Using palm-mat geotextiles for soil conservation on arable loamy sands in the United Kingdom

Abstract

To date, most studies on the effectiveness of geotextiles on soil erosion rates were conducted in laboratory experiments for <1 h. Hence, at Hilton, East Shropshire, UK, this study investigated the effectiveness of palm-mat geotextiles (Borassus and Buriti mats) in reducing rainsplash erosion, runoff and soil loss and changing selected soil properties under field conditions over two years (January 2007-January 2009). Mat-cover effects on rainsplash erosion were studied in two sets on a loamy sand soil (0o slope). In both sets, six randomly-selected plots (each 1 m2) were completely matcovered and six were bare. Unlike Buriti mats, Borassus mat-cover on bare soil significantly (P<0.001) decreased rainsplash erosion (by ~89%). Duplicate runoff plots (10 x 1 m on a 15o slope) had five treatments (bare, permanent grass, Borassus completely-cover, Borassus buffer strip and Buriti buffer strip). Using Borassus buffer strips (area coverage ~10%) on bare soil decreased runoff by ~71% (P>0.05) and soil erosion by ~92% (P<0.001). Borassus buffer strip, Buriti buffer strip and Borassus completely-covered plots had similar effects in decreasing runoff and soil loss. However, the longevity of Borassus mats was ~twice that of Buriti mats. Despite physical protection, runoff control and sediment entrapment, biomat buffer zones may considerably alter and protect flow direction by presenting barriers and creating several cross-drains. Except Borassus completely-covered plots, all plots had significant (P<0.05) increases in topsoil (0-5 cm) bulk density and decreased aggregate stability. However, buffer strips were more effective in trapping fine particles than Borassus completely-covered plots. No treatments had significant (P>0.05) effects on changes in pH, soil organic matter, total soil carbon or N. Plots with Borassus mats significantly (P<0.05) increased total P and decreased total Ca. Treatments had no significant effects on changes in total S, Mg, Zn, Cu, Fe, Mn, Mo or Cl concentrations. Borassus buffer strips can effectively conserve soil and water and improve and maintain selected soil properties, with results similar to Borassus completely-covered plots. The mechanisms explaining the effectiveness of buffer zones require further studies under varied pedo-climatic conditions.