Effects Of Corn Straw Returning Combined With Microbial Agents On Wheat Yield And Soil Carbon And Nitrogen Components

Straw contains a lot of mineral elements needed for crop growth,which is an important agricultural renewable resource.Microbial agents is a kind of non-toxic,pure natural and environment-friendly biological fertilizer,which can not only improve the p H of soil and replace some chemical fertilizers,but also help to transform soil nutrients and improve soil structure.At present,there is a problem of excessive nitrogen fertilizer input in agricultural production.It is of great significance to study the high-yield and high-efficiency ways and mechanisms of reducing nitrogen fertilizer application by using green fertilizers such as straw,microbial agents and organic fertilizers.Therefore,the wheat variety Shannong 20 was selected as the test material,and the split plot design was adopted.The main area was straw removal,straw returning,straw returning+microbial agents,commercial organic fertilizer and microbial agents,and the secondary area was four nitrogen application levels,namely 0,120,180 and 240 kg ha^-1respectively.The dynamic changes of soil total nitrogen,soil organic carbon,soil easily oxidizable organic carbon,soil particulate nitrogen and mineral bound nitrogen in 0-40 cm soil layer at jointing stage,flowering stage and maturity stage of wheat and their relationship with wheat yield were studied,in order to clarify the mechanism of straw returning to field with microbial agents to achieve soil carbon fixation and nitrogen increase.The main results are as follows:1.The effect of straw returning combined with microbial agents on the grain yield of winter wheat.The wheat yield of different treatments showed the maximum value under the nitrogen application rate of 240 kg ha^-1,and the influence of each treatment on wheat yield was as follows:straw returning+microbial agents>straw returning>organic fertilizer>microbial agents>no straw returning.Among them,the wheat yield of straw returning combined with microbial agents was the highest under the nitrogen application rate of 240 kg ha^-1(9038.52kg ha^-1),which was not significantly different from that of 180 kg ha^-1.2.Effect of straw returning combined with microbial agents on nitrogen efficiency of winter wheat.Compared with other treatments,straw returning combined with microbial agents application at 180 kg ha^-1nitrogen application rate is more beneficial to improve the agronomic efficiency of nitrogen fertilizer and nitrogen harvest index of winter wheat.Compared with the nitrogen application rate of 240 kg ha^-1,the agronomy efficiency and nitrogen absorption efficiency of wheat nitrogen fertilizer increased by 26.52%and 2.82%respectively under the nitrogen application rate of 180 kg ha^-1.3.Effects of straw returning combined with microbial anents on soil carbon components.The contents of soil organic carbon and easily oxidized organic carbon in the 0-40 cm soil layer at the jointing stage,flowering stage and maturity stage of wheat decreased with the deepening of soil depth.Under the same nitrogen application rate,compared with the treatments of returning straws alone,applying organic fertilizers only,not returning straws to the fields,and applying microbial agents alone,the effects of straw returning combined with microbial agents on soil organic carbon and easily oxidized organic carbon most notably.And when the nitrogen application rate was 180 kg ha^-1,the effect of straw returning combined with microbial agents on soil organic carbon and easily oxidized organic carbon in the 0-20cm soil layer was the most significant at the flowering stage of wheat.4.Effect of straw returning combined with microbial agents on soil nitrogen components.The contents of soil total nitrogen and particulate nitrogen in 0-40 cm soil layer at jointing stage,flowering stage and maturity stage of wheat decreased with the deepening of soil depth,and the content of soil mineral bound nitrogen first increased and then decreased with the deepening of soil depth.Under the same nitrogen application rate,compared with the treatments of returning straws alone,applying organic fertilizers alone,not returning straws to the fields,and applying microbial agents alone,the treatments of straw returning combined with microbial agents had significant effects on soil particulate nitrogen and mineral-bound nitrogen contents.the most significant impact.And when the nitrogen application rate was180 kg ha^-1,the effect of straw returning combined with microbial agents on soil particulate nitrogen in the 0-20 cm soil layer at the flowering stage of wheat was the most significant.When the nitrogen application rate was 180 kg ha^-1,the effect of straw returning combined with microbial agents on the content of soil mineral-bound nitrogen in the 0-20 cm soil layer at the maturity stage of wheat was the most significant.To sum up,straw returning combined with microbial agents application at 180 kg ha^-1nitrogen application rate can significantly improve the easily oxidizable organic carbon and particulate nitrogen content,agricultural efficiency of nitrogen fertilizer and nitrogen absorption efficiency of nitrogen fertilizer,which is more conducive to the accumulation of soil nutrients and the improvement of soil structure.Therefore,based on the comprehensive yield and the distribution of soil nutrients in the soil,it is recommended to return straw to the field and apply microbial agents in this experimental area to realize a green,yield increasing and efficient soil management mode under the condition of 180 kg ha^-1nitrogen fertilizer application.