Effect of Humic Acid on Rice Production at Tidal Swampland South Kalimantan

Up to 24% of tidal swamplands in South Kalimantan are used for rice cultivation, but these fields face challenges like acidic pH, high exchangeable aluminum (Al-Exch), and low nutrient levels, resulting in low productivity of around 2.9 tons/ha. This study, conducted in Kolam Kanan Village, Barambai District, Barito Kuala Regency, investigated the application of humic substances as a potential solution. Humic compounds improved soil pH, stabilized Al3+ levels, and increased total N, P, K, and soil cation exchange capacity (CEC). The optimal dose of 10 kg/ha resulted in the highest plant height and number of productive tillers at 2, 4, and 6 weeks after planting (WAP). Root weight and length were greatest at 5 and 15 kg/ha doses, though root effectiveness was better represented by tertiary and quaternary root absorption efficiency. At 10 kg/ha, rice productivity reached 3.2 tons/ha, more than 100% higher than the control (0 kg/ha). Humic substances also enhanced plant resistance to rice blast, with higher doses leading to lower disease intensity.