The effect of bush burning on microbial activity and some chemical and physical properties of a forest soii. in Ghana

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The toll in its natural environment is constantly exposed to the fluctuating conditions of temperature, moisture, pressure and air movements, Furthermore, the addition and removal of organic and inorganic materials, through the agency of man. animals and plants are always occurring. These factors are undoubtedly responsible for the perpetuation of the active biological conditions in the soil. They exert their action either directly on the soil micro-organisms or indirectly by influencing the plant and the soil, which in turn modify the development the micro-organism. Man has developed various means to till the land to obtain a good crop yield. one of such practices which changes soil conditions physically, chemically and biolo¬gically is the burning of plant debris on a newly cleared land prior to cultivation. Stewart (1956) reported of archeological evidence on the widespread use of fire for agricultural and pastoral purposes ever since the domestication of plants and animals about 8000 BC. In parts of tropical Africa, America and Asia, particularly in the Malay Peninsula, the custom of burning timber and dead vegetation on land cleared for agricultural purposes is a, very common practice (Corbet, 1935) .For the ordinary peasant farmer armed only with an axe, a hoe and a cutlass, burning is perhaps the quickest and easiest way of Clearing dead plant material thereby leaving the farms neat and orderly. Burning has also been used as a pasture management practice to control hush and to encourage fresh grass turf. There are m nays lay which burning can be done but the most common practice in the forest areas involves cutting of vegetation usually towards the end of the dry season. It is then allowed to dry. The dried debris is then piled into smaller heaps and burnt as the rainy season approaches. The toning generates heat which consumes the dry vegetative cover. The heat generated cause a change in temperature and moisture conditions in the uppermost soil layer depending on the intensity of the fire (Ahlgren and Ahlgren, 1965). Various groups of organisms occur within the topmost one foot layer of the soil. Each kind of organism plays some significant role in the decomposition of plant and animal residues, liberation of plant nutrients or in the development of soil structure. These organisms nay be affected differently by the heat and changes in the soil conditions namely; temperature, moisture, aeration, pH and nutrients elements. The interplay of all these factors will reflect on the yield of the crop growing on that particular soil. As Ahlgren (1960) put it, burning either wild or prescribed has a temporary effect on the physical, chemical and biological status of the Soil as well as on the vegetation growing on it. This, however, depends on the area, soil type, fire intensity, the previous vegetation and other factors. Recently, the practice of hush burning prior to culti¬vation of crops has been strongly criticized in Ghana mostly because of damage caused to agricultural and non-agricultural properties. In this paper an attempt is made to find proof of the influence of burning on microbial population and plant growth on a forest Soil of Ghana of which no soil microbial studies have been made.
A thesis submitted to the University of Science and Technology in partial fufilment of the requirements for a Master's degree in Agriculture