1. Parent rock: The pH value of a
soil is influenced by the kinds of parent materials from which the soil was
formed. Soils developed from basic rocks generally have higher pH values than
those formed from acid rocks.
2. Rainfall: Rainfall also affects soil pH. Water
passing through the soil leaches basic nutrients such as calcium and magnesium
from the soil. They are replaced by acidic elements such as aluminum and iron.
For this reason, soils formed under high rainfall conditions are more acidic
than those formed under arid (dry) conditions.
3. Human activities: like pollution alter the pH of soil. Researchers have also revealed that soil pH is affected by the vehicular and ongoing traffic. This largely hampers the soil pH and in turns the primary productivity by compacting the soil and decreasing its friability.
4. Fertilizer: the application of fertilizers containing ammonium or urea speeds up the rate at which acidity develops. The decomposition of organic matter also adds to soil acidity
A pH level of around 6.3-6.8 is also the
optimum range preferred by most soil bacteria, although fungi, molds, and
anaerobic bacteria have a broader tolerance and tends to multiply at lower pH
values.
Therefore, more acidic soils tend to be
susceptible to souring and putrefaction, rather than undergoing the sweet decay
processes associated with the decay of organic matter, which immeasurably
benefit the soil. These processes also prefer near-neutral conditions.