Fecha de publicación: -- Fuente: WIPO "tomato" The present invention relates to a biopolymer composition for generating a superabsorbent hydrogel comprising at least a) a matrix formed by a mixture of polysaccharides; b) a hydrolysable tannin-derived physical cross-linking agent, and c) a chemical crosslinker of natural origin. This biopolymer composition is presented in dry powder form, which forms the superabsorbent hydrogel when applied to soil and in contact with water, the hydrogel having a water absorption capacity above 100 g/g. Moreover, in addition to water, said hydrogel can also store substances dissolved in water, such as salts, fertilisers or agrochemical products. As a result, it is suitable for releasing water and other agronomically useful substances.