[Effect of long-term fertilization on NO3(-)-N accumulation and moisture distribution in soil profiles]

On the basis of long-term fertilization experiments in gully area of Loess Plateau, the relationships among fertilizations, NO3(-)-N accumulation, and moisture distribution in soil profiles were evaluated. The results showed that fertilization and rainfall significantly influenced the yields. NO3(-)-was accumulated in soil profiles under N and P fertilizers and organic manure(NPM) and N and P fertilizer (NP) treatment. The accumulated NO3-N reached 340 kg.hm-2 in 60-120 cm under NPM treatment, and 220 kg.hm-2 in 80-140 cm under NP treatment, respectively. Soil moisture in 100-300 cm was significantly reduced under NPM treatment. Under NP treatment, it was significantly reduced in dry year and normal year, while under organic manure(M) treatment, it was significantly reduced in dry year. Soil moisture under P and CK treatments was relatively stable in different years. N uptake under NPM and NP treatments was significantly decreased in dry year. It reflected the close relationship among soil moisture, crops, and fertilization.