Farmers can save money and help the environment by targeting fertiliser nitrogen applications to ensure the correct quantity is applied at the correct time. CSRIO research is revealing more about the timing of the crop nitrogen demand and the amounts and timing of nitrogen supply from soil, fertiliser, and pasture and crop residues. Optimum nitrogen management means balancing crop nitrogen demand with supply from soil and fertiliser. Farmers can use this balance between nitrogen supply and crop nitrogen demand to calculate nitrogen fertiliser requirements using tools such as the Lime and Nutrient Balance software package.