设施农业雨水集蓄利用与番茄灌溉方案优化

为充分利用雨水资源，提高设施农业灌溉用水效率，该研究对雨水蓄水池容积和大棚番茄灌溉方案进行了优化。以天津市武清区一设施农业小区为研究区，根据2020年6个场次降雨，对蓄水池集雨情况进行分析，基于AquaCrop模型优化大棚番茄灌溉方案，最终设置3种集雨灌溉情景，采用水量平衡法，分别绘制不同情景的丰、平、枯水年雨水集蓄系统的评价指标变化曲线，综合分析其变化特征并确定雨水蓄水池最优容积。结果表明：研究区已建蓄水池集雨率约为57%，有较大改进空间；番茄优化灌溉方案与实际灌溉方案相比，在产量仅减少5.5%的情况下，可节省水量23.6 m3，水分利用效率和灌溉利用效率分别提高7.2%和39%，说明优化方案在保证作物产量的同时可有效节水；实际集雨率和实际灌溉情景下，雨水蓄水池的最佳容积平均值为362 m3，在优化灌溉方案和提高雨水收集设施集雨率后，容积平均值分别为298和288 m3，说明节水灌溉和提高雨水蓄水池集雨率等措施，对雨水蓄水池容积优化和提高复用率具有显著影响。该研究可为指导农业雨水集蓄利用工程建设、促进非常规水利用的推广、保障农业可持续发展提供参考。

Rainwater harvesting and tomato irrigation schemes optimization for facilities agriculture

Abstract: A rainwater harvesting has been widely used to collect and store the rainwater into natural reservoirs or tanks for later purposes, further to balance between water supply and demand in recent years. In this study, a systematic optimization was conducted on rainwater harvesting for tomato irrigation. A protected agricultural plot was also chosen as the study area in the Wuqing District, Tianjin of China. A storage tank was then built with a volume of 200 m3. A rainwater harvesting rate was calculated, according to six rainfall events in 2020 and the runoff from the surfaces of seven greenhouses. At the same time, the data set on tomato irrigation in the greenhouses was collected for the crop models. An irrigation scheme was first optimized for the tomatoes in the greenhouses using the improved Penman-Monteith formula and AquaCrop model. Then, three schemes of rainwater harvesting and irrigation were established, including the actual rainwater harvesting with the actual irrigation scheme, the actual rainwater harvesting with the optimized irrigation scheme, and the improved rainwater harvesting with the optimized irrigation scheme. Finally, the water balance was applied to calculate the rainwater retention rate, groundwater replacement rate, and water supply guarantee rate in the rainwater harvesting system for different schemes in a wet, normal, and dry year. Optimal storage was thus achieved after the comprehensive analysis of reliability indexes. The results showed that the rainwater harvesting rate of the project in the study area was about 57%, indicating much potential for improvement. The optimized irrigation scheme for the tomatoes saved 23.6 m3 of water, but the yield decreased by 5.5%, compared with the actual. Furthermore, the water use and irrigation efficiency increased by 7.2% and 39%, respectively, indicating that the optimized scheme effectively saved the water while holding the crop yield. Besides, the rainwater interception rate, groundwater replacement rate, and probability of water supply increased as the volume of storage tank increased. There was no change in the groundwater replacement rate and the probability of water supply when the storage tank volume reached the optimum volume. Additionally, the magnitude of the rainwater interception rate increased with the decrease of the precipitation. More importantly, the total annual water supply was 356.3 m3 in the existing project, where the rainwater interception rate, groundwater replacement rate, and probability of water supply were 35.78%, 68.78%, and 65.48%, respectively. Correspondingly, there was also an urgent need to improve rainwater harvesting and irrigation schemes. Specifically, the average volume of the rainwater storage tank was saved 64 m3 for the higher reuse, while the lower construction costs in Scheme 2, compared with Scheme 1. Similarly, Schemes 3 saved 10 m3 average volume of the rainwater storage tank, compared with Scheme 2. Moreover, the optimal volumes of the storage tank in each scheme were 362, 298, and 288 m3, respectively. Consequently, improved rainwater harvesting and irrigation schemes were achieved to optimize the rainwater tank, thereby reducing the consumption of irrigation water for a higher rainwater collection rate. This finding can also provide a strong reference to guide the construction of agricultural rainwater harvesting and storage projects, as well as the promotion of non-conventional water use in sustainable agriculture.