Soil fertility: This is the capacity of soil to provide all essential elements for specific crop production in an easily available form and in proper proportion.
Soil productivity: Capacity of soil to produce maximum yield of a special plant/crop or a sequence of crop under specified system of management.
Hidden hunger: A situation in which a crop needs more nutrients, yet has shown no deficiency symptoms, and a crop does not give top profitable is known as hidden hunger.
Critical nutrient range (CNR): Range of nutrient concentration at a specific growth stage above which the crop is amply supplied and below which crop is deficient.
Lower critical limit: It refers to that concentration of a nutrient in plant or soil below which the plant cannot complete its life cycle.
Upper critical limit: It refers to that concentration of nutrient in plant above which the sufficiency range start.