Chitosan-Sugarcane Bagasse Microspheres as Fertilizer Delivery: On/Off Water Availability System

Enhanced efficiency fertilizer is a sustainable alternative to increase agricultural productivity. In this regard, the nutrient coating or encapsulation is one of the alternatives to improve the effectiveness of the fertilizer. Several matrices can be used, but predominantly the biodegradable ones, which have no environmental impacts. Chitosan has favorable characteristics, as biodegradation and harmless impacts on the soil, to use as a holder for fertilizers. In this work, microspheres of chitosan and sugarcane bagasse were prepared by the inversion phase method followed by potassium nitrate (KNO 3 ) fertilizer sorption. The structural, morphological and thermal properties were evaluated by Fourier transformed infrared, (FTIR), X-ray diffractometry (XDR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA) before and after release evaluation. The release profile of fertilizer ions was assessed in water and soil. The matrices served only as support for KNO 3 and no chemical interaction was observed. KNO 3 releasing behavior reached a plateau after one hour of test for all samples. The release process generated cavities on the surface of microspheres since these spaces were previously fulfilled with fertilizer as observed by SEM. However, in the soil, the materials were dependent on the amount of water available and we observed a diffusion process for the nutrient release. Graphic Abstract