Effects Of Straw Application Mode And Fertilizer Reduction On Soil Ammonia Volatilization Of Summer Maize

Ammonia emission is an important cause of atmospheric environmental pollution and non-point source pollution.The large application of nitrogen fertilizer during agricultural planting is the main source of soil ammonia volatilization.Especially in the GuanZhong area of Shaanxi Province,which is dominated by wheat-maize rotation system,with the severe situation of heavy air haze,and the low utilization rate of nitrogen fertilizer and straw resources.Therefore,this research is based on the local agricultural planting model,and studied about the effects of different straw returning mode and reducing nitrogen,on ammonia emission reduction and yield of summer maize,at Cao xinzhuang experimental farm in 2018.A split plot design was developed in the research,with two nitrogen applications as main treatments(conventional nitrogen application:G,70% conventional nitrogen application: 70% G).In addition,there were four straw returning modes as sub-treatments(straw not returned to the field: N,straw returned to the field: S,straw returned to the field with plastic film coverage: SP,straw returned to the field and used Biochar: SB).The effects of different straw returning modes and nitrogen application,on ammonia volatilization and related soil factors of summer maize were studied,and main results were as follows:(1)During the growing period,the variation trend of ammonia volatilization rate in each treatment was basically the same.All reached the maximum peak on the 5th day after fertilization,and about 80% of ammonia volatilization loss occurred within one month after fertilization.Under the two nitrogen application levels,the ammonia volatilization rate of each treatment is N>S>SB>SP.The maximum ammonia volatilization rate at G level decreased by 10 ~19% compared with that at G level.(2)Soil ammonia volatilization cumulative emissions gradually increased with the extension of growth period,and then tended to be flat.Under the two nitrogen application levels,the cumulative ammonia volatilization emissions are: N>S>SB>SP.The cumulative emissions of ammonia volatilization under G treatment were significantly higher than 70%G treatment.The cumulative emissions of ammonia volatilization under 70%GSP treatment were the least.However,the ammonia volatilization loss rate of 70%G treatment was higher.(3)The dynamic changes of soil environmental factors in different straw returning modes and nitrogen application levels during summer maize growth period were different.SP treatment has obvious warming and heat preservation effect.The soil temperature of other treatments has little difference.SP,SB and S treatments of soil water content,urease activity,and microbial biomass nitrogen content were higher than N treatment.SP and SB treatments alleviated the leaching of available nitrogen to some extent.(4)Straw returning and nitrogen application can both increase corn yield by increasing grain number per ear and grain weight per ear,but GSP treatment works best.The nitrogen uptake efficiency(NupE)and nitrogen partial factor productivity(Nfp)are better at 70%G level,and SP treatment is the highest.The water utilization rate(WUE)of each treatment was higher at the G level.Under the two nitrogen application levels,the water utilization rate of each treatment was: SP>SB>S>N.Therefore,the combined mode of straw returning with plastic film mulching,combined with the tillage method of nitrogen reduction and application can effectively reduce the ammonia volatilization cumulative emissions,and maintain a high level of yield and water-nitrogen utilization ratio.On the basis of giving consideration to the effect of agricultural production,the better effect of ammonia emission reduction in farmland can be achieved.