【摘 要】
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Large amounts of nitrate-N (NO3--N) accumulated in agricultural soils will typically leach to deeper soil layers.If it moves below the root zone it will be lost from the system,but the deep-rooted cro
【出 处】
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第十五次全国小麦栽培科学学术研讨会
论文部分内容阅读
Large amounts of nitrate-N (NO3--N) accumulated in agricultural soils will typically leach to deeper soil layers.If it moves below the root zone it will be lost from the system,but the deep-rooted crops can recycle NO3--N leached from shallow-rooted crop root zone.The study was to clarify the characteristics of soil NO3--N accumulation under different N rates in summer maize (Zea mays L.) and its residual effects on succeeding deep-rooted winter wheat (Triticum aestivum L.).Different N rates was applied in summer maize growing season and the cultivation techniques of water and N fertilizer saving was adopted in winter wheat season.There was a highly significant positive correlation between N rates and NO3--N accumulation amount in 0-2 m soil profile after summer maize harvest,the yield of following wheat also showed a significant positive relationship with the NO3--N amount accumulated in soil profile before sowing,which could be fitted by a linear model.Comparing with maize harvest,NO3--N content in each soil layer sharply decreased at wheat maturity stage under the condition of 157.5 kg N ha-1 or no N fertilizer was applied during wheat growing season.Applying 240 kg N ha-1 in maize season at the same time 157.5 kg N ha-1 in wheat season( N240+157.5 )could meet wheat demand for N,eventually maintain yield,N uptake and annual apparent N recovery efficiency at a higher level.The treatment N360+0 (360 kg N ha-1 was applied to summer maize but no N-fertilizer application in winter wheat season)could also obtain similar results but have a great leaching risk.N-fertilizer applied in maize season had strong residual effectiveness to subsequent winter wheat.Adopting the cultivation techniques of water and N fertilizer saving in winter wheat season could not only shrink sharply the NO3--N in the soil profile at summer maize harvest,but sustain yield and increase N-fertilizer recovery efficiency.
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