2-Reduction of Pesticides Effect on Soil Microorganisms by Addition of Organic Matter under Laboratory Conditions

The widespread used of  pesticides during agricultural service caused soil pollution by toxic chemicals found in these compounds in the soils, affecting on soil microorganisms, changing their numbers. Also heated matter  affects the period of maintain of these pollutants in soils whereas the pesticide mobility depends on its reacting with soil particles and soil organic matter according to adsorption and desorption.
The objectives of this work were to study the effect of pesticides on the soil microbial and reduction of ecosystem pollution by addition of organic matter, for that, laboratory experiment was conducted to valence the pesticide addition effect on soil microbial numbers and possibility of reduction of there effects by organic matter supplying in Kirkuk province. So two soils were chosen in Shwan and Alton –Kopri, soil samples were air dried, sieved throw 2mm sieve. Hundred gms of soil were taken in plastic dishes, treated with insecticides, herbicides and fungicide includes malathion, tripline and phycotop respectively in recommended and three times more than recommended doses, 1% organic matter (Liq-humus 18%) was added to reduce pesticides effects ,then the soils incubated at 28-⁺2C^o and moisture humidity maintain at 70% of field capacity, Soil samples were taken periodically after 1, 10, 25 and 35days to estimate total bacterial colony, fungus and actinomycetes.
The obtained result  indicated that the soil microorganisms have important roles for studying pesticides side-effects, whereas these pesticides, generally, reduce soil microbial numbers. In recommended dosages, the greatest effect on soil bacteria occurred by phycotop treatment followed by tripline and malathion,but actinomycetes were more affected by malathion. In three times more than recommended treatment ,tripline was more effective on bacteria followed by phycotop and malathion, but phycotop was more inhibitor for fungus and actinomycetes.
The results also indicated that organic matter reduces inhibition effects of used pesticides in both soils. Shwan soil treated by organic matter exceed on all other treatments in all soil microbial numbers, followed by Alton-Kopri treated by organic matter and then Shwan and Alton-Kopri  un treated soils. The obtained data showed that all used pesticides have toxic effect on soil microorganisms with differences caused by there maintain in soil and dosage concentration.Data showed that the greatest number of soil microorganisms occurred at the 35^th day of the experiment.