Little information existed on nutrient needs, plant tests and critical nutrient ranges (CNR) or “target levels” for nitrogen (N) and potassium (K) in plant tests for maximum yield and quality of Brussels sprouts crops grown in Australia. This project assessed the effects of nitrogen (N) and potassium (K) on the yield and quality of irrigated Brussels sprouts. It also developed and calibrated plant tests for N and K for improved and sustainable nutrient management of Brussels sprouts.