Hyun Ho Lee, Keun-Ki Kim, Yong-Bok Lee
Dec 31, 2016
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Journal
Korean Journal of Environmental Agriculture
Abstract
BACKGROUND: To determine effect of phosphate (P) application on Cadmium (Cd) extractability and its uptake by rice plant in Cd contaminated paddy soil, dipotassium (K 2 HPO 4 ) 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 P 2 O 5 /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 K 2 HPO 4 . The trend of 1 M NH 4 OAc extractable Cd concentration in soil was similar to that of Cd uptake by rice plant. One M NH 4 OAc 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 K 2 HPO 4 application rates as Grain yield = 5.38 + 2.39 ×10 -3 K 2 HPO 4 – 6.65 × 10 -6 K 2 HPO 42 (model R 2 = 0.968). Using this equations, the greatest grain yield (5.6 Mg/ha) was at the rate of 180 kg P 2 O 5 /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).