Corn yield response to phosphorus and potassium fertilization in Arkansas
2021
Drescher, Gerson L. | Slaton, Nathan A. | Roberts, Trenton L. | Smartt, Alden D.
Phosphorus and potassium are key nutrients for plant physiological processes and are required in large amounts for adequate corn (Zea mays L.) production. Corn is a major row crop, and up‐to‐date soil test‐based fertilizer recommendations are required to enhance production and profitability. The results from 32 P and 42 K field trials evaluating irrigated corn response to fertilizer P and K rates were used to (i) correlate corn's relative yield response to Mehlich‐3 soil test P and K, (ii) determine the frequency and magnitude of the yield response to fertilization, and (iii) calibrate fertilizer P and K rates to soil test P and K. The quadratic and linear models identified 36 parts per million (ppm) P (r² = .68, P < .0001) and 110 ppm K (r² = .36, P < .0001) as the Mehlich‐3 soil test P and K values needed to produce 95% of maximum yield without fertilization. Additional research is needed on soils with P < 15 and > 35 ppm and K < 60 and > 120 ppm to enhance the scope of data in the analyses and improve our understanding of corn's response to P and K fertilization. The current thresholds defining soil test K levels perform well in interpreting soil K availability and corn's response to K fertilization. Mehlich‐3 soil test P level definitions should be modified to improve the accuracy of soil test‐based decisions for irrigated corn. The calibration results suggest the recommended P₂O₅ and K₂O rates are greater than needed to maximize yield.
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