| The long-term excessive input of fertilizer has lead to the decline of soil fertility,nutrient utilization and crop quality,and may also pose a risk of ecological environmental pollution.The effects of fertilization management and organic substitution(straw,biogas slurry and organic fertilizer)on soil nutrient and microbial communities were studied through pot experiments and field trial,by phospholipid fatty acid(PLFA),Biolog and MicroRespTM,tn this paper.The main results are as follows:1?The effects of different nitrogen application levels,50%nitrogen replacement by biogas slurry and nitrogen application time on soil nutrients and microbial community under the conditions of straw return to the field were discussed.The results showed that:biogas slurry replacement treatment(1)promoted the accumulation of soil nitrogen,but had no significant effect on other nutrients in the soil,and the effective phosphorus content was even lower than that of conventional fertilization treatment;(2)it could significantly increase the total soil microorganism Biomass,pre-transplantation and maturity can significantly increase the soil microbial F/B value,in which the nitrogen fertilizer level of 180 kg·hm-2 is better than that of other nitrogen fertilizer levels;(3)can increase soil microbial respiratory metabolic activity and microbial community diversity.In general,the nitrogen fertilization level was 180 kg·hm-2,and nitrogen replacement treatment,such as 50%biogas slurry,was more conducive to improving soil nutrients,total soil microorganisms,and community diversity.2?The effects of applying chemical fertilizers and organic fertilizers on the soil nutrients and microbial community structure of rice fields under the conditions of returning straws to non-rcturning fields were studied,in order to explore which organic nutrient(straw,organic Fertilizer)replacement application mode is more conducive to the sustainable development of rice soil environment.The results showed that:(1)Chemical fertilizer and straw return to the field could promote the increase of soil organic matter,available nitrogen,available phosphorus and available potassium content.(2)The application of commercial organic fertilizer significantly increased the metabolic activity of soil microorganisms.Returning straw to the field and commercial organic fertilizer was beneficial to increase the use of phenolic acids and carboxylic acids by soil microorganisms and reduce the use of amines by soil microorganisms.(3)Commercial organic fertilizer and straw return to the field significantly increased the richness of soil microbial communities..(4)There is a correlation between soil nutrient content and PLFA microbial community.In summary,the application of commercial organic fertilizer under the condition of returning straw to the field is conducive to increasing the soil nutrient content,increasing the metabolic activity and species richness of microorganisms in the soil3?The ecological effects of different fertilizer types and straw combined application on paddy soil were further discussed,and four treatments were set up(no nitrogen fertilizer+straw return(B+JG);chemical fertilizer+straw return(HF+JG);biogas slurry+ straw return(Z+JG);commercial organic fertilizer+straw return(S+JG)),the results showed that:(1)under the straw return to the field,fertilization was the highest in soil nutrient accumulation,and shortterm application of biogas The effect of liquid and commercial organic fertilizer treatment on soil nutrient accumulation is not obvious;(2)the application of biogas slurry treatment can significantly improve soil microbial metabolism and carbon source utilization,while the effect of commercial organic fertilizer application is not obvious;(3)Both biogas slurry and commercial organic fertilizer can increase the diversity of soil microbial communities,and the effect of biogas slurry application is more obvious.(4)Both the application of biogas slurry and commercial organic fertilizer can increase the total biomass and Fungi/Bacteria(F/B)value of soil microorganisms.Among them,the total biomass of soil microorganisms applied by biogas slurry is higher than that of commercial organic fertilizer,but the Fungi/Bacteria(F/B)value is relatively low.In summary,the combined application of biogas slurry and straw in a short period of time is more conducive to improving the total amount of soil microorganisms and community diversity.4?Finally,this paper uses phospholipid fatty acid(PLFA)and Biolog-Eco micro-plate method to explore four nitrogen fertilizer management modes(no nitrogen fertilizer(CK);farmers customary fertilizer(FP);nitrogen fertilizer optimization management 1(OPT1);nitrogen fertilizer optimization management 2(OPT2))on soil microbial community structure in paddy fields.The results showed that(1)OPT1 treatment increased the soil microorganism's metabolic activity and carbon source utilization ability,while FP and OPT2 treatments both reduced the microorganism's metabolic activity and carbon source utilization ability;(2)OPT1 treatment soil had high total biomass and soil The microbial diversity is more complex and the F/B value is the highest,indicating that the optimal management of nitrogen fertilizer can also improve the soil ecological environmentIn summary,the short-term application of biogas slurry(partially replacing chemical fertilizers)and commercial organic fertilizers on soil nutrient accumulation has no obvious effect on soil nutrient accumulation under the condition of straw return to the field,but it can effectively increase soil microbial content and diversity.Obviously;It is beneficial to improve the total biomass,biodiversity and F/B value of soil microorganisms,and improve the soil ecological environment.Therefore,in the exploration of reduced fertilization conditions for rice fertilizer,the proportion of organic nutrients replacing fertilizers and the nitrogen fertilizer operation in the whole growth period will affect the Ecological sustainable development plays a key role. |
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