Introduction
Soil fertility refers to the inherent capacity of the soil to supply essential plant nutrients in adequate amounts and suitable proportions, whereas soil productivity reflects its overall capacity to produce an economic crop yield under a specified management system. At present, nearly 115 to 120 million hectares—representing approximately 33% of India's Total Geographical Area—suffer from various forms of degradation, placing acute stress on baseline fertility and national agricultural output.
Factors Responsible for Declining Soil Fertility
Soil degradation stems from interactive chemical, physical, and biological factors that compromise its nutrient-supplying capacity:
- Chemical Degradation: Skewed macronutrient application—demonstrated by an unbalanced N:P:K consumption ratio of 9.3:3.5:1 against the ideal 4:2:1—induces severe secondary and micronutrient mining, particularly of zinc and sulphur. Additionally, faulty surface flood irrigation in canal commands without subsurface drainage leads to secondary salinization and alkalinization, while continuous use of acidifying mineral fertilizers reduces soil pH and fixes available phosphorus.
- Physical Degradation: Accelerated water and wind erosion strip away nutrient-rich topsoil and humus. Furthermore, intensive mechanization and repetitive puddling in cereal-based monocultures create subsurface hardpans and compaction, restricting aeration, hydraulic conductivity, and root proliferation.
- Biological Degradation: Monocropping and widespread crop residue burning deplete Soil Organic Carbon (SOC) levels below critical thresholds (often <0.5%), decimating the beneficial soil microbial biomass essential for organic matter mineralization and nutrient cycling.
Measures Adopted for Improving Soil Productivity
Restoring and sustaining soil productivity requires a blend of agronomic remediation, precision nutrient stewardship, and targeted policy frameworks:
- Agronomic and Ameliorative Interventions: Chemical reclamation of problem soils through agricultural lime for acidic soils and gypsum application for sodic lands restores optimal pH and exchangeable sodium percentage (ESP). Incorporating organic amendments such as Farmyard Manure (FYM), pressmud, and compost enhances soil aggregation, cation exchange capacity, and water-holding capacity. In addition, surface mulching reduces soil evaporation, preserving moisture for transpiration.
- Precision Nutrient Stewardship: Implementing the 4R Nutrient Stewardship framework (Right Source, Right Rate, Right Time, Right Place) maximizes nutrient-use efficiency. This includes deploying nitrification inhibitors like Neem-coated urea, adopting urea deep placement (7–9 cm) to prevent ammonia volatilization, and timing broadcast applications at field capacity rather than immediately before flooding to curtail nitrate leaching.
- Biological Supplementation: Inoculating biofertilizers such as Cyanobacteria, Azolla, and Rhizobium, along with practicing green manuring using legumes like Sesbania aculeata (Dhaincha) and Crotalaria juncea (Sunn hemp), enriches biological nitrogen fixation and elevates labile organic carbon.
- Institutional and Policy Frameworks: The Soil Health Card (SHC) Scheme facilitates site-specific, test-based nutrient dispensing. The PM-PRANAM scheme provides financial incentives for states promoting balanced fertilization and bio-fertilizer usage, while the National Mission on Natural Farming (NMNF) supports chemical-free regenerative farming to rebuild biological soil vitality.
Conclusion
Transitioning from input-intensive cultivation to Integrated Nutrient Management (INM) and conservation agriculture is essential to arrest land degradation. Sustaining soil productivity is not only vital for smallholder livelihood security but also serves as the operational foundation for national food security and environmental resilience under SDG 2 and SDG 15.