Use of Humic and Silica Materials as Soil Ameliorant to Improve the Chemical Properties of Acid Sulphate Soil

Abstract

Ameliorant is needed to improve the fertility of acid-sulfate soils. Humic material and Silica (Si) are soil-ameliorants that can reduce Al and Fe toxicity. This research aimed to study the effect of humic and silica-based ameliorants in improving soil properties under reduced (flooded) and oxidizing conditions. Acid-sulfate soil with a pyrite content of 2.5% was taken from tidal land in Tamban Baru Tengah Village, Tamban Catur, Kapuas Regency, Central Kalimantan, Indonesia. Soil incubation research was conducted at the Balittra Laboratory from March to July 2020. the study used a factorial randomized block design. The first factor was the type of Si source material (rice husk ash and biochar), and the second was the humic source (water hyacinth compost and manufactured humic); each combination was repeated four times. Observations included soil pH, Eh, EC, available P, Fe, Al, and Sulfate. Combining humic materials from water hyacinth and Si from rice husk biochar decreased Fe concentration under reduced conditions. In oxidation conditions, it increased pH and decreased Al and Sulfate concentration. Using soil ameliorations with a combination of humic and Si effectively improves acid-sulfate soil properties.