Pedogenesis and Soil Biota Interactions in the Pedosphere

Abstract

Pedogenesis can be considered as the process of soil development influenced by several climatic, physical, geological and biological factors. The process of soil formation begins with the weathering of the parent material through sequences of changes. Before the formation of soil occurs, sequences of changes have to ensue to the parent material resulting in the establishment of different layers or stratums of soil commonly referred to as soil horizons. Soil biota consists of the microorganisms, soil animals and plants living all or part of their lives in or on the soil or pedosphere. Microorganisms found in the soil include bacteria, fungi, archaea and algae, while soil animals may include protozoa, nematodes, mites, springtails, spiders, insects and earthworms. Millions of species of soil organisms exist, but only a fraction of them are culturable and properly identified. Soil organisms serve numerous roles in the pedosphere. The most critical function played by soil organisms is the regulation of biogeochemical transformations, among several other roles. The formation and turnover of soil organic matter that include mineralization and sequestration of carbon, nutrient cycling, disease transmission and prevention, pollutant degradation and improvement of soil structure are some of the functions mediated by the soil biota. The combined mass of microorganisms in the soil otherwise known as microbial biomass is reliant upon soil properties and the source(s) of C available for energy and cell metabolism. Carbon sources to the soil organisms vary in their ability to be decomposed and nutrient content. Carbon turnover, decomposition and microbial activity often lead to increases in organic matter and soil aggregation.