水稻控制灌排模式的节水高产减排控污效果

为合理地集成控制灌溉和控制排水技术,实现节水、高产、减污目标的统一,该文应用控制灌排技术于2015-2016年在涟水县水利试验站开展大田小区试验,对稻田灌溉用水量、产量及氮磷流失情况进行监测和分析。2 a研究结果表明:与对照处理(控制灌溉)相比,采用轻旱控制灌排技术并不导致水稻减产,且稻田灌溉定额能够降低11.89%(P0.05),同时由于排水峰值和排水次数明显减少,总磷、铵态氮、硝态氮稻田表面径流流失负荷分别降低54.58%、36.29%和60.10%(P0.05),但在雨量较多的年份会增加渗漏量,从而造成总磷、铵态氮淋失负荷升高;采用重旱控制灌排技术时,水稻减产不显著,稻田灌溉定额减少29.88%,排水定额减少58.95%,总磷、氨态氮、硝态氮地表径流流失负荷分别降低59.23%、38.88%和62.97%,但淋失负荷分别增加了24.57%、30.17%和15.88%,可能造成地下水污染。应用基于序关系分析法和熵值法组合权重的TOPSIS理想解法对水稻灌排方案进行优选决策,结果表明轻旱控制灌排在保证粮食生产量的前提下具有良好的节水减排控污效果。

Effect of controlled irrigation and drainage on water saving, nitrogen and phosphorus loss reduction with high yield in paddy field

Abstract: In order to integrate water-saving irrigation and controlled drainage technology reasonably and realize the multiple targets including water saving, high yield and pollution alleviation by scientific irrigation and drainage program, this paper carried out a field plot experiment in Lianshui Water Conservancy Research Institute from 2015 to 2016. In the field trial, the water level of paddy field was taken as the technical indicator of irrigation and drainage control, and the amount of irrigation, drainage, leakage, yield and loss of nitrogen and phosphorus in paddy field were monitored and analyzed. A total of 3 treatments were designed in the field test plot, including CK (controlled irrigation and traditional drainage), LCID (controlled irrigation and drainage that allowed mild water stress) and HCID (controlled irrigation and drainage that allowed severe water stress). These 2 kinds of controlled irrigation and drainage procedures both added the allowed flooding depth after rain but had different lower limits of irrigation, one of which was -200 mm and the other of which was -500 mm. The results showed that compared with CK, the utilization of LCID can reduce 11.89% of the irrigation quota and 52.72% of the drainage amount. At the same time, the runoff losses of the total phosphorus (TP), ammonia nitrogen (NH4+-N) and nitrate nitrogen (NO3--N) were significantly decreased by 54.58%, 36.29% and 60.10% respectively owing to the drop of drainage peak value and drainage times during the critical periods, but the leaching losses of TP and NH4+-N increased on the account of higher seepage in the rain spell. Meanwhile, by comparison with CK, the irrigation times deducted, irrigation amount saved by 29.88% and drainage amount reduced by 58.95% under HCID. Besides, the runoff losses of TP, NH4+-N and NO3--N were significantly decreased by 59.23%, 38.88% and 62.97% respectively, but the leaching losses of those were increased by 24.57%, 30.17% and 15.88% which would be likely to cause groundwater contamination and soil nutrients loss. In terms of rice yields and its components, LCID and HCID cut down the number of effective panicles per square meters, but the theoretical and actual rice yield showed no significant decline. On the basis of test results, this paper optimized the irrigation and drainage schemes so as to guide practice in southern China rice cultivable area. The evaluation index system was comprised of 3 first-class indexes as field, water-saving and pollution control and 9 second-class indexes. In addition, the combination weights method based on rank correlation analysis method and entropy method was used to obtain the weights of evaluation index, in addition, TOPSIS (technique for order preference by similarity to an ideal solution) served as decision-making method. The evaluation results revealed that LCID had great water conservation benefit and pollutant abatement effect on the premise of ensuring grain production.