Journal of Experimental Agriculture International

Alluvial soils with sandy calcic subsoils can constrain nutrient availability for jute through leaching, fixation, and redox-driven transformations, necessitating pedologically informed fertility management. This study characterised the vertical patterns of soil reaction, organic carbon, and macro- and micronutrient availability in the Pararia Series of the Kosi region to identify depletion zones and subsoil nutrient reservoirs relevant to jute-oriented management practices. Horizon-wise observations to a depth of 130 cm showed slightly alkaline surface conditions in the Ap horizon (0–20 cm; pH 7.7) and a highly alkaline calcic C1 horizon (20–52 cm; pH 8.5) with free carbonates, followed by a gradual decline in pH with depth (C2, 8.3; C3, 8.1), consistent with partial carbonate leaching and reducing conditions under an Aeric Endoaquents moisture regime. Available P, K, S, Zn, and Cu declined from the Ap to the C1 horizon (P, 12.5 to 6.2 kg ha⁻¹; K, 180 to 95 kg ha⁻¹; S, 8.2 to 4.5 ppm; Zn, 0.65 to 0.32 ppm; Cu, 1.20 to 0.75 ppm) and recovered in the clay-rich C3 horizon (P, 11.0 kg ha⁻¹; K, 165 kg ha⁻¹; S, 7.3 ppm; Zn, 0.55 ppm; Cu, 0.95 ppm), indicating subsoil nutrient reservoirs. Mg peaked in C2 (52 ppm; Ca:Mg ≈ 7.3), while Fe and Mn also reached their maxima in C2 (Fe, 3.2 ppm; Mn, 15.2 ppm), where mottling indicated redox cycling. Overall, the Pararia soils are suitable for jute cultivation, provided that management targets the nutrient-poor, alkaline, sandy calcic C1 horizon through organic amendments; localised or banded P–Zn–Cu application; balanced N and split K application; S replenishment, such as gypsum; local pH moderation using acidifying inputs; improved drainage; and regular soil testing for site-specific recommendations.