Maize planting date and maturity in the US central Great Plains: Exploring windows for maximizing yields

Region-specific guidelines for maize in the US Great Plains are needed to account for variability in farmer practices and inherent soil and climate differences. Therefore, it becomes critical to define environment tailored management strategies for maize crop to improve and sustain yields over time. The aims of this study were to: i) define homogenous maize yield environments classified as related to the maximum yield and its stability over time in the US central Great Plains region; ii) explore the combinations of planting date and hybrid maturity that lead to optimal yield for each of the previously defined homogenous maize yield environments; and iii) identify environments presenting different windows for maximizing yields (combinations of planting date by hybrid maturity). Hybrid maturity (growth cycle) by planting date combinations were explored at 70 sites within central and eastern Kansas and northern Oklahoma (herein defined as the US central Great Plains region) using 30 years of historical weather data. In addition to the analysis of an extensive maize field dataset, a crop growth model, Agricultural Production Systems Simulator (APSIM), was utilized to evaluate the crop yield and phenology of all hybrid maturity by planting date combinations to define environment tailored management strategies. The simulated yields were spatially clustered based on attainable yield and stability over time to delimit more homogeneous productivity environments. Overall, greater yields were attained with long-maturing hybrids (comparative relative maturity, CRM, 101 and 115). Delaying the planting date from April to mid-May decreased yield in eastern environments. Moreover, late planting maintained yields and increased stability in central environments. For central Kansas and Oklahoma, anticipation of physiological maturity date (3-16 days) with reduced yield penalties (<5%) were possible by using short-season hybrid maturities (CRM 85). Future scenarios for intensification could be explored in those environments presenting more windows for maximizing yields, either with early planting and harvest dates or via late planting providing time for a short crop before maize. Adoption of more region-specific guidelines for maize management could help to optimize yield and its stability over time and seek further opportunities to diversify risk and intensify our current maize-based farming systems in the US central Great Plains.