长期施肥条件下黄土旱塬土壤NO_3^-N的淋溶分布规律

NO_3^-N leaching and distribution in soil profile in dry highland of Loess Plateau under long-term fertilization

在黄土旱塬区 ,长期施肥对土壤剖面NO3- N含量和分布有显著影响 .施用化学氮肥 ,土壤剖面中出现NO3- N的淋溶与深层累积 ,而施用磷肥和有机肥有减弱NO3- N向更深层淋溶的作用 .单施氮肥处理 (N) ,NO3- N的累积峰深度最大 ,为 1 2 0～ 2 0 0cm ;N、P有机肥配施处理 (NPM ) ,NO3- N的累积峰值最高 ,但峰深度降低至 60～ 1 2 0cm ;N、P配施 (NP)累积深度为 80～ 1 4 0cm .不施氮肥 ,分布在土壤剖面中NO3- N含量显著降低 .氮肥用量愈大 ,NO3- N的累积量愈大 .N、P配施可以有效降低NO3- N累积 .在同一氮肥用量下 ,NO3-

The NO 3 - N accumulation and distribution in soil profile of Loess Plateau dry highland were studied by long term field trials. The results showed that NO 3 - N was accumulated in the soil profile under N fertilization. Application of P fertilizer or organic manure reduced the NO 3 - N content and its leaching depth in the soil profile. The deepest depth of NO 3 - N accumulation was 120～200 cm under N treatment, and the peak of the accumulation was the highest in NPM treatment, with the depth of 60～120 cm. The NO 3 - N accumulation depth was 80～140 cm for NP. Without nitrogen application, there was no evident accumulation of NO 3 - N in soil profile. The more nitrogen used, the more NO 3 - N accumulated in soil profile. Under the same nitrogen application rate, NO 3 - N accumulation might decrease with increasing P application.