Page 183 - Area 9 - Relevant Document

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- Affects root development primarily through influence of
texture on aeration and nutrient retention.

B.6. SOIL STRUCTURE

- Favorable structure permits good percolation of both
water and air and reduces erosion.
- Favorable structure is promoted by the incorporation of
organic matter deep into surface horizons.

C. TOPOGRAPHIC FACTORS: elevation, slope, exposure or aspect

C.1. EARTH CONFIGURATION

- Topographic relief determines direction of prevailing wind,
atmospheric humidity and the amount of rainfall.
- Decreases in rock formation may cause differences in
vegetation because of the effect on soil water availability.
- Soil in valleys is deeper, richer and more productive than
soils in ridges and shoulder of the hills.

C.2. ALTITUDE

- Geographic climate is very much affected by altitude.
- Winds are stronger at higher elevation than lower
elevations.
- Growth in height of trees diminishes with increase in
elevation.

C.3. SLOPE

- important in relation to its effects on soil erosion,
drainage, run-off and water content of the soil
- orients the site with regard to sun and wind

C.4. EXPOSURE

- Determines the amount of sunlight received by the site
which in turn modifies the moisture content of the air and
the soil temperature.
- A pole ward exposure is considerably moister and cooler
than slopes exposed to the equator.
- effects may also be modified by the gradient or steepness
of the slope and by action of air currents