Effects Of Phosphorus Application Rate And Combined Application Of Organic And Inorganic Fertilizer On Soil Microorganism,phosphorus Status And Yield In Cotton Field

In order to clarify the influence characteristics of different phosphorus application measures on soil quality of cotton field in Xinjiang,taking the cotton field of four-year continuous positioning fertilization test in Shawan 144 regiment as the research object,this paper discusses the influence characteristics and mutual relationship of different phosphorus application amount and low phosphorus application with organic fertilizer or organic acid on soil physical and chemical properties,enzyme activity,microbial biomass,bacterial diversity,phosphorus composition,yield and constituent factors,To provide scientific basis for improving soil productivity of cotton field and sustainable development of agriculture.The main results are as follows:1.Compared with no phosphorus application,phosphorus application could increase soil total carbon,total phosphorus,available phosphorus,alkali hydrolyzable nitrogen,microbial biomass content and enzyme activity.Among them,soil total carbon,alkali hydrolyzable nitrogen content,catalase,sucrase,urease activity and microbial biomass carbon,nitrogen and phosphorus content first increased and then decreased with the increase of phosphorus application,while soil total phosphorus,available phosphorus content Alkaline phosphatase activity increased with the increase of phosphorus application.Compared with the single application of inorganic fertilizer,organic fertilizer combined with inorganic fertilizer could significantly increase soil organic carbon,total carbon,available phosphorus,alkali hydrolyzable nitrogen content,catalase,sucrase,alkaline phosphatase activity and microbial biomass carbon and phosphorus content,with an increase range of 32.97%,9.59%,52.88%,24.19%,6.50%,11.37%,37.49%,35.19%,73.19%respectively;organic acid combined with inorganic fertilizer could significantly increase soil alkali hydrolyzable nitrogen content,alkaline phosphatase activity and microbial biomass phosphorus content by20.17%,17.46%,22.08%respectively.2.At the phylum level,phosphorus application could increase the relative abundance of Proteobacter--ia,Actinobacteria and Gemmatimonadetes;reduce the relative abundance of Acidobacteria,Bacteroidetes and Nitrospirae.Compared with the single application of inorganic fertilizer,organic fertilizer combined with inorganic fertilizer can significantly increase the relative abundance of Acidobacteria and significantly reduce the relative abundance of Actinobacteria and Patescibacteria;organic acid combined with inorganic fertilizer can significantly increase the relative abundance of Acidobacteria,Bacteroidetes and Firmicutes,and significantly reduce the relative abundance of Proteobacteria,Actinobacteria,Gemmatimonadetes and Patescibacteria.3.Compared with no phosphorus application,phosphorus application could increase the components of soil organic phosphorus,which increased with the increase of phosphorus application;Phosphorus application can increase soil inorganic phosphorus components,the contents of Ca₈-P,Al-P and O-P increased with the increase of phosphorus application,and the contents of Ca₂-P,Fe-P and Ca₁₀-P increased first and then decreased with the increase of phosphorus application.Compared with the single application of inorganic fertilizer,organic fertilizer combined with inorganic fertilizer significantly increased the contents of soil LOP,MLOP and Ca₂-P by 26.25%,50.74%and 24.23%;organic acid combined with inorganic fertilizer significantly increased the contents of soil LOP and MLOP by 33.16%and 41.34%.4.Compared with no phosphorus application,phosphorus application can increase the biomass and yield of cotton.The biomass of cotton shell,floc,seed,boll number per plant,boll weight per plant and seed cotton yield,which increased with the increase of phosphorus application.Compared with the single application of inorganic fertilizer,organic fertilizer combined with inorganic fertilizer could significantly increase the biomass of cotton shell,floc,seed,he single boll weight,the yield of seed cotton by 46.41%,58.98%,59.08%,25.15%and 34.10%respectively;the application of organic acid combined with inorganic fertilizer significantly increased the number of bolls per plant,the yield of seed cotton and the biomass of shell,floc and seeds by 28.57%,27.26%,21.10%,37.84%and 37.89%respectively.In this study,phosphorus application improved soil physical and chemical properties,increased soil enzyme activity and microbial biomass content,and then increased cotton yield,and when phosphorus application was 247 kg P₂O₅/hm²,the seed cotton yield reached the maximum.Adding organic fertilizer or organic acid could significantly increase cotton yield,and adding organic fertilizer had a better synergistic effect.Soil available phosphorus is the most important environmental factor affecting soil enzyme activity.Soil organic carbon is the most important environmental factor affecting soil microbial biomass.Soil alkali-hydrolyzable nitrogen,total nitrogen,total phosphorus and p H are important environmental factors affecting soil bacterial community structure.Soil Ca₈-P and MLOP are the main sources of soil available phosphorus in this study area.