**4. Conclusions**

Many field landscape, soil, and weather factors impacted the performance of VRN in the farm MRB fields analyzed in this study. Soils with higher organic matter content, deeper profiles, and that are more erodible produced higher lint yields using VRN compared to the FP. In contrast, coarser soils, fields at higher elevations, or fields in locations with warmer temperatures were negatively associated with VRN yields compared to the FP. More N was applied using VRN compared to the FP on fields associated with greater water-holding capacity, more erodible soils, or warmer temperatures. In contrast, deeper profiled soils had a negative association to VRN N rate compared to FP. Soil, landscape, and weather had less of an impact on VRN NRs than on lint yields and fertilizer N rates. Most notable was the positive association with greater NRs with VRN relative to the FP for soils that were deeper and had higher organic matter. Soils with more organic matter had a positive relation to N e fficiency of VRN compared to the FP. More erodible fields and warmer climates had negative associations to N e fficiency, likely due to the need for higher N rates to account for lower available N in soils. Supplementing OS information with other map-based information resulted in higher VRN N rates but not yields and NRs. In addition, the additional expense of map-based information also impeded VRN profitability.

VRN may provide downside risk managemen<sup>t</sup> benefits on fields with greater water-holding capacity, higher organic matter, or deeper profile soils by being associated with a smaller probability of low yields relative to the FP. Fields with silt and loam soils would likely benefit from VRN fertilizer N cost savings and environmental benefits because of a high probability of VRN resulting in lower N rates than the FP. In addition, the probability of enhanced N e fficiency is more likely on a loam texture soil. However, the potential environmental benefits on these two soil textures may be obtained at the cost of a higher probability of lower NRs.

Key findings can be used by extension educators and cotton farmers to determine if adopting OS-based VRN on fields with certain characteristics would likely provide positive benefits. However, an important caveat of this study is that the profitability of OS and VRN were evaluated at the sub-field level to identify the conditions where the technology may provide an advantage over the FP. Notwithstanding the potential benefits of VRN, farmers are interested in the profitability of the technology at the field and farm levels. Future analyses should assess the profitability and risk managemen<sup>t</sup> potential of the technology at the field level and farm levels as influenced by landscape, soil, and weather.

**Author Contributions:** Conceptualization, J.A.L., X.Y., B.S.T., P.S., J.J.V., D.J.D., H.J.S. and M.J.B.; data curation, J.A.L., M.S., X.Y. and X.V.Z.; formal analysis, J.A.L., M.S., X.Y., C.N.B. and D.M.L.; funding acquisition, J.A.L., X.Y., B.S.T., P.S., J.J.V., D.J.D., H.J.S. and M.J.B.; investigation, J.A.L., X.Y., B.S.T., P.S., J.J.V., D.J.D., H.J.S. and M.J.B.; methodology, J.A.L., X.Y., C.N.B. and D.M.L.; project administration, X.Y.; resources, J.A.L., B.S.T., P.S., J.J.V., D.J.D., H.J.S. and M.J.B.; software, J.A.L., M.S., D.M.L. and X.V.Z.; supervision, X.Y.; validation, J.A.L., M.S. and X.V.Z.; writing—Original draft preparation, J.A.L., M.S., X.Y., C.N.B. and D.M.L.; writing—Review and editing, J.A.L., X.Y., C.N.B., D.M.L., X.V.Z., B.S.T., P.S., J.J.V. and M.J.B. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by USDA NRCS Conservation Innovation Grant Project No. 69-3A75-11-177, USDA Hatch Project TN TEN00442 and agricultural research institutions at Louisiana State University, Mississippi State University, University of Missouri, and University of Tennessee.

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