Research In The Effect Of Combined Application Of Organic And Inorganic Fertilizer On Crop Growth And Soil Microbiological Properties Under Rice-wheat Rotation System

A field experiment was laid out with randomized block design with five replicates to explore the effects of different combined applications of pig manure compost and chemical fertilizers on rice-wheat yield,nutrient utilization,soil fertility and soil microbiological properties under rice-wheat rotation system at Tai Lake region.Six treatments were set up as follows:CK(no fertilizer)as blank control,NPK(inorganic fertilizer,N application 240 m2)as a conventional control,PMCF1(70%NPK with pig manure compost 3000 m2),PMCF2(50%NPK with pig manure compost 6000 m2),PMC 1(organic and inorganiccompound fertilizer 1800 m);PMC2((organic and inorganic compound fertilizer 3600 m).The main results were as follows:Fertilization promoted the crop grain yield significantly.Similar or even higher grain yield was obtained in the chemical fetilizaition of PMCF1 and PMCF2 when compared with NPK,though the chemical fertilizer input was only 70%and 50%,respectivley.In detail,treatments PMCF1 and PMCF2 promoted the yield compared with NPK by 4.8%and 3.7%at rice season,and 1.5%and 0.3%at wheat season,respectively.The treatment PMC2 resulted in the highest grain yield,which increased the yield of rice and wheat by 7.9%and 11.1%,significantly.The treatments of combined application of inorganic fertilizer and pig manure compost showed higher nitrogen accumulation aboveground.The nitrogen harvest index of treatments PMCF1,PMCF2,PMC 1 and PMC2 were significantly higher than that of NPK in rice season.The nitrogen apparent recovery fraction of treatment PMCF1 and PMCF2 was significantly higher than NPK.In addition,the nitrogen physiological efficiency of treatments PMCF1 and PMCF2 was significantly higher than NPK.Fertilization(especially treatment PMCF1 and PMC2)significantly increased nitrogen,phosphorus and potassium content,organic matter content,soil microbial biomass C and N and the main soil enzyme activity in topsoil under rice-wheat rotation,which was positively correlated with grain yield.Which means that inorganic fertilizers combined with organic compost helped to promote the quality of soil fertility thus resulting in higher yield.Real-time PCR analysis indicated that fertilization can significantly improve the microbe population in topsoil.In rice season,the highest fungal abundance was found in PMC2,followed by PMCF1 and PMCF2.The highest azotobacter abundance was observed in PMC1 and PMC2,followed by PMCF1 and PMCF2,while all of the azotobacter density in the four treatments revealed was higher than treatment NPK and CK.The highest ammonia-oxidizing archaea(AOA)abundance was detected in PMC1,followed by PMC2,PMCF1 and PMCF2.Fertilization increased the denitrifying bacteria(nirK)abunudance compared with CK and treatment PMCF2 showed the highest nirK abundance.In wheat season,except for treatment CK,the fungal abundance was highest in PMC1,which is followed by NPK.There was no significant difference in azotobacter abundance between different fertilization treatments.Abundance of AOA and nirK were both found to be highest in NPK,followed by PMC1.The application of fertilizer significantly promoted the abundance of ammonia oxidizing bacteria(AOB),which is higher in wheat season than rice season.Another denitrification gene nosZ showed similar trends as nirK.High-throughput sequencing(Miseq sequencing)indicated that fertilization can significantly affect several major soil microflora,including Proteobacteria,Acidobacteria,Bacteroidetes,Chloroflexi and so on.The microbial diversity was higher under the application of inorganic combined with organic fertilizer,which also revealed a significant difference between rice and wheat season.In conclusion,application of inorganic fertilizer combined with pig manure compost can significantly affect the soil microflora and help the soil build a high-yield microflora.Overall,compared with NPK,PMCF1 or PMCF2 not only promoted the accumulation and transfer of nitrogen in vivo and fertilizer use efficiency,regulating the nutrient uptake at different growth stages,which help achieve the harmonization of yield components,but also improved soil fertility,quality and soil microflora.