Cellulose-Based Hydrogels for Agricultures

Abstract

The cellulose-based hydrogel characteristics such as biodegradability and biocompatibility mark its suitability toward agriculture application. In agriculture, the hydrogels are specifically used as water reservoirs, phyto-pharmaceuticals (protected cultivations, soilless cultivations, and open-field cultivations), pesticide release, and nutrient release to the soil. The hydrogels are impregnated by fertilizer components (e.g., soluble phosphate, potassium ions, nitrogen compounds), and those chemicals which are trapped in a polymer network cannot be immediately washed out by water but gradually released into the soil and then absorbed by plants. The hydrogels are classified as two classes, i.e., soluble and insoluble hydrogels. The soluble variety is used to reduce irrigation erosion in fields. The insoluble variety is used in gardens, nurseries, and landscapes to reduce frequency of watering. They are produced either in the form of powder or of a bulky material with a well-defined shape and a strong memory of its shape after swelling. The material can be charged with small molecules, such as nutrients, to be released under a controlled kinetic. The main advantage is controlled release of water, longtime maintaining soil humidity, increase of soil porosity, and therefore better oxygenation of plant roots. The agricultural hydrogel behavior depends on various factors such as temperature, relative humidity, soil type, stress, etc. The performance of the gels is evaluated through different techniques like moisture retention, nutrition release rate, biodegradation rate, relative humidity, and temperature maintained in the soil. Several studies reveal that the amount of moisture retained in the soil is dependent on the concentration of the cellulose-based superabsorbent matrices. Those SAPs/hydrogels were used in specific agriculture application such as nutrient release, conservation of land, and drought stress reduction due to several advantages. The advantage of cellulose-based hydrogels include eco-friendliness, high water holding capacity, low cost, and biodegradability. Moreover, their application helps reduce irrigation water consumption, causes lower death rate of plants, improves fertilizer retention in soil, and increases plant growth rate.