Soil fertility refers to a soil's ability to provide nutrients in the proper amounts and proportions to support plant growth, while soil productivity is a soil's ability to produce a specified plant under a given management system. There are three criteria for determining if a nutrient is essential: 1) a plant cannot complete its lifecycle without the element, 2) no other element can substitute for it, and 3) the element must be directly involved in the plant's metabolic pathways or enzyme activity.

1. Soil Fertility vs Soil Productivity
•Soil Fertility
• quality that enables a soil to provide the proper
compounds in the proper amounts and in the
proper proportion, for the proper growth of
specified kind of plants when all factors are
favorable for growth.
•Soil productivity
• capability of the soil to produce a specified plant
under a specified system of management

3. Three Criteria for Essentiality of Nutrients
• A plant cannot complete its life-cycle in the absence of
the element
• The action of the element must be specific, with no
other element being able to completely substitute for
it
• The element must be shown to be directly involved in
the nutrition of the plant. It must be a constituent of a
metabolic pathway or at least be required for the
activity of an essential enzyme.