Effects of agrochemical application on the diversity and abundance of soil macro-fauna in cocoa-based (Theobroma cacao) agroforestry systems in Cameroon

Cocoa farmers’ excessive use of agrochemicals in cocoa agroforests has major repercussions on soil organisms, which play a great role in soil fertility enhancement. This study was carried out to examine the relationship between agrochemical use and soil macro-fauna diversity and abundance in cocoa agroforests in Cameroon. A mixed research approach was used, and data were analyzed using descriptive and inferential statistical tools. It was found that the main types of agrochemicals used by cocoa farmers in cocoa-based agroforestry systems were fungicides (100%), insecticides (100%), and herbicides (36.7%). The categorization of the major types of agrochemicals used by cocoa farmers revealed that, two types of herbicides, eight types of fungicides, and nine types of insecticides were used by cocoa farmers in cocoa-based agroforestry systems. Most cocoa farmers perceived that all the agrochemicals lead to a decrease in soil macro-fauna diversity and abundance in cocoa-based agroforestry systems. Chi-square test statistic results (X2 > 78, p<0.05) showed that cocoa farmers’ perceptions of the effects of agrochemicals on the diversity and abundance of soil macro-fauna in cocoa-based agroforestry systems differed significantly across the main types of agrochemicals (herbicides, fungicides, and insecticides). Correlation and regression analyses showed the existence of a statistically significant (p<0.05) inverse non-causal and causal relationship respectively between most agrochemicals and soil macro-fauna diversity and abundance in cocoa-based agroforestry systems, implying that the use of these agrochemicals leads to a reduction in soil macro-fauna diversity and abundance in cocoa agroforests. Thus, it is recommended that measures be taken to reduce the use of agrochemicals in cocoa agroforests in order to safeguard the diversity and abundance of soil macro-fauna in these systems.