Effects Of Combined Application Of Organic And Inorganic Fertilizers On Yield And Quality Of Winter Wheat And Soil Physicochemical Properties In Dryland

As an important wheat production area in China,the northwest dryland has a problem of water stress,poor soil nutrients,and low and unstable yield.For a long time,in order to increase local wheat production,people apply excessive fertilizer has become the main way to increase production.This has resulted in excessive nitrate nitrogen residue in the soil,reduced soil fertility and quality,environmental pollution and other problems.It's very important that inorganic fertilizer combined with organic fertilizer in reducing nitrogen and yield of wheat,improving soil quality,and improving soil fertility to reduce environmental pollution.In this study,we have adopted a split-zone test to make the field positioning experiments run which were conducted for five consecutive years on winter wheat in the dryland of Northwest China.The main treatment is 5 nitrogen levels with nitrogen application rates of 0,75,150,225 and 300 kg/hm~2(represented by N0,N75,N150,N225and N300),while the secondary treatment was mixed with or without organic fertilizer(30t/hm~2).In order to find out the optimal nitrogen fertilizer application rate suitable for the growth and production of winter wheat in dry land under the condition of combined application of quantitative organic fertilizer,and provide scientific basis for fertilization.The research results are as follows:1.As the quantity of nitrogen applied adds,the grain yield of winter wheat increases first and then decreases.Compared with single application of chemical fertilizer,the treatment of inorganic fertilizer combined with organic fertilizer can greatly increase the production of winter wheat grains,up to 20.6%,and make yield increase by 9.1%under reduced nitrogen application of 7.1%.Analysis of the components of winter wheat yield shows that inorganic fertilizer combined with organic fertilizer makes wheat yield increase by significantly increasing the number of effective panicles by 25.3%.2.2.Regardless of organic fertilizer is applied or not,the quality indicators such as crude protein,wet gluten,sedimentation value,water absorption and extensibility increase with the increasing of nitrogen application.The application of nitrogen fertilizer and organic fertilizer can significantly improve the quality of wheat grain,but the effect of organic fertilizer is lower than that of nitrogen fertilizer.The inorganic fertilizer combined with organic fertilizer greatly increased wheat grain crude protein,wet gluten,sedimentation value,water absorption,and extensibility values,reaching 5.8%,6.2%,10.0%,1.1%,and 5.4%,respectively.In the application of organic fertilizer,the amount of nitrogen applied exceeded 150kg/hm~2,which did not significantly improve the wheat quality.3.After the application of organic fertilizer,the bulk density of the tested soil decreased and the porosity increased.In the 0-10?10-20 and 20-40 cm soil layers,the bulk density of the applied organic fertilizer respectively decreased by 3.8%,1.5%and3.7%,while the porosity respectively increased by 3.9%,2.1%and 6.6%.In the 0-10cm,the treatment of inorganic fertilizer combined with organic fertilizer reduced the saturated hydraulic conductivity of each treatment compared with the single application of chemical fertilizers,but failed to reach a significant difference.Compared with N0,the water-stable aggregates of>2 mm respectively increased by 223.6%,105.1%and 2.9%in the 0-10,10-20 and 20-40 cm soil layers under N0+M treatment.The MWD and GMD values of the soil aggregates in the 0-40 cm soil layer did not change significantly when the organic and inorganic fertilizers were combined with chemical fertilizers.4.Compared with single application of chemical fertilizer,the treatment of inorganic fertilizer combined with organic fertilizer can make the soil fertility raise significantly.In the 0-20 cm soil layer,the content of total nitrogen,organic matter,available phosphorus and potassium increased by 27.7%,25.3%,228.4%41.3%,of which the treatment effect with N75+M or N150+M is the best.Both before and after sowing,compared with single application of chemical fertilizer,the treatment of inorganic fertilizer combined with organic fertilizer can raise the soil water content of 0-20 cm soil layer.Combined application of organic and inorganic fertilizers is more conducive to reducing nitrate nitrogen leaching than single chemical fertilizer treatment.