On sandy soils, apply nitrogen fertiliser in small, regular doses throughout the life of the crop. Slow-release nitrogen fertilisers can reduce leaching, because they supply nitrogen at a steady rate over an extended period. This can result in efficient nitrogen use by crops, with less nutrients available for leaching. At present these forms of nitrogen are more expensive and generally uneconomic. Match nitrogen application rates with crop growth stage.
Young crops require lower rates of nutrients than crops in mid-growth.
However, apply nutrients in more frequent, smaller doses when crops are young, because their root systems are smaller. Reduce nutrient applications as the crop approaches maturity. When plants are young, place nitrogen fertiliser with droppers immediately adjacent to plants. When crops develop more extensive roots they are better able to extract nutrients spread over the whole garden, orchard or vineyard. Do not apply high rates of poultry manure, which will increase soil nitrogen levels far beyond what the plant can use and lead to nitrogen leaching.