Chapter 12 - The application of natural polymer-based hydrogels for agriculture

Abstract

Globally, agriculture is the largest consumer of water, creating some challenges to limiting water usage. Natural polymers have received have attention for agricultural applications in respect to their excellent biodegradability, biocompatibility, bioactivity, and hydrophilic character. Natural polymers can be classified into three major classes consistent with their structure: (1) polyesters, (2) proteins, and (3) polysaccharides. This chapter gives an overview of polysaccharide-based hydrogels, their structures in the biological receptors present in plant systems, and applications in agriculture. Polysaccharides in their native form cannot be cross-linked. Thus, this chapter is concerned with the derivatives of polysaccharides and their incorporation with other synthetic polymers to produce valuable polysaccharide hydrogel materials with excellent properties for use in agriculture as soil conditioners and fertilizer carriers. Agricultural polysaccharide hydrogel (APH)s enhance the water-holding capacity and porosity of soil, as well as improving plant viability and total vegetable yield, which affords a conducive ecosystem for increasing flora. In this chapter, the significance of polysaccharide hydrogels and future trends for using them in the agricultural sector are discussed. The use of APH as a fertilizer carrier has shown slow release of fertilizers and controlled-release fertilizers (CRFs) that reduce the quantity of fertilization needed and are cost effective compared with conventional fertilizers. Ideally, CRFs release nutrients in response to several parameters being changed, this is known as a “smart” fertilizer. In addition, loaded fertilizers or those capsulated by nanostructure biodegradable hydrogel are known as “nano” fertilizers that are easily root diffused and speared in all plants causing enhanced crop yield. In general both “smart” fertilizers and “nano” fertilizers offer advantages compared to conventional fertilizers. This chapter highlights current researches in using APHs as a plant defense against insects, fungi, bacteria, pathogens, and desiccation, and the future impacts they may have.