Thesis (M.Sc.)--Chulalongkorn University, 2009

In this work the effects of organic fertilizer on the pH, Cd phytoavailability and Cd distribution in rice plants was examined in a pot experiment and field experiments using Cd contaminated soil at high concentration (> 60 mg /kg soil) for the pot experiment; and for the field experiment both high (> 3 mg /kg soil) and low (< 0.5 mg/kg) Cd concentrations were selected for the evaluation. For pot experiment, the 5 kg soil/pot was treated with 1 Mol/L KOH addition with 80 and 240 mL and organic fertilizer addition at 4 levels; 0 (control), 10, 20, and 100 g/pot (5 kg soil). For KOH addition, increasing pH was found to be an obvious effect which resulted to the rice during the vegetative stage became dwarf and died finally. . The result showed that the combination of the soluble and exchangeable Cd fraction (F1) and the reducible Cd fraction (F2) was decreasing when KOH addition increased. For the organic fertilizer addition, the result showed that addition of organic fertilizer increased oxidizable Cd fraction (F3) and decreased the soluble and exchangeable Cd fraction (F1). There was an increase of dry matter yield with increasing organic fertilizer addition. Cd concentration in plant parts was found in root > stem > grain. No such significant reduction in rice plant was seen for Cd by organic fertilizer addition. For field experiment, despite the fact that the organic fertilizer addition was not shown an effect on the increasing F3 significantly, Cd in rice grain were found decreasing for both plots of high and low Cd contaminations. However, it may not be confident to conclude that the increasing is occurred only form organic fertilizer addition since there were several factors in the field study were out of control. Productivity of rice grain from the four filed sites experiment were found insignificantly different, only one control plot with low concentration that show the higher production from organic fertilizer addition.