Potash Rate Calculator from Univ. of Arkansas

An Apr. 11, 2022 FarmProgress article by Fred Miller titled “Potash rate calculator: Updated decision tool helps farmers optimize fertilizer inputs”provides information about an updated potassium (K) fertilizer rate calculator (PRC–Potash Rate Calculator) that has been developed by Univ. of Arkansas scientists. The calculator can help crop producers make the most economical decision about how much K fertilizer to apply to a crop based on soil test results, potash costs, crop price, and anticipated yield. The program, developed by Dr. Michael Popp in collaboration with Drs. Trent Roberts and Nathan Slaton, can be found here and downloaded free of charge. Click here for a PRC tutorial, and here for an Agronomy Journal article titled “Profit-maximizing potassium fertilizer recommendations for soybean” by Popp, Slaton, and Roberts that provides information about K rates for soybean in the Midsouth.

The calculator provides producers with a K fertilizer rate recommendation that is aimed at maximizing profit from its application rather than maximizing yield. This is done by considering the soil test value for K, the cost of K fertilizer, the anticipated crop yield, and the anticipated price received for the crop. Once these values are entered into the calculator, the program provides a profit-maximizing K fertilizer rate that should be applied. The recommendation can be tailored to individual fields that will be planted to soybean.

The recommendation provided by the PRC is based on results from a soil sample that is tested for soil K level. Thus, obtaining quality soil samples is essential for getting the best results from the PRC. Click here for a White Paper on this website that provides information about and links to guidelines for collecting quality soil samples. Click here to access Miss. State Univ. publications regarding K fertility for soybeans.

Composed by Larry G. Heatherly, Apr. 2022, larryh91746@gmail.com