Effect of biomats on runoff and water erosion under selected agro-environmental conditions

Abstract

© 2010 Nova Science Publishers, Inc. Available studies do not allow comparison and quantification of the effects of organic fibre-based geotextiles (biomats) on runoff and water erosion rates under different agro-environmental conditions. Hence, this Chapter addresses this issue by comparing soil loss data obtained from field experiments (using different types of biomats) conducted in the United Kingdom, Lithuania, Hungary, Brazil, South Africa, China, Thailand and Vietnam, which are all integral components of the European Union funded BORASSUS Project. Palm-mat geotextiles manufactured from leaves of Borassus aethiopum (Black Rhun palm of West Africa), Mauritia flexuosa (Buriti palm of South America) and Hyphaene natalensis (Lala palm of South Africa) are termed Borassus, Buriti and Lala mats, respectively. Borassus and Buriti mats were used by the European countries. In the UK, both mats were used on bare soil with 1 m buffer zones at the lower end of 10 m plots. Lala mats were used in South Africa. Biomats constructed using indigenous local materials, such as bamboo, rice straw and maize stalks, were used in South-East Asia. Only Buriti mats were used in Brazil. Biomats were used on bare plots in Brazil, South Africa and the European countries. However, in South-East Asia, different crops were grown on the biomat-covered plots. Results suggest that palm-mats were very effective for soil conservation in all locations and the effectiveness for decreasing water erosion rates was in the range of ∼66- 98%. In the UK, total runoff and sediment yield (during 8 January 2007-14 January 2008; total precipitation = 931.4 mm) from the Borassus buffer zone plots (area coverage = 10%) were ∼83 and ∼93% less, respectively, than the bare plots. Indigenous bioresources (rice straw mats in China, bamboo mats in Thailand and Vietnam and maize stalk mats in Vietnam) were also very effective (∼67-98%) in conserving soil. The effectiveness of biomats mainly depended on rainfall characteristics (amount, duration and intensity), soil conditions (slope, texture and soil organic carbon content), the canopy cover and the percentage of mat cover. In Hungary and China, plots with 50% biomat-cover had ~75- 96% less soil loss than bare plots. In most months with low rainfall in Hungary and the UK, runoff volume was greater from plots with biomat-cover than from bare soils. This was not the case in Lithuania and Brazil, where Borassus and Buriti mats decreased runoff and sediment yield compared with bare soil in all rainfall events. Results from the UK showed that plots with buffer strips of Borassus and Buriti mats had similar effects in reducing sediment yields as completely-covered plots of the Borassus mats. Thus, biomat-cover on vulnerable segments of the landscape (such as bare soil on convex slopes and/or erodible soils) is highly effective for soil and water conservation.