| Under the background of long-term rigid demand for food production and fertilizer"zero growth",with less nitrogen fertilizer inputs to achieve higher yields need to tap the potential of inherent soil production.However,it is unclear whether the improvement of inherent soil productivity(ISP)can improve maize yield and nitrogen use efficiency(NUE).Therefore,quantitative analysis the relationship of inherent soil productivity(ISP)with yield and NUE,and to explore the main control factors of ISP,which will provide fundamental basis for the realization of maize yield and NUE continuous improvement rely on the improvement of inherent soil productivity.This study is based on the difference of ISP between the East and the west of the Inner Mongolia Region,using multi-ecological lacation network test conbained soil management strategy(current management,CP;improve CP);improve inherent soil productivity,IISP)with density(60000 plants/hm2,82500 plants/hm2,and N application(0 kg/hm2,220 kg/hm2)interaction to create different nitrogen efficiency group,in order to system analysis the relationship of ISP with yield and NUE,and its soil ecological and crop physiological processes.The main results were as follows:(1)Improving inherent soil productivity can achieve synergistic improvement in maize yield and nitrogen fertilizer efficiency.When the ISP improved to 8.7 t/hm2 above,can achieve the yield and PFPN synchronization improved;when the ISP improved to 10 t/hm2 above,can achieve the yield and NUE synchronization improved.The high density and low nitrogen groups can obtain higher yield at higher ISP levels indicating that improving ISP is an important foundation for increasing density and reducing nitrogen to increase yield.(2)The soil organic matter content,available nitrogen content,soil nitrogen mineraliza-tion,soil nitrogen losses(N losses)and water use efficiency(WUE)were the main factors affecting ISP and NUE was mainly affected by soil nitrogen mineralization,N losses and WUE.Soil organic matter content indirectly affected the soil available nitrogen level,nitrogen mineralization ability and water conservation ability,which was the core of ISP.IISP strategy significantly improve soil nitrogen mineralization rate(16.0%),reduced N losses(11.4%),and significantly increased WUE(12.9%),and its better soil water and nitrogen environment is an important foundation for its high yield and high efficiency.(3)When the ISP was below 10 t/hm2,the nitrogen supply capacity of the soil was lower than that of the ISP,decreased NUE with the ISP.When the ISP improved to 10 t/hm2,the soil nitrogen supply capacity was not the restraining factor,ⅡSP promoted synergistic optimization of carbon and nitrogen transport capacity of source and sink and postharvest vegetative organs,and the yield and NUE system were improved by increasing grain weight and nitrogen internal efficiency(NIE).The effect of nitrogen application rate and density on the relationship between ISP with yield and NUE,and the significant interaction effect of soil management strategy × nitrogen application rate × density showed that improving yield and nitrogen efficiency by improving soil productivity should combine with other measures to play its comprehensive interaction with density and nitrogen.(4)Based on the current maize yield level,if yield and(Nitrogen partial factor productivity)PFPN increased by 15%,the ISP will be increased to 10 t/hm2.Under this situation,the soil mineralization and WUE will reach 99.1 kg/hm2 and 27.2 kg hm-2 mm-1,while N losses will be reduced to117.3kg/hm2,and the nitrogen application rate was 206.1 kg/hm2,which was 46.4%higher than that of 8.7 t/hm2 ISP.If the yield and PFPN was increased by 30%,the ISP will increase to 11.6t/hm2,and the soil mineralization and WUE will reach 119.4 kg/hm2 and 32.7 kg hm-2 mm-1.and the N losses will be reduced to 96.7 kg/hm2;and the nitrogen application rate was reduced to 176.1 kg/hm2.which would be 67.4%higher than that of 8.7 t/hm2 ISP. |
