长期施肥条件下黄土旱塬土壤N03^--N的淋溶分布规律

在黄土旱塬区，长期施肥对土壤剖面NO3^-1—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^-1—N的淋溶与深层累积，而施用磷肥和有机肥有减弱NO3^-1—N向更深层淋溶的作用．单施氮肥处理(N)，NO3^-1—N的累积峰深度最大，为120～200cm；N、P有机肥配施处理(NPM)，NO3^-1—N的累积峰值最高，但峰深度降低至60～120cm；N、P配施(NP)累积深度为80～140cm．不施氮肥，分布在土壤剖面中NO3^-1—N含量显著降低．氮肥用量愈大，NO3^-1—N的累积量愈大．N、P配施可以有效降低NO3^-1—N累积．在同一氮肥用量下，NO3^-1—N累积量随磷肥用量的增加而减少．

NO3--N leaching and distribution in soil profile in dry highland of Loess Plateau under long-term fertilization

The NO3(-)-N accumulation and distribution in soil profile of Loess Plateau dry highland were studied by long-term field trials. The results showed that NO3(-)-N was accumulated in the soil profile under N-fertilization. Application of P-fertilizer or organic manure reduced the NO3(-)-N content and its leaching depth in the soil profile. The deepest depth of NO3(-)-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 NO3(-)-N accumulation depth was 80-140 cm for NP. Without nitrogen application, there was no evident accumulation of NO3(-)-N in soil profile. The more nitrogen used, the more NO3(-)-N accumulated in soil profile. Under the same nitrogen application rate, NO3(-)-N accumulation might decrease with increasing P application.