2026 Volume 35 Issue 2 Pages 47-59
Recently, hydroponics using organic fertilizers has gained significant attention. However, the conventional multiple parallel mineralization method faces challenges, including increased labor due to the “gradual addition” of fertilizer during pretreatment and the instability of nitrification caused by soil-derived microorganisms. This study investigated a simplified pretreatment using circulating ceramic filter media (one-time addition method) and evaluated its effects on the growth, quality, and root system development of tomatoes in rockwool cultivation. The pretreatment results showed that the mineralization rate reached 81.9% after 14 days with a one-time addition at standard concentration, demonstrating a high decomposition capacity equivalent to conventional split additions. In cultivation trials, the fresh fruit weights of the first and second clusters in the “nitrification” and “nitrification+mineral (supplemented with Ca, Mg, and Fe)” plots significantly exceeded those of the control plot using chemical fertilizer. This was attributed to effective nitrogen management. Conversely, the organic fertilizer was deficient in potassium (K) and phosphorus (P), which led to reduced fruit sugar content and a significant decrease in root dry weight, to approximately 0.2 to 0.4 times that of the control. These results indicate that circulating ceramic filter media allow for simplified pretreatment and a stable nitrogen supply. However, establishing fertilization management that appropriately supplements essential elements other than nitrogen—specifically K and P—is a crucial future task for maintaining healthy root development and fruit quality.
