A team from DWI-Leibniz Institute for Interactive Materials in Aachen, RWTH Aachen University, and the University of Bonn has now developed a foliar fertilization system based on biocompatible microgels that adhere selectively to leaves for a long period and slowly deliver nutrients in a controlled fashion. Microgels are tiny particles of cross-linked macromolecules that can bind water and other molecules, such as fertilizers very efficiently.
Led by Ulrich Schwaneberg and Andrij Pich, the researchers equipped the interiors of gel particles with binding sites modeled on the iron-binding proteins of bacteria. These ensure that the iron ions are released slowly. The microgels are loaded with an iron-containing solution at a pH of 3. When the pH rises to 7, the microgels shrink, releasing water and binding the iron.
The surface of the gel particles is equipped with anchor peptides from lactic acid bacteria. These bind securely to leaf surfaces to hinder rinsing away of the microgels. The water in the gel provides an aqueous microenvironment that allows the iron to diffuse into the leaves. Yellow leaves of iron-deficient cucumber plants rapidly turned green in spots where the new foliar fertilizer was applied.
By incorporating different binding sites, the microgel “containers” can be loaded with a multitude of other metal ions or agents. A controlled delivery of agents as required would minimize the applied quantities as well as the release of fertilizers and pesticides into the environment. Low production costs, high levels of loading, easy application, and adjustable adhesive properties should make broad industrial applications possible. The goal is to make self-regulating delivery systems for sustainable agriculture.
Biofunctional Microgel-Based Fertilizers for Controlled Foliar Delivery of Nutrients to Plants – Meurer – 2017 – Angewandte Chemie International Edition – Wiley Online Library