Effectiveness of tropical grass species as sediment filters in the riparian zone of Lake Victoria
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Date
2012
Journal Title
Journal ISSN
Volume Title
Publisher
Soil Use and Management
Abstract
The effectiveness of tropical grass species in strips of different length in trapping sediment from
cropland was assessed, and the influence of filter length was determined. The assessment was made
under natural rainfall which induced sheet and rill erosion in run-off plots and then using simulated
run-off which caused concentrated erosion. The evaluated grasses were elephant grass, lemon grass,
paspalum and sugarcane. Run-off plots were on a 10% slope in a randomized complete block design
replicated three times. Filter lengths were 2.5, 5 and 10 m against a 10-m-long sediment source area
planted with maize on a clay loam soil. The results show that sediment trapping effectiveness (TE)
increases nonlinearly with increasing filter length for all grasses. Under natural rainfall, more than 70%
of sediment was trapped in the first 5 m, and lengthening the strip to 10 m only resulted in a marginal
increase in TE. With concentrated run-off, more than 70% of sediment was trapped in the first 5 m
and lengthening the strip to 10 m resulted in a significant increase in TE. Paspalum and lemon grass
performed significantly better than other grasses (P < 0.05), owing to their spreading growth pattern
over the soil surface. Paspalum also has the highest root density in the upper 0.3-m layer of the soil
followed by lemon grass, hence offering the greatest resistance to erosion from concentrated flow. The
results demonstrate that tropical grass filter strips provide a viable means for reducing the sediment flux
from cropland.
Description
Keywords
Tropical grass species, Sediment trapping, Lake Victoria basin
Citation
Wanyama, J., Herremans, K., Maetens, W., Isabirye, M., Kahimba, F., Kimaro, D., ... & Deckers, J. (2012). Effectiveness of tropical grass species as sediment filters in the riparian zone of Lake Victoria. Soil Use and Management, 28(3), 409-418. doi: 10.1111/j.1475-2743.2012.00409.x