The Effect of Adding Some Pesticides in Inhibiting the Activity of the Urease Enzyme in Sandy Loam Soil Treated with Different Organic Sources

Abstract

      Due to the increased use of agricultural pesticides for the purpose of reducing agricultural diseases and thus increasing production, this research was conducted to find out the effect of four types of agricultural fungicide (Difenoconazole 25% EC), insecticide  (Demethoate 40% EC), Herbicide( Atlants) and Biocide  (Tricoderma harzianum  ) with four different concentrations. (Zero , according to the recommendation, double of the recommendation, and four times the recommendation) in inhibiting the activity of the enzyme urease in soils treated with five types of organic sources separately (Cows' manure , poultry wastes mixed with sawdust, alfalfa grinded, molasses of yellow corn grinded and urea) for five incubation periods (7, 14, 21, 28 and 35) days. The results showed the highest percentage of inhibition of the enzyme at the incubation period of 14 and 21 days from the addition of the fungicide and insecticide and at 28 and 35 days of adding the biocide and herbicide compared with the rest of the incubation periods, and the treatments of alfalfa grinded showed the lowest percentage inhibition of enzyme activity in fungicide, herbicide and biocide  treatments, while it showed the highest rate of inhibition in the insecticide treatments . The poultry waste mixed with sawdust showed the highest rate of inhibition in the fungicide, insecticide and biocide  treatments, while it showed the lowest rate of inhibition with the herbicide .The percentage of enzyme inhibition was increased by increasing the concentration of the pesticide compared to the control treatment.