Managing controlled drainage in irrigated farmers' fields: A case study in the Moghan plain, Iran
Managing controlled drainage in irrigated farmers' fields: A case study in the Moghan plain, Iran
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DOI：
10.1016/j.agwat.2018.06.037
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发表时间：
2018-09-30
影响因子：
6.7
通讯作者：
Henk, Ritzema
中科院分区：
文献类型：
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作者：
Jouni, Hamidreza Javani;Liaghat, Abdolmajid;Henk, Ritzema
在伊朗西北部的Moghan计划中，传统的免费地下排水做法导致灌溉效率低，排水量过大，造成广泛的环境问题。提倡控制排水（CD），以提高作物产量，减少地下排水流量和养分的淋失。本研究旨在试验莫干平原灌区农田防治CD的管理方案。测试了三种方案：地下排水2米自由流出（FD），土壤表面以下70厘米的控制排水（CD70）和根据作物阶段不同深度的控制排水（CDch）。灌溉赠品是基于每日测量的土壤含水量，因此不同的排水处理。冬天种小麦和大麦，夏天种玉米。每种作物和处理做3个重复。在所有作物中，使用CDch的作物产量最高，其次是CD70。与FD相比，CD70和CDch的小麦产量分别高出27%和41%。大麦增加了23% （CD70）和34% (CDch)，玉米（饲料产量）增加了19% （CD70）和25% （CDch）。在水分利用效率（WUE）方面也观察到相同的趋势：与FD相比，CD70的WUE高26%，CDch的WUE高40%；大麦分别增加19% （CD70）和32% (CDch)，玉米（饲料产量）分别增加30% （CD70）和44% （CDch）。控制排水不仅降低了地下排水速率，而且减少了硝态氮和磷的损失。小麦、大麦和玉米施用CDch的平均排水量分别比施用FD低33%、45%和44%。与FD相比，CD70和CDch的排水量NO3流量加权浓度分别降低了小麦的15%和9%，大麦的9%和13%，玉米的8%和7%。土壤盐度在FD处理下降低，CD处理下略有升高。因此，尽管控制排水明显优于自由排水，但为了优化CD管理方案，还需要对控制排水对土壤盐分的长期影响进行更多的研究。
Conventional free subsurface drainage practices in the Moghan Plan, in northwest Iran, result in low irrigation efficiency and excessive volumes of drainage water causing extensive environmental problems. Controlled drainage (CD) is promoted to boost crop yields and reduce subsurface drainage flows and leaching of nutrients. This study was conducted to test management options for CD in irrigated farmers' fields in the Moghan plain. Three options were tested: subsurface drains at 2 m with free outflow (FD), controlled drainage at 70 cm below soil surface (CD70) and controlled drainage with a varying depth depending on the crop stage (CDch). Irrigation gifts were based on the daily measured soil water content and thus varied per drainage treatment. In winter, wheat and barley were grown followed by maize in summer. For each crop and treatment, three replicates were made. The highest crop yields (for all crops) were found with CDch, followed by CD70. For wheat, the yields ware respectively 27% and 41% higher in the CD70 and CDch compared to FD. For barley these increase was respectively 23% (CD70) and 34% (CDch) and for maize (forage yields) 19% (CD70) and 25% (CDch). The same trends were observed in water use efficiencies (WUE): compared to FD, the WUE was 26% in CD70 and 40% higher in CDch; for barley these increases were respectively 19% (CD70) and 32% (CDch), and for maize (forage yields) 30% (CD70) and 44% (CDch). Controlled drainage not only reduced subsurface drainage rates, but also nitrate and phosphorous losses. The average drain discharges with CDch were respectively 33%, 45% and 44% lower than FD for wheat, barley and maize. Flow-weighted NO3 concentration in drainage discharge of CD70 and CDch were, respectively, 15% and 9% for wheat, 9% and 13% for barley, and 8% and 7% for maize lower than in FD. Soil salinity decreased in FD, but slightly increased in the CD treatments. Thus, although controlled drainage clearly has advantages above free drainage practices, to optimize CD management options, more research is needed on the long-term effects of controlled drainage on soil salinity.