Preliminary study on improvement of soil water retention characteristics by Spirulina

Abstract

Spirulina is a planctonic blue-green algae classified as cyanobacteria, which inhabits strongly alkaline water body in the tropics and subtropics. Further, the microalgae including the spirulina secretes Extracellular Polymeric Substances (EPS). Since the improvement of the soil water retention characteristics is necessary for desert greening and prevention of desertification in arid and semi-arid area, the current study aims to study on the effect of application of the spirulina and the spirulina derived EPS on the improvement of water retention characteristics of soils.

Three different types of soil were used. One is Toyoura sand, and the others are collected from Kourimalei and Ali-fareen, Djibouti. The texture of those soils were Sand, Silty Loam, and Sandy Loam, respectively. For those soils, 0.5 and 1.0% by mass of the spirulina powder and 1.0% by mass of the EPS powder were treated respectively. A significant increase in the readily available water content for crop growth was observed under both the spirulina and the EPS treatments for the Toyoura sand. Although further research is required, it is suggested that the effect of the application of the spirulina and EPS on the soil water retention depends on the texture.