Based on a theoretical approach for the optimisation of plant production a so-called “method of biological correction” was developed. It was hypothesized that foliar applied compost extracts have a promoting effect on plant physiology and thereby on yield and quality. For further evaluation field experiments were carried out on agricultural farms near Leningrad (Northwest Russia) and in the Tambov regions (Central Russia) during the last 6 years. The results of these experiments support that vermicompost extracts (i.e. extracts from compost treated with earthworms) was very successful for increasing yield and improving plant quality.