Soil carbon sequestration plays an important role in global carbon cycle. Increasing green house gases had lead to emphasis on carbon sequestration into various forms around the globe. The top one metre of soil contains 1500 Gt C (Johnson and Henderson 1995) and small relative fluxes into and out of this pool can amount to large fluxes on a global scale. Soil carbon is significantly lower in human altered landscapes compared to natural systems like evergreen and deciduous. There is a considerable concern that land use change, in particular may lead to depletion of soil carbon and consequent increase in atmospheric CO2 (IPCC, 1997; Bruce et al. 1999). This leads to a major concern about soil carbon status in agricultural or human influenced land use systems in the Western Ghats. Soil carbon is an important indicator of soil health.

Soil pH is mostly acidic throughout the district which may be due to the parent material i.e. laterite, granite and gneiss. Slightly neutral soil pH was found in the talukes of Haliyal, Mundgod, Yellapur; which may be due to the Dharwar schist’s which is predominant in the region. It was found that soil bulk density was higher in case of agricultural soils than that in other natural land use systems like evergreen, deciduous forest. Bulk density is a function of soil water holding capacity. It has an inverse relationship with porosity. When the forest are cleared for pastures and agricultural purposes, soil aggregates break down due to activities such as tilling leading to compaction of soil, which influences the soil porosity. Such soils have poor soil moisture content which invariably affects the cation exchange capacity in such soils. Significantly lower amount of nitrogen were found in agricultural and barren soils which may be due to leaching out of soil nitrogen sue to physical forces such are runoff and soil erosion. The leaf litter contributes as a major source of soil nitrogen in the natural forests. In agricultural systems soil uptake of nutrients is not compensated by replenishing soil with organic mater from leaf litter (Adejuwon and Ekanade, 1988).

Arecanut plantations with good land management practices have relatively good soil quality. Various practices like drip irrigation, organic mulching and addition of ash are responsible for maintenance of soil properties. Available Phosphorus, calcium, available potassium were found to be higher in this land use type compared to all others.

Amongst the exchangeable bases, available K, calcium and magnesium were significantly lower in agricultural soils than that compared to other land use forms. Soil properties in monoculture plantations (acacia, etc.) are comparable to the natural evergreen and deciduous forest.

The soil quality of barren lands was found to be poor as compared to natural forest systems. Soil carbon and nitrogen are degraded, which is a matter of concern. Apart from looking at these lands just as pasture lands it is necessary to address the current grave conditions facing such lands which are in quite a large number in the entire district. The degradation of soil due to various anthropogenic activities has affected the endemic species, and also hydrologic regime in the ecologically sensitive Western Ghats, a global biodiversity hotspot, evident from earlier studies (Ali et al. 2007). The study informs a major concern regarding agricultural soil quality which is seen to be degrading rapidly compared to the optimal situations which are assumed to be the natural forest systems. In order to improve the life of the soil and to utilize it for longer time for agricultural purposes there is a need of devising proper management plans which will help sustainable use of these lands in future.