Impact of nitrogen and sulphur fertilization on soil properties and economic efficiency of Indian mustard (Brassica juncea L.) under Dehradun valley conditions

Although Indian mustard (Brassica juncea L.) is a significant rabi oilseed crop in India, nutrient imbalances and dwindling soil quality frequently limit yield. Two essential nutrients that affect crop profitability, nutrient availability, and soil chemical characteristics are nitrogen (N) and sulfur (S). During the 2023-24 Rabi season, a field experiment was carried out at the Agronomy Research Farm, Jigyasa University, Dehradun, to assess the impact of different N and S dosages on soil characteristics and mustard (variety HY-805) economic efficiency. With three replications and sixteen treatment combinations of N (0, 60, 120, and 180 kg ha⁻¹) and S (0, 20, 40, and 60 kg ha⁻¹), the experiment was conducted using a Randomized Block Design (RBD). Recommended doses of phosphorus (80 kg ha⁻¹) and potassium (40 kg ha⁻¹) were applied uniformly. pH, electrical conductivity (EC), organic carbon (OC), and the amounts of accessible nitrogen (N), phosphorus (P), and potassium (K) were measured in soil samples that were taken both before and after harvest. Because sulfur has an acidifying impact, the results showed that increasing N and S doses marginally decreased soil pH and EC while increasing organic carbon content and N and P availability, indicating increased soil fertility. Under the highest N and S combination (N180S60), the highest available nitrogen (170.46 kg ha⁻¹) and phosphorus (27.53 kg ha⁻¹) were found, along with a slight improvement in organic carbon, suggesting increased microbial activity and nutrient cycling. Higher N and S dose treatments produced higher gross returns, net returns, and benefit-cost (B:C) ratios, according to economic study. The N180S60 treatment yielded the highest B:C ratio (2.20) and net return (Rs. 69,550.33 ha⁻¹), proving that even with higher input costs, investing in higher nutrient dosages is financially justified. Reduced B:C ratios and net returns were the results of reduced nutrient levels, underscoring the significance of balanced fertilization for soil fertility and profitability. According to the study's findings, applying nitrogen and sulfur together improves the chemical characteristics of soil, increases nutrient availability, and guarantees larger financial returns. In the Dehradun Valley's semi-arid irrigated mustard production, balanced N and S fertilization is thus advised as a sustainable method for preserving soil health and optimizing yield.