Unravelling the nutrient availability of forest communitiesunder Shiwalik foothills of Western Himalaya

Abstract

This study aims to investigate the surface and profile distribution of macronutrients, micronutrients and physicochemical parameters in different forest communities in dry deciduous forest. The research was conducted in six forest Communities viz., Acacia nilotica (FC1), Leucaena leuchocephala (FC2), Acacia catecheu (FC3), Dalbergia sissoo (FC4), Bamboo (FC5) and Mixed Forest (FC6) and profile distribution among different depths in forest communities viz., depths: 0-5 cm (D1), 5-15 cm (D2), 15-30 cm (D3), 30-60 cm (D4) and 60-100 cm (D5). The results revealed that the content of available macronutrients (N, P, and K) consistently declined with increasing soil depth across all forest communities. Nitrogen was most concentrated in the surface layer (243.44 kg ha- 1), with the highest value in the FC6 (362.22 kg ha- 1) and 62% of total nitrogen was found in the top two layers (0–15 cm). Similarly, phosphorus was highest in FC2 (50.33 kg ha-1). Potassium levels were also surface enriched, with maximum values in FC3 (362.56 mg kg- 1). The DTPA-extractable micronutrients (Zn, Fe, Mn, and Cu) decreased significantly with increasing soil depth across all forest communities. Zinc was highest in FC3 (6.01 mg kg- 1), with about 75% concentrated in the top two layers. Iron content ranged from 9.33 mg kg- 1 in FC6 to 19.01 mg kg- 1 in (FC1), with FC3 showing the highest mean Fe. Manganese varied from 8.93 to 12.90 mg kg- 1 (lowest in FC5, highest in FC1), and copper ranged from 0.34 mg kg- 1 in FC6 to 0.75 mg kg- 1 in FC1. Soils under all forest communities exhibited neutral pH in upper layers (0-30 cm) and slightly alkaline values at greater depths. Electrical conductivity remained within normal range, with slightly higher values in surface soils. Organic carbon content decreased significantly with depth, highest in FC3 (0.78%) and surface layer D1 (0.95%), with over 50% concentrated in the top two horizons. The cations exchange capacity (CEC) also declined with depth, highest in FC5 (18.52 Cmol kg- 1) and in surface soil (20.38 Cmol kg- 1), while FC6 showed the lowest CEC (12.38 Cmol kg- 1). The principal component analysis (PCA) showed the position of soil variables with respect to different forest communities, in orthogonal space determined by two PCs, which explained total variability of 79.04%. The distribution of PC1 and PC2 evidenced variability of 67.75 and 11.30%, respectively.