Soil And Plant Nutrition Basics For High Yield And High Water And Nutrient Use Efficiency Cultivation Of Winter Wheat On Dryland In Northwest Of China

Winter wheat is one of the most important crops in Weibei dryland, while the shortage of water and low soil fertility seriously restrict winter wheat production. In this area, therefore, searching for effective measures to improve the use of limited precipitation and nutrient is the key to obtain high and stable yields of winter wheat as well as the important issues of agricultural production urgently need to be resolved. In this study, we delt with the above problems in the way of setting field experiments in Changwu County, Shaanxi Province during September 2008 to June 2010. By integration of different fertilization and mulching cultivation practices, seven different kinds of fertilization and mulching cultivation modes were designed and used to explore their impacts on winter wheat yield, absorption of nutrients, soil temperature and the use of water and nutrient, which included control, farmers'mode, early spring topdressing, N reduced topdressing 1, N reduced topdressing 2, ridge-mulching and furrow seeding and ridge-mulching and furrow seeding with higher seeding rate. The results were as below:1. Topdressing in early spring in drylands increased winter wheat yield by 10% and water use efficiency by 8.5%. Besides, N reduced topdressing with ridge-mulching and furrow seeding mode averagely increased the yield by 28%, while the water use efficiency by 20%.2. Early spring topdressing mode and ridge-mulching and furrow seeding mode averagely increased N uptake of winter wheat by 10.3% and 17.9%, P uptake by 14.3% and 25.9% and K uptake by 14.3% and 25.9% separately, with the effect being not obvious with N reduced topdressing treatment.3. Topdressing promoted nitrogen accumulation by winter wheat before anthesis and enhanced nitrogen transportation. The impact was more obvious when the amount of topdressing fertilizer was increased. Topdressing decreased nitrogen accumulation of winter wheat after anthesis. N reduced topdressing with ridge-mulching and furrow seeding mode enhanced the nitrogen accumulation of winter wheat after anthesis and finaly increased total nitrogen accumulation. 4. Nitrogen efficiency was significantly different with different topdressing and cultivation mode. Topdressing promoted nitrogen use of winter wheat. N reduced topdressing combined with ridge-mulching and furrow seeding mode further increased nitrogen use of winter wheat. The sequent trends of recovery effienciey of applied N, partial factor productivity from applied N, physiological efficiency of applied N and agronomic efficiency of applied N among different treatments were the same with the performance of ridge-mulching and furrow seeding mode > topdressing mode > farmers'mode.5. According to two-year results, ridge-mulching and furrow covering with straw maximized fallow efficiency during summer fallow. Fallow efficiency of ridge-mulching and furrow covering with straw averagely reached 56.8%, the highest among 7 treatments.6. Soil nitrogen and phosphorus content changed obviously during different stages of winter wheat among different topdressing and cultivation mode. Changes of nitrate nitrogen reached the depth of 300cm soil layer while phosphorus mainly to 50cm soil layer. Ridge-mulching and furrow seeding mode promoted unptaking and usage of deep soil nutrients by winter wheat, therefore its soil nitrate nitrogen and available phosphorus contents were lowered between 50 to 300cm soil depth. Rdge-mulching and furrow seeding mode soil nitrate nitrogen leached to 200-220cm soil depth after summer fallow, therefore much attention should be paid to regulation of its nitrogen input to prevent too much fertilizer nitrogen residual in the soil leaching to deep soil layers by rainfall. Soil available potassium content changed uniformly through 0-300cm soil layers during whole growing stages of winter wheat and different fertilization and cultivation modes had no significant effect on soil available potassium content.7. Ridge-mulching and furrow seeding mode increased topsoil temperature during whole stage of winter wheat, especially from booting stage to harvest. Early spring topdressing mode decreased topsoil temperature during whole stage of winte wheat.