Effects Of Different Fertilization Measures On Soil Fertility And Microbial Communities In The Southern Mountains Of Ningxia

To study the intrinsic relationship between different organic and chemical fertilizer applications on soil physical and chemical properties,soil enzyme activity,crop growth characteristics and yield in the southern mountains ofNingxia,Ningdan 19 was used as the test maize and planted with double-monopoly furrow mulch.No fertilizer(CK),fertilizer alone(T1),50%fertilizer+low amount of well-rotted cow manure(T2),50%fertilizer+medium amount of well-rotted cow manure(T3),50%fertilizer+high amount of well-rotted cow manure(T4),50%fertilizer+straw return(T5),50%fertilizer+1:1 mixture of straw return and well-rotted cow manure(T6)were set up for 7 treatments.The relationship between soil microorganisms,soil environmental factors and crop yield was investigated by studying the changes in soil physical and chemical properties,soil enzyme activity and crop growth characteristics and yield,and by using Illumina MiSeq high-throughput sequencing technology to analyze the changes in soil bacterial and fungal communities under the treatments of 50%fertilizer+medium-rotted cow manure(T3),50%fertilizer+high-rotted cow manure(T4)and 50%fertilizer+straw return(T5).The results of the study are as follows:(1)Different fertilization treatments reduced soil bulking weight in the 0-40 cm soil layer,but the differences between treatments were not significant.The different fertilizer treatments increased the average soil water content in the 0-100 cm soil layer during maize fertility,and the straw return T5 treatment was more effective.With the increase in the amount of rotted cow manure,the content of>0.25 mm water-stable aggregates showed a trend of increasing first and then decreasing,and the medium amount of rotted cow manure T3 treatment was better.Different fertilization treatments significantly increased the average organic matter,available phosphorus,available potassium and organic matter contents in the 0-40 cm soil layer,and the medium amount of well-rotted cow manure T3 treatment was better in all cases.(2)Soil-β-glucosidase,soil cellobiohydrolase,N-acetyl-glucosaminidase and alkaline phosphatase activities were significantly increased by different fertilization treatments.soil cellobiohydrolase,Nacetyl-glucosaminidase and alkaline phosphatase activities were better for medium amount of rotted cow manure T3 treatment and higher amount of rotted cow manure T4 treatment for soil-β-glucosidase.(3)The dominant bacterial phyla were Actinobacteria,Proteobacteria,Chloroflexi and Acidobacteria,and the dominant fungal community phyla were Ascomycota,Peridiomycota and Mortierellomycota and Basidiomycota.The bacterial diversity index and richness index showed that CK>T3>T4>T5,and the fungal community showed T4>T3>CK>T5.(4)The number of rows of ears,the number of grains of ears,the number of grains of rows,the weight of 100 grains,and the yield of maize in different fertilization treatments were all improved compared with no fertilization and single fertilization treatments,and there was no significant difference among fertilization treatments in the weight of 100 grains,and the medium amount of rotted cow manure T3 treatment was better.(5)Correlation analysis revealed that soil environmental factors were the key factors affecting crop yield.Soil total nitrogen,available potassium,organic matter,N-acetyl-glucosaminidase,and soil cellobiohydrolase were the main factors affecting maize yield,and soil available potassium content,organic matter content,and soil-β-glucosidase activity were the main factors affecting soil microbial bacterial and fungal communities in the southern mountains of Ningxia.In conclusion,in this study,fertilizer application with medium amount of well-rotted cow manure 18000 kg hm-2 was beneficial to improve soil physicochemical properties,to enhance soil enzyme activity and soil microbial community growth and reproduction,to promote the increase of maize ears grain number and 100 grain weight,and thus to increase the increase of maize yield,and there were significant differences between soil environmental factors and bacterial and fungal community diversity and structure.