Effects Of Nitrogen Reduction Combined With Biochar On Soil Nitrogen And Maize Growth And Yields

Nitrogen is a necessary nutrient element for maize growth and development,but long-term high nitrogen fertilizer input in agriculture is likely to cause potential environmental risks,and reducing the amount of nitrogen fertilizer is imperative.Biochar has a certain regulatory effect on soil nitrogen,but the mechanism is not yet clear,especially the impact of biochar on nitrogen under reduced nitrogen.Based on this,this paper used rice husk biochar as a test material to explore the effect of biochar application on maize seed germination and seedling growth under different soil textures;and through the pot simulation test,we found a group of optimal biochar application levels under the condition of 30%nitrogen reduction in maize seedlings;finally,the above test results were applied to the field,and further revealed the effect of combined application of biochar on soil nitrogen,related properties and maize yield during the full growth period of maize under a 30%nitrogen reduction condition.The main findings are as follows:?1?The influence of biochar on maize seed germination and seedling growth is related to the addition amount and soil texture.Under the conditions of this study,the optimum amount of biochar added to loam was 7.5%.Compared with no biochar,the seed germination rate,plant height,and storage material transport efficiency were increased by 5.98%,51.20%,and 18.90%,respectively.The optimal addition amount of loamy clay biochar was 10.0%.Compared with no biochar,the seed germination rate,plant height and storage material transport efficiency were increased by 6.63%,39.32%and 17.87%,respectively.The optimum amount of biochar added to loamy sand was 2.5%.Compared with no biochar,the seed germination rate,plant height and storage material transport efficiency were increased by 5.00%,13.61%and 4.03%,respectively.?2?Compared with conventional nitrogen application,the application of appropriate amount of biochar under nitrogen reduction conditions can significantly increase the soil total nitrogen and microbial biomass nitrogen content.In the pot simulation test,the application amount of biochar with the most obvious effect of increasing the total nitrogen and microbial biomass nitrogen content of soil under the condition of reducing nitrogen by 30%(196 kg·hm^-2)was 5.0%?w/w?.Nitrogen reduction and appropriate application of biochar can also reduce the residual of inorganic nitrogen in the soil during maize maturity.In the field test,nitrogen reduction was 30%and 7 t·hm^-2?equivalent to 5.0%biochar application in pot simulation test?Biochar treatment?N2B1?compared to conventional nitrogen treatment?N1?,the ammonium nitrogen content and nitrate nitrogen content in the soil during maize maturity were reduced by 15.39%and 10.91%,respectively.?3?Compared with conventional nitrogen application,the application of appropriate amount of biochar under nitrogen reduction has a significant effect on the absorption and accumulation of nitrogen in maize.In the pot experiment,the optimum application rate of biochar was 5.0%?w/w?under the condition of 30%nitrogen reduction(196 kg·hm^-2).Compared with the conventional nitrogen treatment alone,the total nitrogen content of the maize aerial parts and underground parts increased by 11.08%and 11.42%,respectively.In the field test,the effect of 30%nitrogen reduction combined with 7 t·hm^-2 biochar treatment?N2B1?on maize nitrogen accumulation was the most significant.?4?Compared with the conventional nitrogen treatment,the application of appropriate amount of biochar under nitrogen-reducing conditions can significantly increase the yield of maize;when excessive application of biochar will cause maize yield reduction.In the field experiment,the yield of maize with 30%nitrogen reduction and 7 t·hm^-2 biochar treatment?N2B1?was 10704.96 kg·hm^-2,which was an increase of 4.33%compared with conventional nitrogen treatment;The maize yield of 14 t·hm^-2 biochar treatment?N2B2?was significantly lower than that of conventional fertilization treatment.?5?Combined application of biochar under nitrogen reduction conditions can significantly improve the utilization efficiency of maize nitrogen fertilizer.In the field test,reducing nitrogen by30%and applying 7 t·hm^-2 biochar had the highest effect on improving the nitrogen fertilizer utilization rate of maize.Compared with conventional nitrogen treatment,the nitrogen fertilizer utilization rate,nitrogen fertilizer agronomic efficiency,and nitrogen fertilizer partial productivity were increased by 13.62%,64.64%and 49.03%,respectively.In summary,on the basis of conventional nitrogen application,reducing nitrogen by 30%(196kg·hm^-2)and applying 7 t·hm^-2 biochar on the activation of soil nitrogen and the effect of improving maize yield and nitrogen utilization efficiency optimal.This result provides the theoretical basis and practical basis for the new maize nitrogen reduction,yield increase and efficiency improvement technology,black soil protection and sustainable use,and agricultural waste resource utilization and rational utilization in Heilongjiang Province.