Characteristics Of Soil Carbon And Nitrogen In Long-Term Different Fertilization

In order to reveal the effect of Fertilization on the sustainable utilization of soil,this paper systematically studied the effects of different fertilization treatments on the absorption and utilization of nutrients,the characteristics of soil fertility,and the change characteristics of soil carbon and nitrogen on the basis of the long-term fertilization experiment of oriented cultivation under the wheat maize rotation for 11 years.The main results are as follows:1.The yield of crops is very low without applying nitrogen fertilizer（CK,PK）in 11years.Applying nitrogen fertilizer（NK,NP,NPK）in 11 years can maintain high yield level and nutrient absorption,resulting in higher physiological efficiency and harvest index of P and K,but lower nitrogen harvest index.2.Applying chemical nitrogen fertilizer（NK,NP,NPK）in 11 years,the soil shows a slow acidification trend,and the content of soil organic matter,total nitrogen,alkali hydrolyzed nitrogen shows an increasing trend;applying chemical phosphorus fertilizer（PK,NP,NPK）in 11 years,the soil available phosphorus maintains at a high level,and the soil available phosphorus without applying phosphorus fertilizer（CK,PK）in 11 years decreases to less than 15mg·kg^-1,which will be the limiting factor for crop growth;11 The content of soil available K increased with the application of chemical K fertilizer（NK,PK,NPK）every year and exceeded 140mg·kg^-1,while the content of soil available K decreased to about70mg·kg^-1without the application of K fertilizer（CK and PK）,which became the limiting factor of crop growth.3.After long-term directional fertilization,the content of soil humus is in the range of3.03-3.56g·kg^-1,and NPK treatment is the highest;the content of recombinant humus is in the range of 10.51-13.88g·kg^-1,and the content of long-term non fertilization treatment is the lowest;compared with long-term non fertilization treatment,long-term fertilization treatment can improve the ratio of Hu/Fu,loose/tight,and improve the quality of soil humus,especially NPK treatment with Hu/Fu,loose/tight/The ratio of fullness to tightness and the ratio of looseness to tightness increased more.4.4.11 years of application of NK,PK,NP and NPK increased the content of soil total acid hydrolyzable nitrogen by 5.18%-23.91%,and NPK Combined Application of soil total acid hydrolyzable nitrogen was the highest.Among the total acidolysis nitrogen,the proportion of acidolysis ammonium nitrogen and amino acid nitrogen is the highest.5.11 years of fertilization significantly increased soil urease activity,sucrase activity and soil microbial biomass carbon and nitrogen content,especially NP,NK and NPK treatment increased more;the ratio of microbial biomass carbon/soil organic carbon,microbial biomass carbon/microbial biomass nitrogen was relatively high,soil carbon and nitrogen were relatively low,microbial decomposition was faster.