What are biotic and abiotic factors?

What are the abiotic and biotic factors that affect soil pH?

• I would like to know what factors effect soil pH... aspects that can be tested from the point of view of a chemist, environmentalist, bioligist and physicist. Thanks

• Answer:

  Factors affecting soil pH 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. 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. Human distractions like pollution alter the pH of soil. Researches have also revealed that soil pH is affected by the vehicular and ongoing traffic. This largely hampers the soil pH and in turn the primary productivity by compacting the soil and decreasing its friability. 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 tend 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.