New environmentally friendly bio-based micronutrient fertilizer by biosorption: From laboratory studies to the field

This paper reports the studies on the elaboration of new environmentally friendly fertilizer obtained by valorization of post-extraction biomass residues of alfalfa (Medicago) and goldenrod (Solidago), after extraction with supercritical carbon dioxide, via biosorption process. The performance and controlled release properties of fertilizer were assessed in laboratory under in vitro and in vivo conditions, as well as on the field. In vitro tests show high bioavailability of micronutrients (Cu, Mn, Zn) administered on the biological carrier - between 60 and 80%, in relation to 100% availability of sulphate microelements. This phenomenon is desirable and indicates slowed release pattern of micronutrients. Germination tests demonstrated the phytotoxicity effect of sulphates, while yield increase and biofortification effect by the use of new fertilizers was achieved. Field trials showed, that with respect to conventional micronutrient fertilizers (mineral salts), fertilizers obtained via biosorption resulted in increase of the content of Cu, Mn and Zn by 2.6, 88.6 and 50.6% in plant biomass, respectively. This is important from the point of view of plant and animal nutrition. In addition, the uptake of fertilizer components was calculated, indicating their degree of use. Calculations of micronutrient uptake in field trials shows a higher uptake of fertilizing microelements of products obtained via biosorption by 4.04% (Zn), 1.47% (Cu) and 20.63% (Mn) in relation to sulphates.