Effect of water absorbing polymer amendment on water retention properties of cohesionless soil

Water absorbing polymers (WAP) are chemically cross-linked structures formed with different hydrophilic groups (hydroxyl, amine, and carboxyl) capable of absorbing and storing a huge quantity of water within its three-dimensional network. Due to its high water absorbing capacity, these polymers find applications in improving the water retention behavior of the soil, particularly in arid and semiarid regions. Therefore, it is very important to study the improvement in water retention behavior of soil with different concentration of WAP amendment. The objective of this work is to investigate the effect of different rates (0, 1 g, 2 g, and 4 g/kg of soil) of WAP application on the water retention behavior of a locally available cohesionless soil. For this purpose, water retention characteristics curve (WRCC) of the soil was obtained by monitoring the soil suction and water content variation from saturated state to air-dried condition. The saturated water content and field capacity of the soil was found to be increased by 1.9 times and 2 times with highest amount of WAP addition than the control condition (without WAP). The results indicated that the water retention properties as well as the plant available water content (PAWC) significantly increased with WAP application, which indirectly indicates an increase in plant survival time in water stress conditions.