Effects Of Growing Green Manure And Nitrogen Fertilizer Rate On Winter Wheat Yield In Dryland

Growing and incorporating of green manure(GM)crops instead of the summer fallow is one of the environmental friendly soil amendments that improving soil fertility and rainfall utilization,preventing further soil erosion,and reducing fertilizer application,which is recommended for the development of sustainable agriculture in dryland area of China.Understanding the response of winter wheat(Triticumaestivum L.)growth to the approach of GM crops is important for designing the precise nutrient management strategies in this region.A two-year experiment was arranged by the spilt-pot design.The main-treatment included 3 winter wheat-rotation patterns: fallow,black bean(Phaseolus vulgaris),and rapeseed(Brassica napus L.).The sub-treatment included the five N fertilizer rates(0,60,120,180,240 kg N ha-1)applied to winter wheat.The objective of the study was to investigate the effects of different GM and N fertilizer rate on wheat growth,yield and soil properties in dryland.The main results include:(1)The annual precipitation of two years was lower than 480 mm,which would be considered as the dry year.In the first-year,the N fertilizer level applied to wheat could be reduced by 66.7% compared with the recommend one(180 kg N ha-1)in all the treatments.(2)In the second year,growing the black bean and rapeseed as GM crops reduced the water use efficiency by 18% and 15%(P<0.05),respectively.Besides,the grain yield in the corresponding treatments was reduced by 20% and 14%(P<0.05),respectively.(3)Although GM decreased the soil nitrate-N content at wheat sowing,GM could reduce N leaching at the depth of 0-100 cm during summer fallow period.Rapeseed has less effects on soil water storage and water consumption compared to black bean.Besides,rapeseed increased soil available P by 21% and 48% at the times of GM incorporation and wheat sowing,respectively.Moreover,rapeseed could not only increase wheat tiller but also maintain the wheat yield and improve grain P contents compared with the fallow treatment.In summary,growing the rapeseed as GM crop is a better choice than the black bean and summer fallow which cloud maintain the wheat productivity and improve soil fertility in dryland.This study will be hopefully used to provide the theoretical basis of the sustainable agriculture in dryland of China and other worldwide dryland regions.