A pilot project on the potential contribution of palm-mat geotextiles to soil conservation

Abstract

Geotextiles constructed from Borassus aethiopum (black rhun palm) leaves are currently being investigated for their effectiveness in decreasing water erosion. The study aims to develop sustainable methods of soil conservation where the material meets selected criteria (readily available, simple and cost-effective to manufacture, provides immediate erosion control and possibly increases soil fertility and organic matter content). Grid mats were manufactured in a cottage workshop in The Gambia, West Africa. They are currently under investigation at the Hilton Experimental Site in Shropshire, UK. Eight runoff plots (10 × 1 m on a 15° slope) are being used, with duplicate treatments: (i) bare soil; (ii) grassed; (iii) bare soil with 1 m palm-mat buffer zones at the lower end of the plots; and (iv) completely covered with palm-mats. Results from one year of field study (2002-03) indicate sediment yield is 36·8 per cent from replicated covered plots and 35·9 per cent from the replicated buffer zone plots, compared to the control bare plots. Sediment yield equated to 0·45 t ha-1 from bare soil, 0·09 t ha-1 from grassed plots and 0·17 t ha-1 from both the covered and buffer zone plots. The results suggest palm-mat application as protective buffer strips is highly effective in temperate climates. Future work is intended to follow this pilot study and develop well-researched guidelines for practical field applications in other global regions, namely Africa, Southeast Asia and South America.