Effects Of Green Manure In Different Crop Rotations Systems In Dryland

Barren soils and limited water resources are two main factors to restrict the improvementof agricultural production in Weibei dryland. Introduction of summer leguminous greenmanure into the summer fallow-winter wheat rotation system or spring maize-winter wheatrotation system will buildup soil fertility and increase crop yields and economic benefits. Afield experiment was conducted to study the effect of different fertilization treatments (CK, nofertilizer; P, P2O540kg·hm-2; SP, special fertilizer for leguminous crop30kg·hm-2) on thegrowth of leguminous green manure and succeeding crops. Effects of the green manuretreatment methods (summer fallow-winter wheat: Early Incorporation, Early Mulch, LateIncorporation, Fallow; spring maize-winter wheat: Mulch, Incorporation and Moved Away)on crop growth, grain yield and soil fertility have been investigated in the summer greenmanure-winter wheat crop rotation and summer green manure-spring maize-winter wheatrotation systems. The results were as below:（1）Green manure biomass and nutrients returned to soil of SF and P treatments were higherthan that of CK treatment. Green manure treatments increased spike number and yield ofwinter wheat. Green manure treatments also increased WUE of winter wheat, and EarlyMulch treatment had significantly higher WUE compared with Fallow. The soil organicmatter, active organic matter, total nitrogen and rapidly available potassium contents of EarlyIncorporation treatment were significantly enhanced due to the higher green manure biomassand nutrients returned to soil compared with Fallow, CPMI was significantly increased as well.Green manure increased significantly soil nitrate content and a notable accumulation peakappeared at around160cm soil depth of green manure treatments. Early Incorporationtreatment had higher nitrate content compared to Early Mulch. Soil water content above160cm layer showed no significant difference between green manure treatments and Fallow,while green manure treatments revealed lower soil water content at160~200cm layer. Waterstorage of Early Mulch treatment was significantly lower in0~200cm depth compared withFallow in2011.（2） In the green manure-spring maize-winter wheat rotation system, Mulch andIncorporation treatment had a higher maize yield than that of the Move Away. Compared withMove Away treatment, water storage and nitrate N storage in0~200cm soil depth had significantly higher in Mulch and Incorporation treatment before maize sowing. Soil organicmatter, active organic matter, total nitrogen, available phosphorus and available potassiumcontent had been enhanced in Mulch and Incorporation treatment. The content of totalnitrogen and available potassium has significantly increased in Mulch and Incorporationtreatment, compared with Move Away treatment.（3）In the full-blossom stage, SF treatment had significantly higher K uptake, compared withCK. In the full podding stage, the dry weight and P uptake were significantly higher in Ptreatment. The biomass of aboveground in all the fertilizer treatments has shown the trend ofdropping after the former increase, and the peak value emerged in the full podding stage, inwhich time, the dry weight and nutrient uptake was higher in P treatment compared with SFand CK.