微咸水灌溉对土壤盐分平衡与作物产量的影响

Effect of brackish water irrigation on soil salt balance and yield of both winter wheat and summer maize

  • 摘要: 河北低平原淡水资源短缺, 微咸水资源丰富, 合理开发利用微咸水已经成为缓解水资源供需矛盾的重要途径之一。本研究于2011—2015年在河北省沧州市中国科学院南皮生态农业试验站进行, 以冬小麦和夏玉米一年两熟种植体系为研究对象, 开展了河北低平原区实施微咸水灌溉对冬小麦及下茬作物夏玉米产量及灌溉对土壤盐分周年平衡的影响。2013—2014年冬小麦灌溉处理设雨养旱作处理(CK)、拔节期淡水灌溉1水(F1)、拔节期用2 g.L-1、3 g.L-1、4 g.L-1、5 g.L-1的微咸水灌溉1次(B21、B31、B41、B51)、拔节期和灌浆期用淡水灌溉(F2)、拔节期用3 g.L-1的微咸水+灌浆期用淡水灌溉(B31F1)、拔节期用淡水+灌浆期用3 g.L-1微咸水灌溉(F1B31)、拔节期和灌浆期都用3 g.L-1的微咸水灌溉(B32)、拔节期、抽穗期和灌浆期都用淡水灌溉(F3)。2014—2015年根据上年度的试验结果对试验处理进行了精简, 冬小麦灌溉处理设CK、F1、B31、B41、B51、B42(拔节期和灌浆期都用4 g.L-1的微咸水灌溉)。结果表明, 一般年型下冬小麦生育期灌溉2水就能获得高产和稳产, 平均产量为6 593.4 kg.hm-2。利用小于5 g.L-1的微咸水灌溉, 与淡水灌溉相比, 不会造成冬小麦产量降低, 灌溉1次微咸水比雨养旱作处理增产10%~30%, 可用微咸水替代1次淡水。微咸水灌溉条件下冬小麦收获时土壤盐分有所积累, 表层土壤含盐量大于1 g.L-1, 影响下茬玉米的出苗和生长, 但夏玉米播种后用675~750 m3.hm-2淡水灌溉可满足耕层淋盐需求, 达到玉米生长的安全阈值, 与淡水灌溉处理的玉米产量相比不减产。利用夏季降雨, 可使土壤盐分得到淋洗, 当夏季降雨量大于300 mm时, 冬小麦微咸水灌溉下土壤盐分达到周年平衡。沧州地区73%以上的年份, 夏季降雨量大于300 mm, 为土壤淋盐创造了条件, 保证了微咸水替代一次淡水灌溉的安全性。

     

    Abstract: There is rich brackish water and a shortage of fresh water in the coastal low plains of Hebei Province. The reasonable exploitation and utilization of brackish water has become an important way of meeting the conflict between water supply and demand in the region. An experiment was conducted in Nanpi Eco-Agricultural Station of Chinese Academy of Sciences in 2011–2015. The objective of the experiment was to study the effect of brackish water irrigation during winter wheat growth period on the yield of winter wheat and the following crop, summer maize. The study also investigated soil salinity balance in winter wheat/summer maize double cropping system. The irrigation treatments in 20132014 included CK (rainfed farming), F1 (one fresh water irrigation at jointing stage), B21 (one brackish water irrigation of 2 g.L-1 at jointing stage), B31 (one brackish water irrigation of 3 g.L-1 at jointing stage), B41 (one brackish water irrigation of 4 g.L-1 at jointing stage), B51 (one brackish water irrigation of 5 g.L-1 at jointing stage), B32 (two brackish water irrigations of 3 g.L-1 at jointing and grain-filling stages), F2 (two fresh water irrigations at jointing and grain-filling stages), F3 (three fresh water irrigations at jointing, heading and grain-filling stages), F1B31 (one fresh water irrigation at jointing stage and one brackish water irrigation of 3 g.L-1 at grain-filling stage), and B31F1 (one brackish water irrigation of 3 g.L-1 at jointing stage and one fresh water irrigation at grain-filling stage). The irrigation treatments in 20142015 were CK, F1, B31, B41, B51 and B42 (two brackish water irrigations of 4 g.L-1 at jointing and grain-filling stages). The results showed that higher winter wheat yield was obtainable under irrigation at jointing stage and grain-filling stage, with an average yield of 6 593.4 kg.hm-1. Irrigation of brackish water with less than 5 g?L1 salinity at joining stage did not reduced winter wheat yield compared with fresh water irrigation. Winter wheat yield increased by 10%30% under brackish water irrigation at joining stage compared with that under CK. It was possible to replace fresh water irrigation with brackish water irrigation during winter wheat growth. However, soil salt content in the 020 cm topsoil was more than 1 g.L-1 in brackish water irrigation treatments, which affected summer maize germination and growth during early growth stage. If irrigated with 600750 m3.hm-1 of fresh water after summer maize planting, the yield of summer maize did not reduce obviously. There was a heavy leaching of soil salt driven by precipitation in June through September. Over 300 mm rainfall during summer season could keep the soil salt balance for winter wheat and summer maize double cropping system. As over 73% of summer precipitation in Cangzhou region exceeded 300 mm, it ensured the safety of the brackish water irrigation instead of fresh water irrigation one time during winter wheat growth period.

     

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