ECOLOGY OF SOIL BIOTA AND ITS ROLES IN BIO DEGRADATION

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ABSTRACT

The effect of the soil biota in ecosystem was carried out by  extracting the soil biota from the soil using streaking and pour plate method. By inoculating the different soil samples collected from the school premises. The media used were saboraud and nutrient afar incoperated soil sample to make it selective for the soil organisms only. The culture was incubated at 370C for 48 hours for full growth to appear. Then the isolates were finally inoculated into dead organic matter prepared with soil, just to verify effect. The biota isolated was micro-biota and mesobiota. Among the microbiota the fungi and bacterial and the mesobiota are the protozoas. And fungi was found to have the highest percentage distribution of (63.3%), bacterial (20.9%), mesofauna (32.8%) and protozoa (17.5). This shows that fungi are the predominant soil-biota.

Key words: Biota, Mesobiota,  mesofauna

CHAPTER ONE

INTRODUCTION

1.1Background of the Study

Soil biota consist of the micro-organisms (bacteria, fungi, archaea and algae), soil animals (protozoa, nematodes, mites, springtails, insects, and earthworms) and plants, living all or part of their lives in or on the soil or pedosphere, Van (2007; 20). Millions of species of soil organisms exist but only a fraction of them have been cultured and identified. Microorganisms (Fungi, archaea, bacteria, algae and cyanobacteria) are members of the soil biota but are not members of soil fauna. The soil fauna is the collection of all the microscopic and macroscopic animals in a given soil. Soil animals can be conventionally grouped by size classes: macrofauna (enchytraeide, earthworms,macroarthropods),mesofauna (microarthropods, mites, and collmbolan), and microfauna (protozoa, nematodes). The size of a soil organism can restrict its location in the soil habitat, Comis, (2007; 10). Smaller members of the microfauna like nematodes are basically aquatic organisms that lives in the thin water films or capillary pores of aggregates preying or grazing on other aquatic microfauna such as amoeba. Soil protozoa are also land – adapted members of aquatic microfauna that can dwell in water films in field moist soils, Tate (2002; 10). Water films are created by adsorption of water to soil particles. Soil has a direct effect on the environmental conditions, habitat and nutrient sources available on the soil biota. The term pedosphere is often used interchangeably with soil and captures the concept that soil is a habitat where the integration of sphere occurs, Simeonson (2009; 150). These spheres include the lithosphere, atmosphere, hydrosphere, and the biosphere, Brady and Weil (2002; 50). Numerous biogeochemical processes regulated by soil biota occur in the pedosphere.

Soil organisms serves numerous roles in the pedospheres. Their most critical function is the regulation of biogeochemical transformations. Five functions mediated by soil biota are (1) the formation and turnover of soil organic matter, that includes mineralization and sequestration of carbon (2) nutrient cycling (3) disease transmission and prevention: for instance many soil microbes like streptomyces are used for production of antibiotic and also most of soil microbes like nematodes such as Ascaris lubricoides causes disease (4) Pollutant degradation and (5) imrpovemnet of soil structure, Alexander (2007; 5). The by products of metabolic oxidation or reduction of C and N compounds in soil microbes. The size and composition of the microbial biomass (the combined mass of micro-organisms in the soil) is dependent upon soil properties and the sources of carbon available for energy and cell synthesis. Carbon inputs to the soil vary in their biochemical composition (e.g their ability to be decomposed) and nutrient content. Carbon turnover, decomposition and microbial activity often lead to increases in organic nutrients and soil aggregation.