Shuitu baochi tongbao (Jun 2023)
Soil Selenium Characteristics and Availability in Jujube Orchard in Minqin County of Gansu Province
Abstract
[Objective] The distribution status and availability of soil selenium in three jujube orchards in Minqin County, Gansu Province was analyzed in order to provide a theoretical basis for the development of the selenium-enriched jujube industry. [Methods] The contents of total selenium and various forms of selenium in the 0—60 cm soil layer in three jujube orchards of Minqin County were measured by a method of successive extraction. Jujube distribution characteristics and availability were determined. [Results] ① The total selenium content was 24—520 μg/kg (average was 210.625 μg/kg), suggesting that total soil selenium was not deficient. ② Total soil selenium content increasingly declined with increasing soil depth in the 0—60 cm soil layer, with values in the three orchards following the order of Liugou>Zhangba>Xinguoyuan. According to the partition criterion for soil selenium content, the surface soil (0—20 cm) was categorized as selenium-rich; the subsurface soil (20—40 cm) was selenium-rich and selenium-poor; and the bottom soil layer (40—60 cm) was selenium-rich, selenium-poor, and selenium-deficient. ③ The available selenium content was 42.5 μg/kg and accounted for 20.2% of total selenium. Soluble selenium was 1.1—1.4 μg/kg, exchangeable selenium was 1.4—2.8 μg/kg. Both of these selenium forms together accounted for only 7.7% of the available selenium. The remaining available selenium was all organic selenium. ④ The available soil selenium increased with increasing number of reclamation years and followed the order of Xinguoyuan>Liugou>Zhangba among the three orchards. ⑤ The contents of total selenium, available selenium, and ineffective selenium were greater under trees than between tree rows. [Conclusion] Total selenium was not deficient in the soil of jujube orchards of Minqin County, but available selenium was deficient. Hence, development of the selenium-enriched jujube industry will require artificially supplementing soils with selenium fertilizer.
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