| Abstrakt: |
Humic acid has been widely known to increase nutrient uptake and rice growth. It also benefits crops in terms of enhancing chemical fertilizer use efficiency. However, there is still a paucity of information regarding the use of the substance in acid sulfate soils. Our study aimed to evaluate the effect of humic acid addition and NPK fertilizer application on the growth and yield of rice grown in acid sulfate soils. A field experiment arranged in factorial randomized complete block design was conducted from June to October 2021 in Dadahup, Central Kalimantan, using two factors, i.e., humic acid and NPK fertilizer rate. Humic acid treatment consisted of 0, 2, 4, and 6 kg material per hectare in each NPK fertilizer application. NPK fertilizer treatment comprised 25%, 50%, 75%, and 100% of the recommended rate. In this study, we could not find any main effect difference in treatment apart from humic acid treatment on above-ground biomass. The interaction effect between humic acid and NPK application was found only on the harvest index. The highest rate of humic acid (6 kg/ha) increased the above-ground mass by 21.74%. The combined factor of 6 kg of humic acid and 75% NPK resulted in the highest harvest index of 0.41. Irrespective of the non-optimal result of the experiment, there is likely still a prosperous use of humic acid since rice benefits from applying humic acid as a single treatment. [ABSTRACT FROM AUTHOR] |
