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Abstract. Soil fertility and organic carbon (C) stock estimations are crucial to soil management, especially that of degraded soils, for productive agricultural use and in soil C sequestration studies. Currently, estimations based on generalized soil mass (hectare furrow basis) or bulk density are used which may be suitable for normal agricultural soils, but not for degraded soils. In this study, soil organic C, available nitrogen (N), available phosphorus (P 2 O 5 ) and available potassium (K 2 O), and their stocks were estimated using three methods: (i) generalized soil mass (GSM, 2 million kg ha −1 furrow soil), (ii) bulk-density-based soil mass (BDSM) and (iii) the proportion of fine earth volume (FEV) method, for soils sampled from physically degraded lands in the eastern dry zone of Karnataka State in India. Comparative analyses using these methods revealed that the soil organic C, N, P 2 O and K 2 O stocks determined by using BDSM were higher than those determined by the GSM method. The soil organic C values were the lowest in the FEV method. The GSM method overestimated soil organic C, N, P 2 O and K 2 O by 9.3-72.1, 9.5-72.3, 7.1-66.6 and 9.2-72.3 %, respectively, compared to FEV-based estimations for physically degraded soils. The differences among the three methods of estimation were lower in soils with low gravel content and increased with an increase in gravel volume. There was overestimation of soil organic C and soil fertility with GSM and BDSM methods. A reassessment of methods of estimation was, therefore, attempted to provide fair estimates for land development projects in degraded lands.

Study was undertaken in Western Ghats and Coastal area in Karnataka state, India with the aim of evaluating the fertility status of soils using nutrient index approach, mainly for primary nutrients. Based on fertility ratings, pH of soils was strongly acidic to moderately acidic. Electrical conductivity was normal (<1.0 dS m-1). Soil organic carbon was medium to high. Primary nutrient status i.e., N, P and K were low in >60 % samples. Whereas, >80 % of samples were low in exchangeable Ca, Mg and available S content. Among the micronutrients Cu and B were found to be low in >70% of samples, whereas Fe, Mn and Zn were adequate in >85 % of samples. Nutrient index value for major nutrients (available N, available P and available K) was found to be low (<1.67 range).