Laser diffraction analysis of aggregate stability and disintegration in forest and grassland soils of northern Minnesota, USA
Laser diffraction analysis of aggregate stability and disintegration in forest and grassland soils of northern Minnesota, USA
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DOI：
10.1016/j.geoderma.2018.06.020
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发表时间：
2019-03
期刊：
影响因子：
6.1
通讯作者：
C. Kasmerchak;J. Mason;M. Liang
中科院分区：
文献类型：
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作者：
C. Kasmerchak;J. Mason;M. Liang
在美国明尼苏达州北方草原-森林交错带土壤上，采用重复激光衍射测量表征团聚体稳定性的方法进行了试验。这些土壤形成类似的母质，但显示出广泛的上层形态，有机碳含量和化学，允许评估的方法的性能在广泛的聚集体稳定性和其效用，确定影响聚集体行为的因素。代表细物质释放的方程，通过分解两个聚集人口的一阶过程拟合实验数据。这些方程的最佳拟合参数，以及持久性水稳性团聚体含量的附加指数，表明在团聚体行为的主要视野的软土和淋溶土之间的显着差异。线性模型的开发，以探讨这些参数和土壤理化特性的数据集作为一个整体，并为子集对应于四个不同的植被历史，土壤订单，和主要土壤层带之间的关系。确定的关系相对较弱（R2= 0.30至0.70）。最好的预测参数代表早期解体的不太稳定的聚集体的阳离子交换容量（CEC）和有效的CEC（ECEC）为整个数据集，虽然有机碳和氮含量也出现了森林和Alfisol子集的预测。持久性水稳性团聚体含量的指数的最佳预测因子是有机碳含量，盐基饱和度，或交换性钙/镁比，这取决于特定的子集和细材料的尺寸分数在分析中使用。在这些实验中，有机碳含量作为聚集体行为的预测因子的解释力相对较弱，这有点令人惊讶，因为之前的工作是关于聚集体稳定性的。CEC和ECEC可以作为代理的有机质和粘土含量的各种组合，影响聚集体的稳定性，在这些样品中，解释其作为预测的重要性。很可能，在这项研究中没有检查的其他因素有助于团聚体的稳定性，包括碳酸盐含量，粘土矿物，以及不同的频率和类型的pedoturbation草地和森林。这项研究的结果是有关重建的纹理对比剖面的发展，森林入侵草原在过去的4000年在研究区，记录的古生态研究。特别是，薄A层以下的有机质损失可能促进了E层的初步发展，其中弱聚集有利于粘土洗脱;粘土的损失将进一步削弱聚集体的稳定性。我们建议这种新的方法来评估团聚体的稳定性也可以应用于土壤侵蚀和径流潜力的研究，土地利用和管理的影响。
A method for characterizing aggregate stability with repeated laser diffraction measurements was tested on soils spanning the prairie-forest ecotone in northern Minnesota, USA. These soils formed in similar parent material but display a wide range of upper horizon morphology, organic carbon content, and chemistry, allowing assessment of the method's performance over a wide range of aggregate stability and its utility in identifying factors influencing aggregate behavior. Equations representing fine material release through breakdown of two aggregate populations as first-order processes were fit to experimental data. The best-fit parameters for these equations, and an additional index of persistent water-stable aggregate content, indicated distinct differences in aggregate behavior among the major horizons of Mollisols and Alfisols. Linear models were developed to explore the relationships between these parameters and soil physicochemical characteristics for the dataset as a whole and for subsets corresponding to four zones with different vegetation history, soil orders, and major soil horizons. The relationships identified were relatively weak (R2= 0.30 to 0.70). The best predictors for the parameters representing early disintegration of less stable aggregates were cation exchange capacity (CEC) and effective CEC (ECEC) for the whole dataset, although organic carbon and nitrogen contents also emerged as predictors for forest and Alfisol subsets. The best predictors for the index of persistent water-stable aggregate content were organic carbon content, base saturation, or exchangeable Ca/Mg ratio, depending on the particular subset and fine material size fraction used in the analysis. The relatively weak explanatory power of organic carbon content as a predictor of aggregate behavior in these experiments was somewhat surprising, given prior work on aggregate stability. Both CEC and ECEC may serve as proxies for the various combinations of organic matter and clay content that influence aggregate stability in these samples, explaining their importance as predictors. It is likely that other factors not examined in this research contributed to aggregate stability, including carbonate content, clay mineralogy, and differing frequency and types of pedoturbation under grassland and forest. The results of this study are relevant to reconstructing the development of texture-contrast profiles as forest invaded grassland over the past 4000 in the study area, as documented by paleoecological research. In particular, loss of organic matter below a thin A horizon may have facilitated initial development of an E horizon in which weak aggregation favored clay eluviation; loss of clay would then have weakened aggregate stability still further. We suggest this new method for assessing aggregate stability can also be applied to research on soil erosion and runoff potential as affected by land use and management.