Soil pH: A measure of soil acidity or alkalinity, defined as the negative logarithm of hydrogen ion (H⁺) activity in the soil solution; it governs nutrient solubility and microbial activity.

Cation Exchange Capacity (CEC): The total quantity of exchangeable cations a soil can adsorb and hold on negatively charged surfaces (clay and organic matter), expressed as cmol(+)/kg; it reflects nutrient retention capacity.

Electrical Conductivity (EC): A measure of the soil solution’s ability to conduct electrical current, indicating the concentration of soluble salts; commonly used as an index of soil salinity.

Soil Organic Carbon (SOC): The carbon component of soil organic matter derived from plant and microbial residues; a key indicator of soil fertility, structure, and biological activity.

Base Saturation: The proportion (%) of the cation exchange capacity occupied by basic cations (Ca²⁺, Mg²⁺, K⁺, Na⁺); it reflects soil fertility status and degree of acidity.

Soil Salinity: The accumulation of soluble salts (e.g., chlorides, sulfates of Na, Ca, Mg) in the soil to levels that negatively affect plant growth, typically assessed via EC.

Soil Sodicity: A condition where sodium (Na⁺) dominates the exchange complex (high exchangeable sodium percentage, ESP), leading to soil dispersion, poor structure, and reduced permeability.

Nutrient Availability: The fraction of essential nutrients present in forms accessible for plant uptake, controlled by soil pH, CEC, moisture, microbial activity, and chemical transformations.

Soil Chemical Properties MCQs, Soil acidity and alkalinity, Soil health indicators, Soil buffering capacity, Relationship between soil pH and nutrient availability