Comparative Evaluation of Organic and Inorganic Fertilizers on Maize Productivity

Maize (Zea mays L.), a cornerstone of global food security and Pakistan’s third-largest cereal crop, exhibits high genetic yield potential yet remains heavily dependent on nutrient inputs, with intensive inorganic fertilizer use driving productivity gains alongside soil degradation, groundwater nitrate contamination, and greenhouse gas emissions. This review synthesizes comparative field and controlled studies evaluating organic fertilizers (farmyard manure, compost, poultry manure, vermicompost, green manures) versus inorganic sources (urea, DAP, NP formulations) and integrated nutrient management (INM) strategies in maize systems. Results consistently show that sole inorganic fertilization maximizes short-term grain yield (8–12 t ha⁻¹) but leads to declining soil organic carbon (SOC), reduced microbial activity, and elevated N₂O emissions. Organic amendments alone sustain or slightly reduce yield (6–9 t ha⁻¹) while significantly improving soil health indicators SOC (+0.2–0.8%), aggregate stability, microbial biomass carbon, enzyme activities (dehydrogenase, urease), and water-holding capacity and lowering nitrate leaching risk. Integrated approaches (e.g., 50–75% inorganic N replaced by organic sources) achieve near-parity with full inorganic yields (8–11 t ha⁻¹), enhance nutrient use efficiency (N recovery up 15–35%), reduce fertilizer costs (10–25%), and deliver superior long-term soil quality and environmental outcomes (lower GWP, improved C sequestration). Climate-resilient benefits include better drought tolerance and nutrient cycling under rainfed or deficit irrigation conditions prevalent in Pakistan. Adoption barriers lower initial nutrient release from organics, labor for composting, and farmer risk aversion are addressed through policy incentives, extension on INM packages, and localized research on optimized organic–inorganic ratios. The evidence supports a paradigm shift toward integrated, organic-enriched fertilization as a sustainable pathway for maintaining maize productivity while reversing soil degradation and mitigating environmental externalities in resource-constrained agroecosystems.