Effects Of Reduced Chemical Nitrogen Fertilizer On Nitrogen Characteristics And Nitrogen Footprint Of Paddy Field System

Chemical nitrogen fertilizer plays an important role in agricultural production,but the large-scale and unreasonable application of nitrogen fertilizer not only reduces fertilizer utilization and increases agricultural production costs,but also causes waste of nutrient resources and exacerbates ecological and environmental risks.The scientific application of chemical nitrogen fertilizer is one of the effective ways to prevent agricultural non-point source pollution.Replacing chemical nitrogen fertilizer with nitrogen-containing organic material monosodium glutamate residues can not only open up fertilizer sources and reduce chemical fertilizer input,but also realize the resourceization of MSG waste liquid and reduce environmental pollution.pressure.Therefore,carrying out relevant research is of practical significance for promoting the clean production of rice cultivation and achieving sustainable development of agriculture.In this study,through the combination of field dynamic monitoring and indoor analysis,we explored the use of monosodium glutamate waste liquid residue(GM)50% instead of chemical fertilizer under the premise of conventional fertilization(CF),reduced application of 20% chemical nitrogen fertilizer(N80%),reduced nitrogen 20% The effects of nitrogen fertilizer(GM50%)and monosodium glutamate residue 100% instead of chemical nitrogen fertilizer(GM100%)on nitrogen loss and its characteristic changes in rice fields,rice yield and nitrogen absorption.The nitrogen footprint per unit output is estimated to provide a reference for the rational reduction of chemical nitrogen fertilizers,the reduction of agricultural production environmental risks,and the promotion of the continuous development of the MSG industry and the rice industry.The main conclusions are as follows:1.Reduced application of chemical nitrogen fertilizer can reduce the loss of gaseous active nitrogen in rice fields.Compared with CF treatment,the cumulative emissions of N2 O in N80% and GM50% treatments decreased by 41%(P<0.01)and 37%(P<0.01)respectively;the cumulative amount of NH3 volatilization decreased by 8% and 1%,but the difference not reached a significant level.2.The concentration of ammonium nitrogen and nitrate nitrogen in the soil solution of different fertilization treatments shows a long-term and negative relationship,and both decrease continuously with time.Compared with CF treatment,the average ammonium nitrogen concentration of N80% treatment has decreased,while the GM50% and GM100% treatments have increased;the nitrate nitrogen concentration of each nitrogen reduction fertilization treatment has been reduced,and the N80% reduction effect is especially obvious.3.Application of monosodium glutamate residue can increase the total nitrogen,acid digested total nitrogen and non-acid digested total nitrogen content of the paddy soil,and help to increase the content of organic nitrogen components.Under the conditions of equal nitrogen,GM50% treatment can increase the content of acid hydrolysis ammonia nitrogen;GM100% treatment can increase the content of amino sugar nitrogen,acid hydrolysis ammonia nitrogen,acid hydrolysis unknown nitrogen.4.Application of monosodium glutamate residue is conducive to improving rice yield and promoting rice's nitrogen absorption.Under equal nitrogen conditions,GM50% and GM100% treated rice yields increased by 21%(P<0.05)and 16%,respectively,and the total nitrogen content of rice,straw,and roots also increased,but the difference did not reach a significant level.5.Different reduction methods can reduce indirect nitrogen emissions and direct nitrogen emissions from rice production,thereby reducing the nitrogen footprint of rice production.The nitrogen footprint and nitrogen yield per unit yield of different reduction methods were reduced by 18%~33% and 11%~40%,among which GM50% had the best effect.In summary,nitrogen reduction and fertilization,and monosodium glutamate residues instead of chemical fertilizers can reduce the environmental risk of nitrogen loss,improve soil nitrogen composition,increase rice yield and plant nitrogen content,and help promote clean rice production.