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INTRODUCTION

Soils contribute to general ecosystem services. Biomass production from agriculture and forestry
is one of the seven functions of soil. Presently, soil degradation affects global crop production.
Out of many reasons, soil degradation due to soil nutrients deficiency affects crop productivity in
various parts of the world including India. Therefore, assessment of changes in soils to achieve
the knowledge for improving soil quality and avoiding soil degradation is the need of the hour.

Essential nutrient elements for plants and their categories
Soil contains elements in varied proportion. Plants absorb certain elements in different quantities
from soil for their growth and development. A nutrient element is one that is required to
complete the life cycle of the organism and its relative deficiency produces specific deficiency
symptoms. Soil available form of a nutrient is that fraction whose variation in amount is
responsible for significant changes in crop yield and response. Available nutrient constitutes only
a small portion of the total nutrient present in the soil. An element must satisfy the following
criteria to be called as an essential nutrient:
(i) Plants cannot complete the vegetative and reproductive stages of lifecycle in
deficiency of the nutrient.
(ii) The deficiency produced by the plants is specific to the element and can be prevented
or corrected only by supplying that element.

(iii) The element is directly involved in the metabolic activity of the plants.

Till now seventeen nutrients have been recognized essential for plant growth and they are
carbon(C), hydrogen(H), oxygen(O), nitrogen(N), phosphorus(P), potassium(K), calcium(Ca),
magnesium(Mg), sulphur(S), iron(Fe), manganese(Mn), zinc(Zn), copper(Cu), boron(B),
molybdenum(Mo), chlorine(Cl) and nickel (Ni). Out of which C, H, O are called framework
element as they contribute more than 90% of plant constituent. Whereas, nutrients like Fe, Mn,
Zn, Cu, B, Mo, Cl and Ni are required in relatively smaller quantities and are called as
micronutrients. As per requirement, N, P, and K and Ca, Mg and S are called primary and
secondary nutrients respectively.

Nutrient uptake in different crops is dependent on soil nutrient availability, crop and variety
types and crop management practices. It is very much important to critically assess the secondary
and micronutrient deficiency in soil for the inclusion of these nutrients in balanced nutrient
management schedule for improving crop production and crop quality.