Soil fertility
The ability of the soil to supply essential plant nutrients and soil water in adequate amounts and proportions for plant growth and reproduction in the absence of toxic substances which may inhibit plant growth.
Slope
The inclination of the land surface from the horizontal. Percentage of slope is the vertical distance divided by horizontal distance, multiplied by 100. Thus, a slope of 20 percent is a drop of 20 m in 100 m of horizontal distance.
Relief
The elevations or inequalities of a land surface, considered collectively.
Exposure
Compass orientation of a slope.
Aspect
Compass orientation of a slope.
Texture triangle
Diagram allotting names to soils with specific portions of sand, silt and clay (http://www.fao.org/3/a-i3794e.pdf), consult Figure:
Texture
The relative proportions of sand, silt, and clay particles in a mass of soil. Texture can be coarse (sand particles predominate), medium (equal parts of sand, silt and clay), or fine (clay particles predominate). The basic textural classes, in order of increasing proportion of fine particles, are; sand, loamy sand, sandy loam, loam, silt loam, [...]
Structure
The aggregation of primary soil particles into units separated from each other by surfaces of weakness, ‘architecture’ of soil - how it is constructed and made up.
Stones
Soil particles more than 2 mm in diameter.
Specific Heat Capacity
The amount of heat which is required in order to increase its temperature. Measured in ‘joules per kilogram per kelvin degree’, or J/kg/oK , it is specifically the amount of heat energy in joules needed to increase the temperature of one kilogram of the substance by one Kelvin degree.