宁南山区草田轮作研究 Ⅱ.不同轮作制度下的农田水分平衡

Study on Grass --Grain Crop Rotation System in South Ningxia Hilly Area Ⅱ. Field Water Balance under Different Crop Rotatiun Systems

通过对宁南山区不同轮作方式的耗水量和水分利用效率的研究评价,结果发现:在当前生产水平下,各种作物收获后0～2m土层内都还存有一定数量的有效水分;粮豆轮作较春小麦连作具有较强的调节土壤水分的能力,对水的利用效率较高,适应于本区降水不均的气候条件、苜蓿耗水量大,能造成土壤深层水分枯竭,但随种植年限加长,耕作层的水分可得到恢复。研究表明,只要安排合理,在半干旱的宁南山区发展以苜蓿为主的草粮轮作制是可行的。

The crop evapotranspiration (ET) and water use efficiency (WUE) under the different rota tion systems in the south Ningxia hilly area were studied and evaluated. Experiment results show that. under the recent farming production level. the amount of available water in some degree still re- mained in the soil of 2 meter layer at reaping time for different crops. Comparing with spring wheat continuous cultivation in the grain-legume rotation pattern. soil moisture regulating ability and WUF were mcreased. such a pattern was suitable to the climate conditions where rainfall distrabution was uneven. The ET value in alfalfa field was higher and it made the soil moisture in the deep layer use up. The soil water content in cultivated layer was able to be recovered after cropping time was elon- gated for several years. therefore. if the cropping arrangement is suitable. this rotation system is real- izable in such a semi-arid area.