Replication data for: Landscape approach to estimate soil carbon: the potential and usefulness of Mid Infrared (MIR) spectroscopy

The study was conducted in six sites (Akonolinga, Ayos, Lekié1, Lekie2, Ebolowa and Efoulan) located in the humid forest zone in southern Cameroon. In each site, four villages were selected based on settlement, agroforestry practices around the homestead, land-use system diversity and density of trees in the systems. The study area is located between 2o48’ and 4o7’E, and between 10o55’ and 12o30’E, and the average elevation is about 685 meters above the sea level. Field survey and soil sampling were carried out using the quadrat approach. Nested sampling plots of variable sizes adjusted to the land use systems to be sampl ed were used along with methods of soil sampling. Before the proper soil sampling, subplot samples were set up in each selected plot with three considerations: for land use with high tree population density, two rectangular plots (5 m × 40 m = 200 m2) were selected by running a 40 m line through the area within a plot of at least 1 ha, avoiding the boundary of the plot. The geo-position of each plot was recorded using a GPS. Rectangular plots were chosen because of its ability to include more of the within plot heterogeneity, and thus more representative. Plot location was therefore randomized making sure that the plots do not only fall in areas with the densest or least vegetation. For the land use system with low tree population density, we set out 500 m2 quadrats (20 m × 25 m) instead of 200 m2. Two 0.5 × 0.5 m small plots within the 40 × 5 m transect were chosen on each site from which soil samples were taken at two depths: 0 – 10 cm and 10 – 30cm layers of the soil using a cylinder of 100 m3 for chemical analysis.