松辽平原玉米带黑土肥力退化机理研究

通过田间调查和土壤肥力指标分析，探讨了松辽平原玉米带黑土肥力退化的原因和机理。结果发现，现行的以小四轮拖拉机为主要动力的耕作制度下，土壤剖面中耕层与犁底层的界面为“波浪型”，而年年进行秋翻的玉米田，其耕层与梨底层的界面为“平面型”。而且两者耕层土壤的养分含量和理化性质等指标也有明显差异。研究还发现，现行的以无机氮磷肥为主的施肥制度和玉米连作种植制度对土壤养分平衡有很大影响。因此认为，现行的不合理的耕作、施肥及玉米连作制度是导致松辽平原玉米带黑土肥力退化主要原因。

MECHANISM OF FERTILITY DEGRADATION OF BLACK SOIL IN CORN BELT OF SONGLIAO PLAIN

Through field investigation and soil fertility index analysis, causes and mechanism of fertility degradation of black soil in the Songliao Plain were explored. The results show that the interface between the cultivated layer and the plough sole in the soil profile was undulated under the current cropping system mainly using small-sized four-wheeled tractors and flat under the cropping system of deep plowing annually in the fall. Besides, the two systems were significantly different in soil nutrient content and soil physical and chemical properties. The study also discovered that both the present fertilization system based on inorganic N and inorganic P and the present system of continuous cropping of corn had greats effect on balance of soil nutrients. It thus follows that the present improper systems of cultivation, fertilization and continuous corn cultivation are the main causes of fertility degradation of black soil in the corn belt of the Songliao Plain.