Impactos da salinidade no hidrogel utilizado como melhorador de solo no semiárido

Abstract

Hydrogels are hidroabsorventes polymers that have the ability to retain, store and release water to the plants and which have been applied in various fields of knowledge. In agriculture, it is used as soil conditioners, especially in arid and semiarid regions in order to provide greater water storage in the soil. External factors can intervene in the efficiency of the hydrogel in the soil, being the salinity of these factors. It is assumed that the excess salts in the medium reduces the hydrogel water retention and that the product can release substances that increase the salinity of soil. In this study objectives were to evaluate the effect of increasing the electrical conductivity (EC) and assess attributes salinity in the soil that received the hydrogel and water passing through the soil. Two experiments were conducted, the first under laboratory conditions, with a completely randomized design, four treatments (solutions with EC 0.5, 1.5, 3.0, and 4.5 dS m-1) and four replications. In this experiment, 500 ml of water with different ECs were used to saturate 1g hydrogel polymer. After 24 hours of saturation, the water was gravity drained and the material was weighed. The second experiment was conducted in a greenhouse with a completely randomized design in a 2x4 factorial design with four replications. They evaluated the hydrogel polymer (0 to 4.0 grams of the hydrogel) and four salt solutions (0.5, 1.5, 3.0 and 4.5 dS m-1). The experimental units were comprised of PVC column with 10 cm diameter and 50 cm length, filled with soil to which has been applied or not the hydrogel. In each column was cultivated maize and, after a week of germination, irrigation was initiated with saline solutions. The evaluated attributes were: volume of water drained, soil moisture, electrical conductivity, sodium and potassium in the drained soil and water, as well as soil moisture. The stored capacity of the hydrogel decreases with water salinity irrigation water, increasing the volume of water drained. The EC, both the water drained as soil was greater in treatment with hydrogel. The content of Na and K vary by many conditions, which may have influenced the saline solution for its excess Na or the hydrogel itself because it contains potassium in their training. In conclusion, the polymer water retention capacity is compromised by salinity. Saline resulted in soil salinity, and this higher salinity soils that received treatment with hydrogel.