Selenium fertilization strategies for bio-fortification of food: an agro-ecosystem approach

Aims Although the global importance of selenium (Se) deficiency to human and animal health has been recognized for decades, strategic Se fertilization interventions addressing agro-ecosystem specific conditions have not been developed. This research aims to identify such strategies based on an inventory of production-ecological factors controlling the potential impact of Se fertilizers on crop performance and nutritional content. Methods The effect of agro-ecosystem properties on crop response to Se fertilization was assessed using a meta-analysis approach based on 243 experiments performed during 1960 to 2014. Results The meta-analysis confirms the high impact of fertilization as an effective agronomic biofortification strategy. Site specific properties strongly affect crop responses to Se fertilization implying the need for tailor-made solutions. However, the minor influence of soil organic matter, total soil Se levels and acidity suggests that consideration of other agro-ecosystem properties like climate and bioavailable Se measurements is also required to optimize fertilizer strategies. Conclusions Fertilization characteristics including formulation, dose and timing were found to be driving variables enhancing crop Se uptake. The highest uptake efficiencies are found for foliar and selenate based fertilizers. The current low recoveries and the scarce resource availability challenges the fertilizer approach to develop strategies that maximize the uptake efficiency of Se.