This research studied the effects of pesticide application on the growth of soil nitrifying bacteria.
Nitrosomonas
sp. was isolated from the Soil samples gotten from five different locations within the University of
Benin, Benin City and cultured using Winogradsky medium. The bacterial isolate was characterized and identified
based on its cultural, morphological and biochemical characteristics. After 4 to 5 days of growth, Nitrosomonas Counts
obtained from Winogradsky medium ranged from 4.8×10
3 to 9.2×10
3cfu/g. There was an increase in bacteria growth at
lower pesticide concentration which began to decrease as the pesticide concentration increased with time. The
percentage nitrite accumulation gradually decreased with time, the LC
50 values were higher than EC
50 values which
shows that the bacteria could survive and grow at lower pesticide concentrations but were completely inhibited at
higher pesticide concentrations. It is therefore very important to examine pesticides so as to determine its toxicity to
soil bacteria before application.
