**5. Conclusions**

These results demonstrate the challenges of field study management to optimize WUE. Future research in the study region might explore agroecological strategies to mitigate poor soil nutrient supply and weed competition for pearl millet by practicing intercropping with legumes or agroforestry where possible [24]. Despite the factors that obscured the main effects and interactions, greatest average forage production was achieved with the highest irrigation level, however, highest WUE was attained in tilled soil due to greater LAI, light interception, and plant growth than in no-till. While the application of water increases forage production, low LAI values will increase estimated E and reduce WUE, especially without adequate nutrient application. Differences in DM were associated with changes in

soil management, which ultimately resulted in higher WUE for tilled soil. The DM/WU pearl millet forage production function lacked strong correlation because of weeds and LAI < 2. An agronomic WUE optimization plan for pearl millet forage production should include conventional till, weed control, and proper nutrient management. Narrow is preferable to wide row spacing for greater LAI and light interception earlier in the growing season. If irrigation is available, water application should range from 400–600 mm of total water available for ET to maximize forage production, however, climatic demand will cause greater water loss from transpiration than if limited water is applied. Future research has an opportunity to conduct a more comprehensive review and meta-analysis of global pearl millet management practices used to improve water use efficiency and the effective use of water [47].

**Author Contributions:** Conceptualization, B.C., B.B., M.R.; Methodology, B.C., B.B., and M.R.; Formal analysis, B.C., M.D., and M.R.; Funding acquisition, B.B.; Investigation, B.C., and B.B.; Project administration, B.C., and B.B.; Resources, B.B.; Supervision, B.B., M.D., and M.R.; Validation, B.B., M.D., and M.R.; Visualization, B.C.; Writing—original draft, B.C.; Writing—review and editing, B.C., B.B., M.D., and M.R. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Acknowledgments:** Research funding was provided by the Dryland Agriculture Institute, West Texas A&M University, Canyon, TX, USA. The authors also wish to express their gratitude for the time and efforts of two anonymous reviewers whose thoughts contributed to the improvement of the manuscript.

**Conflicts of Interest:** The authors declare no conflict of interest.
