摘要
为探索巢湖流域稻麦(油)轮作区水稻季减少农田氮素流失的有效耕作措施,降低其对湖区水质的威胁,采用野外定位观测试验并结合室内实验分析,研究了连续两年秸秆还田条件下稻田田面水总氮(TN)、溶解态氮(DN)、溶解态有机氮(DON)、铵态氮(NH4^+-N)和硝态氮(N03^--N)浓度的动态变化特征。结果表明,稻田施用尿素后第2天或第4天田面水的TN、DN、DON和NH4^+-N浓度达到峰值,然后随着时间的推移迅速降低,至8~10d后趋于稳定;在整个水稻生育期内,NO3^--N浓度普遍较低;尿素施用后8~10d之内是控制稻田氮素流失的关键时期,秸秆还田降低这一时期TN、DN、NH4^+-N浓度的效果显著,而DON浓度差异未达显著水平。DN是稻田田面水氮素存在的主要形态,所占TN比例达63.2%~88-8%,尿素施用后6d内DN又以NH4^+-N为主,NH4^+-N所占TN的比例为33.8%-69.9%。DON是稻田田面水氮素的重要组成部分,其生态环境效应不容忽视。秸秆还田还有利于水稻产量的提高,增产幅度分别为12.25%和7.68%,平均为9.96%。在保证水稻产量的前提下,秸秆还田可以作为控制稻田氮素流失的措施在巢湖流域使用。
In order to explore the effective tillage for reducing nitrogen losse and improving lake water qual-ity, field experiments were conducted to study the dynamics of TN (total nitrogen), DN (dissolved nitro-gen), DON (dissolved organic nitrogen), ammonia nitrogen (NH4^+-N) and nitrate nitrogen (NO3^--N) concen- trations in surface water of paddy field in the Chaohu Lake region in two consecutive years. The results show that the concentrations of TN,DN,DON and NH4^+-N in surface water reached the maximums after 2 or 4 days of urea application, then declined rapidly, and finally leveled off after 8-10 days. The NO3^--N concentration remained at a low level during the whole rice growing seasons, although it showed a little raise after 4 or 6 days of urea application. Obviously, it is the critical period for controlling N loss from paddy field within 8-10 days after urea application. Straw return could effectively decrease the higher con-centrations of TN, DN and NH4^+-N in surface water during the earlier stage, whereas the differences in DON concentration was not so significant. Therefore, straw return is beneficial for lowering the potential risk of N loss. Furthermore, DN was the predominant form of TN in surface water, which accounted for 63.2 %-88.8 % of the TN. Within 8 days after urea application, the proportion of NH4^+-N to TN was 33.8 %-69.9 %. DON was a significant component of TN in surface water, which suggested that its ecologi-cal and environmental effects should not be neglected. The results also show that the rice yields of CTS in-creased significantly by 12.25 % and 7.68 % compared with CT, which indicated that straw return could in- crease the rice yields. The findings indicate that assuring the production of rice yields, straw return ap-peared to be an effective measure for the source control of the nitrogen loss from paddy field in the Chao-hu Lake region.
出处
《水利学报》
EI
CSCD
北大核心
2014年第4期410-418,共9页
Journal of Hydraulic Engineering
基金
国家科技支撑计划项目(2012BAD15B03)
国家科技支撑计划项目(2007BAD87B06)
安徽省科技厅项目(1406C085025
1206C0805033)
安徽省农业科学院科技创新团队建设项目(11C1007)
关键词
农业面源污染
氮素
秸秆还田
水体富营养化
agriculture non-point source pollution
nitrogen
straw return
eutrophication