Soil Test Calibration for P, K. Mg, and Zn in the Production of Durum Wheat

Abstract

Additional data to calibrate and refine current guidelines for interpreting soil test values is an ongoing need in Arizona. This includes information for soils testing above and below the level that may currently be considered adequate for optimum plant growth. An experiment was conducted at the Maricopa Agricultural Center during the 1985-86 crop year to evaluate the response of durum wheat to the application of phosphorus (P), potassium (K), magnesium (Mg), or zinc (Zn) on a soil testing adequate or higher for all of these nutrients. Grain yields from plots receiving every combination of three of the four nutrients were compared to yields obtained when all four nutrients were applied. No significant change in grain yield was measured as a result of witholding any one of the nutrients. Current guidelines used to interpret soil test results for wheat production correctly predicted the nutrient status of this soil with respect to P, K, Mg, and Zn.