Historic winter wheat yield, production, and economic value trends in Kansas, the "Wheat State"

Year-to-year weather variability and technologies (fertilizer, irrigation, herbicides, conservation tillage, varieties, mechanization, and others) are among factors that affect winter wheat (Triticum aestivum L.) yields in water-limited cropping systems. The objective of these analyses was to quantify winter wheat yield trends, variability, relationship with weather, yield gap, and value in the "Wheat State," Kansas. Two data sources were used for this study, that is, annual winter wheat yield reported for selected counties from the United States Department of Agriculture and the Kansas State University wheat variety performance trial near Colby, Garden City, Hays, and Tribune, Kansas. Results of the study showed a decline in harvest area and inflation-adjusted market value per area of winter wheat beginning in the 1930s. However, both the survey and research data showed continuous increase in winter wheat yield at rates of 3-180 kg ha-1 year-1 that varied by irrigation, location, data source, or time range considered, except for a few years where yield stagnated or declined. Despite increased productivity, results indicated an increase in annual winter wheat yield variation over time. A positive correlation was observed between nonirrigated wheat yield and all months of precipitation except for January, February, and June. October through December precipitation provided the best positive correlation with nonirrigated wheat yield. Wheat yields were negatively correlated with high temperature in months that coincided with wheat flowering and maturity. The yield gap between actual and potential wheat yield was estimated at 15%-55%. The decreasing revenue per land area may be one of the reasons for decreasing wheat planted acreage over time. We concluded producers need to increase adoption of latest technology (varieties with drought and heat tolerance) and management to obtain yield potential. Research should investigate methods to increase the stability of state-wide wheat production and financial return. Winter wheat harvest area and inflation-adjusted market value was in a decline since 1930s.Winter wheat yield increased over the study period but varied from year-to-year.Wheat yields were negatively correlated with high temperatures at flowering and maturity.Over time, there was little change in precipitation despite trends of increasing temperature.Yield changes over the past seven decades were mostly driven by weather and less from technological advances.