Development and optimization of hydrogels for agricultural applications

Abstract

The efficiency of the use of fertilizers depends on environmental factors such as: volatilization, leaching, erosion, among others, as well as the adequate retention of soil moisture for the absorption of the plants. From this, a multifunctional material that provides crop water for an extended time and that promotes the control of the release of nutrients to ensure that they are in the soil in a controlled and absorbable manner by the plants would reduce nutrient expenses and risks of environmental contamination. Hydrogels, materials that present high water capacity, could meet both requirements, however, there is no recommendation for their use in fertilization. Currently the commercially available materials are imported products that aim only at water control for cultivars and with water loading capacity of 200-400 times their weight in water. The use of these products is restricted to seedlings (forest, citrus, among others), with no significant history in annual crops and, in general, manufacturers do not recommend the concomitant administration with fertilizers in the same application because they claim a significant drop in swelling capacity. However, previous studies carried out by the proponent of this PIPE project have demonstrated that modifications in the polymeric structure of hydrogels can considerably increase the swelling values (from 800 to 5000 times), besides proving that the use of clay minerals as modifiers favors the interaction with nutrients and lead to controlled release behavior and lower production costs. From this, for there to be a consistent proof of concept aimed at the agronomic market, it is necessary to answer some questions: what the ideal ratio between reagents and hydrogel modifiers is considering desired properties and cost-effective production; what the effective biodegradability of these materials in soil is, considering the possibility of application in annual crops; and the ability to control nutrient release in greenhouse studies using real systems. It is hoped to find in this PIPE project the answers to these questions and, from this, to design an economically feasible synthesis material for large-scale production, competitive with the currently available hydrogels and suitable for the controlled release of nutrients that is an important differential in relation to the products marketed. The viability assessments, in greenhouse, compared to economic production data will allow the product to be adapted to diversified markets, mainly by visualizing annual or seasonal crops (sugar cane, corn, vegetables, among others) in which the demand for materials may far exceed the current market for perennials crops. (AU)