稻田土壤上控释氮肥的氮素利用率与硝态氮的淋溶损失

在稻田土壤上对水稻的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,一次性全量作基肥施用控释氮肥与尿素分二次施用的相比,两年的早稻产量分别平均提高7.7%和11.6%。在N90 kg hm-2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%1。5N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%。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9.19 kg hm-2和6.7 kg hm-2,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。

Nitrogen Recovery and Nitrate Leaching from a Controlled Release Nitrogen Fertilizer in an Irrigated Paddy Soil

High amounts of N fertilizer applied to rice on paddy soils often results in nitrate(NO-3-N) leaching and low recovery of the applied fertilizer nitrogen.This study was conducted to determine the effect of a controlled release nitrogen fertilizer(CRNF) on the recovery and nitrate leaching on paddy soils by using lysimeter,microplot and field plot experiments.During early rice grown for two years(2002 and 2003),a single basal application of CRNF at 90 kg N hm-2 increased grain yields of early rice by 7.7 to 11.6% compared with two application of urea.Fertilizer N recovery of CRNF(mean 76.3%) estimated by the difference method was higher than 38.9 percent point that of urea (mean 37.4%).Fertilizer N recovery of CRNF(mean 67.1%) estimated by 15N isotope method(mean 49.6%) was higher than 35.9 percent point that of urea(mean 31.2%).During early rice growing season,NO-3-N leaching losses were 9.19 and 6.70 kg hm-2for urea and CRNF,respectively.NO-3-N leaching during the early rice cropping season was 27.1% lower with CRNF than two application of urea.These losses represent 10.2% and 7.4% of applied urea-N and CRNF-N.Results from this study indicate that CRNF improve N recovery and reduce NO-3-N leaching and increase rice yield.