Planning is fundamental to successful crop nutrition management. It defines the quantities and timings of organic material and inorganic fertiliser applications to maximize crop yields whilst minimising environmental impacts. A nutrient management plan tends to be created before fertilisers are purchased, and is ideally finalised before crops are sown . Growers should work on a field-by-field basis to ensure applications will meet each crop's nutrient demands. Planning tends to make use of national or regional recommendation systems, and must account for relevant legislation. Software packages are often available for farmers and advisors, to create nutrient management plans. Crop choices and markets, fertiliser availabilities and prices, and soil analyses tend to form the framework of a nutrient management plan, but additional information may contribute to plan accuracy, such as manure analyses and nutritional performance of recent crops. Crop nutrition management must extend beyond the planning phase, as weather and other unexpected events usually alter crop behaviour from that initially expected.