Evaluation of physicochemical properties and enzymatic activity of organic substrates during four crop cycles in soilless containers

BACKGROUND: Organic soilless production in containers requires substrates with appropriate physicochemical and biological properties to ensure that production is sustainable and profitable for several production cycles. The main objective of this study was to comprehensively evaluate these properties in three different mixtures of organic substrates (vermicompost [V] and coconut fibers [CF] in ratios 20V80CF, 40V60CF, 60V40CF) for four horticultural crop production cycles (PCs) using vermicompost tea (VT) as the main source of nutrients. RESULTS: Readily available water (25%) in the control treatment (20V80CF) was below the recommended limit, and dry bulk density (>450 g/L) surpassed the recommended limit in the 60V40CF treatment (p < 0.05). In terms of chemical properties, cations and anions in the saturated media extract decreased significantly to values below established optimal conditions. Furthermore, the substrates presented high enzymatic activity in successive production cycles (p < 0.05), including dehydrogenase (350–400 μg TFF g(−1)), acid phosphatase (4,700 μg p‐nitrophenol g(−1) soil hr(−1)), and β‐glucosidase (1,200 μg p‐nitrophenol g(−1) soil hr(−1)) activity during transformation from organic matter to inorganic compounds. CONCLUSION: The 40V60CF treatment presents adequate physicochemical and biological characteristics for reuse for more than four growing cycles when organic supplements are administered.