The goal of this new project is to better understand relationships between potassium (K) fertilization, grain yield, K uptake and removal, K recycling with residue, and K distribution into soil pools to improve the efficacy of K management and economic benefits from fertilization. The project began in October 2008, and this goal will be achieved by using a combination of new short-term conventional plot experiments and sampling of selected plots of ongoing long-term experiments that were established years ago with partial support from ISA.