Abstract Understanding the soil-water dynamics and maize evapotranspiration (ETc) under variable rate irrigation (VRI) and variable rate fertigation (VRF) management with respect to soil spatial variability constitutes the basis for developing effective variable rate water and nitrogen management strategies. This long-term research was designed to quantify and compare the soil-water dynamics, including available water (AW), and ETc during vegetative and reproductive growth periods of VRI, fixed rate irrigation (FRI) and no-irrigation (NI) under fixed rate fertigation (FRF), VRF and pre-plant (PP) nitrogen management in three different soil types [Crete silt loam (S1); Hastings silty clay loam (S2) and Hastings silt loam (S3)] with different topography in the same field under the same environmental and management conditions. The research was conducted in the Irmak Research Laboratory in south central Nebraska, U.S.A., in 2015, 2016 and 2017 maize (Zea mays L.) growing seasons under a variable-rate linear move sprinkler irrigation system. No effect of irrigation and nitrogen fertilizer on AW was observed in the vegetative period. Overall, greater AW was observed in S3 as compared with S1 and S2 due to lower elevation. Maize ETc during the vegetative period was significantly (P 0.05) in ETc between FRI and VRI was observed in any soil type. Similarly, in 2017, no significant difference in reproductive ETc was observed between VRI and FRI in S1. During reproductive period, averaged across years, soil types and irrigation treatments, the PP nitrogen treatment had greater ETc and lower AW than VRF and FRF. The results indicate that vegetative period ETc was primarily affected by soil type, weather conditions (evaporative demand and soil wetting) and nitrogen fertilizer application timing. The findings of this research showed that soil-water dynamics is a strong function of not only management practices (irrigation and nitrogen treatments), but also soil type, topography and soil physical properties, which all need to be taken into account for effective management of VRI and FRI under VRF, FRF or PP nitrogen management in different soil types. This research quantified the impact of these management practices on soil-water dynamics and ETc which can be used as a guidance.

中文翻译：

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不同土壤类型玉米可变和固定速率灌溉和氮管理的比较分析：第 I 部分。对土壤-水动力学和作物蒸散的影响

摘要 了解可变速率灌溉 (VRI) 和可变速率施肥 (VRF) 管理下的土壤水动力学和玉米蒸散 (ETc) 与土壤空间变异性相关，是制定有效的可变速率水和氮管理策略的基础。这项长期研究旨在量化和比较土壤-水动态，包括 VRI、固定速率灌溉 (FRI) 和固定灌溉 (NI) 营养和生殖生长期期间的可用水 (AW) 和 ETc。三种不同土壤类型的施肥 (FRF)、VRF 和种植前 (PP) 氮管理 [克里特粉砂壤土 (S1); 黑斯廷斯粉质粘壤土 (S2) 和黑斯廷斯粉质粘壤土 (S3)] 在相同的环境和管理条件下，在同一领域具有不同的地形。该研究在美国内布拉斯加州中南部的 Irmak 研究实验室进行，在 2015 年、2016 年和 2017 年玉米 (Zea mays L.) 生长季节在可变速率线性移动喷灌系统下进行。在营养期未观察到灌溉和氮肥对AW的影响。总体而言，由于海拔较低，与 S1 和 S2 相比，在 S3 中观察到了更大的 AW。在任何土壤类型中观察到 FRI 和 VRI 之间的 ETc 营养期期间的玉米 ETc 显着（P < 0.05）。同样，在 2017 年，S1 的 VRI 和 FRI 之间没有观察到生殖 ETc​​ 的显着差异。在繁殖期，平均跨年、土壤类型和灌溉处理，PP 氮处理比 VRF 和 FRF 具有更大的 ETc 和更低的 AW。结果表明，营养期ETc主要受土壤类型、天气条件（蒸发需求和土壤润湿）和氮肥施用时机的影响。这项研究的结果表明，土壤-水动态不仅是管理实践（灌溉和氮处理）的强大功能，也是土壤类型、地形和土壤物理特性的强大功能，这些都需要考虑到有效管理不同土壤类型中 VRF、FRF 或 PP 氮管理下的 VRI 和 FRI。该研究量化了这些管理实践对土壤-水动力学和 ETc 的影响，可用作指导。这项研究的结果表明，土壤-水动态不仅是管理实践（灌溉和氮处理）的强大功能，也是土壤类型、地形和土壤物理特性的强大功能，这些都需要考虑到有效管理不同土壤类型中 VRF、FRF 或 PP 氮管理下的 VRI 和 FRI。该研究量化了这些管理实践对土壤-水动力学和 ETc 的影响，可用作指导。这项研究的结果表明，土壤-水动态不仅是管理实践（灌溉和氮处理）的强大功能，也是土壤类型、地形和土壤物理特性的强大功能，这些都需要考虑到有效管理不同土壤类型中 VRF、FRF 或 PP 氮管理下的 VRI 和 FRI。该研究量化了这些管理实践对土壤-水动力学和 ETc 的影响，可用作指导。