| Phosphorus is an essential element in crop growth and development and plays a key role in a gricultural production.Phosphorus is the limiting factor for a gricultural production in nor thwest China.Tomeett heneeds of a gricultural production,the consumption of phosphate fertilizer resources is increasing,but the utilization rate of phosphate fertilizer is very low in the season,and itiseasy to be fixed after being applied to the soil,causing waste of phosphate fertilizer and other resources.Phosphorus fertilizer applied to the soil may cause phosphorus a ccumulation in the water environment through farmland irrigation and groundwater migration,and cause environmental and ecological problems such as eutrophication of the water.Therefore,to study of phosphorus fraction and its in fluencing factors after fertilization is great significance for the rational application of phosphate fertilizer and efficient utilization of phosphate fertilizer resources.Based on long-term fertilization,to study the application of different phosphorus gradients,different nitrogen gradients,and combined application of nitrogen and phosphorus organic fertilizers on soil phosphorus fractions,soil chemistry and soil microbial characteristics through soil agrochemical analysis methods,modern molecular biology methods,and phospholipid fatty acid technology.The research focuses on the distribution and driving factors of soil phosphorus fractions,phosphorus transformation,and characteristics of soil microorganisms.The main conclusions reached are as follows:1.Effects of phosphorus fertilizer application on phosphorus fractions and related microorganisms in LoessAfter the addition of different phosphorus gradients,the inorganic phosphorus in the soil accounts for 53.9%- 71.8%of the total phosphorus.The inorganic phosphorus fractions of each treatment increased significantly with the increase in the amount of phosphorus applied.Ca2-P?Ca8-P?Al-P and Fe-P content increased significantly.Ca10-P is the main component of inorganic phosphorus,a ccounting for 57.8%?77.3%of inorganic phosphorus,followed by Ca 8-P and Al-P,accounting for 7.76%?17.98%?The main driving factors of soil inorganic phosphorus fractions are available phosphorus and pH.The total amount of soil organic phosphorus is 28 7.00?558.22 mg·kg-1,which a ccounts for a bout 36.5%?4 3.5%of the total soil phosphorus.It increases with the gradient supply of phosphorus,and the increase of the moderately labile organic phosphorus is the most significant,and its content is 22 7.63?503.71 mg·kg-1.The proportion of active organic phosphorus was the largest in each treatment.The main driving factor of soil organic phosphorus component was a vailable phosphorus.Soil bacterial abundance increased significantly with increasing phosphorus application levels.Soil microbial gene abundance bacteria>fungi>archaea>alkaline phosphatase gene?phosphorus transporter.The main factors affecting soil microbial genes were total phosphorus,available phosphorus,and pH.2.Effects of nitrogen fertilizer supply on phosphorus morphology and related microbial processes in LoessAfter the addition of different nitrogen gradients,the inorganic phosphorus in the soil a ccounted for 60.0%?71.9% of total phosphorus,and the difference in the inorganic phosphorus fractions was not significant in each treatment.Compared with CK,Ca2-P,C a8-P,A 1-P,Fe-The P content increased significantly.Ca10-P is the main component of inorganic phosphorus,accounting for 55.43%?69.67%of inorganic phosphorus,followed by Ca8-P,A 1-P and O-P,accounting for 2.57%?15.97%.The main driving factors of soil inorganic phosphorus components are organic phosphorus and pH.The total amount of soil organic phosphorus was 335.22?449.13 mg·kg-1,which accounted for about 33.6%?41.2%of the total soil phosphorus.There was no significant difference in the total organic phosphorus content of each treatment.The increase of moderately labile organic phosphorus increased significantly,and its content was 227.63?386.38 mg·kg-1.The proportion of labile organic phosphorus was the largest in each treatment.The main driving factors of soil organic phosphorus components are available phosphorus and inorganic phosphorus.Soil fungal abundance increased significantly with increasing nitrogen application levels.Bacterial,archaea,and fungal soil microbial gene a bundance is higher,two orders of magnitude higher than alkaline phosphatase genes and phosphorus transporters.The main factor affecting soil microbial genes is available phosphorus.3.Effects of combined application of nitrogen and phosphorus organic fertilizers on soil phosphorus transformation and microbial characteristicsThe application of nitrogen and phosphorus and organic fertilizer changed the inorganic phosphorus composition in the soil,and the inorganic phosphorus in the soil accounted for 43.7%?70.3%of the total phosphorus.Ca10-P is the main component of inorganic phosphorus,a ccounting for 57.30%?86.60%of inorganic phosphorus,followed by Ca8-P,Al-P,and O-P,accounting for 4.90%-13.95%.The content of Ca2-P and Ca8-P in PM and PNM treatments increased significantly.The contents of O-P and Ca10-Pin PM and NM treatments were significantly higher than those in other treatments.The main driving factors of soil inorganic phosphorus components are available phosphorus and organic phosphorus.The total amount of soil organic phosphorus is 254.17?422.95 mg·kg-1,which accounts for 28.5%?44.6%of total soil phosphorus.The migration and transformation of organic phosphorus are mainly contributed by labile organic phosphorus and moderately labile organic phosphorus.PM and PNM treatments significantly in creased the content of labile organic phosphorus and moderately labile organic phosphorus.The proportion of each component of organic phosphorus in the total organic phosphorus is in the order of moderately labile organic phosphorus,labile organic phosphorus,highly stable organic phosphorus,and moderately stable organic phosphorus.The main driving factors of soil organicphosphorus components are available phosphorus and inorganic phosphorus.The gene abundance of bacteria,archaea,and fungi is high.P and PN treatments had higher bacterial a bundance,PN and PNM treatments had higher soil archaea abundance,and PN treatment had the highest gene abundance of soil fungi.There was no significant difference in the abundance of alkaline phosphatase genes.The abundance of soil phosphorus transporter geneincreased significantly in M treatment.Total phosphorus was positively correlated with soil alkaline phosphatase gene abundance,and pH was negatively correlated with microbial gene abundance.4 Correlation analysis of soil microbial community structure and phosphorus componentsNitrogen fertilizer combined with organic fertilizer and two or more fertilizers can significantly increase the amount of microorganisms in the soil compared with only one fertilizer and no fertilizer.Nitrogen fertilizer combined with organic fertilizer treatment can increase soil bacterial,fungal,arbuscular fungi,and actinomycete microbial communities.There was no significant difference in soil bacteria/fungi ratio after adding different nitrogen,phosphorus and organic fertilizer.There were significant differences in soil microbial community structure with different nitrogen,phosphorus,and organic fertilizer additions.Redundant a nalysiss howed that pH,a vailable phosphorus,and inorganic phosphorus were important factors affecting the formation of soil microbial communities,and the role of inorganic phosphorus was particularly significant.The soil microbial community structure is closely related to soil phosphorus components.C as-P and Al-P are important factors affecting soil microbial community,and Ca8-P plays a significant role.Active organic phosphorus and high-stability organic phosphorus are important factors affecting soil microbial community,among which active organic phosphorus plays a significant role. |
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