Influence of Eichhornia crassipes fibre on water retention and cracking of vegetated soils

Abstract

Eichhornia crassipes also known as water hyacinth (WH) is listed among world's most invasive weed species. In tropical regions, green infrastructures have to undergo multiple drought cycles, which induces desiccation cracks and also lead to water-stressed condition of plants. The use of organic materials is advocated in green infrastructure for increasing water retention and ground-covering ability of vegetation. The main objective of this paper is to explore the influence of inclusion of waste WH fibres on hydraulic characteristics (water retention and cracking) of vegetated soils. Three soil series including bare (without vegetation) soil (BS), soil + grass (SG) and soil + grass + WH-fibre (SGWH) were tested for 73 days. The grass parameters stomatal conductance (SC), evapotranspiration (Etr), grass density (GD), shoot length (SL) and soil parameters (i.e. suction (ψ), volumetric moisture content (θ), crack intensity factor (CIF), evaporation (Er)) were monitored for all series. SGWH decreases the CIF potential of soil by 55·5 and 25% for BS and SG respectively. The inclusion of WH fibres increases the GD and SL as compared with SG. Furthermore, WH-fibre inclusion increased the soils’ water-retention capacity throughout the suction range due to its hydrophilic nature. The higher hemicellulose content and porous surface morphology of WH fibre, naturally improves soil's ability to retain water which is conducive to vegetation even under drought conditions.