| Increasing crop nutrient absorption and reducing nitrogen loss has been a hot topic in agricultural production.The effects of nitrogen fertilizer,arbuscular mycorrhizal fungus(AMF)and straw returning to field on nitrogen uptake and loss in summer maize were studied in pot experiment..This experiment is a three-factor experiment with two nitrogen fertilizer gradients(N1;180 kg.hm-2and N2;360 kg.hm-2),AMF processing uses a compartment system to set up three processes(both the root and AMF can pass through the compartment: A1 R,only AMF can pass through the compartment: A1,the root and AMF can not pass through the compartment: A0);The yield,biomass of each organ,root characteristics,nitrogen accumulation in each organ,ammonium nitrogen and nitrate nitrogen in soil at maturity stage were measured in 2016 and 2017 at the level of returning two stalks(straw returning,straw not returning to the field),and in 2016 and 2017,the yield of maize,biomass of various organs,characteristics of root system,accumulation of nitrogen in each organ were measured.NH3 volatilization rate and N2 O emission flux were used to analyze the relationship between nitrogen accumulation and gaseous nitrogen emission and yield of summer maize by correlation analysis.The results of multivariate ANOVA showed that nitrogen fertilizer,straw and amf had significant effects on yield,biomass,nitrate nitrogen and N2 O emissions,and interaction of nitrogen and amf had significant effects on ammonium,nitrate and N 2O emissions.The results of correlation analysis showed that the yield and biomass,root nitrogen accumulation and shoot nitrogen accumulation of summer maize had significant positive correlation.Compared with N1 treatment,the root infection rate of N2 treatment decreased22.75%,the average yield of maize increased 37.03%,the ear length,ear diameter,row number and grain number per row of summer maize were increased by 37.03%The average 100-seed weight increased by 16.38%,6.45%,2.84%,21.57%,7.63%,the average length of baldness decreased by 32.25%,the root biomass,stem biomass,leaf biomass,sheath biomass,bract biomass,and so on,increased by 16.38%,6.45%,2.84%,21.57% and 7.63%,respectively.Spikelet biomass,other organ biomass and individual plant biomass increased by 6.34%,10.8%,11.51%,12.21%,27.14%,36.62%,10.07%,22.05%,total root length,root volume,respectively.The root surface area and root diameter increased 8.23%,14.86%,8.75%,5.28%,the two-year average nitrogen accumulation increased 35.25%,and the two-year average nitrogen accumulation increased 47.25% in the aboveground,and the root surface area and diameter increased by 8.23%,14.86%,8.75% and 5.28%,respectively.The two-year average content of ammonium nitrogen,nitrate nitrogen and inorganic nitrogen increased by 60.25%,16.25% and 53.25%.Compared with the non-returning straw,the root infection rate of straw returning treatment decreased 10.43%,the average yield of maize decreased 12.34%,the ear length,ear diameter,row number and grain number of summer maize were decreased by 10.43%,12.34% and 12.34% respectively,and the ear length,ear diameter,row number and number of grains per row.The average 100-seed weight decreased by11.16%,3.36%,1.51%,7.33%,4.36%,the average baldness tip length increased by7.15%,and the two-year average root biomass decreased by 0.58%.The two-year average of stem biomass,leaf biomass,sheath biomass and bract biomass decreased by 12.35%,3.10%,2.84% and 3.11%,respectively.The two-year average of ear biomass increased by 3.64%,other organ biomass increased by 72.69%,single plant biomass increased by 1.21%,total root length,root volume and root surface area of maize increased by 3.64%,72.69% and 1.21%,respectively.The two-year average of root diameter increased by 9.01%,8.83%,8.22%,5.51%,the two-year average of total nitrogen accumulation in maize roots increased by 4.67%,and the two-year average of total nitrogen accumulation in above-ground parts of maize decreased by6.17%,and the root diameter increased by 