富硒土壤中有效硒浸提剂和浸提条件研究

Extractants and Extraction Conditions of Soil Available Selenium in Selenium-enriched Soil

以青海东部富硒土壤为供试材料,对6种有效硒浸提剂NaHCO_3、KH_2PO_4、K_2SO_4、EDTA、ABDTPA和DTPA的最佳浸提时间和土液比进行了筛选,并结合土壤有效硒最佳浸提剂的小麦生物学校验,以找出适宜富硒土壤有效硒提取的浸提剂及其浸提条件。结果表明:6种有效硒浸提剂对富硒土壤中硒的浸提量均随着土液比的增大而减少,且均随浸提时间的逐渐增加而增加。EDTA和DTPA的最佳土液比则为1/20,振荡时间为30min;K_2SO_4、AB-DTPA、NaHCO_3和KH_2PO_4四种浸提剂最佳浸提土液比均为1/15,其中K_2SO_4和AB-DTPA的最佳提取时间为60min,其余两种浸提剂NaHCO_3和KH_2PO_4的最佳浸提时间均为90min。6种不同浸提剂在最佳提取条件下提取的土壤有效硒含量与小麦籽粒中富集的硒含量呈极显著正相关关系,但土壤有效硒的提取量以DTPA最少,其次为K_2SO_4,分别只占KH_2PO_4、NaHCO_3、AB-DTPA及EDTA提取量的16%~47%和36%~85%,故不适用于作为石灰性富硒土壤有效硒的浸提剂。KH_2PO_4、NaHCO_3、AB-DTPA和EDTA提取的硒含量不仅与小麦籽粒中硒含量呈极显著正相关,而且浸提量高,提取过程简单,重复性好,故均可作为石灰性富硒土壤的有效硒浸提剂。

Selenium-enriched soil in eastern Qinghai was used as test material to select optimum extractants（from NaHCO3、KH2PO4、K2SO4、EDTA、AB-DTPA and DTPA） and the corresponding extraction conditions for soil available selenium,and the optimum extractant and extraction condition were studied by wheat test.The results showed that the amounts of available selenium which extracted by six extractants all decreased with the ratio of soil to solution,and increased with the shaking time.The optimum ratio of soil to solution and shaking time of EDTA and DTPA were 1/20 and 30 min; the optimum ratio of soil to solution was 1/15 for K2SO4,AB-DTPA,NaHCO3 and KH2PO4; and the optimum shaking time was 60 min for K2SO4 and AB-DTPA; and that for NaHCO3 and KH2PO4 was 90 min.There was a significantly positive correlation between the contents of available selenium in soil and the contents of selenium enrichment in wheat grain under the optimum extraction condition,but selenium amount that extracted by DTPA was the minimum,then was that extracted by K2SO4,which were only 16% to 47% and 36% to 85% of those of KH2PO4,NaHCO3,AB-DTPA and EDTA,so DTPA and K2SO4 were not suitable for available selenium extraction from selenium-enriched limy soil.The contents of selenium extracted by KH2PO4,NaHCO3,AB-DTPA and EDTA were not only significantly correlated with selenium contents in wheat grain,but also had high extraction rate,and the extraction process was simple and reproducible,so the four kinds of extractants could be used in selenium-enriched limy soil.