Replacing Commercial Substrate with Millicompost: A Sustainable Approach Using Different Green Wastes Combined with Millicompost for Bell Pepper Seedling Production in Urban Agriculture

This study demonstrates that the millicompost is as a sustainable peat-alternative substrate for vegetable seedling production, leveraging its optimal physicochemical properties. We developed seven novel growing media by combining millicompost with regional agro-wastescoconut coir (Cocos nucifera), shavings of the gliricidia (Gliricidia sepium), and elephant grass (Pennisetum purpureum) for the production of bell pepper seedlings. The substrates formulated were as follows: (S1) millicompost; (S2) Commercial substrate; (S3) 33% millicompost + 33% gliricidia + 33% elephant grass; (S4) 33% millicompost + 33% gliricidia + 33% coconut fiber; (S5) 33% millicompost + 33% elephant grass + 33% coconut fiber; (S6) 25% millicompost + 25% gliricidia + 25% elephant grass + 25% coconut fiber; (S7) 50% millicompost + 50% elephant grass; (S8) 50% millicompost + 50% gliricidia; (S9) 50% millicompost + 50% coconut fiber. Substrates S4 and S8 produced seedlings of a similar quality to millicompost (S1), followed by substrates S3 and S6, which, although they had lower phytotechnical parameters than those mentioned above, have potential for use. The mixture is effective when the substrates are formulated with millicompost, gliricidia and coconut fiber in a ratio (volume/volume) of 33% of each material, respectively, or 50% millicompost + 50% gliricidia. Combining millicompost with vegetable waste allows producers to maximize its use, as well as obtaining quality seedlings and eliminating the need to use commercial substrates.