Research objective: This research aims to evaluate the biostimulant potential of biohumus in different substrate replacement rates on the growth of Zea mays seedlings. This is to increase knowledge of the use of biohumus in plant cultivation, which could be used in the formulation of new growing media and organic fertilisers. Materials and Methods: The experiments, which began in January 2023, were conducted in the CREA-OF greenhouses in Pescia (Pt), on seedlings of Zea mays. The experimental groups were: group control, irrigated with water and substrate previously fertilized; group with 10% biohumus, irrigated and fertilised substrate; group with 20% biohumus, irrigated and fertilized substrate; group with 30% biohumus, irrigated and fertilized substrate; group with 40% biohumus, irrigated and fertilized substrate; group with 50% biohumus, irrigated and fertilized substrate; group with 60% biohumus, irrigated and fertilized substrate; group with 70%, irrigated and fertilized substrate; group with 100% biohumus, irrigated and fertilized substrate. On May 18, 2023, plant height, vegetative weight, roots volume and length, the number of microorganisms and pH in the substrate were determined. Results and Discussion: The experiment showed that the use of biohumus enriched with microorganisms can significantly improved the vegetative and root growth of sown Zea mays seedlings. In general, a significant increase in plant height, vegetative and root weight, and root length was observed from 20% substitution of biohumus in the substrate. The theses that show a particularly clear improvement for all agronomic parameters analysed are those with 50% and 60% biohumus, peat substitution. Plants that received biohumus grew better than those that did not, and cereal plants grew better than those that were grown in plain soil. The nutrient content of biohumus stimulates the growth of the following crops: tomatoes, peppers, garlic, sweet corn, aubergines, bananas. Among other things, it stimulates the growth of chrysanthemum, marigold, geranium, petunia, and poinsettia flowers, as well as acacia and eucalyptus. Due to its macro- and micronutrient content, biohumus has a positive effect on plants (leaf area, root volume, root branching), and improves the soil's biological functions. Plants that received biohumus grew better than those that did not, and cereal plants grew better than those that were grown in plain soil. The growth of barley and cereals improved on a maize farm after biohumus was applied. There was a significant improvement in soil porosity on a maize farmland. Among the benefits of using biohumus as a fertiliser are: it eliminates harmful insects, reduces the infestation of harmful insects, reduces pathogen infestation of plants, fertilizes the soil, and improves the soil structure as a soil conditioner. Conclusions: In order to maintain soil health and fertility, farmers need a sustainable alternative that is economically viable and productive. As part of ecological agriculture, the protection of food, agricultural and human ecosystems is emphasized, along with the improvement of soil fertility and the development of secondary income for farmers. The use of biohumus provides the best answer to ecological agriculture, which is synonymous with 'sustainable agriculture'. This article provides a basis for further research