The Effects Of Biofertilizer Application On Crop Yield And Soil Nitrogen Mineralization

Biofertilizer has been identified as a substitute for chemical fertilizer to increase the nitrogen use efficiency（NUE）and crop production in sustainable crop-livestock farming.The use of biofertilizer can not only increase the plant biomass but also improve plant total N assimilation.Nitrogen plays a vital role in winter wheat growth and yeild,and is one of the main nutrients for water pollution.A field experiment with five treatments（CK,B₁N₂P₂,B₁ON₁P₁,B₂N₂P₂,B₂ON₁P₁）was conducted using to reduce application of chemical fertilizer,combined with biofertilizer and organic fertilizer to study the winter wheat over ground nitrogen uptake amount and rate in different growing stages and soil nitrogen mineralization by two methods & yield of summer maize at coastal moisture soil zone.The results showed that nitrogen mineralization amount among different growing stages had a similar dynamic changing tendency,but the two treatments combined with biofertilizer and organic fertilizer changed more obviously.In the jointing and tasseling stages,the nitrogen mineralization amount of B₁ON₁P₁ was higher than that of B₁N₂P₂ by 151.29%,120.09% respectively;B₂ON₁P₁ was 56.28% and 245.04% higher than B₂N₂P₂,respectively.The results of the study showed that 25% reduction in chemical fertilizer and application of biofertilizer could maintain a stable nitrogen mineralization.In-situ method to study nitrogen mineralization of CK had been negative for many times,indicated that chemical fertilizers’ immobilization was greater than mineralization,and the addition of organic fertilizer also leads to high leaching nitrate.These treatments all had risks to the environment.The results of both the anaerobic method and the resin core method indicated that the addition of organic fertilizer could promote nitrogen mineralization,while the chemical fertilizer reduction of 25 % combined with biofertilizers treatments caused less leaching nitrate in the ploughed soil,of course lower relative risk to environment.Biofertilizer combined with chemical fertilizer had significant effects on the yield of maize,and the yield of B₁N₂P₂ was the highest,reaching 9962.24 kg·ha-1.The ear average kernel number of B₁N₂P₂ was 29.99% higher than that of the CK.The 1000-kernel weight of B₂N₂P₂ was 2.28% higher than that of the CK.The application of biofertilizer significantly reduced the Barren ear tips length,and B₂N₂P₂ could reduce 73.29% of the length compared to CK,which was the greatest.In the meantime,chemical fertilizer 25% reduction and combined with biofertilizer could also improve winter wheat over ground nitrogen uptake amount and rate & its distribution ratio in the grain,as well as wheat yield components & the leaf age & number of tillers in the same period.Biofertilizer 1 could increase nitrogen physiological utilization efficiency and harvest index.Total nitrogen absorption of B₁N₂P₂ was significantly higher than that of B₁ON₁P₁,which was consistent with the production composition factor.At harvest,B₂N₂P₂ had the highest over ground nitrogen uptake,grain nitrogen uptake.The nitrogen uptake efficiency showed that the two treatments of biofertilizer 2 were significantly higher than CK,but not significantly different from biofertilizer 1.The application of organic fertilizer treatment had the lowest physiological utilization efficiency.The application of biofertilizer could increase the partial productivity of nitrogen fertilizer.The NUE and NHI under the conventional fertilization amount（N-200 kg·ha-1）were low,and the PFP was very low,too.The 25% reduction of chemical fertilizer under the application of biofertilizers could increase the nitrogen uptake and utilization of plants to different extents,and that of B₂N₂P₂ was the highest.There was no significant difference between B₂ON₁P₁ and two biofertilizer treatments of chemical fertilizers 1/4 reduced（P>0.05）,indicated that biofertilizer 2 was superior to biofertilizer 1.This study provided reference and basis for the scientific management of nitrogen in farmland at coastal moisture soil zone and the reduction of agricultural non-point source pollution caused by excessive fertilization.