Abstract This article presents data on agrotechnical factors for the formation of a biocenotic complex of phytonematodes of agrocenosis of cotton and alfalfa. Also the dependence of the formation of fitonematodes communities on the value of agrocenoses of alfalfa and cotton on their surrounding ecosystems is determined, the role of the latter as a place of reservation and the settlement of certain species is determined, the significance of organic – mineral fertilizers in the accumulation of pytonematodes in the soil of agrocenoses. Agrocenoses are greatly influenced by the formation of the phytonematodes community by soil factors and agro-technical factors in agrosenosis. The formation of the biocenotic complex of phytoenomatodes of agrosenoses is influenced by agro-technical factors and the environmental ecosystems that surround them. be surrounded by the surrounding ecosystems The laws of the ecosystem include the accumulation and distribution of parasitic species in agrosenosis, the deep processing of organic mineral fertilizers in the soil, which results in the accumulation of phytonematodes in agrosenosis.