Evaluation of integrated fertilization strategies on soil nutrient dynamics, crop productivity, and ecological risks in intensively farmed regions of Punjab, India

Abstract

Sustainable soil fertility ensures long-term productivity and food security. In intensively cultivated systems, imbalanced synthetic fertilization depletes nutrients and degrades soil. Integrating organic inputs can curb elemental imbalances and improve soil health. This study assesses the environmental and agronomic impacts of four fertilization strategies on soil quality and wheat productivity across 33 farms in Punjab, India: (1) farmyard manure (FYM; ∼6000 kg ha⁻¹), (2) diammonium phosphate + urea (DU; 130 + 130 kg ha⁻¹), (3) DU + FYM (DUF), and (4) DU + FYM + micronutrients Fe and Zn (DUFZ). Soil samples were analyzed for pH, EC, OC, macronutrients (N, P, and K), and micronutrients (Na, Mg, Al, Ca, Fe, Mn, and Zn) using standard protocols and advanced techniques (INAA, PIGE, and EDXRF). FYM-treated soils showed the highest OC (1.17%) and Ca levels, while DU raised EC and caused acidification (pH 6.82 ± 0.1). Integrated treatments improved micronutrient levels and yield, with DUFZ recording the highest wheat productivity (21.78 q per acre). However, excess N, P, and K depletion were noted. Mn concentration (667 ± 29 mg kg⁻¹) exceeded the MCA (500 mg kg⁻¹), and Zn levels surpassed 200 mg kg⁻¹, indicating potential environmental risks and degraded food quality. Multivariate analyses (PCA and HCA) indicated distinct clustering and a strong Zn and Mg synergism under integrated fertilization practices, highlighting enhanced soil nutrient status. The observed link between elevated Zn and Fe concentrations under integrated regimes suggests a potential cause of reported regional micronutrient deficiencies and associated public health burdens. This study offers an evidence-based vision for sustainable soil fertility management with benefits for both agroecosystem integrity and human nutrition.