Selenium (Se) biofortification of staple cereal crops can improve the Se nutritional status of populations. A field trial employing an enriched stable isotope of Se (⁷⁷Se) was undertaken over three consecutive cropping seasons in a coarse-textured, calcareous soil in Gilgit-Baltistan, Pakistan. The objectives were to (1) assess the feasibility and efficiency of Se biofortification, (2) determine the fate of residual Se, and (3) assess the consequences for dietary Se intake. Isotopically enriched ⁷⁷Se (⁷⁷Se_Fert) was applied, either as selenate or as selenite, at three levels (0, 10, and 20 g ha⁻¹) to a wheat crop. Residual ⁷⁷Se_Fert availability was assessed in subsequent crops of maize and wheat without further ⁷⁷Se_Fert addition. Loss of ⁷⁷Se_Fert was c.35% by the first (wheat) harvest, for both selenium species, attributable to the practice of flood irrigation and low adsorption capacity of the soil. No ⁷⁷Se_Fert was detectable in subsequent maize or wheat crops. The remaining ⁷⁷Se_Fert in soil was almost entirely organically bound and diminished with time following a reversible (pseudo-)first-order trend. Thus, repeat applications of Se would be required to adequately biofortify grain each year. In contrast to native soil Se, there was no transfer of ⁷⁷Se_Fert to a recalcitrant form. Grain from control plots would provide only 0.5 µg person⁻¹ day⁻¹ of Se. By contrast, a single application of 20 g ha⁻¹ Se^VI could provide c. 47 µg person⁻¹ day⁻¹ Se in wheat, sufficient to avoid deficiency when combined with dietary Se intake from other sources (c. 25 µg day⁻¹).

主要谷类作物的硒（Se）生物强化可以改善人群的硒营养状况。在巴基斯坦吉尔吉特-巴尔蒂斯坦的一块质地粗糙的钙质土壤中，连续三个种植季节进行了一项采用富集稳定同位素硒 ( ^{77 Se) 的田间试验。}目标是 (1) 评估硒生物强化的可行性和效率，(2) 确定残留硒的去向，以及 (3) 评估膳食硒摄入的后果。将同位素富集的⁷⁷ Se ( ⁷⁷ Se _Fert ) 作为硒酸盐或亚硒酸盐以三个水平（0、10 和 20 g ha ^-1）施用于小麦作物。残留⁷⁷ Se _Fert^{在没有进一步添加77} Se _Fert的情况下，评估了随后的玉米和小麦作物的可用性。^{对于两种硒物种，第一次（小麦）收获时77} Se _Fert的损失约为 35%，这归因于洪水灌溉的做法和土壤的低吸附能力。在随后的玉米或小麦作物中未检测到77 ^Se Fert _。土壤中剩余的⁷⁷ Se _Fert几乎完全有机结合并随着时间的推移而减少，遵循可逆（伪）一级趋势。因此，每年都需要重复施用硒来充分生物强化谷物。与原生土壤 Se 相比，没有转移⁷⁷ Se _Fert以顽固的形式出现。来自对照地块的谷物将仅提供 0.5 µg 人^-1 天^-1硒。相比之下，单次施用 20 g ha ^-1 Se ^VI可以提供 c。小麦中47 µg 人^-1 天^-1硒，与其他来源的膳食硒摄入相结合时足以避免缺乏（约 25 微克天^-1）。