开垦对农牧交错带地带性和非地带性草地土壤性质的影响

Effect of reclamation on soil properties of zonal and intrazonal grasslands in agro-pastoral ecotone

该文以农牧交错带由地带性和非地带性草地开垦的农田及其相应的草地类型为研究对象,采用野外取样与实验室分析相结合的方法研究了开垦对农牧交错带草地土壤理化性质的影响,以期为农牧交错带土地的合理利用提供参考。结果表明,草地开垦后,其土壤特性出现颗粒组成粗化,体积质量增加,土壤毛管持水力降低,土壤有机碳、可溶性有机碳全氮、有效磷、有效钾和土壤有效态微量元素质量分数降低的现象;开垦导致了地带性草地土壤中有效铁、有效锰质量分数不能够满足农作物生长发育之需要。基于对地带性和非地带性两类草地开垦后土壤性质变化的分析及对比,提出了在农牧交错带秋季收获时应该对作物进行高留茬处理并适当延后春季翻耕时间,以减少风蚀作用的负面影响;应该通过秸秆还田和增施有机肥等方法来改善土壤性质,建议研究区应严格贯彻执行禁止对地带性草地的开垦,对已开垦的地带性草地应尽快实施国家提出的退耕还草政策;对于非地带性草地开垦的农田,应注重科学管理,合理利用。

A paired-site design was adopted to quantitatively evaluate and compare the changes of soil properties between reclaimed lands from zonal and intrazonal grasslands, which would be applied to develop scientific strategies and programs for land use in the agro-pastoral ecotone of northern China. The results showed that the soil texture became coarse after reclamation, accordingly, soil bulk density increased and soil water holding capacity reduced;The contents of soil organic carbon, dissoluble organic carbon, available phosphorus, available kalium and soil available trace elements decreased. The reclamation of zonal grassland led to the shortage of available Fe and Mn in the soil. It would make a strong impact on growth of crop. Based on the analysis and comparison of soil properties changes of reclamation land in the zonal and intrazonal grasslands, it was concluded that the farmers should reserve high crop residue in the farmland, postpone properly the ploughing time for the sake of reducing wind erosion, and improve soil quality through returning straw to field and applying organic fertilizer. Meanwhile it would be important measures to stop reclaiming zonal grassland, to return the crop field into grassland and scientifically use the intrazonal grassland in agro-pastoral ecotone ＇of northern China.