Some 30% of world arable land has become unproductive, largely due to soil erosion. Considerable efforts have been devoted to studying and controlling water erosion. However, there remains the need for efficient, environmentallyfriendly and economically-viable options. An innovative approach has used geotextiles constructed from Borassus aethiopum (Black Rhun Palm of West Africa) leaves to decrease soil erosion. The effectiveness of employing palmmats to reduce soil erosion have been investigated by measuring runoff, soil loss and soil splash on humid temperate soils. Twelve experimental soil plots (each measuring 1.0 x 1.0 m) were established at Hilton, east Shropshire, UK, to study the effects of geotextiles on splash erosion (six plots completely covered with Borassus mats and six non-protected bare soil plots). Soil splash was measured (10/06/02-09/02/04; total precipitation = 1038 mm) by collecting splashed particles in a centrally positioned trap in each plot. An additional field study (25/03/02-10/05/04; total precipitation = 1320 mm) of eight experimental runoff plots (10 x 1 m on a 15o slope) were used at the same site, 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. Runoff volume and sediment yield were measured after each substantial storm. Results indicate that total splash erosion in bare plots was 34.2 g m-2 and mean splash height was 20.5 cm. The use of Borassus mats on bare soil significantly (P<0.05) reduced soil splash height by ~31% and splash erosion by ~50%. Total runoff from bare plots was 3.58 L m-2 and total sediment yield was 8.58 g m-2. Thus, application of geotextiles as 1 m protective buffer strips on bare soil reduced runoff by ~36% and soil erosion by ~57%. Although total soil loss from the completely covered geotextile plots was ~16% less than the buffer zone plots, total runoff volume from the completely covered plots was ~94% more than the buffer zone plots. Thus, palm-mat (buffer strips) cover on vulnerable segments of the landscape is highly effective for soil and water conservation on temperate loamy sand soils.

Previously, most studies on the effectiveness of geotextiles on soil erosion rates and processes were conducted in laboratory experiments for <1 h. Hence, at Hilton (52o33' N, 2o19' W), East Shropshire, UK, we investigated the effectiveness of employing palm-mat geotextiles (Borassus and Buriti mats) to reduce rainsplash erosion, runoff and soil loss under field conditions. This study is a component of the European Union-funded BORASSUS Project. The effects of Borassus mats on rainsplash erosion were studied for ~2 years (2002-2004), and re-established in January 2007 on a 0o slope. There were 12 experimental plots (six plots completely-covered with mats and six bare plots; each measuring 1.0 x 1.0 m). Runoff-plot studies were also conducted on the loamy sand soil at Hilton for 2 years (2002-2004) with duplicate treatments: (i) bare soil; (ii) grassed, (iii) bare soil with 1 m Borassus-mat buffer zones at the lower end of the plots and (iv) completely-covered with Borassus-mats. Each plot was 10 x 1 m on a 15o (26.6%) slope. To confirm the results, another set of experiments have been in progress at Hilton since January 2007, with one additional treatment (bare soil with 1 m Buriti-mat buffer zones) compared with the earlier experiment. Runoff and soil erosion were collected from each plot in a concrete gutter, leading to a 0.02 m3 (20 liters) capacity receptacle placed inside a 0.14 m3 (140 liters) capacity container. Results (06/10/02-02/09/04; total precipitation = 1038.3 mm) showed Borassus mats on bare soil reduced total rainsplash erosion by ~50% compared with bare plots (9.64 kg m-2; 1.97 lb ft-2). The use of Borassus mats on bare soil (during 01/22/07-01/21/08; total precipitation = 919.2 mm) also reduced soil splash erosion by ~90%. During 03/25/02-05/10/04 (total precipitation = 1319.8 mm) complete cover of Borassus mats on bare soil reduced total runoff by ~19% and soil erosion by ~64%. Furthermore, Borassus mats as 1 m buffer strips on bare soil reduced runoff by ~36% and soil erosion by ~57%. During 01/08/07-01/14/08 (total precipitation = 923.4 mm), plots with Borassus and Buriti mats as buffer strips on bare soil reduced sediment yield by ~93 and 98%, respectively, and runoff by ~83 and 63%, respectively. Buffer strips of Borassus mats were also as effective as complete cover of the same mats. Thus, utilization of palm-mat geotextiles as buffer strips on bare plots (area coverage ~10%) is highly effective for soil and water conservation.

