Cellulose Microbeads: Toward the Controlled Release of Nutrients to Plants

The use of conventional fertilizers is associated with pollution due to leaching and a mismatch between release rates and crop requirements for optimal development. Slow-release fertilizers could address both problems. Here, the synthesis and properties of a zinc fertilizer composed of cellulose microbeads loaded with aqueous ZnSO4 are reported for the first time. UV–vis spectrophotometry showed that the beads immersed in water released all Zn2+ in about 30 min, regardless of the initial Zn2+ concentration. In two sandy substrates (a pure sand and a sandy loam substrate), microprobe X-ray fluorescence spectroscopy determined Zn2+ release from beads to the substrate corresponding to count rates of about 0.115 mm min–1 s–1, irrespective of the substrate and with a low sensitivity for the water content, except in a very dry range. These results indicate that these microbeads could represent a practical and sustainable solution for efficient nutrient supply in agriculture.