Starch composites materials / polyvinyl alcohol for the controlled release of urea

Sergio Espinoza Orellana; Jorge Rojas Beltrán

Abstract

Nitrogen is one of the most important elements for the growth of crops. Its current application, usually as urea, implies low yields, with more than 50% of the fertilizer being wasted by the crop of interest. Several strategies have been developed to improve this efficiency of use, with controlled release fertilizers being a promising alternative. In this sense, the present work proposed the development of films composed of cassava starch / polyvinyl alcohol (PVA) incorporated with urea as a means to achieve its controlled release. In this way, a factorial filtering design was initially proposed to determine the most significant factors that affect the water absorption capacity of composite films (response variable); which were analyzed by a factorial design 23 with three central points. Films prepared with higher proportions of citric acid (plasticizer) resulted in a lower water absorption capacity regardless of the amount of urea used. The amount of glycerol, polyvinyl alcohol and starch did not exert a significant effect on the conditions employed. The conditions that gave rise to the lower water absorption capacity were sought since it is related to a slower release of the incorporated urea. A slower release of urea could be in better synchrony with the nitrogen demand of the crop, improving the use of its efficiency.