Effect of chemical and biological pesticides on soil microbial population, enzymatic activities and physicochemical parameters as indicators of soil fertility, soil health and food safety

Abstract

In agricultural fields, insect pests are regularly controlled with pesticides in an effort to boost crop yields and alleviate food scarcity. Along with non-target microbial floral and soil physicochemical characteristics, these herbicides also impact the activity and abundance of useful soil microbial communities. Significant ecological repercussions follow from this. Assessing the impact of chemical and biological pesticides on microbial population, enzymatic activities and physicochemical parameters as indicators of soil fertility with a view to promoting soil health and food safety was the aim of this investigation. Soil samples treated with chemical and biological pesticide were evaluated. Microbial counts were carried out by soil dilution plate technique. The enzymatic activities, soil respiration and physicochemical parameters of the soil were done using standard procedures. Microbial population of treated and untreated soil samples ranged from 2.15 ± 0.81 × 10³ to 3.40 ± 0.20 × 10⁶ CFU/mL, enzymatic activities (0.00 ± 0.00 to 0.16 ± 0.00 µg), soil respiration (10.15 ± 1.07 to 17.00 ± 0.90 mg/kg), and physiochemical parameters (0.10 ± 0.00 to 177.28 ± 2.00 mg/kg). The application of biological pesticides; tobacco (Nicotiana tabacum), titonia (T.diversifolia), and neems (Azadirachta indica) extracts singly or in combination and most importantly in combination with 10% chemical pesticides when compare to application of 100% chemical pesticides provided optimal microbial population, enzymatic activities and physiochemical parameters which are indictors of excellent soil fertility. This study has revealed the need for farmers to consider the use of the combination of biological pesticides and 10% percentage of chemical pesticides in order to reduce the deleterious effect of 100% use of chemical pesticides and promote soil fertility and health for better food quality and safety.