Weather Factors Affecting 22 Years of Tallgrass Prairie Hay Production and Quality

Abstract

Tallgrass prairie annual hay production and chemical composition (N, P, K, CA) data from a 23-year study conducted by H.J. Harper, Oklahoma State University, from 1929 through 1951 were correlated with corresponding monthly and seasonal temperature (mean, maximum and minimum, and absolute maximum and minimum), precipitation, wind, spring and fall growing season freeze dates, current and previous year's harvest dates, and previous year's yield. Multiple regression analyses were used to determine the weather variables and multiple regression equations which accounted for the greatest percentage of variation in annual hay production and nutrient concentrations. Equations with 4 independent weather variables for all months prior to the date of hay harvest produced high R2 values for production (82%), and N (80%), P (81%), K (81%) and CA (91%) concentrations. In general temperature values, especially in the fall of the previous year and January and mid-summer of the current year, accounted for more of the variation in all response variables than did any other kind of weather variable, such as precipitation, wind, or freeze date. Equations with 4 independent weather variables for those months prior to June produced only a moderate R2 value (48%) for production, but produced high R2 values for N (76%), P (74%), K (74%) and Ca (79%) concentrations. Relationships deserving additional research are suggested.