Comparative Effects of Organic Waste Formulation and Inorganic Fertilizer on the Microbial Activity and Biomass of Glyphosate contaminated Soil

Abstrak

The toxicity of pesticides to the environment can be ameliorated if accompanied by other sustainable agricultural practices. The practices which will confer enhanced degradation on these chemicals are expected to be more complementary when a sustainable and healthy environment is the priority. This study compared a compost formulation and an inorganic fertilizer in their abilities to cushion the ripple effects of the glyphosate
herbicide on soil microbial biomass and activity. Compost formulation and NPK mineral fertilizer were separately added to soil samples contaminated with the field rate of glyphosate to compare the effects on soil microbial activity and microbial biomass in the laboratory. The treated samples were incubated for 28 days and soil microbial activity and microbial biomass were measured. Soil microbial metabolic quotient and carbon
mineralization quotient were also determined. Glyphosate applied alone gave transient inhibition of soil basal respiration, soil microbial biomass and soil mineralization quotient and was followed by their mild stimulation.
The addition of fertilizer increased these parameters and the highest figures were obtained when NPK was present at the early stage of incubation. The boost in soil microbial activities, biomass and carbon mineralization quotient was however sustained to the end of incubation by the addition of compost. The addition of NPK fertilizer significantly reduced CO2 compared to the other treatments at the beginning of incubation but NPK significantly raises it at the end. Therefore, the addition of organic fertilizers would be preferred as biostimulants in pesticide bioremediation programmes.