土地利用方式和施肥管理对黑土物理性质的影响

Effects of Land Use and Fertilization on Physical Properties of Black Soil

为了探讨东北黑土区土壤水分的调控能力及其影响因素以及土壤水分对降水和不同植被覆盖的响应,以海伦农田生态系统国家野外科学观测研究站内的长期定位试验为基础,利用中子水分仪测定土壤体积含水量,研究裸地、休闲地以及包括单施有机肥、化肥+秸秆还田、单施化肥和不施肥4种处理的农田耕层土壤物理性质和土壤水分动态。结果表明:与休闲地相比,农田土壤容重增加7.47%,而孔隙度、饱和含水量和田间持水量均呈降低趋势,分别下降2.59、6.04和1.90百分点;肥料的施入尤其是施用有机肥和秸秆还田能够改善土壤物理性质;裸地土壤物理性质最差。由于植被耗水量较大,农田和休闲地土壤剖面年平均体积含水量显著低于裸地,施用化肥和秸秆还田可显著降低农田土壤剖面年平均体积含水量。各处理土壤剖面水分变异系数均随土壤深度的增加(0～70 cm深处)而呈先减小后增加趋势。由于植被生长的耗水作用,休闲地和农田土壤水分变化比裸地强烈,秸秆还田加剧了农田土壤水分的变异。土壤储水量的动态变化与降水量之间存在明显相关性,不同土地利用方式和施肥管理对浅层土壤储水量的影响较大,但随着土壤深度的增加,各处理对土壤储水量的影响越来越不明显。

A long-term field experiment,designed to have 4 treatments,i.e.（1） organic manure only （OM） ; （2） chemical fertilizer and straw incorporation （NPKS） ; （3） chemical fertilizer only; and （4） no fertilizer,was carried out at the Hailun Agricultural Ecology Station of Chinese Academy of Sciences,to explore soil water regulating capacity of black soil in Northeast China and its affecting factors,responses of soil moisture to rainfall and vegetational cover,and effects of the four treatments on physical properties and soil water dynamics in the plough layer of the black soil.In the experiment,a neutron probe was used.Results show that compared to fallow land,farmland increased in bulk density by 7.47％,but decreased in soil total porosity,saturated water content and water holding capacity by 2.59,6.04 and 1.09 percentage points,respectively.Fertilization,especially application of OM and NPKS,improved soil physical properties.Bare land was the worst in soil physical properties.As vegetation consumes much water,farmland and fallow land was significantly lower than bare land in annual mean water content.The treatment of application of chemical fertilizer and straw incorporation significantly lowered annual mean water content.Variation coefficients of soil water content in all the treatments showed a similar trend,i.e.decreasing first and then increasing with soil depth within the 0-70 cm soil layer.As a result of water consumption by vegetation,soil water content changed more sharply in the fallow land and farmland than in the bare land and incorporation of crop straw exaggerated the change.Dynamic variation of soil water storage was significantly related with precipitation,and land use pattern and fertilization management were the two factors affecting soil water storage in the surface soil layer the most,but with increasing soil depth,the effects of the treatments decreased significantly.