农田不同土地利用氮素渗漏量的研究

Assessment of nitrogen leaching amount on various land use in field

对福建省漳州市南靖县五小川流域香蕉、蔬菜、甘蔗、水稻和荒地5种土地利用类型进行了土壤氮素淋失状况的研究．每月采集不同土地利用下的浅层地下水水样，分析水中氨氮浓度和硝氨浓度．采用水量平衡法，确定大田条件下浅层地下水渗漏水量．利用Penman-Monteith方程确定作物田间腾发量，根据产流系数和时段降雨量计算地表径流量．以不同土地利用类型地块浅层地下水氮的监测浓度与渗漏水量的乘积来估算氮渗漏量．结果表明，不同土地利用氮渗漏量差异较大，渗漏量范围在11．8-54kg／hm^2，约占施肥量的3．1％-7．7％．香蕉地与水稻田渗漏量最高．

Assessment of soil nitrogen leaching was conducted under five kinds of land uses, such as bananas, vegetables, sugarcane, paddy and uncultivated land, at Wuchuan small watershed of Najing county in Zhangzhou city, Fujian province. Subsurface water samples of various land use plots were collected monthly and analyzed for both nitrate nitrogen and ammonium nitrogen concentration. Percolation was calculated based on water balance method. Evapotranspiration （ETs） of related crops within watershed were estimated by Penman- Monteith equation. Surface runoff equals to the ratio of stormflow discharge to precipitation which monitored in outlet of watershed. Change in subsurface amount was calculated based on field soil content increasing. Nitrogen leaching amount of various land use equals to nitrogen concentration of various land use multiplying by leaching amount. Assessment results showed that nitrogen leaching amount varied from 11.8 to 54 kg/hm^2, about 3.1% - 7.7 % of fertilizer input. Banana and paddy plots had maximum nitrogen leaching loss.