Effect of soil leaching and organic matter on Fe2+concentration and rice yields in acid sulfate soils

The negative impact of climate change causes extreme weather become unpredictable, leading to flood and drought. In acid sulfate soil, El Nino increases pyrite oxidation which causes sulfate and iron toxicity when flood comes. Iron toxicity in plants is caused by excess concentrations of iron Ferro (Fe2+) in the soil solution. This research aims to determine the effect of leaching and organic matter on Fe2+ concentration, physiological response and yield of rice in acid sulfate soils. The research was conducted in the Indonesian Swampland Agricultural Research Institute (ISARI) Greenhouse from August to December 2020, using a completely randomized design with three factors. The first factor: actual acid sulfate soil (AASS) and potential acid sulfate soil (PASS), the second factor: waterlogging without leaching (-SL) and soil leaching (+SL), and the third factor: without organic matter (OM) and with organic matter (+OM). The results showed that soil leaching and adding organic matter decreased Fe2+ concentration, thereby increasing root length, relative water content, width of stomata, leaf K and Mg content, root-shoot dry weight, number of grain and crop yield. In comparison to the treatment of without leaching and organic matter, the leaching and organic matter treatment in AASS showed the lowest increase in Fe2+concentration from 123.4 to 241.9 ppm and increased yield from 3.13 to 3.80 ton ha-1. Whereas in PASS, the leaching and organic matter treatment showed the highest decrease in Fe2+ concentration from 2,298.7 to 686.6 ppm and increased crop yield from 2.39 to 2.77 ton ha-1.