Effects Of Equivalent Replacement Of Chemical Nitrogen Fertilizer With Organic Nitrogen Fertilizer On Soil Properties And Rice And Wheat Yield

The input of nitrogen fertilizer in China’s agricultural production is too high,and a large amount of nitrogen fertilizer input has caused damage to the soil and environment.As a green and high-quality fertilizer,organic fertilizer can improve soil structure when applied together with chemical fertilizer,improve soil microbial activity,better promote soil nutrient transformation,and improve crop quality and yield.The study of different proportions of organic nitrogen to replace inorganic nitrogen input is of positive significance for reducing the application of inorganic nitrogen in agriculture in China and improving nitrogen fertilizer utilization and crop yield.In this experiment,wheat(Yangmai 20)and rice(Nanjing 9108)were used as test materials,and different proportions of organic nitrogen were set up to replace inorganic nitrogen under the condition of isonitrogen substitution:single application of chemical nitrogen(W100),10%organic nitrogen+90%inorganic nitrogen(Y1W9),20%organic nitrogen+80%inorganic nitrogen(Y2W8),30%organic nitrogen+70%inorganic nitrogen(Y3W7),40%organic nitrogen+60%inorganic nitrogen(Y4W6)and 50%organic nitrogen+50%Inorganic nitrogen(Y5W5).The physical and chemical properties,organic carbon and nitrogen components,rice and wheat yields and composition factors and microbial diversity of soil under different proportions of organic nitrogen instead of inorganic nitrogen were studied,which provided a theoretical basis for soil fertilization and yield increase in Yangzhou Hanjiang area.The study concluded:1.Changes in soil physical and chemical properties.Compared with only chemical nitrogen,the treatment of both fertilizers can effectively reduce soil bulk density.Soil pH can be adjusted to slow down the progress of soil acidification.The degree of improvement between different nutrients is different,the effective phosphorus increase is higher than that of organic matter and total nitrogen,all three are with the increase of organic nitrogen proportion and show a trend of first increase and then decrease,available potassium increase has no obvious regularity,the best treatment is 40%organic nitrogen+60 inorganic nitrogen(Y4W6),soil nutrient improvement is obvious,soil fertilization effect is the best.2 Changes in soil carbon and nitrogen fractions.Compared to the fertilizer N treatment alone,the organic N and fertilizer N treatments significantly increased soil organic carbon fractions,with all organic carbon fractions increasing except MOC(mineral bound carbon).Compared to the W00 treatment,the ROC(easily oxidized organic carbon)content increased by 8.33%-39.58%,POC(particulate organic carbon)increased by 0.65%-39.38%,DOC(soluble organic carbon)increased by 3.33%27.4%,MBC(microbial carbon and nitrogen)increased by 6.87%-125.25%,and MOC(mineral bound carbon)varied in the range of-15.43%-4.62%.All components of soil organic nitrogen were enhanced.The changes in AAN(amino acid nitrogen)ranged from-12.16%to 8.44%,ASN(amino sugar nitrogen)increased from 33.6%to 41.16%,AN(ammonium nitrogen)ranged from-7.05%to 25.5%,and HUN(acidolytic unknown nitrogen)was elevated from 44.05%to 78.77%compared to W100 treatment.6.92%-45.58%.(3)Changes in rice and wheat yield and constituent factors.Compared with the single application of chemical fertilizer nitrogen treatment,the simultaneous application of both organic and inorganic fertilizers has an increasing effect on the effective ear number,ear number and 1,000 grain weight of wheat,thereby increasing wheat yield.It also has an effect on the effective number of ears,the number of ear grains,the weight of 1,000 grains,the setting rate and the yield of rice.20%organic nitrogen+80%fertilizer nitrogen treatment has the best effect on increasing rice and wheat yield.3.Changes in microorganisms.The activity and number of bacteria and fungi,as well as their diversity,were increased,and the number and species of strains beneficial to nutrient cycling in the soil were also increased compared to the N treatment with chemical fertilizers alone and the inorganic two fertilizers together.4 Changes in yield and constituents of rice and wheat.The combined application of both organic and inorganic fertilizers increased the effective spike number,spike grain number,and thousand grain weight of wheat compared to the chemical fertilizer N treatment alone,thereby increasing wheat yield.The changes in wheat yield in 2021-2022 were-7.74%-11.89%and-5.44%-19.92%,respectively,compared with the W100 treatment,and the changes in rice yield in 2021 were-9.75%-17.39%and4.62%-23.84%,respectively.In summary,the application of chemical fertilizer and organic fertilizer together can improve soil fertility and increase the yield of rice and wheat.