施氮对黄土高原水蚀风蚀交错区土壤矿质氮的影响

Effect of N fertilization on the mineral nitrogen in soil in wind-water erosion crisscross region on the Loess Plateau

【目的】研究施氮对黄土高原水蚀风蚀交错区不同土层土壤矿质氮含量和累积量的影响。【方法】试验设作物和施肥2个因子,分析不同施氮水平和不同作物处理下黄土高原水蚀风蚀交错区0～100 cm土层土壤矿质氮的差异。【结果】不同施氮处理对土壤硝态氮含量及矿质氮累积量有明显影响,土壤硝态氮含量和0～100 cm土层土壤矿质氮累积量均随施氮量的增加而增加,但施氮量对土壤铵态氮的影响较小;不同施氮条件下,不同土层土壤硝态氮含量和矿质氮累积量均以0～20 cm土层最高,从总体上看,随着施氮量增加,较深土层（80～100 cm）土壤硝态氮含量和矿质氮累积量亦有所增加;不同作物间,除施90 kg/hm2磷＋45 kg/hm2氮处理时,种植黑麦草作物的0～20cm土层土壤NO3^--N含量有所增加外,其余施氮处理对种植两种不同作物土壤的NO3--N含量和NH4^＋-N含量均未产生明显影响,在相同施氮处理下,黑麦草地和苜蓿地0～100 cm土层土壤总矿质氮累积量的差异不明显。【结论】不同水平氮肥处理均对黄土高原水蚀风蚀交错区土壤矿质氮含量及累积量有一定影响,土壤矿质氮含量及累积量均与施氮量密切相关。

[Objective] Field trials were carried out to study the effect of fertilizer on the content and accumulation of mineral nitrogen in soil in wind-water erosion crisscross region on the loess plateau. [Method] Two factors,crop plant and N fertilizer,were selected for,under different N fertilizer and crop, analyzing mineral nitrogen in 0-100 cm soil layer in wind-water erosion crisscross region on the loess plateau. [Result] The content and accumulation of the mineral nitrogen varied with layer and fertilization treatments. And the same to NO3^-N,but NH4^＋-N had no significant change. The content and accumulation of the mineral nitrogen was the highest in 0-20 cm layer under different fertilization treatments, and the content and accumulation of NO3^--N in different layers had a similar variation as it improved with the increase of nitrogen level. Different fertilization treatments affected insignificantly the content of NO3^- -N and mineral nitrogen in soil except the content of NO3^- -N in 0-20 cm layer in the 90 kg/hm^2 P＋45 kg/hm^2 N treatment. In the same fertilization treatments,the content of mineral nitrogen in alfalfa soil and ryegrass soil had no significant change. [Conclusion] The content and accumulation of the mineral nitrogen varied with layer and fertilization treatments. There was a close relation between the content and accumulation of the mineral nitrogen in soil and N fertilizer.