Anthropogenous transformation of soils of agri-cultural use changes their biological activity which is reflected in the structure and abundance of soil mesofauna. The research objective was to find out how biometric parameters of the soil population after introduction of organic fertilizers on the basis of birds’ dung and sawdust changed. The applica-tion of organic waste of woodworking and poultry farming as organic fertilizers allows not only im-proving the quality of soils, but also partially solving the problem of utilization of large-capacity produc-tion wastes. The indicators of quantitative abun-dance and biomass, and also group representation of mesofauna of soils against change of seasonal and year parameters of soils were considered. The researches conducted in Krasnoyarsk forest-steppe on the chernozyom lixivious showed that the after-effect fades after the third year after their introduc-tion which was shown in alignment of biometric in-dicators of mesofauna of experimental options and control. In the period of after-effect of organic ferti-lizers on the basis of sawdust and bird's dung secu-rity with available fossils leading to the reduction of the variety, abundance and biomass of soil inhabit-ants decreased. The most noticeable effect of after-effect was observed for options with complex intro-duction of a double dose of birds’ dung and saw-dust. For these options the maximum indicators of the number and variety of soil biota both in the first years of supervision, and in the period of an after-effect of the introduced fertilizers were revealed. Seasonal dynamics of the number and biomass of mesobiota for different years of supervision were defined, first of all, by hydrothermal indicators of the season and the intensity of transformation of organ-ic compounds in the soil. The maximum duration of an after-effect was noted at the introduction of sawdust in combination with urea.