Hydrogels in Agriculture: Prospects and Challenges

Hydrogels retain substantial quantities of both water and nutrients within their three dimensional polymeric network. As such they have the ability to modify the local micro-environment of seeds/seedlings to enhance their growth outcomes. In terms of both safety and sustainability, the use of natural biopolymer based hydrogels is more advantageous. The network structure of hydrogels is typically formed by physical interaction and/or chemical crosslinking between polymer chains. The nature, strength and extent of crosslinking can be tailored to customize gel properties (such as mechanical strength, porosity and swelling behaviour) to suit a given type of application. This review highlights the use of hydrogels in agriculture where they (i) provide drought resistance to crops, (ii) act as reservoirs for critical nutrients, (iii) function as seed coating agents and (iv) improve transplantation success rate. The biodegradability and environmental compatibility of hydrogels for a range of applications in the farming sector is also discussed. Finally, the challenges of modifying hydrogels to suit specific agricultural applications are elaborated including issues that need to be overcome to exploit the full potential of these novel soft materials in sustainable farming practices of the future.