关键词: 普通尿素；控释尿素；氨挥发；氮淋溶；柴河流域

Abstract:

At Chaihe catchment of Dianchi Lake, application of fertilizer in vegetable soils exerted negative influence on water body due to discharge of nitrogen (N) from vegetable land via nitrogen leaching, runoff and ammonia volatilization and subsequent deposition. Pot experiment was carried out to compare the loss of nitrogen via leaching and ammonia volatilization when applying 2 nitrogen sources (CU: common urea and CRU: controlled release urea) with different rates (0 mg N/kg soil, 280 mg N/kg soil, 320 mg N/kg soil and 400 mg N/kg soil) of N supply. The results showed that N loss in soil was significantly greater via leaching than via ammonia volatilization irrespective of N sources and application rates. There was no significant difference in ammonia volatilization between CU and CRU, and the cumulative ammonia volatilization in treatments of 320 mg N/kg soil and 280 mg N/kg soil accounted for 3.64% and 3.57% in supplied CU respectively, while accounted for 3.64% and 2.78% in supplied CRU respectively. However, the leaching loss of N was significantly greater in CU treatment than that in CRU treatment, and the leaching loss of N in treatments of 320 mg N/kg soil and 280 mg N/kg soil accounted for 14.38% and 14.46% in supplied CU respectively, while accounted for 11.60% and 8.37% in supplied CRU respectively. The leaching loss of N decreased with reduced application rate of supplied CRU. However, no obvious difference of N leaching loss among rates of CRU supplied was found. The decrease of nitrogen loss in supplied CRU is mainly attributed to the decrease of N leaching, rather than ammonia volatilization. Therefore, the NO3-\|N leaching may be the main pathway for transportation of N from vegetable soils to water body in Chaihe catchment. The lower application rate of CRU might have a practical influence on reducing risk of eutrophication in Dianchi Lake.

Key words: common urea, controlled release urea, ammonia volatilization, nitrogen leaching, chaihe catchment