| The dry farming area at the southeast foot of the Daxingan Mountains is the main corn producing area.The maize production is often reduced due to the poor moisture content in spring.Although straw mulching has the effect of preserving soil moisture,there are some problems such as poor seedling quality and difficult topdressing.At the same time,farmers in this region generally adopt the "one-shot" fertilization mode,which causes a large amount of greenhouse gas emissions.To solve the above problems,straw mulch strip tillage technology and single-use application technology of controlled release nitrogen fertilizer and urea were introduced in this study.Four different tillage modes were set up: conventional raised bed(CP),off-field no-tillage(NT),mulch no-tillage(RNT),mulch strip tillage(RST),and four fertilization modes were set up under straw mulch strip tillage: no nitrogen fertilizer(0N),conventional fertilization(Sd),30% slow mixed fertilization(30%Cr),50% slow mixed fertilization(50%Cr).The effects of straw mulch strip tillage and slow mixed fertilization on nitrogen utilization and greenhouse gas emission of maize were systematically studied.The main results are as follows:(1)Compared with NT,CP and RNT,RST increased maize emergence rate by 1.6%,9.0% and 9.1%,population biomass by 4.4%,14.3% and 18.4%,and yield by 4.2%,6% and7.2%,respectively.Among them,RST mainly increased the material accumulation before flowering,and the increase of effective ear number was the main reason for the increase of yield.Under straw mulching strip tillage,50%Cr promoted the pre-flowering and postflowering material accumulation of corn,increased the number of grains per ear and 1000-grain weight,and thus increased corn yield.Compared with 30%Cr and Sd,the biomass of corn increased by 3.3% and 10.6%,and the yield increased by 4.0% and 9.2%,respectively.(2)Compared with NT,CP and RNT,the nitrogen use efficiency of RST increased by29.7%,45.5% and 60.0%,and the physiological efficiency of RST increased by 22.6%,23.8%and 19.8%,respectively.There was no significant difference between NT and RST,and RST was 17.9% and 32.7% higher than CP and RNT.Under straw mulch strip tillage,slow mixing fertilizer treatment significantly increased nitrogen accumulation,transfer volume and postflowering grain nitrogen accumulation,and reduced soil inorganic nitrogen residue and apparent nitrogen loss,among which 50%Cr was more obvious.Compared with 30%Cr and Sd,the nitrogen use efficiency of 50%Cr was increased by 16.3% and 49.0%,and the nitrogen absorption efficiency was increased by 8.1% and 37.1%,respectively.There was no difference in nitrogen physiological efficiency among all treatments.(3)RNT is the largest greenhouse gas emission intensity,and compared with RNT,NT,CP and RST are reduced by 12.1%,10.9% and 8.0%,respectively.RST has no significant difference with CP and NT.Net income and net ecosystem budget value both have the highest RST,RST increased by 7.0%,9.7% and 10.0% compared with NT,CP and RNT net income,and net ecosystem budget value increased by 6.8%,9.7% and 11.1%,respectively.Under straw mulch strip tillage,the greenhouse gas emission intensity of 50%Cr and 30%Cr decreased by 10.4% and 7.3% compared with Sd,respectively.The economic and environmental benefits of 50%Cr were the highest.Compared with Sd,the net benefits increased by 6.7% and the net ecosystem budget value increased by 7.4%.In the dry crop areas along the Daxingan Mountains in Inner Mongolia,straw mulching strip-till significantly improved maize seedling emergence,effective ears and yield,and 50%Cr significantly reduced on-farm greenhouse gas emissions and improved maize yield and nitrogen uptake efficiency.Straw mulch strip-till with 50% Cr slow-mix fertilizer is a feasible technology model for moisture conservation and yield increase,nitrogen efficiency and environmental safety of maize in the dry crop areas along the Daxingan Mountains in Inner Mongolia. |
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