THE WATER HOLDING CAPACITY OF HYDROGEL AS AFFECTED BY CONCENTRATIONS OF DIFFERENT SALTS

The hydrogel used in the Brazilian agriculture, mainly in the forestry, fruits fields and growth media is being consolidated by its capacity of holding and releasing water (nutrient solution) to plants. This work aimed to study the water holding capacity (W) of hydrogel when hydrated into different nutrient solutions. This study was carried out at the Irrigation Technical Center of State University of Maringá. It was conducted in a 10 x 5 factorial way with 51 treatments and four replications and the randomized design. It was used as treatment in 10 fertilizers (potassium nitrate, calcium nitrate, urea, boric acid, monoammonium phosphate, ferrous sulphate, ammonium sulphate, zinc sulphate, copper sulphate and magnesium sulphate) and five doses (0.4; 0.8; 1.2, 1.6 and 2.0 g to each 500 g of distilled water). The distilled water and hydrogel treatment was used as control treatment. The hydrogel was hydrated for 24 hours for a later measure of its nutrient solution holding capacity. We noticed that besides the electric conductivity of nutrient solution, the different fertilizers interfered in the nutrient solution holding capacity. The urea did not interfere in the hydrogel holding capacity, but the zinc sulphate and mainly copper sulphate decreased expressively the water holding capacity.