Formulation of soil ameliorant material based on humic and silica to reduce Fe concentration in acid sulfate soils and improve rice growth

Abstract

Abstract Applying soil ameliorants can suppress the Iron (Fe) toxicity of paddy cultivation in acid-sulfate soils. Humic materials can interact with Fe and Al metal ions to form chelates so that their solubility decreases. Silica plays a role in reducing the uptake of Fe and Al, reducing the Fe content on the surface of rice roots by increasing the oxidizing strength of rice roots. The research aim was to study the effect of ameliorant material formulation based on humate and silica on decreasing the Fe content in acid sulfate soils and increasing the growth of rice plants. The research was conducted in the Greenhouse, Swampland Agricultural Research Institute, Banjarbaru, from March to October 2022. The experimental design was randomized complete block factorial with the following treatments: Factor 1. Formula of soil ameliorant (F0 = 100% agricultural lime, F1 = 30% humate manufacturer+30% rice husk ash+40% agricultural lime, F2=30% water hyacinth humate+30% rice husk ash+40% agricultural lime, F3=30% water hyacinth humate+30% rice husk biochar + 40% agricultural lime, F4 = 30% humate manufacturer+30% rice husk biochar+40% agricultural lime), Factor 2. Dosage of soil ameliorant (D1 = 1 t/ha, D2 = 2 t/ha, D3 = 4 t/ha). Parameters observed were soil Fe content, available P and soil pH, plant height, and number of rice tillers every two weeks. The results showed that the formula F3, namely 30% water hyacinth humic acid + 30% rice husk biochar + 40% agricultural lime, was capable of decreasing soil Fe levels from 540ppm (F0) to 422 ppm and increasing soil pH from 4.23 (F0) to 4.48 and availability of P from 27 ppm (F0) to 55.20 ppm in acid sulfate soils. In addition, the formula can also increase the growth of rice plants. Improvements in soil chemical properties and plant growth are expected to increase the productivity of Inpara 8 rice plants in acid-sulfate soils.