小麦-玉米轮作下土壤-作物系统对氮肥的缓冲能力

 通过田间试验研究了小麦－玉米轮作条件下兼顾产量时土壤对施用氮肥的承受能力。应用线性－平台模型拟合作物产量和施氮量的关系,用平台－线性模型拟合土壤硝态氮和施氮量的关系,并且引入了土壤－作物缓冲力的概念来表示土壤对施用氮肥的承受力。试验结果表明,在适量施用氮肥（１５０～１８０ ｋｇ Ｎ／ｈａ）的情况下,施氮处理和对照之间土壤剖面无机氮没有明显差异,当施氮量较高时,在作物整个生育期间土壤剖面都存在高量无机氮。不同种植方式和土壤条件下,土壤－作物系统缓冲力存在较大差异。种植小麦时土壤缓冲力大于种植玉米时,壤质土壤对施用氮肥的缓冲力大于砂质土壤。

Soil-plant Buffer Power for Nitrogen Fertilizer Under Wheat-corn Rotation

Both the impact of N fertilizer on soil Nmin accumulation and the grain yield were studied in the field plot under wheat-corn rotation system. A linear-plateau model of grain yield on N fertilizer applied and a plateau-linear model of Nmin accumulation in soil was used in the experiment, and the concept of soil-plant buffer power was introduced to indicate the impact of N fertilizer application on soil and environment. The results suggested that there were not significant differences of Nmin accumulation in soil profile between N fertilizer treatment and control when optimum rate of N(150----l8Okg N/ha) was applied,but if a large amount of N fertilizer was applied,the Nmin content in soil profile maintained a relatively high level during the crop growth stage. There were significant differencese of soil-plant buffer power for different crop, and soil types. Higher buffer power for Nmin accumulation was found in wheat crop and in loamy soil than in corn crop and in sandy soils.