Hydrogels: An Effective Tool to Improve Nitrogen Use Efficiency in Crops

Abstract

Hydrogels are hydrophilic polymeric materials with three-dimensional(3D) network structures physic and/or chemically crosslinked. They can absorb large amounts of water or aqueous solutions for a short period of time. When the hydrogel is loaded with a drug and meets an aqueous medium, the water penetrates the system and dissolves the drug. To improve the nitrogen use efficiency by plants, controlled release fertilizers are developed with hydrogels as matrices. In particular, biodegradable polymers such as starch, xanthan, chitosan, cellulose derivatives, pectin and their mixtures have been essayed to avoid residues in soils. In addition, the superabsorbent capacity of the hydrogels improves the retention of fertilizers in the soil, reduces water losses through evaporation and decreases the frequency of irrigation.In this chapter, the behavior of different hydrogels to improve the availability of nitrogen by the plants during their crop cycle will be reviewed.