Despite palm-leaf geotextile mats having the potential to advance soil conservation technologies, field studies using geotextiles as complete cover and buffer strips in reducing rates of soil erosion by water are limited. Hence, the utilization of these mats as a potential soil conservation technique is investigated at Hilton, east Shropshire, UK (52°33′5.7″N, 2°19′18.3″W). Geotextile mats constructed from Borassus aethiopum (Borassus palm of West Africa) and Mauritia flexuosa (Buriti palm of South America) leaves are termed Borassus mats and Buriti mats, respectively. Field experiments have been conducted at Hilton since January 2007, to study the effects of emplacing Borassus and Buriti mats on the erosion of a loamy sand soil. Two sets (12 plots each) of experiments were established to study the effects of Borassus and Buriti mats on splash height and splash erosion. In both sets, 6 randomly-selected plots were completely covered with mats, and the rest were bare. Ten runoff plots (10 × 1 m on a 15° slope) were also established, with duplicate treatments to study the effectiveness of these mats for soil and water conservation. The treatments were: (i) bare soil; (ii) permanent grassed; (iii) bare soil with 1 m Borassus mat buffer zones at the lower end of the plots; (iv) bare soil with 1 m Buriti mat buffer zones at the lower end of the plots and (v) completely covered with Borassus mats. Results (during 22/01/07–21/01/08; total precipitation = 919.0 mm; n = 22 sets of measurements) indicate that Borassus mat-cover on bare soil significantly (P < 0.05) reduced total soil splash erosion by 90% compared with bare plots (24.81 kg m−2). Plots with Borassus mats had 51% less mean splash height than bare plots (n = 21 sets of measurements). However, Buriti mat-cover on bare soils had no significant (P < 0.05) effect on soil splash height or splash erosion. Results of runoff plots (08/01/07–14/01/08; total precipitation = 923.4 mm; n = 29 sets of measurements) showed permanent grass plots had the smallest runoff coefficient and the largest sediment yield reduction effectiveness (SYRE). Total runoff from the Borassus buffer zone plots (4.1 L m−2) was 83% less than the bare plots and total sediment yield was 93% less than the bare plots (2.32 kg m−2). Although, Borassus buffer zone plots had similar effects in reducing soil loss to Borassus completely-covered plots, the later treatment yielded 50% more runoff. Borassus buffer strip plots had less SYRE than the Buriti buffer zone plots. Mass per unit area and thickness of both geotextiles decreased after 3 months of surface application. However, moisture sorption depth and cover percentage of both geotextiles increased. Hence, it is recommended to cover palm-mat geotextiles as buffer strips for soil and water conservation on erodible moderate slopes.

Field and laboratory experiments has shown that geotextile mats made from palm leaves are an effective, sustainable and economically-viable soil conservation method, with huge global potential. The EU-funded BORASSUS Project (2005-09; Contract Number INCO-CT-2005-510745) is evaluating the long-term effectiveness of biogeotextiles in controlling soil erosion and assessing their sustainability and economic viability. These experiments are in progress in 10 countries, both in the ‘industrial north’ (in Europe) and in the ‘developing south’ (Africa, South America and South-East Asia). This paper discusses the significance of geotextile palm mats in European countries (Belgium, Hungary, Lithuania and the UK). Geotextile mats were effective in reducing splash erosion, runoff and soil erosion on arable sloping land in Shropshire, UK. The use of Borassus-mats on bare soil reduced soil splash height by ~31% and splash erosion by ~42%. The application of Borassus-mats as complete cover on bare soil reduced runoff by ~49% and soil erosion by ~75%. Borassus and Buriti mats as 1 m buffer strips reduced runoff by ~56 and 34%, respectively, and soil erosion by ~83 and 77%, respectively. Results from selected types of vineyards in Hungary suggest that the geotextile mats are effective in reducing soil erosion, particularly erosive rainfall. The geotextiles mats are also helpful in maintaining moisture and temperature conditions in the surface soil at levels particularly conducive to the establishment and growth of young plants. Experiments in Lithuania show that geotextile mats are effective in encouraging the establishment and growth of natural vegetation, thereby reducing erosion on roadside slopes. Simulated experiments in controlled laboratory conditions in Belgium suggest that palm-leaf geotextiles are effective in increasing infiltration rates and reducing interrill runoff and erosion rates on medium (i.e. 15%) and steep (i.e. 45%) slope gradients. The effectiveness of geotextile mats when used as technical materials for the construction industry in ground strengthening was investigated. Generally, the tensile strength of the Buriti mats was approximately twice that of the Borassus mats. The tensile strength of the palm-leaf geotextile mats is influenced by the mat strip formation pattern. Research and development activities of the BORASSUS Project have improved our knowledge on the effect of palm geotextile mats on the micro- and macro- soil environments and at larger scales through controlled laboratory and field experiments in diverse environments.