Alterações em um horizonte com caráter coeso ocasionadas por hidrogel e ciclos de umedecimento e secagem

Abstract

Superabsorbent polymers are formed by a three-dimensional network consisting of linear or branched polymers from chemical-physical interconnections, which in turn have polarization, presenting anionic, cationic or neutral surface charges, capable of absorbing high amounts of water or biological fluids. The geomorphological unit called Coastal tableland, has as predominant soil classes, Oxisols and Ultisols, which may commonly have the cohesive character, a diagnostic attribute used by SIBCS to distinguish soils with densified subsurface pedogenic horizons. Such feature causes physical impediment to root growth and development. The present research proposed, through the use of hydrogel doses and wetting and drying cycles, to evaluate if physical changes occur on the horizon with cohesive character. Evaluations were performed on a Ultisols. The applied treatments were 5 moistening and drying levels (2, 4, 8, 16 and 32 cycles) and 4 hydrogel doses (0.0; 0.5; 1.0; and 2.0g L-1). Physical soil attributes such as soil density, tensile strength, soil penetration resistance and aggregate stability were evaluated by means of the GMD and WAD indices. The data related to the wetting and drying cycles were submitted to variance analysis and the averages were compared by Tukey test at 5% probability. Hydrogel doses were compared by fitting to regression models. The selection of the models was based on the significance of the models and the coefficient of determination (R2). It was observed that the use of hydrogel caused significant difference in the highest levels of wetting and drying, soil density, tensile strength, soil penetration resistance were influenced by the greater number of wetting and drying cycles. GMD and WAD were not affected by hydrogel use.