦试验对此进行了研究。从经过一个多世纪不同施肥处理或恢复为天然林地的地块中采集高度为7厘米、直径为10厘米的三个重复土芯，利用体素大小为40微米的X射线计算机断层扫描进行成像。然后我们将每个土芯打碎，从中选取三个团聚体，以1.5微米的体素大小进行扫描。对于每个土芯和团聚体样本，我们计算其孔隙大小分布、渗透率和迂曲度。结果表明，170多年前的施肥变化在土芯尺度和团聚体尺度上对土壤结构的重塑有所不同。未施肥或施无机肥的土芯中孔隙（>40微米）的大孔隙度较低，且在土壤表层10厘米内孔隙连通性差，相比之下，施农家肥的或林地中的情况则不同。在所有处理中，土芯图像中的孔隙在水力上是各向异性的，其水平方向的渗透率高于垂直方向，而团聚体则相对各向同性。施肥对土芯尺度的图像孔隙度和渗透率的影响比对团聚体尺度的影响更显著，施农家肥的团聚体和林地中的团聚体比其他处理中的团聚体更具渗透性。还发现，与不施肥或施完全肥料相比，过去20年不施磷的施肥方式增加了团聚体的孔隙度和渗透率，但没有增加土芯的孔隙度和渗透率。与不施肥相比，施无机肥增加了土芯中大孔隙的迂曲度，但没有增加团聚体内孔隙的迂曲度。未施肥或施无机肥的团聚体的孔隙度 - 渗透率关系遵循幂律，R²>0.8。相比之下，随着孔隙度增加，施农家肥的团聚体和林地中的团聚体的渗透率变化趋势不同。结果还表明，团聚体和土芯的传输能力对碳的响应不同，随着土壤碳含量增加，团聚体的渗透率渐近增加，而土芯的渗透率，尤其是其水平分量，呈指数增加。
Soil samples were taken from field under different fertilizations for 175 years. Soil permeability was calculated using X-ray tomography and pore-scale simulation. Soil was more isotropic and homogenous at aggregate scale than at core scale. Soil permeability at core scale increased exponentially with soil carbon. Soil permeability at aggregate scale increased asymptotically with soil carbon. Soil structure is an indicator of soil quality and its alterations following cropping system conversion or fertilization change evolve slowly. How such alterations vary with scale remains elusive. We investigated this based on the Rothamsted long-term wheat experiment (since 1843) in the UK. Triplicate cores 7 cm high and 10 cm in diameter were taken from plots that have been under different fertilizations or returned to natural woodland for more than one century for imaging using X-ray computed tomography with the voxel size being 40 µm. We then broke each core and sampled three aggregates from it to scan with the voxel size being 1.5 µm. For each core and aggregate sample, we calculated its pore size distribution, permeability and tortuosity. The results showed that the fertilization change >170 years ago reshaped the soil structure differently between the core scale and the aggregate scale. Macro-porosity of the pores (>40 µm) in the cores unfertilized or fertilized with inorganic fertilizers was low and the pores were poorly connected in the top 10 cm of soil, compared to those given farmyard manure or in the woodland. In all treatments, the pores in the core images were hydraulically anisotropic with their permeability in the horizontal direction being higher than that in the vertical direction, whereas the aggregates were comparatively isotropic. The fertilization affected image porosity and permeability at core scale more significantly than at aggregate scale, and the aggregates fertilized with farmyard manure and in the woodland were more permeable than the aggregates in other treatments. It was also found that compared to no-fertilization or fertilization with complete fertilizers, fertilizing without phosphorus over the past 20 years increased the porosity and permeability of the aggregates but not of the cores. Fertilization with inorganic fertilizers increased the tortuosity of the macropores in the cores but not of the intra-aggregate pores, compared to no-fertilization. Porosity-permeability relationship for aggregates unfertilized or fertilized with inorganic fertilisers followed a power law with R2 > 0.8. In contrast, the permeability of the aggregates in farmyard manure and in the woodland trended differently as their porosity increased. The results also revealed that the transport ability of the aggregates and cores responded differently to carbon in that with soil carbon increasing, the permeability of the aggregates increased asymptotically while the permeability of the cores, especially its horizontal component, increased exponentially.
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影响因子：
6.5
作者：
Blair, Nelly;Faulkner, R. D.;Poulton, P. R.
通讯作者：
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影响因子：
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作者：
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通讯作者：
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影响因子：
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作者：
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通讯作者：
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影响因子：
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作者：
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通讯作者：
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影响因子：
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