Effects Of Combined Application Of Organic And Inorganic Fertilizer On Yield And Nutrient Uptake And Utilization Of Winter Wheat In Dryland

The Loess Plateau is an important winter wheat growing area in the dryland of northwest China.In order to pursue high yield of wheat,farmers overuse chemical fertilizer and neglect the application of organic fertilizer in agricultural production.While increasing production costs,it also wastes a lot of organic fertilizer resources.The excessive use of chemical fertilizer not only causes the degradation of farmland soil quality,but also causes serious pollution to the environment.The results showed that the combined application of organic and inorganic fertilizers could enhance soil water and fertilizer retention and improve soil fertility while reducing nitrogen and increasing yield.In order to further explore the internal mechanism of combined application of organic and inorganic fertilizers on reducing weight and increasing efficiency of winter wheat.On the basis of the seven-year long-term positioning test,the fissure zone design was adopted,with five nitrogen levels as the main treatment,mixed and non-application of organic fertilizer as the by-treatment,single application of chemical fertilizer treatment labeled(N0,N75,N150,N225,N300),compound application of organic fertilizer treatment label(MN0,MN75,MN150,MN225,MN300)to explore the effects of single application of chemical fertilizer and combined application of organic and inorganic fertilizer on winter wheat yield,growth and development,soil fertility and uptake and utilization of nitrogen,phosphorus and potassium in dryland.The optimal nitrogen application rate was determined under the combination of organic and inorganic fertilizers.In order to provide theoretical basis for increasing winter wheat yield and managing nitrogen fertilizer rationally in dryland of northwest China.The main conclusions are as follows:(1)The biomass of winter wheat under MN150 treatment was the highest.Biomass did not increase significantly when nitrogen application rate was more than 150 kg N/hm~2.Combined application of organic fertilizer significantly increased the biomass at late growth stage,which increased by 11.0%and 12.4%at flowering and maturity stage,respectively.With the increase of nitrogen application rate,the number of effective panicle and grain per panicle increased first and then decreased,while the 1000-grain weight decreased gradually.The key of increasing yield was that the number of effective panicles was increased by 7.1%compared with that of chemical fertilizer alone.MN150 treatment had the highest grain yield,which reached 6311 kg/hm~2.(2)Combined application of organic and inorganic fertilizers significantly increased the contents of organic matter,total nitrogen,available phosphorus and available potassium.It increased by 44.9%,53.9%,342.2%and 73.9%at maturity,respectively.The contents of organic matter and total nitrogen did not change significantly with the increase of nitrogen application rate.Similarly,the content of available P and available K did not change significantly under the single application of chemical fertilizer.However,under the combined application of organic fertilizer,its content not only increased significantly,but also increased with the increase of nitrogen application in the early growth stage,and decreased significantly with the increase of nitrogen application in the mature stage.The content of available potassium was the highest under MN150 treatment.Under the combined application of organic and inorganic fertilizers,the nitrate nitrogen content in 0-20 cm soil layer increased by 32.0%and 57.9%before sowing and at maturity,respectively.The nitrate content increased with the increase of nitrogen application rate.When the nitrogen application rate was more than 150 kg N/hm~2,the residual nitrate nitrogen in the soil layer of100 cm-200 cm increased significantly.When the nitrogen application rate reaches 300 kg N/hm~2,the risk of leaching of nitrate nitrogen in the 200 cm soil layer is easily increased.(3)The root activity of different growth stages was the highest at jointing stage.Proper amount of n fertilizer could increase the root activity,and organic fertilizer could increase the root activity at tillering stage,which increased by 16.8%compared with N fertilizer alone.The increase of root activity promoted the uptake of nutrients.Compared with single fertilizer application,organic and inorganic fertilizer combined application increased plant nitrogen accumulation by 7.73%,26.19%,19.67%and 24.74%at tiller,jointing,flowering and maturity stages,respectively.The absorption of nitrogen in the single fertilizer treatment was mainly through pre-anthesis nitrogen transport,while the pre-anthesis nitrogen transport and post-anthesis nitrogen absorption played an equally important role in the accumulation of nitrogen in the combined fertilizer treatment.Compared with single application of chemical fertilizer,organic and inorganic fertilizer combined application increased pre-anthesis nitrogen transshipment,post-anthesis nitrogen accumulation and grain nitrogen accumulation by 9.8%,33.1%and 22.0%,respectively.Pre-anthesis nitrogen transport was mainly in stem,and nitrogen accumulation reached the highest in MN150 treatment.The application of organic fertilizer significantly improved nitrogen use efficiency and agronomic efficiency,and reducing nitrogen application rate increased nitrogen utilization efficiency and agronomic efficiency while increasing nitrogen harvest index.Nitrate reductase activity increased by 25.94%,12.88%,9.90%and 12.35%at tiller,jointing,flowering and filling stage,respectively,under combined application of organic and inorganic fertilizers.The maximum value of N225 and MN150 treatment was achieved by single application of chemical fertilizer and combined application of organic fertilizer,respectively.(4)From jointing stage to anthesis stage is the critical period for the rapid increase of plant phosphorus accumulation.Compared with the single application of chemical fertilizer,the phosphorus accumulation of plant at tiller,jointing,flowering and maturity stage was increased by 20.3%,46.3%,27.2%and 21.7%,respectively.When N application rate was more than 150 kg N/hm~2,the accumulation of plant phosphorus tended to decrease.The contribution rate of pre-anthesis P transport and pre-anthesis P transport to grain P was the highest in MN150 treatment.The phosphorus harvest index could be improved by reducing nitrogen application rate,and the phosphorus utilization efficiency could be improved significantly by nitrogen application compared with no nitrogen application.(5)Plant K accumulation and pre-anthesis K transshipment were the highest under MN150 treatment.Compared with single application of chemical fertilizer,organic and inorganic fertilizer combined treatment increased plant K accumulation by 10.6%,15.6%,39.8%and 39.5%at tiller,jointing,flowering and maturity,respectively,and pre-flowering k translocation increased by 24.3%.There was no significant difference in pre-anthesis K transport rate and the ratio of K to K in grains between single fertilizer application and compound application of organic fertilizer treatment.Nitrogen application increased the pre-anthesis K transport rate but decreased the ratio of K to K transport in grains compared with no nitrogen application.The K harvest index and utilization efficiency of winter wheat could be improved by decreasing nitrogen application rate.In conclusion,the application of 150 kg N/hm~2nitrogen fertilizer combined with 30t/hm~2organic fertilizer is beneficial to improve soil fertility,promote the growth and development of winter wheat and the absorption and utilization of nitrogen,phosphorus and potassium in various parts of the plant,and ensure stable and high yield of winter wheat in dryland of northwest China.