| The effects of controlled pH and redox potential (Eh) conditions on transformations of several metals and their effects on rice growth were studied in laboratory microcosms using acid sulfate (Sulfic Tropaquept) and non-acid sulfate (Typic Tropaquept) soil materials from Thailand. Some microcosms were incubated at selected controlled Eh conditions (500, 250, 50, and ;Water-soluble Al and percent Al saturation of the CEC was negatively related to pH in both soil types under controlled pH and Eh conditions, but was negatively related to pH in only acid sulfate soils under controlled Eh conditions. Aluminum activity was negatively correlated with pH in both soil types and over all controlled conditions.;Rice uptake of Fe increased with decreasing Eh and pH. Iron uptake was significantly correlated with water-soluble Fe, Fe;The Mn content in shoot tissue was positively correlated with Eh and pH. Iron possibly had an antagonist effect on Mn uptake.;Aluminum uptake of both rice varieties correlated best with Al;In general, growth of rice was negatively related to the Fe:Mn ratio in shoot tissue and Al;Iron solubility was probably controlled by amorphous Fe(OH)... |
