Vermicompost: a pathway to transform organic waste into substrate for seedling production

Seedling production is a critical component in both agriculture and forestry. The prohibitive cost of commercial substrates, however, poses a significant barrier for small-scale farmers. Vermicomposting, a process that transforms organic waste into a usable substrate, could offer a practical solution. This method has shown promise for horticultural crops, but further investigation is needed to determine its effectiveness for other species, including trees, especially in terms of concentration. Our study examined the technical feasibility of using vermicompost as a substrate for seedling production. We conducted six treatments with specific soil to vermicompost ratios (100:0, 75:25, 50:50, 25:75, and 0:100), and a control group that used a commercial substrate. Corymbia citriodora was used as a biological model, manually sown into polypropylene tubes, and monitored weekly. Our comparative analysis revealed that vermicompost contains higher levels of essential nutrients such as phosphorus, potassium, and zinc, suggesting its potential to enhance soil fertility and promote plant growth. Nitrogen plays a central role in the substrate’s technical viability, as network analysis and principal component analysis highlighted its pivotal influence, extensive connectivity, and rapid impact on other factors, such as pH, organic matter, and the essential nutrients, fostering effective substrate interactions and seedling development under stress conditions. It improved the performance of our biological model comparably, if not better, than the commercial substrate and soil alone. The treatment using 100% vermicompost produced germination results similar to those of the treatment using a commercial substrate. However, the Dickson Quality Index (DQI) decreased with increasing vermicompost content.