Amelioration of an acid sulfate soil in the Philippines; 1: the effect of organic and inorganic matter amendments on rice growth and yield in an acid sulfate soil
1985
Pei, L.J. (International Rice Research Inst., Los Banos, Laguna (Philippines). Soil Chemistry Dept.)
Greenhouse experiments were conducted to determine the effects of straw, CaCO3 and MnO2 on the electrochemical and chemical kinetics and rice growth and yield in a flooded acid sulfate soil. Straw application had a pronounced effect on soil reduction. High concentration of water-soluble Fe2+ stunted plants at early growth; but the Fe2+ concentration gradually decreased and plants had vigorous growth at maturity. Grain and straw yields at harvest were higher. Potassium in the plant tissue was high where straw was added. Adding CaCO3 markedly increased soil solution pH, decreased Eh and EC, and significantly depressed concentration of water-soluble Fe2+, Mn2+, and Al3+. Calcium carbonate, alone or in combination with MnO2, depressed Fe2+ concentration in the soil solution and significantly increased straw and grain yields. Calcium carbonate and MnO2 applications also enhanced N and P content in the straw but decreased Zn content. Adding 0.005% MnO2 increased the Mn2+ in the soil solution, depressed the Fe:Mn ratio in the plant tissue, and increased grain yield significantly over the control
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