Soils on Jhum cultivated hill slopes of Narang-Kongripara Watershed in Meghalaya

The objective of detailed soil survey in Narang-Kongripara watershed was to describe and analyse the soils for use as benchmarks in land evaluation programmes. The soils on nearly level to strongly sloping uplands (Juntru, Bongsiki, Kongripara, Syrion, Bynlip and Ir Kmol series) have distinct red horizons, mostly of 10R hues with thickness of 0.35 to 1.5 m in the toposequence. These soils are very strongly to moderately acid with high exchangeable aluminium [>1.5 cmol(p⁺)kg⁻¹], low effective cation exchange capacity [<3 cmol(p⁺)kg⁻¹] and base saturation less than 50% in argillic horizons. Most of these sites are under jhum cultivation with a sparse forest cover in the surroundings. The soils in inter-hill valleys (Narang and Umdu series) have endoaquic saturation throughout the year with low chroma mottles and distinct lithological discontinuities in the profiles. The significant positive relation of organic carbon with effective cation exchange capacity indicated that these soils are in quasi-steady state condition where in majority of nutrient cycling occurs in organic enriched surface horizons. The surface horizons in upland soils have sufficient amounts of DTPA extractable iron, manganese, copper and zinc but high concentration of iron and manganese in soils of valleys. Based on organic carbon, base saturation and morphology, the soils in uplands were classified in the subgroups of Ultisols and Entisols but the Umdu series in valleys classified in the subgroups of Inceptisols. The soil genetic relationships reported here are site-specific and serve as benchmark sites for land evaluation programmes at watershed level.