摘要
通过在中国科学院盐亭农业生态站进行定位监测研究。探讨了川中紫色土区旱坡地氮紊的农业非点源输出规律。研究表明：紫色土早坡地非点源氮输出以无机氮和颗粒态为主，全氮输出量不高。川中丘陵农田生态系统的早地径流中，颗粒态氮占比例最大，达到35％，硝态氮和氨态氮的输出水平相反，各径流场的NH4^＋-N浓度略高于NO2^--N的浓度。旱地径流全年总氮污染输出为0．95kg／（hm^2·a），全年通过径流输出的氮素占化肥施用量的0．56％。早地地表径流中总氮平均浓度顺坡种植〉平板种植〉聚土垄作。小流域非点源氮污染负荷的季节变化与流域降水的季节变化基本一致，非点源氮污染约从6月开始上升，一直持续到10月，集中在降雨丰富的时段。夏季2个月（7～8月）是非点源污染的高发季节，非点源氮污染负荷的绝大部分发生于该时期，这与年雨量的60％集中于该季节而降水多以暴雨形式出现有关。通过土地利用类型的优化配置，合理采用水土保持耕作法，控制施肥量和适宜的农田耕作方式，可减少地表径流和地下淋洗中氮的含量，减轻农业非点源物质对环境的压力，保护农业生态环境。
Nitrogen non-point sources pollution researches from purple soil cropland were carried out in Yanting agro-ecological station （CAS） watershed. Nitrogen output and transportation observation was conducted in surface runoff plots of different purple soil farmlands. Nitrogen concentrations and forms of runoff were monitored twice a month with two replicates. Nitrogen pollution load was calculated based on above observed and investigated data. Impact of non-point sources pollution of nitrogen on the environment was discussed here. Results showed, In the upland runoff, particle nitrogen contributes 35% to total nitrogen（TN）. Average concentration of total nitrogen in farmland runoff was in following sequence： SNTRCS （seasonal no-tillage ridge cropping system）〈FT （flat tillage） 〈 ST （straight tillage）. It showed that SNTRCS could preserve more nitrogen than traditional tillage when same amount of fertilizers applied to them was same. The loss of total nitrogen was 0. 95 kg/hm^2, and annual output of nitrogen through the surface runoff accounts of 0. 55 % of total applied fertilizers,and the rest nitrogen remains in soil and could be lost by leakage and volatilization. Nitrogen non-point sources pollution load changed with precipitation along seasonal alteration. The increase of non-point pollution began from June and lasted to October, and concentrated in the raining season. Especially June and August were the seasons when most of non-point sources pollution happened frequently. Therefore, some measures should taken to control the quantities and management of nitrogen fertilizers, along with conservation tillage in upland and rational utilization of pond and low land in order to control nitrogen contents in surface runoff and ground leakage.
出处
《水土保持学报》
CSCD
北大核心
2006年第2期54-58,共5页
Journal of Soil and Water Conservation
基金
中国科学院知识创新工程重大项目(KZCX2-413-5)
国家自然科学基金(40576024)
