Effects of fertilization before sowing of leguminous green manure and its incorporation methods on soil moisture and nutrient regime of wheat field in Weibei Dryland

The effect of different fertilizers and green manure incorporations on soil properties have been investigated through field experiment in Weibei area.Fertilizer treatments included CK(no fertilizer),P(phosphate fertilizer,P2O540 kg·hm-2),and SF(special fertilizer for leguminous green manure crops,30 kg·hm-2).Green manure incorporation treatments included early incorporation(green manure was incorporated into soil half month before wheat sowing),early mulching(green manure crop was cut and left on the soil surface half month before wheat sowing,then incorporated into soil before wheat sowing),late incorporation(green manure was incorporated into soil before wheat sowing),and summer fallow(no green manure).The results showed that green manure biomass and nutrients returned to soils of SF and P treatments were higher than that of CK.For early incorporation treatment,green manure biomass and nutrients returned to soils of SF increased significantly compared with CK.The contents of soil organic matter,active organic matter,total nitrogen and available potassium of early incorporation treatment were sig-nificantly enhanced due to the higher green manure biomass and nutrients returned to soil compared with summer fallow,CPMI was significantly increased as well.Incorporation of green manure increased significantly nitrate content in soil profile and a notable accumulation peak appeared at around 160 cm depth of green manure treatments.Early incorporation treatment had higher nitrate content compared to early mulching treatment.No significant difference of soil water content above 160 cm layer emerged between the green manure treatment and summer fallow,while green manure treatments had lower soil water content in 160~200 cm layer than summer fallow.Early mulching treatment had significantly lower water storage in 0~200 cm depth compared to summer fallow in 2011.