基于AquaCrop和WinSRFR组合的夏玉米沟灌方案优化

    Optimization of furrow irrigation programs of summer maize by using the AquaCrop model and WinSRFR software

    • 摘要: 确定作物合理的灌溉制度和灌水技术要素组合是科学管理农业水资源的基础,可有效缓解水资源短缺矛盾和保障区域粮食安全。基于此,该研究利用在陕西省杨陵区(2022年)和武功县(2017年)进行的夏玉米田间试验,分别对AquaCrop模型和WinSRFR软件进行校准和验证,确定了研究区夏玉米典型水文年(丰水年、平水年和干旱年)的灌溉制度;通过反演沟灌土壤入渗参数和田面糙率,结合确定的灌溉制度,优化了沟灌灌水技术要素组合(入沟流量和灌水时间),并量化评价了优化灌溉制度和灌水技术要素组合对夏玉米的增产能力。结果表明,AquaCrop模型能准确模拟研究区夏玉米生长过程,其中产量模拟值与实测值的相对误差绝对值均值分别为1.85%(校准)和7.47%(验证);研究区夏玉米丰水年(灌浆期)和平水年(拔节期)需灌水1次,干旱年(拔节期和灌浆期)需灌水2次,单次灌水量均为55 mm;反演所得研究区沟灌土壤入渗参数kα取值范围分别为是55.416~98.437 mm/hα和0.351~0.858,田面糙率n均值为0.056;合理的入沟流量和停水时间取值范围分别为2.2~3.3 L/s和35~16 min,可获得高灌水质量(综合灌水质量指标Ci ≥ 85%);以2022年夏玉米优化的灌溉制度和灌水技术要素优化组合为基础,模拟所得夏玉米产量为7.819 t/hm2,与无灌溉(5.972 t/hm2)、现状条件(7.424 t/hm2)和仅对灌溉制度优化(7.659 t/hm2)情景相比较,分别提高了30.9%、5.3%和2.1%,且所需灌水量较现状条件可减少59 mm。研究结果可为研究区域夏玉米灌溉制度制定和沟灌方案设计提供理论基础和技术支撑。

       

      Abstract: Determining a reasonable irrigation schedule for crops and a combination of irrigation technology elements is the basis for scientific management of agricultural water resources, which can effectively alleviate the contradiction of water scarcity and guarantee regional food security. In this study, the AquaCrop model was calibrated and validated based on the summer maize field experiments in Yangling (2022) and Wugong (2017), Shaanxi Province to optimize the irrigation schedule, and the irrigation schedule of summer maize under typical hydrological years (wet year, normal year and dry year) and the required irrigation depth were determined in the study area; the WinSRFR software was calibrated and validated using the Yangling (2022) irrigation experiment; and the soil infiltration parameters of F4, F7, and F5 were selected to be representative of high (k = 98.437 mm/hα, α = 0.824), moderate (k = 85.396 mm/hα, α = 0.659), and low (k = 55.416 mm/hα, α = 0.617) infiltration capacities, and 1.0‰, 2.0‰ and 3.5‰ were used as representative values of typical bottom slopes in the study area, respectively to optimize values furrow irrigation technology elements (discharge and cutoff time) under different soil infiltration capacities and bottom slope by using WinSRFR. Finally, evaluation the yield increasing ability of the optimized irrigation schedule and the irrigation technology elements for summer maize by using AquaCrop model, respectively. The results indicated that the AquaCrop model can accurately simulated the maize growth. The calibration results of the coefficient of determination (R2), root mean square error (RMSE) and Nash-Sutcliffe efficiency coefficient (EF) between simulated and measured values of canopy cover (CC), aboveground biomass (B) and soil water content (SWC) were 0.99, 0.98, 0.89; 3.9%, 1.4 t/hm2, 11.7 mm; and 0.97, 0.94, 0.56, respectively; the verification results were 0.98, 0.99, 0.86; 10.1%, 1.2 t/hm2, 13.6 mm, and 0.76, 0.96, 0.63, respectively; The calibration and verification results of the mean absolute value of the relative error between the simulated and measured values of yield was 1.85% and 7.47%, respectively; Summer maize in the study area must be irrigated once during wet year (during the grain-filling stage) and normal year (during the jointing stage) and twice during dry year (during the jointing and grain-filling stages), with the water quantity used in each irrigation event being 55 mm; the optimised k and α values were 55.416 to 98.437 mm/hα and 0.35 to 0.858, respectively, and the mean n value was 0.056; the optimal discharge and cutoff times were 2.2 to 3.3 L/s and 35 to 16 min, respectively, these values are suitable for meeting the requirement of the comprehensive irrigation performance indicator (Ci) being ≥ 85%. Based on the irrigation schedules of optimization and the combination of irrigation technology elements of optimization for summer maize in 2022, the yield of maize simulated by AquaCrop model is 7.819 t/hm2; compared with rain fed (5.972 t/hm2), current condition (7.424 t/hm2) and irrigation schedule of optimization (7.659 t/hm2), summer maize yield increased by 1.847, 0.395 and 0.160 t/hm2, respectively; and the percentage of summer maize yield increase by 30.9%, 5.3% and 2.1%, respectively, and saved irrigation water 59 mm. Therefore, the optimization of irrigation system and irrigation factor combination can effectively improve crop yield and save irrigation water; and it can be concluded that although irrigation is only used as a supplement to crop water requirements in semiarid and semi-humid, it is important because it has substantive implications on maize yield. The research results can provide theoretical basis for furrow irrigation scheme design of the research region and technology support.

       

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