MODERN CONCEPT OF NUTRIENT AVAILABILITY
The modern concept of nutrient availability is a multifaceted process influenced by various internal and external factors. In the context of specific nutrients, nitrogen exists in complex organic forms in the soil, eventually breaking down into ammonium compounds. These compounds can replace basic cations in the soil, and plants predominantly absorb nitrogen in the form of ammonium and nitrate ions. However, factors such as excess minerals in the soil or leaching can impact nitrogen availability. Phosphorus, on the other hand, originates from both inorganic and organic sources and becomes accessible to plants in the form of orthophosphate ions after microorganism-mediated decomposition. Soil pH, temperature, and interactions with other elements affect phosphorus availability. Excessive potassium levels can be lost through leaching, and certain clays can fix potassium ions, influencing their availability. Calcium and magnesium are released from primary minerals in the soil, affecting soil acidity as they exchange with hydrogen ions. Sulphur primarily exists in organic forms and is converted into sulphides and then sulphates by microorganisms, making them available for plant uptake. Micronutrients are found in primary minerals and can form various compounds in the soil; their solubility and availability vary with soil pH. External factors include soil composition, pH levels, cation exchange capacity, light, temperature, nutrient interactions, and excess minerals, while internal factors encompass plant growth, aging, mycorrhizal associations, and root system development. Understanding these complex interactions is crucial for optimizing nutrient availability in agriculture, ensuring healthy plant growth, and ultimately contributing to human nutrition and food security.
