Soil and plant analyses offer a means to detect potential potassium (K) deficiency conditions in a cotton crop. Soil K analysis serves as an indicator of the presence of enough soil K to meet the demand for an entire growing season. Low soil K values can be offset by the best recommendation for a response to additional K. Plant leaf or petiole analysis provides a means of in-season monitoring of K. The early detection of K deficiency by plant analysis will allow some limited response if yield potentials warrant additional K. Inherently lower subsurface soil K can lead to a situation that would be missed by a surface soil K analysis. Plant tissue K analysis offers a sensitive means to follow the K status of cotton on a reasonably routine basis.