Effect of Phosphate Application on Cadmium Extractability and its Uptake by Rice Cultivated in Contaminated Paddy Soil
2016
Lee, H.H., Pusan National University, Miryang, Republic of Korea | Kim, K.K., Pusan National University, Miryang, Republic of Korea | Lee, Y.B., Gyeongsang National University, Jinju, Republic of Korea | Kwak, Y.S., Gyeongsang National University, Jinju, Republic of Korea | Kim, S.C., National Institute of Agricultural Science, Rural Development Administration, Wanju, Republic of Korea | Lee, S., National Institute of Agricultural Science, Rural Development Administration, Wanju, Republic of Korea | Shim, C.K., National Institute of Agricultural Science, Rural Development Administration, Wanju, Republic of Korea | Hong, C.O., Pusan National University, Miryang, Republic of Korea
BACKGROUND: To determine effect of phosphate (P) application on Cadmium (Cd) extractability and its uptake by rice plant in Cd contaminated paddy soil, dipotassium (K2HPO4) which was the most effective of P materials to decrease Cd extractability in previous study was selected as P fertilizer. METHODS AND RESULTS: Dipotassium phosphate was applied at the rates of 0, 78, 234, and 390 kg P2O5/ha, and then rice was cultivated in submerged paddy soil from Jun. to Oct. in 2015. Cadmium concentrations in grain, straw, and root of rice plant decreased significantly with increasing application rate of K2HPO4. The trend of 1 M NH4OAc extractable Cd concentration in soil was similar to that of Cd uptake by rice plant. One M NH4OAc extractable Cd concentration was negatively related to soil pH and negative charge. Alleviation of Cd phytoavailability of rice in paddy soil might be attributed to increase in pH and negative charge of soil. Using a quadratic response model, amount of grain yield were related to K2HPO4 application rates as Grain yield = 5.38 + 2.39 x10-3 K2HPO4 x 6.65 x 10-6 K2HPO4 2 (model R2 = 0.968). Using this equations, the greatest grain yield (5.6 Mg/ha) was at the rate of 180 kg P2O5/ha. At this application rate of P, the Cd concentration in grain was 0.53 mg/kg, implying ca. 23% lower than the control. CONCLUSION: From the view point of heavy metal safety and crop productivity, it might be good P management to apply P fertilizer with 4 times higher rate than recommendation (45 kg/ha).
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