| China is one of the countries with the richest straw resources in the world,the reasonable and efficient use of straw resources is of great significance to the sustainable development of agriculture.In order to clarify the effects of long-term straw return and nitrogen fertilizer reduction on soil chemical properties,enzyme activities and microbial diversity.This research was conducted in Qianjin Farm Science and Technology Demonstration Park in Heilongjiang Province,using the rice variety Longjing 31 as the test material.The field test is divided into 7treatments,with no straw and nitrogen fertilizer treatment as controls,with single nitrogen fertilizer treatment,single straw treatment,straw return to the field and conventional nitrogen treatment,straw return to the field and nitrogen reduction 10% treatment,Field treatment with nitrogen reduction 20%,straw return to field and nitrogen reduction 30%.Through five-year positioning test,compare the effects of each treatment on soil chemical properties(0-20,20-40 cm soil layer),enzyme activity and microbial diversity(0-20 cm soil layer).The results showed that: Straw returning to the field and reducing nitrogen fertilizer application by 10% can increase soil total nitrogen and total potassium content,Compared with the control treatment,the total nitrogen content of different soil layers increased by 6.25% and25.61% respectively,Total potassium content increased by 9.65% and 4.68%;Straw returning to the field and reducing nitrogen fertilizer application by 10% treatment can increase the content of soil alkaline nitrogen,available phosphorus,and available potassium compared to other straw returning to the nitrogen,Compared with the straw returning to the field and the conventional nitrogen treatment,the alkaline nitrogen decomposition in different soil layers increased by17.37% and 15.69%,Available phosphorus increased by 3.74% and 19.87%,and available potassium increased by 4.64% and 30.76%,respectively;Returning straw to the field and reducing nitrogen fertilizer application by 10% can increase the activity of alkaline phosphatase and catalase;Straw returning to the field and reducing nitrogen fertilizer application by 10% can significantly increase rice yield compared to the treatment without straw returning to the field.Compared with straw returning to the field and conventional nitrogen application,the rice yield was not significantly different.When the reduced nitrogen fertilizer application rate is between 10% and 30%,the rice yield gradually decreases with the decrease of the nitrogenapplication rate.A total of 1713 OTUs were obtained from 5 treatments of soil microbial diversity,They belong to 35 bacteria phyla,95 bacteria class,187 bacteria order,285 bacteria family,434 bacteria genera respectively;At the phylum level,the top five phylums with relative abundance are Proteobacteria,Actinobacteria,Chloroflexi,Bacteroidetes,Acidobacteria,Proteobacteria were dominant flora in all treatments,with a relative abundance of 29.57-33.10%;The relative abundance of Anaerolineae,Anaerolineales and Anaerolineaceae in the soil could be improved by straw returning to the field and nitrogen fertilizer reduction of 10%,The relative abundance of Anaerolineae was 18.73% when the straw was returned and nitrogen fertilizer was reduced by10%;At the genus level,Pseudarthrobacter is the dominant bacterial group in control and single nitrogen fertilizer treatment,uncultured_bacterium_f_Bacteroidetes_vadinHA17 is the dominant bacterial group in single straw treatment,straw returning to the field and conventional nitrogen treatment,uncultured_bacterium_f_Anaerolineaceae is the predominant bacterial group in the straw returning field and nitrogen reduction 10% treatment;Bradyrhizobium,rhizomicrobium and cellulomas have the functions of nitrogen fixation,carbon fixation and cellulose degradation,respectively.The application of straw and nitrogen fertilizer at the same time can improve the relative abundance of three bacterial genera;The types of bacteria in different treated soils are obviously different,A total of 56 species of bacteria show significant differences,Seven of these populations gathered in the control treatment,12 populations gathered in a single nitrogen fertilizer treatment,8 populations gathered in single straw treatment,11 populations were gathered in the straw and returned to the field with conventional nitrogen treatment,36 populations gathered in the treatment of returning straw to the field and reducing nitrogen by10%;Use the network diagram to analyze the correlation of bacterial communities in each treatment,In the control treatment,the correlation number of the two species at the genus level is149,At the genus level,the correlation number between the two species is 123,At the genus level,the number of correlations between the two species was 118,With straw returning to the field and conventional nitrogen treatment,the correlation number of the two species at the genus level is 171,When straw was returned to the field and nitrogen was reduced by 10%,the correlation number of the two species at the genus level was 134;Through redundancy analysis(RDA),five genera of Bradyrhizobium,GOUTB8,Gallionella,Bacteriovorax andDactylosporangium were positively correlated with total nitrogen;Under this test condition,Comprehensively considering the effects of straw returning to the field and reduced nitrogen fertilizer application on soil chemical indicators,enzyme activities and bacterial diversity,We believe that returning straw to the field and reducing nitrogen by 10% is feasible in agricultural production and has high production efficiency. |
