模拟土柱条件下黑土中肥料氮素的迁移转化特征

为明确肥料氮素在土壤中的迁移转化动态特征,利用模拟土柱方法,研究了3倍常规施肥量条件下不同肥料处理(尿素、硫铵)黑土的矿质氮变化。结果表明:不同氮肥处理的氮素养分迁移转化特征有明显差异。对照处理(不施肥)土柱内各层次间NH4+-N和NO3--N含量差异不明显;施用尿素或硫铵后,表层0~50mm土层的NH4+-N和NO3--N含量比不施肥对照分别升高100.8~3408.1mg·kg-1、113.4~388.0mg·kg-1和126.7~4671.1mg·kg-1、51.4~63.3mg·kg-1,且在培养前14d内变化最大。在整个培养期内,施用硫铵处理各层次NH4+-N平均含量比尿素处理高2.54~1423.7mg·kg-1,NO3--N平均含量低4.38~335.1mg·kg-1;而尿素处理各层次的硝化率是硫铵处理的0.79~9.12倍。表明肥料氮素的迁移与转化集中在0~50mm土层内,尿素处理的氮素转化速率较硫铵处理高。

Migration and transformation of fertilizer nitrogen in a simulated black soil column

Urea and ammonium sulfate fertilizer applied with three times application rate of conventional fertilization were used to simulate the migration and transformation characteristics of fertilizer nitrogen with simulated black soil columns. The results show that N migration and transformation vary with fertilizer type. NH₄⁺-N or NO₃^--N concentration is not significantly different across different soil layers under CK (zero fertilization). Whereas NH₄⁺-N and NO₃^--N respectively increase by 100.8~3 408.1 mg·kg^-1 and 113.4~388.0 mg·kg^-1 under urea treatment, 126.7~4 671.1 mg·kg^-1 and 51.4~63.3 mg·kg^-1 under ammonium treatment compared with CK for the 0~50 mm surface layer. The concentration changes most significantly in the first 14 days after fertilization. Under ammonium sulfate treatment, the average contents of NH₄⁺-N and NO₃^--N in different soil layers are respectively 2.54~1 423.7 mg·kg^-1 higher and 4.38~335.1 mg·kg^-1 lower than under urea treatment. Nitrification rate of urea in different soil layers for the whole incubation period is 0.79~9.12 times that for ammonium sulfate. This suggests that migration and transformation of nitrogen mainly occur in the 0~50 mm soil layer, and that nitrogen transformation rate of urea is higher than that of ammonium sulfate.