紫色土丘陵区不同土地利用类型小流域氮素流失规律初探  

Process characteristics of nitrogen loss by runoff in different land use watersheds in purple soil hilly region

作　　者：韩建刚[1] 李占斌[2,3] 

机构地区：[1]江苏大学环境学院,江苏镇江212013 [2]中国科学院水利部水土保持研究所黄土高原土壤侵蚀与旱地农业国家重点实验室,陕西杨凌712100 [3]西安理工大学水利水电学院,陕西西安710048

出　　处：《水利学报》2011年第2期160-165,共6页Journal of Hydraulic Engineering

基　　金：国家自然科学基金资助项目(40771124);江苏省高校自然科学基础研究面上项目(07KJB610017);中国博士后科学基金资助项目(20070420970);中欧合作研究项目(EROCHiNut-ERBIC18CT980372)

摘　　要：以紫色土丘陵区3个土地利用类型各异的小流域为研究对象,监测了20场自然降雨侵蚀下径流氮素的流失过程,旨在为流域尺度养分流失预测模型的发展与校正提供依据。结果表明,次降雨过程中硝态氮的流失浓度随着流量的增加而降低,峰值流量处浓度一般达到最低;此后,随着流量的减小,硝态氮的流失浓度又呈现增加趋势。铵态氮流失过程表现为波浪形变化,径流初期其流失浓度一般较高,随着时间的延长逐渐降低并趋于稳定。硝态氮是紫色土小流域氮素流失的主要形式,其占到径流无机氮流失的50%~97%。单一农田土地利用将导致流域氮素径流流失明显增加,但完全经济林利用类型却易于引起土壤铵态氮的大量流失;相比较而言,流域景观的多样化与综合化对氮素流失的控制更为有效。氮素流失过程对流域面积从1.1→2.0→10.8hm2的递变无明显响应。减少或少量多次适时施用硝态氮肥是控制紫色土区水土流失过程氮素流失的重要途径。Three small watersheds with different land use were employed to investigate the process characteristics of nitrogen loss during various sized natural rainfalls in purple soil hilly region.Results show that [NO-3] concentrations in runoff waters were inversely proportional to the runoff rates.The [NO-3] concentrations reached the lowest at their peak runoff rates;however,a gradually increasing trend occurred after the peak runoff rate for most of runoff events.While [NO＋4] concentrations mainly manifested as violent fluctuation,which were characterized as a high loss concentrations during early stages of runoff and decreased gradually with time.The [NO-3] was the main form of N loss at watershed scale.It accounts for 50%~97% of inorganic N loss and depends on various rain.The farmland-dominated watershed would lead to high amount of nitrogen loss.In contrast,the single woodland-dominated watershed tends to increase the loss of ammonium nitrogen.The watershed with various landscape structures could decrease nitrogen loss by runoff.In addition,nitrogen loss has no scale dependence effects when watershed area varies from 1.1 to 2.0hm2 and even to 10.8hm2.It is suggested that the [NO-3] applied should be reduced in this region.When it is unavoidable,small quantity,repeated and timely applications is advocated.

关 键 词：紫色土 土地利用 硝态氮 铵态氮 径流 

分 类 号：X522[环境科学与工程—环境工程]