Effect of synthetic hydrogel on soil properties and survival of Melia volkensii seedlings in the arid and semi-arid lands of Kenya

Abstract

Arid and semi-arid lands (ASALs) face challenges related to soil degradation, water scarcity and reduced agricultural productivity; exacerbated by climate change. This study assessed the effect of synthetic superabsorbent polymers (hydrogels) on agronomy related soil properties and survival of Melia volkensii seedlings in arid and semi-arid zones of Kenya. Treatments included four hydrogel concentrations (0, 1.0, 3.0 and 6.0 g L-1); and three application modes (Below Roots, whereby hydrogel soil mixture was placed at the bottom of the pit and not in contact with the roots of the seedlings; Within Roots, whereby the hydrogel soil mixture was directly in contact with tips of the roots of the seedlings; and Complete Mix, where the seedlings roots were fully covered in the hydrogel soil mixture) over 26 weeks. The treatments were laid out in randomised complete block design, in four replications and the study repeated three times. Results revealed significant (P<0.05) improvements in soil temperature and pH stability, with hydrogel application rates. Survival rates of seedlings peaked at 95% of mean (n=19; out of 20) when the rate of 6.0 g L-1 hydrogel was used in the Complete Mix (C) mode. No significant association (P>0.05) was found between hydrogels and the soil’s electrical conductivity (EC); while a linear trend suggested predictable changes in EC with varying levels of hydrogel application. The findings highlight the potential of hydrogels to enhance soil water retention, mitigate the impacts of water scarcity, and promote sustainable agricultural practices in ASALs, and has the potential to contribute to climate smart agricultural adaptation.