Development of critical limits for different crops grown in different soils and its use in optimizing fertilizer rates

Soil testing is a useful tool that can help to ensure the efficient use of applied plant nutrients. Soil tests measure the quantity of a nutrient that is extracted from a soil by a particular extractant. The measured quantity of extractable nutrient in soil is then used to predict the crop yield response to application of the nutrient through fertilizer, manure and any other amendments. As soil test levels increase for a particular nutrient, the expected crop yield response to additions of that nutrient decreases.