In the Texas High Plains (THP), groundwater resources for irrigation are declining because of aquifer depletion and reduced well yield. Inability to meet peak water demands of maize under constrained irrigation capacities decreases yield and profitability. The MOPECO crop model, calibrated for the THP, was adapted to simulate maize water use and yield under center pivot irrigation to evaluate water allocation strategies under limited irrigation. Simulations were carried out over a range of irrigation capacities (3 – 12 mm d^-1 for a 50.9 ha area), initial soil water contents, and application depths with irrigation allocated to a fraction (0.5 – 1.0) of the pivot area. Fractional water allocations were achieved by withholding irrigation from circular sectors or from outer spans with unirrigated fractions in fallow or planted to dryland cotton. These strategies were evaluated for growing seasons characterized by typical meteorological years with average (TMY1), average to above average (TMY2), and below average (TMY3) precipitation. Preseason irrigation had little to no influence on grain yield at irrigation capacities ≥ 5 mm d^-1. At irrigation capacities ≤6 mm d^-1 under TMY1, marginally greater yields 50.9 ha^-1 were simulated when a fraction was irrigated. For irrigation capacities ≤8 mm d^-1 under TMY1, reducing the irrigated area was the most prudent option to optimize net returns. As irrigation capacities increased from 4 to 8 mm d^-1, the irrigated fraction that maximized net returns increased from 0.5 to 0.9. Concentrating water generated greater net returns because of greater irrigation water productivities and lower seed and fertilizer costs. Compared with fallow, planting cotton in the unirrigated portion increased net returns except in years with a seasonal drought (TMY3). Because greater irrigation volume did not always increase net returns, there is an opportunity to both increase profitability and conserve water by irrigating a fraction of the area.

在德克萨斯高原 (THP)，由于含水层枯竭和井产量下降，用于灌溉的地下水资源正在减少。在灌溉能力受限的情况下无法满足玉米的高峰用水需求会降低产量和盈利能力。针对 THP 校准的 MOPECO 作物模型适用于模拟中心枢轴灌溉下的玉米用水和产量，以评估有限灌溉下的水分配策略。在一系列灌溉容量 (3 – 12 mm d ^-1对于 50.9 公顷的区域）、初始土壤含水量和灌溉深度，灌溉分配到枢纽区域的一小部分 (0.5 – 1.0)。部分水分配是通过停止从圆形部门或从休耕或种植旱地棉花的未灌溉部分的外部跨度灌溉来实现的。这些策略针对以平均 (TMY1)、平均到高于平均 (TMY2) 和低于平均 (TMY3) 降水的典型气象年为特征的生长季节进行了评估。在灌溉能力 ≥ 5 mm d ^{-1 时，}季前灌溉对谷物产量几乎没有影响。在TMY1 下灌溉能力 ≤6 mm d ^{-1 时}，产量略高 50.9 ha ^-1当部分被灌溉时进行模拟。对于 TMY1下≤8 mm d ^{-1 的}灌溉能力，减少灌溉面积是优化净收益的最谨慎选择。随着灌溉能力从 4 mm d ^-1增加到 8 mm d ^-1，使净收益最大化的灌溉部分从 0.5 增加到 0.9。由于更高的灌溉水生产率和更低的种子和肥料成本，浓缩水产生了更大的净回报。与休耕相比，除季节性干旱年份（TMY3）外，在未灌溉部分种植棉花增加了净收益。由于更大的灌溉量并不总是会增加净收益，因此有机会通过灌溉一小部分区域来提高盈利能力和节约用水。