The present research book has been focused on how introduction of organ chemicals in agriculturalsosoil singly and in combination had significant impimpact on non target forms beneficial too soil ecosystem emphasizing on two pesticides imidacloprid and triadimefon. Over all it deals with two different aspects. One is on the effect of selected pesticides on soil microbial population, nitrogen transformations and soil enzymes. On the other hand, it deals with the biodegradation of these compounds by microbial enrichment technique and analysis of degradation products by HPLC and GC-MS techniques. Further, identification of potent microbial isolates from agricultural soil is also covered in the research study.