Discussion of “Maximizing Irrigated Maize Productivity: Evaluating the Impact of Deficit Irrigation and Nitrogen Rates on Growth, Yield, and Water-Use Efficiency in Southwest Ethiopia”

The discussers would like to express their appreciation to the authors of the original paper for conducting research on the effects of deficit irrigation and nitrogen rates on maize yield and water-use efficiency, with a focus on identifying the best economic benefits for farmers.The discussers have noted some key areas that require attention to improve the irrigation and nitrogen management in a corn production system.While important information can be derived from the original paper, the discussers would like to comment on the methodology used by the authors, specifically on the reference crop evapotranspiration estimation, crop coefficients, irrigation scheduling approach, and net irrigation estimates.The adoption of the Food and Agriculture Organization (FAO) Penman-Monteith equation to estimate the reference crop evapotranspiration (ETo) requires the key climatic variables such as the maximum and minimum temperatures, the maximum and minimum relative humidity, wind speed, and solar radiation.In case of missing parameters, some adjustments are proposed and detailed in Allen et al. (1998).The authors of the original paper collected sunshine duration instead of solar radiation and no transformation of the sunshine hours into solar radiation was presented in the original paper.The discussers are wondering how the FAO Penman-Monteith equation was used to estimate the ETo without the solar radiation data.The authors should have mentioned the precise ETo they used for the ETo estimation.The authors indicated using crop coefficients in combination with ETo to estimate maize actual evapotranspiration (ETc).Throughout the original paper, no maize crop coefficient was reported.Maize crop coefficients are reported as 0.70 for initial stage, 1.20 for midseason, and 0.60-0.35for late-season development stage (Allen et al. 1998).Further, Allen et al. (1998) provided key information for adjusting the midseason crop coefficients when the relative humidity differs from 45% and the wind speed is larger or smaller than 2 m=s, using the average midseason plant height to compensate for differences in aerodynamic roughness and leaf area.Similarly, end-season Kc could also be adjusted.Moreover, many