THE EFFECT OF PESTICIDES DICHLORODIPHENYL TRICHLOROEYHANE (D.D.Y) AND BENZENE HEXACHRORIDE (BHC) ON THE MICROFLORA OF THE THREE TYPES OF SOIL.
The effect of pesticides, chchlorodipheny trichloroethane (DDY) and Benzene hexaxhoride (BHc) on the microflora of the three types of soil (loamy, clay and sandy soil) was conducted. The serial dietitian technique was employed up to 10-3 using nutrient agar, potato dextrose agar and sabourand agar plates. The isolation of both bacterial and fungal organisms were made before treating the soil types with the two pesticides), D.D.T and BHC. and after treating the soil types with D.D.T after treating and BHc. The highest bacterial count before treating the soil types with D.D.T and BHc was got in loamy soil with 133 per ml having PH 7.1, followed by clay soil with 78 per ml and least was sandy soil with 42 per ml. while the highest bacterial count after treating the soil types with D.D.T was gotten in loamy soil 105 per ml, followed by clay soil with 51 and least count was got in sandy with 28 per ml. Also the highest bacterial count after treatment with BHc was obtained in loamy soil with 12F per ml, followed by clay soil with 64 per ml and the least count was got from sand soil with 37 per ml. The highest bacterial isolate from all the soil types before treatment with the two pesticides was pseudomonas with 25 per ml, followed by Bacillus SPP with 24 per ml, and next was achnomycetes with 19 per ml while the least bacterial organism was Rhizobrium SPP. The fungal organisms isolates were Aspergillus species, syncophatastrum species, pernicillum species and mucor species. The results of this project showed that there was reduction in microflora of the soil types after treatment separately with the two pesticides. But the effect was more with D.D.T than with BHc. Also the effects of the two pesticides was highest in sandy soil followed by clay and lastly the loamy soil.
According to crupta and Daroren (2003) soil is that portion of the surface of the land which is essential for plant growth. Plant are anchored in the soil by their root, which spread in all direction and which by holding on to the soil keep the plant in position plant draw all their water and most of their food or nutrient from the soil. Soil is therefore the source of food for plants, animals and man. Soil is of different types, sandy, clay and loamy soil. Sandy soil has or size range of 0.2 to 2mm diameter. They are free draining and do not retain any appreciable amount of soil water. It is brown loose and dry. While clay soil range in size from 0.002mm and lower and contains more than 40% of clay particles. They are sticky, plastic and easily moldable into shape. Another type is loamy soil which contains a fair balance of clay , silt and sand particle and it is the best soil for agriculture, as it has a high proportion of organic matter or content soil organic malter represents on accumulation of partially decayed and animal residues. Such material is continually being broken down as a result of the work of soil micro –organism consequently. It is a rather transitory soil constituent and must be renewed constantly by the additionb of plant residues. The organic matter content of a soil is small, only 3-5 percent by weight in a representative minerals topsoil. It is a major soil