College of Water Resource and Civil Engineering, China Agricultural University, Beijing 100083, China.
College of Water Resource and Civil Engineering, China Agricultural University, Beijing 100083, China.
Sci Total Environ. 2018 Apr 1;619-620:1170-1182. doi: 10.1016/j.scitotenv.2017.11.145. Epub 2017 Nov 29.
Water scarcity and salt stress are two main limitations for agricultural production. Groundwater evapotranspiration (ET) with upward salt movement plays an important role in crop water use and water productivity in arid regions, and it can compensate the impact of deficit irrigation on crop production. Thus, comprehensive impacts of shallow groundwater and deficit irrigation on crop water use results in an improvement of irrigation water productivity (IWP). However, it is difficult to quantify the effects of groundwater and deficit irrigation on IWP. In this study, we built an IWP evaluation model coupled with a water and salt balance model and a crop yield estimation model. As a valuable tool of IWP simulation, the calibrated model was used to investigate the coupling response of sunflower IWP to irrigation water depths (IWDs), groundwater table depth (GTDs) and groundwater salinities (GSs). A total of 210 scenarios were run in which five irrigation water depths (IWDs) and seven groundwater table depths (GTDs) and six groundwater salinities (GSs) were used. Results indicate that increasing GS clearly increases the negative effect on a crop's actual evapotranspiration (ET) as salt accumulation in root zone. When GS is low (0.5-1g/L), increasing GTD produces more positive effect than negative effect. In regard to relatively high GS (2-5g/L), the negative effect of shallow-saline groundwater reaches a maximum at 2m GTD. Additionally, the salt concentration in the root zone maximizes its value at 2.0m GTD. In most cases, increasing GTD and GS reduces the benefits of irrigation water and IWP. The IWP increases with decreasing irrigation water. Overall, in arid regions, capillary rise of shallow groundwater can compensate for the lack of irrigation water and improve IWP. By improving irrigation schedules and taking advantages of shallow saline groundwater, we can obtain higher IWP.
水资源短缺和盐胁迫是农业生产的两个主要限制因素。地下水蒸发蒸腾（ET）伴随着盐分向上运移，在干旱地区对作物水分利用和水分生产率起着重要作用，它可以弥补亏缺灌溉对作物生产的影响。因此，浅层地下水和亏缺灌溉对作物水分利用的综合影响导致灌溉水生产率（IWP）的提高。然而，量化地下水和亏缺灌溉对 IWP 的影响是困难的。在本研究中，我们建立了一个 IWP 评价模型，该模型与水盐平衡模型和作物产量估算模型相结合。作为模拟 IWP 的有价值工具，校准后的模型被用来研究向日葵 IWP 对灌溉水深（IWD）、地下水位深度（GTD）和地下水盐度（GS）的耦合响应。总共运行了 210 个场景，其中使用了 5 种灌溉水深（IWD）、7 种地下水位深度（GTD）和 6 种地下水盐度（GS）。结果表明，随着盐分在根区的积累，GS 的增加明显增加了对作物实际蒸散（ET）的负效应。当 GS 较低（0.5-1g/L）时，增加 GTD 产生的正效应大于负效应。对于相对较高的 GS（2-5g/L），浅盐水地下水的负效应在 GTD 为 2m 时达到最大值。此外，根区盐浓度在 GTD 为 2.0m 时达到最大值。在大多数情况下，增加 GTD 和 GS 降低了灌溉水和 IWP 的效益。随着灌溉水的减少，IWP 增加。总的来说，在干旱地区，浅层地下水的毛细上升可以补偿灌溉水的不足，提高 IWP。通过改进灌溉计划和利用浅层咸地下水，可以获得更高的 IWP。
