Abstract
This study examines the influence of varying vermicompost application rates (0 %, 10 %, and 20 % of the substrate volume) on the growth, development, and yield of cucumber (Cucumis sativus) and tomato (Solanum lycopersicum) cultivated under greenhouse conditions in the Turkestan region of the Republic of Kazakhstan. The research is conducted within the framework of chemical and technological transformation of organic matter in soil substrates. The results indicate that the incorporation of vermicompost leads to notable changes in the physicochemical characteristics of the substrate, including an increase in organic matter content, stabilization of substrate pH, and improved availability of key macronutrients such as nitrogen, phosphorus, and potassium. These modifications contribute to more active mineralization processes and enhanced biochemical transformation of nutrients, which in turn stimulate root system development, promote vegetative growth, and increase crop yield. The highest overall productivity was recorded at a vermicompost application rate of 20 %, demonstrating its maximum agronomic effectiveness. At the same time, the 10 % application rate also showed a consistently positive effect, suggesting that it represents a balanced and economically viable option for greenhouse cultivation. Overall, the findings support the use of vermicompost as an efficient organic component in the chemical technology of soil substrate improvement for greenhouse vegetable production.