Effects of Dicyandiamide on the Accumulation and Leaching Risk of Soil NO3--N in Aquic Brown Soils

A field experiment was conducted at the vegetable production base of Lixiang town in Shenyang city, Liaoning province to study the effects of dicyandiamide (DCD) application on the accumulation and leaching risk of soil nitrate. The results showed that applying DCD significantly decreased the amount of soil NO3--N in the 0-10cm and 10-20cm soil layers compared to without DCD addition (P < 0.01). However, the difference was not significant in the 20-40cm (P > 0.05). These results indicated that the application of DCD reduced the leaching risk of soil nitrate from topsoil to subsoil. At the 28d of fertilizer application, the amount of soil NO3--N was higher in the NP+M, NP+M+2%DCD and NP+M+5%DCD treatments than in the M, M+2%DCD and M+5%DCD treatments, suggesting that the combined application of chemical fertilizer and organic manure weakened inhibiting effect of DCD on the amount of soil NO3--N.