Feature Of Soil Aggregates And Microorganism Community Under Organic And Inorganic Fertilizer Application In Winter Wheat-Summer Maize System

Soil aggregate is the basic structural unit of soil and the living place of soil microorganism.Soil microorganisms are the most active part of soil ecosystem,and soil microbes directly affect the nutrient cycling and aggregate rotation in soil.Therefore,it is significance to study the distribution of nutrient and microorganisms in soil aggregates.Based on the North China Plain fertilizer experiment platform,winter wheat summer maize cropping system,we studied fertilization effect on grain yield,soil aggregate,soil aggregate,water,carbon and nitrogen concentration of the soil microbial community structure and microbial in soil aggregation effects of in distribution.The test set for five treatment process: CK,M0,M20,M50 treatment and M100 treatment,CK treatment is planting winter wheat summer maize rotation system,no fertilizer input,M0 is the local fertilization method,all zero fertilizer,organic fertilizer substitution,M20 treatment,M50 treatment and M100 treatment,respectively.All treatments except CK were adopted same amount of nitrogen.The main findings were as follows:(1)Organic and inorganic fertilizer application can increased the yield of winter wheat and summer maize and agronomic efficiency of nitrogen fertilizer.Compared with M0,M100 showed no obvious increase the yield of winter wheat.While the succession crop summer maize's yield increased significantly.Production increase with the increase of experimental years.Organic and inorganic fertilizer application improved the partial productivity of nitrogen fertilizer and agronomic efficiency of nitrogen fertilizer.M100 had the highest partial productivity of nitrogen fertilizer,the value was 47.88 kg kg-1,it was 12.58 kg kg-1 higher than M0.(2)Organic and inorganic fertilizer application can promote the formation of soil aggregates and improved their organic matter content.Fertilization changed the distribution of soil aggregates with different size fractions.The ratio of fractions particle-size > 2 mm in M50 and M100 increased 35.15 % and 40.92%,Compared with CK.Mean weight diameter of the different treatments showed M100 > M50 > CK > M20 > M0.Dominant particle size was 1-2 mm in CK?M0 and M20,2-5 mm in M50,> 10 mm in M100.The results showed that the application of organic and inorganic fertilizers promoted the formation of soil aggregates.Soil organic matter in different treatments and same particle-size aggregate showed M100>M50> M20 > M0 >CK.(3)Organic and inorganic fertilizer application can promote microbial diversity and activity.The total amount of PLFAs increased with the application of organic fertilizer,and the total amount of M100 treated by PLFA was about 9 times of that of CK.The content of bacteria,fungi and actinomycetes was similar to that total PLFAs,and the content of M100 treatment was the highest.The results of Biolog ECO showed that the higher application rate of organicfertilizer,the greater corresponding Shannon index,richness index,dominance index and AWCD value,the results showed that the application of organic and inorganic fertilizers improved the soil microbial diversity.Meanwhile,the application of organic and inorganic fertilizers enhanced microbial activity.Compared to CK and M0,M50 and M100 increased K value and exponential growth rate of Logistic curve,decreased the latent period.K value were lowest in M0,0.3954;highest in M50 and M100,above 0.45.Exponential growth rate of Logistic curve were lowest in CK,0.0452,it was between 0.045-0.050,it was highest in M100,0.0635.The latent period was more than 24 h in M0,between 12-24 h in others treatments.(4)Organic and inorganic fertilizer application can promote soil microbial biomass distribution.The Shannon index increased in all particle-size aggregate,and small aggregate increased greatly.The total PLFA and bacteria content were higher in particle-size 5-10 mm and 0.25-0.5 mm,while the actinomyces content in 0.25-0.5 mm was the highest.The content of gram positive bacteria gradually increased with the decrease of particle size of soil aggregate.Organic and inorganic fertilizer application can promote soil microbial activity.Aggregate of particle-size 5-10 mm had highest microbial carbon source metabolic potential in M50 and M100,the K value were 0.4635 and 0.4316.The time of reached 0.5K were 57.89 h,61.32 h and 54.31 h in M20,M50 and M100,they were shorter than M0,75.52 h.In short,the winter wheat summer maize rotation system in the North China Plain,organic fertilizer to replace chemical fertilizer can promote the formation of soil aggregates,increasing the concentration of organic carbon and total nitrogen in soil aggregates and increase microbial diversity,increased microbial activity.The factors of soil fertility were affected by fertilization factors,aggregate size,nutrient content,water content and other factors.