Effects Of Long-term Straw Incorporation And Nitrogen Fertilizer Application On Fertility And Bacterial Diversity Of Lime Concretion Black Soil

In recent years,improving the characteristics of black soil of Shajiang,improving the productivity of Shajiang black soil and promoting the increase of crop yield have received extensive attention from researchers.In this study,an 10-year long-term straw returning experiment was conducted to study the effects of total straw smashing and returning nitrogen fertilizer on soil physical and chemical properties and wheat yield in winter wheat-summer maize rotation system,and the high-throughput sequencing technology was used to study straw.Field+nitrogen fertilizer(S2,S3,S4 nitrogen fertilizer application rates are 360,540,720 kg·hm^-2,respectively),simple straw returning?T1? and straw returning+Nitrogen fertilizer(T2,T3,T4 nitrogen fertilizer application rates of 360,540,720 kg·hm^-2,respectively) studied soil bacterial diversity,community structure and relative abundance and its correlation with soil physical and chemical properties.The results of this study are as follows:1.The yield of wheat increased with the increase of nitrogen fertilizer.The effect of straw returning to field and 720 kg·hm^-2 nitrogen fertilizer was the best.The interannual yield of wheat showed fluctuating changes.Increasing nitrogen application rate could alleviate the decline of wheat yield.When straw was returned to the field and 720 kg·hm^-2 nitrogen fertilizer was applied,wheat yield showed an increasing trend.Straw returning+nitrogen fertilizer and straw returning to the field+nitrogen fertilizer can significantly improve the stability and sustainability of wheat,but there is no significant difference between the treatments.2.Straw returning to the field can increase the pH of the soil and increase the available potassium content.The combination of straw returning and nitrogen fertilizer is most beneficial to increase soil organic matter content,but its content is negatively correlated with nitrogen application rate;When field+nitrogen fertilizer(360 kg·hm^-2,540 kg·hm^-2),the effect on soil available potassium was the most significant;when straw returned to field+nitrogen fertilizer(720 kg·hm^-2),it had the greatest influence on soil alkaline nitrogen and ammonium nitrogen content.Each treatment did not significantly improve the nitrate nitrogen content.3.Straw returning to field+nitrogen fertilizer,simple straw returning and straw returning+nitrogen fertilizer had no significant effect on soil bacterial population richness.When nitrogen application rate was 540,720 kg·hm^-2,bacterial diversity was reduced.Bacterial community richness and diversity were affected by soil ammonium nitrogen content and soil pH,respectively.4.The relative abundance of Proteobacteria and Acidobacteria in the soil of the test soil is mainly affected by soil pH;the simple straw returning has the greatest influence on the relative abundance of Actinobacteria;when the straw is returned to the field +540 kg·hm^-2 nitrogen fertilizer The relative abundance of Chloroflexi is most pronounced.Among the common advantages,the relative abundances of Actinobacteria,Alphaproteobacteria and Betaproteobacteria are mainly affected by soil pH.The nitrogen application rate is the most important factor affecting the relative abundance of Acidobacteria.The common advantages are:Sphingomonas,Nitrospira and Bacillus.Compared with straw returning,the effect of nitrogen fertilizer on the genus of bacteria is more significant.5.The relative abundance of soil bacteria is affected by soil fertility.The relative abundance of bacteria is mainly affected by ammonium nitrogen,total nitrogen and available potassium.The relative abundance of bacteria and genera is mainly related to soil pH,total nitrogen and available potassium.