引黄灌区灌淤土氮素淋失特征土柱模拟研究

采取土柱模拟实验的方法研究了不同施氮强度对宁夏引黄灌区灌淤土中氮素淋洗损失特征,以期为氮素淋失控制和合理施用提供科学依据。试验设5个氮水平,分别为对照处理(N0)、常规氮水平300 kg·hm-2(N300)、优化氮水平(N240)、2倍常规氮水平(N600)、2倍优化氮水平(N480)。试验结果表明:不同施氮水平淋洗液中NO3--N的浓度表现出先升高后降低的趋势,浓度峰值出现的时间随施氮水平增加逐渐后移,NO3--N是氮素淋洗损失的主要形态,而NH4+-N的淋失损失主要出现在淋洗前期,增加施氮量可以推迟各形态氮素峰值出现时间,增加淋失风险。N240,N300,N480和N600处理总氮累积淋失量分别为94.53、128.02、222.06 kg·hm-2和268.6 kg·hm-2,淋洗损失比例分别为39.38%、42.67%、46.26%和44.77%,当季施入稻田土壤的氮肥极易淋洗到100 cm深度以下,成为浅层地下水的潜在威胁。施入到灌淤土的氮素有39.38%~46.26%通过淋洗途径损失,各处理总氮累积量淋失规律服从对数方程Yt=a+blnt(R2=0.927~0.975)。

Anthropogenic-alluvial Soil Nitrogen Fertilizer Leaching Loss Characteristics Study Using Soil Column Simu-lation in Yellow River Irrigation Area,China

A soil column simulation experiment was conducted to study the effect of different nitrogen intensity in nitrogen fertilizer leaching loss characteristics in anthropogenic-alluvial soil. There were 5 treatments in this experiment, no nitrogen fertilizer treatment(N0), conventional fertilization treatment(N300), optimized fertilization treatment(N240), double conventional fertilization treatment(N600)and double optimized fertilization treatment(N480). The results showed that with different nitrogen intensity treatments, nitrate nitrogen concentration increased firstly and then decreased and leaching concentration peak appeared delay with nitrogen rates increasing. Nitrate nitrogen was the predominant nitrogen leaching form, increase of nitrogen application could postpone nitrogen peak appear time and lead to leaching risk.Ammonium nitrogen leaching loss occurred in the earlier period. Total N leaching losses were 94.53, 128.02, 222.06 kg·hm-2and 268.6 kg·hm-2in treatments N240, N300, N480 and N600, which accounted for nitrogen leaching losses rates by 39.38%, 42.67%, 46.26% and44.77%, respectively. Applied nitrogen fertilizer was very easily leaching to 100 cm soil depth, indicating that nitrogen fertilizer leaching could be a pollution source for underground water. About 39.38%~46.26% of fertilizer nitrogen applied in soil was lost by leaching. The accu-mulative total N leaching amount was in accordance with logarithmic equation of Yt=a+blnt.