A Correlation Analysis Between Trace Elements Contents of Rice and Soil According to the Soil's Physicochemical Properties.

Abstract

National Agricultural Products Quality Management Service (NAQS) has been examining the pollution levels of water, soil, and heavy metal trace elements of agricultural products harvested from the vicinities ofabandoned mine areas since 2005 in cooperation with the Ministry of Environment (ME). It recommends the contaminated agricultural products to be incinerated or destroyed and the contaminated areas to be planted with non-dietary plants or to be left in fallow. The heavy metal concentration of soil and that of agricultural products differ widely. And the heavy metal concentration of agricultural products varies from year to year.

Investigation into the cause of these phenomena and the means to prevent production of polluted agricultural produce were required. This study researched the correlation between the heavy metal content of soil and rice based on the results of heavy metal analysis of soil conducted by the Ministry of Environment in 2008 and the heavy metal analysis of rice conducted by NAQS in order to investigate the factors causing the production of polluted rice. There was significant correlation between trace element (cadmium, lead) contents of rice and soil. This resulted from the correlation analysis between the cadmium and lead contents

of rice and the cadmium and lead contents of soil and the soil's physicochemical properties. However, organic matter content and the pH of soil did not show significant correlation. The transfer rate of cadmium from soil to rice averaged 0.356, whereas that of lead was 0.004, which indicated that lead hardly transfers from soil to rice and that cadmium transfers easily. The transfer rate of various soil textures was also investigated. The transfer rate was high in rice produced from silty clay loam resulting in 17.4% of the rice produced from silty clay loam exceeded rice criteria for Cd. For the estimation of cadmium content in rice regression equations were formulated. The regression equation utilizing soil's cadmium content, soil texture, and organic matter contents proved to be the most appropriate. It indicated that the soil's cadmium content, soil texture, and organic matter contents had significant effect on the cadmium content of rice.

Key words

Cadmium, Lead, Soil, Rice, Correlation