Renada Davis

Date of Award

Summer 2019

Document Type

Open Access Thesis


Environmental Health Sciences

First Advisor

Robin Kloot


A study conducted on wheat, soybean, and corn crops was designed to assess the effect of potassium fertilization based on current potassium (K) fertilizer recommendations on crop yield, soil K levels, and plant tissue K concentration. The objectives of this study were to 1) evaluate the effect K fertilization has on crop yield; 2) To assess soil K levels through the duration of the experiment and the effect fertilization may have on soil K levels; and 3) to evaluate the effect of fertilization on plant tissue K concentrations. There was no statistical difference in yields between plots treated with the full amount of fertilizer K based on the current recommendations1 and the plots that did not receive any K. For five crops between December 2014 and December 2017, there was no significant reduction in soil test K levels on plots that were not receiving any supplemental fertilizer K. This suggests that exchangeable K was being replaced by sources other than applied fertilizer K.

The results of this research could indicate that the application of K fertilizer on soils with medium levels of K may be an unnecessary expense to growers. Fertilization may also have the potential to harm future crops if soils are unable to leach Cl additions efficiently from KCl fertilizer. Methods for measuring soil K levels and accompanying fertilizer recommendations may need to be re-examined and adjusted to include all forms of K in a soil. This, coupled with a more comprehensive evaluation of a soil’s ability to release and hold K, would allow growers to take a more holistic approach when deciding fertilizer treatments. This could help reduce their environmental impact while also reducing their input cost


© 2019, Renada Davis