Effects of different agricultural practices such as fertilization (organic and NPK), irrigation (dripping and sprinkling), plough tilling and use of the herbicide, Trifluralin EC were tested oil two different Turkish isolates of the entomopathogenic nematodes, Steinernema feltiae (Filipjev, 1934) (Rhabditida: Steinernematidae) and Heterorhabditis bacteriophora (Poinar, 1976) (Rhabditida: Heterorhabditidae) in the field condition. Experiments were conducted between March and November, and replicated in the following 2 years, 2005 and 2006 in Ankara. As all practices together affected negatively only H. bacteriophora in the second year, S. feltiae was not affected by these practices together in both years. S. feltiae persisted longer than H. bacteriophora in the years. Based oil the lack of detection, the shortest persistence was found in the herbicide treated area and tilled plot area in the two years for S. feltiae and H. bacteriophora, respectively.