石灰、磷酸盐及硅酸盐对土壤硒有效性及水稻累积硒的影响

Effects of lime,phosphate and silicate on selenium availability in soil and selenium accumulation in rice

华南地区酸性土壤硒有效性低,本研究旨在探讨石灰、磷酸盐及硅酸盐类土壤改良物质对酸性水稻土硒有效性及水稻吸收硒的影响。结果表明,在施0.25 mg/kg硒基础上,石灰、硅酸钠、磷酸氢二钠以及三者配合施用对水稻单株产量影响不大;对大米硒含量提升效果以石灰、硅酸钠及石灰、硅酸钠、磷酸氢二钠三者配合施用的处理较好;酸性土壤中各形态硒的含量高低依次为有机物/硫化物结合态硒、残渣态硒、铁锰氧化物结合态硒、交换态硒和水溶态硒。石灰、磷酸氢二钠处理显著提升易被植物吸收的水溶态硒及交换态硒含量,显著降低难利用残渣态硒含量;石灰、硅酸钠、磷酸氢二钠三者配合施用的处理显著降低了有机物/硫化物结合态硒的含量。施用石灰以及施用磷酸氢二钠均可有效提升土壤硒的有效性,并促进水稻对硒的吸收,施用硅酸盐对土壤硒有效性影响不大,但能促进水稻对硒的累积。

The availability of selenium in acidic soils in South China is low.The purpose of this study was to investigate the effects of lime,phosphate and silicate on selenium availability in acid paddy soil and selenium uptake by rice.The results showed that on the basis of 0.25 mg/kg selenium application,lime,sodium silicate,disodium hydrogen phosphate and their combined application had little effect on rice yield per plant.The effect of improving the selenium content of rice was better under the combined application of lime and sodium silicate and the combined application of lime,sodium silicate and disodium hydrogen phosphate.The content of various forms of selenium in acidic soil was in the order of organic/sulfide bound selenium,residual selenium,iron-manganese oxide bound selenium,exchangeable selenium and water-soluble selenium.Lime and disodium hydrogen phosphate treatment significantly increased the contents of water-soluble selenium and exchangeable selenium that were easily absorbed by plants,and significantly reduced the content of residual selenium that was difficult to use.The combined application of lime,sodium silicate and disodium hydrogen phosphate significantly reduced the content of organic/sulfide-bound selenium.The application of lime and disodium hydrogen phosphate could effectively improve the availability of selenium in soil and promote the absorption of selenium by rice.The application of silicate had little effect on the availability of selenium in soil,but it could promote the accumulation of selenium by rice.