苗圃潮土氮肥淋溶特征

Leaching Characteristics of Nitrogen in Fluvo-aquic Soil After Applying Urea

采用室内土柱淋溶模拟试验,研究了不同氮肥处理下,不同深度土壤氮素在苗圃潮土中的淋溶特征。结果表明:硝态氮是氮素淋溶的主要形态,土壤经过12次淋溶后,硝态氮的淋溶量占全氮淋溶量的70%以上,而铵态氮的比例不到7%,另外,有5%～27%以有机氮的形式淋溶;氮肥淋溶率为21.36%～54.19%,铵态氮、硝态氮和全氮的淋溶量均随施肥量的增加而增大,并且不同土壤深度不同形态氮素的淋溶量(y)与施氮量(x)之间的关系均可用线性回归方程进行模拟,其中各深度全氮的回归方程为:0～20cm:y=0.5555x+99.888(R2=0.9857);0～40cm:y=0.3708x+148.25(R2=0.9689);0～60cm:y=0.2508x+220.67(R2=0.9297)。

Soil column leaching method was used to investigate nitrogen leaching characteristics of 3 different soil depths after applying different qualities of urea fertilizer. Results showed that the main form of nitrogen leached was NO-3—N. The accumulation amount of NO-3—N occupied more than 70% of the total nitrogen（TN）after 12 leaching events,while the proportion of NH＋4—N was less than 7%,and organic nitrogen accounted for 5%~27% of TN. The leaching rate of nitrogen fertilizer was between 21.36% and 54.19%,and the leaching loss of NH＋4—N,NO-3—N,and TN increased with increasing application rate of urea fertilizer. The relations between leaching amount of NH＋4—N,NO-3—N,TN and nitrogen application rate could be described by regression equations.