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在稻田土壤上高量施用氮肥常常造成硝态氮(NO3--N)淋溶损失和肥料氮利用率低下的问题。本研究采用土壤渗漏器、微区和田间小区试验,研究了15N标记控释氮肥在稻田土壤上的氮素利用率和硝态氮的淋溶损失。在两年早稻种植期间,一次性全量基肥施用控释氮肥与尿素分二次施用相比,两年的早稻产量分别平均提高7.7%和11.6%。在90kgNha-1用量下,由差值法测得的肥料氮利用率,按平均计,控释氮肥的N利用率(平均76.3%)比尿素分次施用的(平均37.4%)高出38.9个百分点。15N同位素法测得的控释氮肥的N利用率(平均67.1%)比尿素分次施用的(平均31.2%)高出35.9个百分点。在早稻种植季节,施用尿素和控释氮肥的NO3--N淋失量分别为9.19kg/hm2和6.7kg/hm2,占施尿素N和控释氮肥氮的10.2%和7.4%。控释氮肥的氮淋失量比尿素分2次施用的降低27.1%。本研究结果表明,在稻田土壤上施用控释氮肥能减少氮的淋失量,提高氮素利用率和水稻产量。
High levels of application of nitrogen fertilizers on paddy soils often result in nitrate leaching (NO3 - N) leaching and fertilizer nitrogen utilization problems. In this study, soil leakage, micro-area and field plots were used to study the nitrogen use efficiency and nitrate leaching loss of 15N labeled controlled-release fertilizer on paddy soil. During the two years of early rice cultivation, the yield of two-year early rice increased by 7.7% and 11.6% respectively on average compared with the second application of urea on a one-off basis. Under the treatment of 90kgNha-1, the nitrogen utilization efficiency of fertilizer by difference method, on average, N utilization rate (average 76.3%) of control release nitrogen fertilizer was 38.9 higher than that of urea application (average 37.4%) percentage point. The N utilization rate (average 67.1%) of controlled-release nitrogen fertilizer measured by 15N isotope method was 35.9% higher than urea fraction application (average 31.2%). During the early rice planting season, the NO3 - N leaching loss was 9.19kg / hm2 and 6.7kg / hm2, respectively, accounting for 10.2% and 7.4% of the urea nitrogen and the controlled release nitrogenous fertilizer. Nitrogen leaching loss of controlled-release nitrogen fertilizer was 27.1% lower than urea application twice. The results of this study show that the application of controlled-release nitrogen fertilizers in paddy soils can reduce the leaching amount of nitrogen and increase the nitrogen utilization rate and rice yield.