近40年泥河沟流域耕地土壤有机质含量的变异性

利用方差和变异系数分析了近40a黄土高原泥河沟流域土壤有机质含量的时间变异性,分离了相关因素对总变异的影响。结果表明,1980年以来耕地土壤有机质含量呈阶段性上升趋势,变异性先增高后降低;修筑梯田、沟边防护和增施化肥对土壤有机质含量的变异起了很大的作用,增施化肥的影响效果略大于修筑梯田的效果;修筑梯田在初期因土壤扰动的影响,会造成土壤有机质含量的下降,而沟坡防护虽然只能在较小的面积上起到作用,但避免了土壤扰动,起到的效果更好;各类因素引起的变异是一种长期积累的过程,这个过程中土壤有机质含量并不会无限度地上升,含量越高上升越不明显。该区耕地土壤有机质含量从1980年的9.52g/kg到2015年的14.58g/kg,已由第二次全国土壤普查含量分级中的第7级上升到第5级,体现了该区的治理效益,也为今后流域的治理和管理提供了依据。

Temporal Variability of Soil Organic Matter Content in Cultivated Lands in Nihegou Watershed

We used variance and coefficient of variation to analyze temporal variability of soil organic matter content in the loess plateau in the loess plateau from 1980 to 2015, and isolated the effects of factors on total variation. The results showed that the organic matter content of cultivated land hasSbeenSreportedStheSstageSofSup-trend since 1980, which is from accelerate growth to slow down. Build terraces, slope protection and improving fertilizer application have a great effect on the variation of soil organic matter content, and the effect of improving fertilizer application is slightly more than that of the build terraces. Build terraces in the initial stage because of the effects of soil disturbance, will cause the loss of soil organic matter content. although lope protection can only play a role in the smaller area, it avoid the soil disturbance, and the effect is better. The variation caused by all kinds of factors is a process of long-term accumulation, in which the content of soil organic matter does not increase without limit. The higher the content, the less obvious the increase. The soil organic matter content in farmland increased from 9.52g/kg in 1980 to 14.58g/kg in 2015, which has risen from seventh to fifth in the second national soil survey classification. It reflects the governance benefit of this area, and provides a basis for watershed management and management in the future.