Physicochemical characterization of hydroponic substrate combinations

Objective. To analyze different combinations of substrates to identify which one provides the most favorable conditions for plant growth and development in hydroponic systems. Design/ Methodology/ Approach. Four combinations of substrates were evaluated as treatments. 1: lava rock and worm castings mixture [1:1, v/v], 2: lava rock and coconut fiber [1:1], 3: lava rock, coconut fiber, and worm castings [1:1:1, v/v], 4: lava rock, worm castings, and coconut fiber [4.7:1:1], and 5: control (TES), lava rock only. Physical properties, total porosity, aeration porosity, water retention porosity, bulk density, water retention curves, readily available water (AFD), reserve water (ADR) and total available water (ATD) were determined. Also, some chemical properties, including organic matter and nitrogen content. Results. The mixture of lava rock with coconut fiber and worm castings (T3) showed better response in porosity for water retention, water retention curves, readily available water, organic matter and nitrogen content. On the other hand, the mixture of lava rock with coconut fiber (T2) was outstanding because it had the highest percentage of reserve water and total available water. The combination of lava rock with worm castings (T1) showed the highest concentration of nitrogen, while T4 and TES were outstanding in aeration porosity and bulk density. Limitations/ Implications of the study. This study was limited to certain types of minerals and organic fibers. Further research could include a greater diversity of materials. Findings/ conclusions. The combination of organic fibers degraded or not, with inorganic materials is recommended to improve the physical and chemical properties of substrates for growing plants.