9.01%,8.83%,8.22%,5.51%.The two-year average of soil ammonium nitrogen decreased by 10.47%,the two-year average of soil nitrate nitrogen increased by 94.21%,and the two-year average of soil inorganic nitrogen increased by 78.06%.Between the three AMF processing,compared to the A0 treatment(neither the root nor the AMF can pass through the compartment),A1(only AMF can pass through compartments)and A1R(both roots and AMF can pass through compartments)increased corn grain yield by 28.71% and 22.73% respectively for two consecutive years at the two levels of straw non-returning and straw returning.56.26%,70.26%;The mean ear length increased by 5.80%,5.62%,17.4%,23.51%,3.85%,6.20%,9.52%,7.21%,respectively,and the mean ear diameter increased by3.85%,6.20%,9.52% and 7.21%,respectively.The number of grains per row increased by 9.31%,3.47%,21.08%,30.73%,and the weight of 100 grains increased by 3.56%,10.24%,11.09%,6.56%,respectively.The length of bald tip decreased by2.57%,15.67%,31.21%,10.70%,and the biomass per plant increased by 19.10%,14.55%,45.89%,24.45%,respectively.Total nitrogen accumulation increased by6.15%,6.40%,37.95%,46.83%,9.79%,9.42%,35.18%,32.57%,respectively,and increased by 9.79%,9.42%,35.18% and 32.57% respectively.Soil ammonium nitrogen content decreased 10.94%,7.13%,21.26%,18.93%,soil nitrate nitrogen content decreased 12.87%,21.69%,34.96%,45.58%,and soil inorganic nitrogen content decreased 12.58%,respectively.20.67%,32.94%,43.68%.The NH3 emission rate and N2 O emission flux changed dynamically during the whole growth period of summer maize.The NH3 emission rate and N2 O emission flux increased first and then decreased after fertilization in maize growing period,and the peak of N2 O emission was at the same time.Under the same compartmentalization system and straw treatment,the NH3 emission rate and N2 O emission flux of N2 O treatment increased significantly.Compared with N 1,the NH3 volatilization rate of N2 treatment increased by 45.73%,27.52%,respectively,compared with N1 treatment,and the N2 treatment increased the NH3 volatilization rate by 45.73% and27.52%,respectively.N2 O emission flux increased by 44.65% and 49.64%respectively under the two straw treatments.Compared with control A0,A1(only AMF can pass through compartment)and A1R(root and AMF can pass through compartment)significantly reduced NH3 and N2 O emissions.Under the same amount of nitrogen application and straw treatment,compared with A0,the volatilization rate of NH3 in A1 treatment(only AMF can pass through compartment)decreased by22.13% and 11.74% under the two straw treatments,respectively.N2 O emission flux decreased by 35.52% and 3.29% respectively,and NH3 volatilization rate of A1 R treatment(both roots and AMF could pass through compartment)decreased 37.38%and 23.49% at the two straw treatments,respectively.N2 O emissions decreased by82.26% and 78.95% respectively.Straw returning decreased soil NH3 volatilization rate and N2 O emission flux significantly.Compared with non-returning straw,NH3 volatilization rate and N2 O emission flux decreased 69.67% and 21.22% respectively.The results show that the amount of nitrogen fertilizer is increased,the amount of nitrogen accumulation in summer maize is increased,the yield of summer maize isincreased,the NH3 volatilization and N2 O emission are increased at the same time,and the AMF can improve the absorption and utilization of nitrogen in summer maize,reduce the volatilization rate of NH3 and the N2 O emission amount,The straw returning to the field has a negative effect on the crop yield,but the loss of gaseous nitrogen in the soil is reduced.In that production,the corn field of the straw return to the field is reasonably applied with the nitrogen fertilizer at the same time,and the amf is simultaneously provided,so that the nitrogen utilization efficiency can be improved,the nitrogen loss is reduced,and technical support is provided for the sustainable development of agriculture. |
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