INFLUENCE OF AGROCHEMICALS ON ABUNDANCE AND DIVERSITY OF AGROFORESTRY SOIL ORGANISMS IN A CONTROLLED ENVIRONMENT

Abstract

Agrochemicals have been known to be toxic chemical substances or a mixture of substances or biological agents that are intentionally released into the environment in order to avert, deter, control and/or kill and destroy populations of insects, weeds, rodents, fungi or other harmful pests. Agrochemicals work by attracting, luring and then destroying or mitigating both plants and microorganisms. Based on these reasons, this research was conducted to investigate the immediate influence of agrochemicals on abundance and diversity of soil organisms in a controlled environment. The treatments used in this study are: Insecticides, Herbicides, Fertilizer and control. Soil samples were obtained and kept in the greenhouse after the application of the treatments; soil samples were obtained and were taken to the laboratory once per month for the duration of three months to isolate mesofauna and microorganisms. A total of seven (7) individuals of mesofauna and seven (7) species were encountered in the control soil respectively. Insecticide treated soil had a total of three (3) individuals and three species while herbicide treated soil had six (6) individuals and six (6) species and the fertilizer treated soil had a total ten(10) individuals and nine (9) species. Fertilizer treated soil had the highest abundance of mesofauna while insecticide treated soil had the least abundance of mesofauna. Earwig was the most abundant species while Mollusca and Centipede were among the least abundant. The result further showed that at the end of the third month there was no mesofauna encountered in all the chemical treated soil and the control. Student T-test table revealed no significant difference between the first and second month (0.002 and 0.004). Also, result further showed that there was no significant (P≥0.05) difference between the means of agrochemicals on bacteria and fungal abundance as thirty one (31) and (39) species were encountered. The correlation relationship between the agrochemicals on bacteria abundance showed that the control and fertilizer treated soils were greatly influenced, this means that fertilizer application had a positive and strong effects on bacteria abundance while the correlation relationship between the agrochemical on fungi showed a weak and negative relationship between herbicides and fertilizer and a strong positive relationship on insecticide treated soil. Therefore, to ensure proper functioning of these soil organisms and minimize damage due to agrochemical applications to soil ecosystem, the following precautionary measures are recommended: Farmers should be properly guided on the indiscriminate use of agrochemicals in agriculture, Promotion of alternative pest control strategies such as application of bio-pesticides and integrated pest management (IPM) and the recommended manufacturer‘s application rates should not be exceeded.