Effects Of Different Fertilizer Treatments On Nitrogen Utilization Efficiency And Greenhouse Gas Of Spring Corn In Northeast Of China

In order to solve the problems of low nitrogen utilization rate and low rate of return of organic materials in maize production in Northeast China,the soil?black soil?-maize system was used as the research object.Through field in-situ tests,different nitrogen application modes including nitrogen Effects of absorption and utilization of nutrients,effects on soil nutrients,effects on microbial and nitrogen-related enzyme activities,and impacts on greenhouse gas emissions.After two years of field positioning trials in 2015and 2016,T0:No nitrogen is applied,N-P₂O₅-K₂O=0-60-75,only P and K fertilizers are applied.Phosphate fertilizer application rate is 60 kg/hm²,potassium fertilizer application rate is 75 kg/hm²,deep-fall+50%straw returning field+rot maturing inoculum,no organic fertilizer is applied,and all phosphorus and potassium are applied.T1:Farmers'habitual pattern,N-P₂O₅-K₂O=210-75-60,deep-falling+50%straw returning+composting fungicide,quick-acting nitrogen-based fertilizer and large bellmouth fertilizer ratio:1:3,total phosphorus and potassium fertilizers are base manure.T2:Optimized N-P₂O₅-K₂O=165-60-75 in the previous stage,deep-fall+50%straw returning+composting,quick-acting nitrogen-based fertilizer:big bellmouth fertilizer=2:1.Potassium and potassium are all based.T3:Continuous high-yield model 1,N-P2O5-K2O=165-60-75,deep turning+50%straw returning+composting,nitrogen fertilizer 60%available nitrogen,20%organic fertilizer nitrogen,20%slow release fertilizer.20%organic fertilizer nitrogen and 20%slow-release fertilizer base application,60%of available nitrogen base fertilizer:large bellmouth fertilizer=2:1,phosphorus and potassium all base application.T4:Continuous high-yield model 2,T3+straw carbon,the main conclusions are as follows:Compared with T1 treatment,the yield of spring maize increased by 14.7%,and the increase was largest among different treatments.In 2015,the amount of nitrogen uptake of crop shoots by T4 treatment was significantly higher than that of T3.Treatment?P<0.05?;In 2016,the nitrogen uptake and the total uptake of nitrogen in stems were all the highest in T4,indicating that the addition of straw carbon has the potential to increase the utilization rate of soil nitrogen.The nitrogen use efficiency was significantly increased by 54.8%?P<0.05?in T4 and T1 treatments in 2015;the N factor productivity in each treatment,T4 and T3 treatments were increased by 61.2%and 47.8%compared with T1 treatments,respectively;Compared with T1,the agronomic efficiency of nitrogen fertilizer in T4 increased by 62.9%compared with that of T1.There was no significant difference in the N use efficiency between the treatments and the N receipt index.Compared with T1,the nitrogen utilization rate in 2016,T3 and T4 increased by27.6%and 47.9%;the nitrogen factor productivity increased by 36.5%and 57.5%.In2015,the economic benefits of nitrogen treatment compared with T1 treatment compared to T3 and T4 treatment.Increased by 35.9%and 47.1%respectively,and the economic benefit of nitrogen fertilizer T4 was increased by 25.5%compared with that of T1 in each treatment in 2016.Based on the above conclusions,it can be seen that T4 treatment has more advantages in terms of crop yield,nitrogen utilization efficiency,and economic benefits,followed by T3 treatment.Compared with the treatment of T1 in 2015,soil urease was increased by 5.2%and6.5%in T3 and T4 treatment,and 6.8%and 3.5%in 2016.T4 increased or maintained soil urease in different years.All have advantages over other treatments.The sucrase enzyme activity in 2015 compared with T1,T4 increased by 20.3%,T4 increased by 29.9%in 2016;in the two-year results,T4 treatment clearly showed the ability to increase soil sucrase activity.The correlations between soil fertility factors,available nitrogen,available phosphorus,soil urease activity and soil invertase activity were the key factors affecting soil fertility.Among them,T3 treatment has more advantages in effective N available nitrogen,and T4 treatment has more advantages in soil enzyme activity.Overall,T4 treatment has better ability than T3 treatment in soil fertility effect.The total amount of CO₂ emissions was the highest during topdressing,and T4treatment was significantly higher than the other 4 treatments.The total N₂O emissions during the entire period were significantly higher in T3 and T4 treatments than in the other three treatments;CH₄ emission under different fertilizer application measures The amount of T3 treatment was significantly lower than that of the other 4 treatments;the total T2 treatment of all treated CH₄ treatments was significantly higher than that of the other 4 treatments during the whole period;the total global warming potential between different treatments was basically the same as that of CO₂ GWP,and compared with T1,T2.Increased by 34.0%,T3 increased by 18.9%,and T4 increased by 44.7%.This shows that the addition of slow-release organic fertilizer and the addition of straw carbon all increase greenhouse gas emissions from northeast spring maize farms to varying degrees.In summary,in terms of nitrogen agronomic effects and soil fertility effects,the T4treatment of organic nitrogen fertilizer slow-release fertilizer plus straw carbon is more advantageous than other treatments in terms of nitrogen agronomic effects and soil fertility effects.The part of nitrogen reduction and fertilizer application is organic fertilizer slow release fertilizer.T3 treatment followed,environmental effects T3 and T4treatment showed varying degrees of increase in greenhouse gas trends,but in fact,compared to the direct combustion of straw and livestock manure,also played a reduced greenhouse effect.The effect of T4 treatment is to increase nitrogen utilization rate of organic fertilizer slow-release fertilizer and then add straw carbon as a measure to increase nitrogen utilization rate in the black soil region of Northeast China and solve the efficient utilization of straw.