Variable-rate irrigation (VRI) can effectively improve the irrigation efficiency. In this study, we evaluated the two key indicators, irrigation uniformity and accuracy for a three-span center pivot VRI system with the combination of two sprinkler types, i.e., the Nelson D3000 (a fixed spray plate sprinkler, FSPS) and the R3000 (a rotating spray plate sprinkler, RSPS), two sets of irrigation depths designed for four management zones (zones 1–4) of 10, 8, 15, and 20 mm and 10, 15, 20, and 25 mm, and three cycle times (CTs) of the solenoid valve of 30, 45, and 60 s, with constant-rate irrigation (CRI) as a reference. In addition, the radially affected lengths of irrigation depths in zones 1–4 under various VRI treatments were further determined. The radial (mean CU_H = 90.8%) and circumferential application uniformity (mean CU_H = 95.6%) as well as radial irrigation accuracy (mean NRMSE = 15.3%) of the R3000 were superior to those of D3000 under VRI. The irrigation uniformity and accuracy of each management zone were less impacted by the designed irrigation depth and CT, but more affected by the location of the management zone. The irrigation uniformity and accuracy of VRI were close to those of CRI, indicating that the VRI system tested could guarantee the same application performance as the CRI system. Changing the D3000 sprinklers to R3000 sprinklers in the VRI system effectively reduced the radially affected lengths of management zones. The radially affected lengths of D3000 under various treatments were primarily distributed from 3–6 m, whereas those of R3000 were 0–3 m. Thus, it was recommended to select RSPSs in the design of the center pivot VRI system, and the transition zone and CT in relation to R3000 sprinklers were suggested to be 0–3 m and 60 s, respectively. This research provides the recommendations for better implementation of VRI.

可变速率灌溉（VRI）可以有效提高灌溉效率。在这项研究中，我们评估了三跨中心枢轴 VRI 系统的两个关键指标，即灌溉均匀性和准确性，该系统结合了两种喷头类型，即 Nelson D3000（固定喷淋板喷头，FSPS）和 R3000（旋转喷洒板喷头 (RSPS)，为 10、8、15 和 20 毫米和 10、15、20 和 25 毫米的四个管理区（1-4 区）设计的两组灌溉深度，以及三个循环时间(CT) 30、45 和 60 秒的电磁阀，以恒速灌溉 (CRI) 作为参考。此外，进一步确定了不同 VRI 处理下 1-4 区灌溉深度的径向影响长度。径向（平均 CU _H= 90.8%）和圆周应用均匀性（平均 CU _H= 95.6%) 以及在 VRI 下，R3000 的径向灌溉精度（平均 NRMSE = 15.3%）优于 D3000。各管理区的灌溉均匀性和准确性受设计灌溉深度和CT的影响较小，但受管理区位置的影响较大。VRI的灌溉均匀度和精度接近CRI，表明所测试的VRI系统可以保证与CRI系统相同的应用性能。在 VRI 系统中将 D3000 喷头更改为 R3000 喷头，有效地减少了管理区域的径向影响长度。不同处理下D3000的径向影响长度主要分布在3-6 m，而R3000的径向影响长度为0-3 m。因此，建议在中心枢轴 VRI 系统的设计中选择 RSPS，与 R3000 喷头相关的过渡区和 CT 建议分别为 0-3 m 和 60 s。本研究为更好地实施 VRI 提供了建议。