Effect Of Replaceing Nitrogenous Fertilizer With Organic Fertilizer On Soil Nutrient And Fertilizer Effect Under Soyean-Maize Rotation

Organic fertilizer instead of nitrogenous fertilizer is the scientific method of fertilization that China has always advocated.This method of fertilization combine s the advantages of nitrogenous fertilizers and organic fertilizers,and has shown incomparable advantages in ensuring the stable and high yield of crops,improving soil fertility,and maintaining the sustainable development of green agriculture.This experiment is based on the research of organic fertilizer instead of nitrogenous fertilizer.Soybean-maize rotation is carried out.A total of four gradients of 1/4nitrogen substitution,1/2 nitrogen substitution,3/4 nitrogen substitution,and total nitrogen substitution were set up.An equal amount of organic fertilizer was used to replace chemica l nitrogen,and the soil nutrients,content soil humus fluorescence characteristics,crop yield and fertilizer agronomic efficiency were tested under the soybean-corn rotation system.The purpose is to explore the effects of different organic fertilizer replacement nitrogenous fertilizer ratio on the chemical properties of soil and humus composition structure.Change of crop productivity and fertilizer effect after organic fertilizer replaces nitrogenous fertilizer has been analyzed,to provide a reference for improving soil fertility,maintaining the green sustainable development of the soil environment,and improving the organic fertilizer application system.The main test results are as follows:（1）Through the measurement of soil chemical properties,it was found that:Replace d organic fertilizer with organic fertilizer can increase the soil nutrient content and organic carbon,maintain the soil p H balance,and have a positive effect on s oil improvement.Co mpared with NPK（optimizd fertilization）,the contents of total nitrogen,total phosphorus,to tal potassium alkali-decomposed nitrogen,available phosphorus,and available potassium of NPK-1/4N+M1（organic fertilizer instead of 25%nitrogenous fertilizer）,NPK-1/2N+M2（organ ic fertilizer instead of 50%nitrogenous fertilizer）,NPK-3/4N+M3（organic fertilizer instead of 75%nitrogenous fertilizer）,PK+M4（organic fertilizer instead of 100%nitrogenous fertili zer）between two years were increased by an average of 6.55%～20.33%compared with C K,5.02%～24.77%,8.26%～13.69%,7.32%～17.01%,7.04%～14.70%,8.51%～17.28%in two yea rs,content of soil organic carbon were increased by an average of 4.76%～10.04%.Besides,soil p H were increased 0.08～0.43.Of which NPK-1/2N+M2 had the largest change range.（2）Through three-dimensional fluorescence spectroscopy analysis of soil humus com ponents,it was found that:During the soybean-maize rotation,as the amount of organic fe rtilizer replacing nitrogenous fertilizer increased,The proportion of humic acids in soil hu mus has increased,the degree of soil humification fluorescence characteristics was increase d.Parallel factor analysis analyzed the humus-like components C1 and C2 and protein-like component C3 of the soil humus components.Among them,the relationship between the component C1 and the relative concentration change of the soil humus was closer.In each treatment,NPK-1/2N+M2 had the highest proportion of humic acids in soil fulvic acid,w ith an average of 59.00%,and the total contribution rate of components C1 and C2 to inc rease the relative concentration of humus-like components in soil fulvic acid also reached t he maximum,The average is 80.73%;The proportion of humic acids in humic acid in NP K-1/2N+M2 soil changed the most,with an average decrease of 25.63%.The total contribu tion rate of components C1 and C2 to increase the relative concentration of humic acid co mponents in soil humic acid also reached the maximum,with an average of 73.00%.（3）Through the analysis of crop yield data,it was found that:Replaced organic fert ilizer with organic fertilizer can effectively increase crop yields,and choos e a reasonable r atio of organic fertilizer to nitrogenous fertilizer can provide a strong guarantee for high a nd stable crop yields.Replaced organic fertilizer with organic fertilizer in the soybean-mai ze rotation,the results showed that,NPK-1/4N+M1 has the highest soybean yield,at 2942.28 kg·ha^-1,and 16.25%increased compared with NPK;NPK-1/2N+M2 has the highest mai ze yield,at 7165.02 kg·ha^-1,and 14.80%increased compared with NPK.（4）Through a joint analysis of crop yield and fertilizer agronomic utilization efficie ncy,it is found that:Choosing a reasonable ratio of organic fertilizer to replace nitrogenou s fertilizer plays an important role in improving the effect of organic fertilizer.As the pro portion of organic fertilizers for nitrogenous fertilizers increased,the agronomic utilization efficiency of organic fertilizers shows a downward trend,and it conforms to the quadratic regression function relationship with crop yield.Of which the relationship between the agr onomic utilization efficiency of nitrogen in organic fertilizers and t he changes in crop yiel ds is closest.Of which the ratio of organic fertilizer instead of nitrogenous fertilizer reach ed 50%,the effect of organic fertilizer is closest to the critical value of the curve,and th e best fertilizer effect in this experiment is obtained.