耕作制对土壤肥力的影响

土壤是农业生产的基础,没有肥沃的土壤就很难获得稳定的农业生产,就没有争取更高产量的物质条件。土壤之所以能够为农业生产提供物质条件,其原因就在于土壤具有肥力。土壤肥力是指土壤从营养条件和环境条件来供应和协调作物生长的能力,它是辨别土壤肥沃和瘦瘾的标准。用养得当,可使土壤肥力上升,如果用和养的矛盾处理不当,就会使土壤肥力衰退。

EFFECT OF CROPPING SYSTEM ON THE FERTILITY OF PADDY SOILS

In comparison with the late-rice in double cropping system, the amount of soil nitrogen mincralized during the growth of early rice in triple cropping system was considcrably lower owing to its shorter growing period togcther with a colder climate in its early stage of growth (from the middle of May to early June). The percentage contribution of soil nitrogen to the nitrogen absorbed by the single cropping late-rice (75.9%)was significantly higher than that by early rice(57.8%),and therefore heavy application of chcmical nitrogen fertilizer, apecially at its carly stage of growth, is indispcnsable for high yield of the early rice.