MECHANISMS AND MANAGEMENT OF SOIL ORGANIC MATTER AND NUTRIENT CYCLING IN AGRICULTURE

Abstract

Soil organic matter (SOM) is a critical determinant of soil fertility and agricultural productivity, primarily through its regulation of nutrient cycling processes essential for plant growth. Comprising a spectrum of organic constituents—from fresh plant residues to highly decomposed humic substances—SOM modulates the dynamics of macro- and micronutrients via mechanisms such as mineralization, immobilization, complexation, and sorption. These processes govern the availability, mobility, and retention of key nutrients, including nitrogen (N), phosphorus (P), sulfur (S), and potassium (K), within the soil matrix. Additionally, SOM enhances cation exchange capacity, stabilizes soil pH, and improves soil structure, thereby optimizing the soil’s capacity to retain nutrients and moisture. This review explores the composition and classification of SOM, its biochemical interactions with essential nutrients, and the microbiological and physicochemical mechanisms underpinning SOM-mediated nutrient cycling. It further evaluates the influence of agricultural practices—including tillage, crop rotation, residue management, and organic amendments—on SOM dynamics and nutrient availability. While conventional practices may accelerate SOM depletion and disrupt nutrient cycling, conservation-oriented approaches offer effective strategies to enhance SOM levels and maintain nutrient balance. Emerging management techniques, such as integrated nutrient management, biochar application, and precision farming, are highlighted for their potential to sustain SOM and improve nutrient-use efficiency. Synthesizing current evidence, this review underscores the pivotal role of SOM-centered strategies in enhancing soil fertility, reinforcing agroecosystem resilience, and promoting sustainable intensification of agriculture