Methods
To evaluate the soil quality, a network of soil quality monitoring sites (SQMS) were established following the agro-climatic variability along the natural forest and traditional coffee growing areas in the Western Ghats. A total of 60 SQMS were excavated of which 46 sites were located in coffee plantations and 14 in forests adjacent to coffee plantations. In Chikmagalur a total of 9 profiles from coffee ecosystem and 4 profiles from natural forest ecosystem were studied. In Wayanad, 8 profiles under coffee plantation and 4 profiles from natural forest ecosystem, and in Idukki, 3 profiles each from coffee plantation and natural forest ecosystem were studied to understand the effects of conversion. From these identified study sites, six typifying pedons representing the area, three from natural forest ecosystem and three from coffee plantation ecosystem from the adjoining areas located in the Eastern (Malanad) hills, Nilgiri hills and Kumili hills of Western Ghats respectively, are described and characterized to meet the objectives of the study.
The details of the profiles for which analyses were carried out include:
Pedon 1 and 2 are located in the Chikmagalur district of Eastern hills of Western Ghats in which pedon 1 (Chikmagalur- Forest) was selected from a natural forest in Chikmagalur district of Karnataka adjacent to the CCRI campus. This steep sloping area (15-25 per cent) with slope length 300-600 m is located at an elevation of 805 m above MSL within latitude 13º 21’ 35.1″ N and longitude 75º 25’ 28.0″ E. Pedon 2 (Chikmagalur- Coffee ) was excavated from the CCRI coffee plantation located at the Balehonnur panchayat, Koppa taluk of Chikmagalur district. The coffee plantation is located within latitude 13º 21’ 40.0″ N and longitude 75º 25’ 38.5″ E at an elevation of 827 m above MSL with a slope of 5-10 per cent with 150-300 m slope length. The geology is granite with weathered granite as the soil parent material.
Pedon 3 and Pedon 4 represents the Nilgiri hills of western Ghats where Pedon 3: (Wayanad- Forest) was excavated from an evergreen forest situated within latitude 11º 46’ 17.5″ N and longitude 76º 07’ 43.2″ E in the Panamaram panchayat of Wayanad district of Kerala. The physiography is gently sloping highlands with 3-5 per cent slope and 150-300 m slope length. The geology is Archean granite gneiss and soil parent material is weathered granite gneiss. Pedon 4 (Wayanad- Coffee) belongs to the coffee plantation in the Vattakkara estate of Meenanagadi panchayat, S. Battery taluk in the Wayanad district of Kerala and it lies within latitude 11º 41’ 54.9″ N and longitude 76º 11’ 33.6″ E. The site has a slope of 5-10 per cent with 150-300 m length. The geology is granite and soil parent material is weathered granite.
Pedon 5 and 6 were excavated from the Kumili hills of Western Ghats in the Idukki district. Pedon 5: (Idukki Forest) is dug from a forest ecosystem belonging to the Udumbanchola Taluk of Shantanpara Panchayat in Idukki district of Kerala. The pedon lies within a latitude of 09º 56’ 13.1″ N and longitude 77º 13’ 43.2″ E. The area has a slope of 5-10 per cent and slope length of 150-300 m. Pedon 6: (Idukki- Coffee) is from Gudanpara MNJ estate in the Shanthanpara panchayat of Idukki district of Kerala. The pedon lies within a latitude of 09º 56’ 42.5″ N and longitude 77º 13’ 11.3″ E. The area has a slope of 3-5 per cent and slope length of 300-600 m. The geology is granite gneiss and formed the soil parent material after weathering.
Horizon-wise soil samples were analyzed using standard procedures for soil morphological, physical and chemical parameters. Soil bulk density was determined by the core method and mechanical composition of soils was determined following the International Pipette method. Cation exchange capacity (CEC) was determined by the ammonium acetate method (Jackson,1958) . The ammonium acetate extract obtained from CEC estimation was used to determine the exchangeable bases by atomic absorption spectro-photometry and other soil chemical parameters were determined using standard analytical techniques (Jackson,1958).
Soil organic carbon was determined following dry combustion method using CHNS analyzer. Soil organic carbon stock for a given soil layer was calculated by multiplying the organic carbon concentration in soil fine earth with bulk density and soil depth using the following equation (Grossman, 2001).
SOC= (C/100) X ρ X D X (1- frag.) x 100
where: SOC = soil organic carbon stock (kg m-2); C = soil organic carbon concentration of soil fines (fraction < 2 mm) determined in the laboratory (%, g kg-1); ρ = soil bulk density (g cm-3); D = depth of the sampled soil layer (cm) and frag. = % volume of coarse fragments/100.