Abstract Previous biofortification studies have established that the residual effect of added selenium (Se) fertilisers on second-season crops is minimal. To explore the fate of exogenous Se in soil, chemical and biological methods were employed to assess the change in Se bioavailability with time. Eight soils varying in physicochemical properties were spiked with sodium selenate (0.5 mg kg−1 Se) and incubated at 25 °C for different periods (1, 30, 60, 90 and 300 d). At the end of the incubation, soil Se was fractionated by a sequential extraction procedure into ‘soluble’, ‘adsorbed’ and ‘organically-bound’ Se fractions. Simultaneously, wheat was grown in the Se-aged soils, under controlled conditions for six weeks, and uptake was determined. A general decrease in Se solubility over time was observed, but the rate of decrease varied depending on soil type. A reversible first order model fitted the Se ageing kinetics well, except in an Oxisol. The most pronounced ageing was observed in calcareous soils. Concentrations of Se in the shoots of wheat grown in freshly spiked soils ranged from 71.8 ± 17.5 mg kg−1 in calcareous soils to 110 ± 31.6 mg kg−1 in non-calcareous, low-OM soils. With ageing, shoot Se concentrations decreased to

中文翻译：

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土壤性质对硒酸盐时间依赖性固定（老化）的影响

摘要 先前的生物强化研究表明，添加硒 (Se) 肥料对第二季作物的残留影响很小。为了探索外源硒在土壤中的归宿，采用化学和生物方法来评估硒生物利用度随时间的变化。八种物理化学性质不同的土壤加入硒酸钠（0.5 mg kg-1 Se），并在 25 °C 下培养不同时期（1、30、60、90 和 300 天）。在培养结束时，土壤硒通过连续提取程序被分成“可溶性”、“吸附”和“有机结合”硒部分。同时，在受控条件下，将小麦在硒老化土壤中种植六周，并测定吸收量。观察到 Se 溶解度随时间普遍降低，但下降速度因土壤类型而异。可逆的一级模型很好地拟合了硒老化动力学，但在 Oxisol 中除外。在钙质土壤中观察到最明显的老化。在新鲜加标土壤中生长的小麦芽中硒的浓度范围从钙质土壤中的 71.8 ± 17.5 mg kg-1 到非钙质低有机质土壤中的 110 ± 31.6 mg kg-1。随着年龄的增长，地上部硒浓度下降到