Effects Of Long-term Different Fertilization Systems On Carbon Nitrogen Nutrient And Grain Yield In Summer Maize(Zea Mays L.)fields

China is the world's largest consumer of chemical fertilizers.The large-scale application of chemical fertilizers in crop production has exacerbated the deterioration of the agricultural ecological environment.However,China has abundant agricultural waste resources such as animal manure and straw,but its utilization rate is low,which has become an important source of rural pollution.How to make full use of organic materials,reduce the amount of fertilizer application,and improve the utilization rate of fertilizers are the key issues that need to be solved in agricultural production.Corn is an important food crop in China,with a large planting area.It is of great significance to study the investment of agricultural waste such as the poultry manure of the livestock and straw in corn planting to alleviate agricultural ecological pressure and optimize rural environment.Therefore,this paper relies on the long-term positioning experiment carried out by the platform of the Huanghuaihai Regional Corn Technology Innovation Center of Shandong Agricultural University and the State Key Laboratory of Crop Biology of Shandong Agricultural University.Positioning experiment?2006-2019?,exploring the characteristics of soil carbon and nitrogen nutrient supply during summer maize growth period in Huanghuaihai region,and providing theoretical basis for future scientific fertilization.A total of 10 treatments were set up in the experiment,which were divided into varieties with nitrogen efficient Zheng Dan 958:Organic and inorganic 1:1combined application(Z_U+M),single organic fertilizer(Z_M1),and single urea(Z_U1)under 200kg N hm^-2 and 100 kg N hm^-2 nitrogen fertilizer application with organic fertilizer(Z_M2),urea(Z_U2)and no fertilizer treatment(Z_CK).Variety with low nitrogen efficiency Lai Nong 14:single application of organic fertilizer(L_M1),single application of urea(L_U1)under 200 kg N hm^-2 and single application of organic fertilizer(L_M2)and single application of urea(L_U2)under 100 kg N hm^-2 nitrogen application rate.The main results are as follows:1.Long-term organic-inorganic combined application and single-organic fertilizer treatments could significantly reduce the soil bulk densities of the 0-40 cm soil layer than those the no-fertilizer treatment,and its soil bulk density was significantly lower than that of the inorganic and control treatments,and there was no significant difference between the inorganic soil and control.Under the same variety and fertilizer type,there was no significant difference between different nitrogen application rates.2.The content of water-stable agglomerates of different grain sizes of different fertilization treatments of the same variety showed a trend of decrease first and then increase with the decrease of grain size,mainly concentrated in two types of grain sizes>5 mm and<0.25 mm.Long-term organic-inorganic combined application and single-organic fertilizer treatments could significantly increase the aggregate size of particles>0.25 mm,and reduce the content of aggregates<0.25 mm.There was no significant difference between the content of aggregates of each size in the long-term single urea application and the control treatment.Under the conditions of the same variety and fertilizer type,there was no significant difference between the different nitrogen application rates.3.Long-term combined application of organic and inorganic fertilizers and single application of organic fertilizer could significantly increase the organic carbon content in different levels of soil compared with single urea application.Under the conditions of the same variety and fertilizer type,the increase of organic fertilizer could significantly increase the organic content in the surface soil range.Carbon content,there was no significant difference in soil organic carbon content between different application rates of urea.Taking 0-10 cm soil as an example,under the condition of 200 kg N hm^-2 nitrogen application,the organic carbon content of the soil treated with Z_M1 was significantly higher than those of Z_U+M+M and Z_U1 treatments,increased by 52.0%and 166.7%,respectively;the organic carbon content of L_M11 was increased by 104.2%compared with L_U1 treatment,and the difference was significant.With the reduction of organic nitrogen fertilizer input,soil organic carbon content was significantly reduced.Under the condition of 100 kg N hm^-2 nitrogen application,Z_M2significantly increased soil organic carbon content by 42.9%compared with Z_U2 treatment;there was no significant difference between L_M22 and L_U2 treatment..4.Long-term fertilization treatment could significantly improve the total nitrogen content of soil in different soil layers.The combination of organic and inorganic fertilizers and single application of organic fertilizers had the most significant effect.Taking 0-10 cm soil layer as an example,the total nitrogen content of Z_U+M and Z_M1 soil increased significantly under the condition of nitrogen application rate at 200 kg N hm^-2,which increased by 22.6%and 21.7%respectively compared with Z_U1 treatment.Under the condition of 100 kg N hm^-2 nitrogen application rate,the total nitrogen content of Z_M2 treatment was significantly higher than that of Z_U2 treatment,which was 21.1%higher than those of Z_U2;L_M2 was significantly higher than L_U2 treatment by 21.1%.5.Long-term organic-inorganic combined application or single organic fertilizer treatment significantly increased dry matter accumulation and grain yield compared to urea treatment.Taking 200 kg N hm^-2 nitrogen as an example,Z_U+M dry matter accumulation was significantly higher than those of Z_M1 and Z_U1 treatments,the three were 42.6%,33.9%,and16.9%higher than Z_CK,respectively.Z_U+M and Z_M1 treatments had significantly higher dry matter accumulation after flowering than Z_U1 treatment.There was no significant difference in dry matter accumulation between L_M1 and L_U1 treatments.Under the same fertilizer type,each fertilizer treatment under 200 kg N hm^-2 nitrogen application significantly increased the dry matter accumulation and distribution ratio to grains after anthesis compared with 100 kg N hm^-22 nitrogen application.In 2018 and 2019,the grain yield of ZhengDan 958 was highest with Z_U+M treatment,which was 72.8%and 83.7%higher than that without fertilization.The grain yield of Lai Nong 14 years was highest with L_M1 treatment,which was 2.2%and 36.3%higher than L_U1 treatment.