Studies on Reducing Cadmium Uptake of Paddy Rice (Oryza sativa L.) by both Soil Dressing and Mixing Tillage
Studies on Reducing Cadmium Uptake of Paddy Rice (Oryza sativa L.) by both Soil Dressing and Mixing Tillage
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DOI：
10.32115/ijerd.7.1_6
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发表时间：
2016
期刊：
影响因子：
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通讯作者：
K. Sasaki;Choichi Sasaki;C. Kato;A. Endo;T. Annaka;S. Moritani;N. Matsuyama
中科院分区：
文献类型：
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作者：
K. Sasaki;Choichi Sasaki;C. Kato;A. Endo;T. Annaka;S. Moritani;N. Matsuyama
土壤追肥是降低镉污染稻田水稻吸收镉的最有效方法之一，但其需土量大，成本高，环境负荷大。在这项研究中，我们探讨了任何可能性，最大限度地减少土壤施肥前利用混合耕作的厚度。用15 cm厚的混合污染土和12.5cm厚的覆土（日本的常规覆土厚度为20-30 cm）形成通常的三层（耕层、犁底层和底土）的分层稻田。污染土壤的Cd浓度通过混合耕作调节到约2.0，1.0和0.5 mg/kg。然后在水稻栽培过程中进行积水栽培，并在两种不同的水流系统（开放和封闭系统）下进行每个处理的试验。结果表明，当土壤Cd浓度为0.5、1.0和2.0 mg/kg时，开放系统中随水流动糙米中Cd浓度分别为0.07、0.05和0.17 mg/kg。2.0mg/kg土处理糙米中Cd含量显著高于其他处理5%。结果表明，将土壤Cd浓度稀释至1.0mg/kg可有效降低水稻对Cd的吸收。各处理间的生长和产量差异不显著.但在蓄水条件下，混合耕作有可能使土壤覆盖厚度减少到常规覆盖厚度的一半（20 ~ 30 cm）。
Though soil dressing is one of the most effective methods for reducing cadmium (Cd) uptake in rice plants of Cd contaminated paddy fields, it needs large amount of soil and thus often requires a high cost and heavy environmental loads. In this study, we investigated any possibility of minimizing the thickness of soil dressing by utilizing mixing tillage before the soil dressing. 15 cm-thick mixed contaminated soil and overlying 12.5 cm-thick soil dressing (the conventional thickness of soil dressing being 20-30 cm in Japan) were used to form the usual stratified paddy field of the three layers (plow layer, plowsole, and subsoil). Cd concentration of the contaminated soil was adjusted to approximately 2.0, 1.0 and 0.5 mg/kg by mixing tillage. Then rice plants were grown under ponding condition during the cultivation and the experiments of each treatment were conducted under two different water flow systems, open and closed systems. As a result, Cd concentration in brown rice with water flow in an open system was 0.07 mg/kg, 0.05 mg/kg, and 0.17 mg/kg when Cd concentration of soil was 0.5, 1.0 and 2.0 mg/kg, respectively. Cd concentration in brown rice of 2.0 mg/kg soil was 5% significantly higher by 5% than those of other treatments. These results indicated that it was effective to dilute soil Cd concentration to 1.0 mg/kg for reducing Cd uptake of rice plants. There was no significant difference in growth and yield a way these treatments. However, we conclude that mixing tillage may have potential to minimize the thickness of soil dressing to half of the conventional thickness, 20 -30 cm, under ponding condition during the cultivation.