Effect of Nitrogen Application on Nitrogen Assimilation and Rhizosphere Soil Nitrogen Transformation in Soybean
To investigate the effects of different nitrogen application rates on soybean nitrogen assimi-lation and rhizosphere nitrogen conversion,and to clarify the rational nitrogen application level of soy-bean,'Wandou 15'was used as the experimental material,six nitrogen application levels were set:N0(0 kg·hm-2),N1(40 kg·hm-2),N2(80 kg·hm-2),N3(120 kg·hm-2),N4(160 kg·hm-2),and N5(200 kg·hm-2).The three-chamber rhizobox experiment method was used to analyze the effect of different nitrogen application rates on nitrogen accumulation,root nodule nitrogen fixation,and soil nitrification and denitrification processes during the soybean branching and podding stages.The results showed that soybean dry matter mass and nitrogen accumulation increased initially and then decreased as nitrogen application increased.In rhizoma development,the number of rhizomes and fresh mass gradually decreased with increasing N application.The abundance of Rhizobium nifH genes firstly decreased and then increased during the branching stage,while it increased first and then de-creased during the flowering and podding stages.Nitrogen application increased the soil's nitrification potential during both periods.The abundance of AOA increased at first and then decreased,while the effect on AOB abundance was minimal.Nitrogen application had no significant effect on denitrification capacity during both periods.As nitrogen application increased,the abundance of the narG gene de-creased,then increased,and finally decreased during the branching stage,while it showed a continuous decrease during the flowering and podding stages.Correlation analysis and PLS-SEM showed that ni-trogen accumulation significantly affected nitrogen accumulation during the branching stage.This pos-itively regulated AOA abundance,indirectly affecting soil nitrification,and also increased the abun-dance of nitrogen-fixing nifH bacteria,indirectly promoting plant nitrogen accumulation.In summa-ry,moderate N application(120 kg·hm-2)effectively increases rhizomes,nitrification,and enhances soybean growth and plant N accumulation.
SoybeanNitrogen applicationNodule fixation of nitrogenNitrogen transformation
万方数据
维普
