Optimum Utilization of Different Nitrogen Fertilizer Sources for Improving Soil Properties and Agro-Physiological Indices of Maize Crop under Humid Subtropical Conditions of Pakistan

Purpose: The purpose of this research was to assess the production potential of maize by examining its agro-physiological traits under different combinations of organic and inorganic nitrogen fertilizers, as well as to evaluate the resulting changes in soil properties. Material and Methods: The study was conducted for two years using randomized complete block split-plot arrangement. Three tillage systems (minimum, conventional and deep) were used in the main plots, while ten different nitrogen treatments, with different proportions of single and combined applications of chemical fertilizer, poultry manure and bioslurry, were used in sub-plots. Further, detail is given in section-2. Findings and Recommendations: The treatment where deep tillage was used in combination with 50% of the recommended nitrogen from chemical fertilizer (67.5 kg ha-1), 25% from poultry manure (1.9 t ha-1) and 25% from bioslurry (2.1 t ha-1) showed the greatest increase in agro-physiological crop growth compared to the control (zero nitrogen application with minimum tillage), with a 76% increase in leaf area index (75 days after sowing), 86% increase in average mean crop growth rate and 38% increase in mean net N assimilation rate. This might be due to a 43% increase in recovery efficiency of fertilizer nitrogen in this treatment compared to the control. This treatment also decreased soil bulk density by 5% and increased soil porosity by 6%, total soil nitrogen by 21%, available soil phosphorous by 55% and available soil potassium by 20% compared to the control. Implications to Theory, Practice and Policy: These results suggest that, in this soil, this treatment provides the optimum nutrient management, both improving soil properties and achieving maximum agro-physiological growth due to enhancing fertilizer nitrogen recovery efficiency.