How much of a supplemental nutrient to apply should be determined based on prior experience of the farmer, obser- vation of plant growth, knowledge of soil characteristics such as organic matter, cation exchange capacity, phosphorus and potassium supplying ability, and base saturation, knowl- edge of crop needs and field history, and understanding of the nutrient supplying power of the material to be used. An example of nutrient application rates is provided in Table 2. Overapplication can cause problems in crop production as well as in the environment. When excess nitrogen or phos- phorus is applied there is.
