Remediation of Abandoned Saline Soils UsingGlycyrrhiza glabra: A Study from the Hungry Steppes of Central Asia

Abstract

Large expansion of the irrigated area in the Aral Sea Basin has exacted a substantial toll on land and water resources in the region. Elevated water tables associated with poor irrigation management and inappropriate drainage infrastructure have resulted in significant secondary salinisation of crop lands resulting in declining cotton and wheat yields and eventual abandonment of lands. Costs associated with the installation of appropriate drainage infrastructure in order to reclaim these areas are prohibitive and hence alternative approaches are required that can be adopted by resource poor farmers. In the current study the potential use of Glycyrrhiza glabra (common name liquorice) to reclaim abandoned saline areas was assessed over a four year period before being returned to a cotton/wheat crop rotation. Two adjacent abandoned fields of 10 and 13 ha respectively were selected for the study on which two treatments were imposed, namely, a control that was maintained as a bare fallow between 1999 and 2003 and a treated plot where liquorice was established over this period. High quality livestock forage with a protein content of 12% was cut from the liquorice plot with dry matter yields ranging from 3.66 (±0.06) to 5.11 (±0.17) t ha⁻¹. In addition, root dry matter yields of 5.63 (±1.19) to 8.55 (±0.82) t ha⁻¹ were recorded, this plant component being used in the preparation of herbal medicines and soft drinks. At the end of four years both plots were returned to a wheat and cotton crop rotation. Yields of wheat on the control and treated plots were 0.87 (±0.05) and 2.42 (±0.02) t ha⁻¹ respectively. Similarly substantial increases in cotton were observed with the control and treated plots yielding 0.31 (±0.01) and 1.89 (±0.18) t ha⁻¹. These levels of production on the treated plot exceed the district average for wheat and cotton of 1.75 and 1.5 t ha⁻¹ respectively, clearly showing the positive benefit associated with the growing of liquorice. Water table levels after four years were maintained below the critical level of 2.5 m in the treated plots whilst rising to within 1.99 m from the surface in the control. Salt content of the soil in the treated plot declined over the study while those in the control increased. This preliminary study has clearly demonstrated the ameliorating affect of liquorice in bringing abandoned salt affected soils back into production that is low cost and could be adopted by resource poor farmers.