Abstract:
Plant roots may have a strong erosion-reducing effect. However, little is known about root
characteristics of tropical plants used for erosion control. A study was thus conducted in
the Western Usambara Mountains, Tanzania to investigate rooting characteristics of Guatemala grass (Tripsacum andersonii), Napier grass (Pennisetum purpureum) and
Tithonia shrub (Tithonia diversifolia), also referred to as wild sunflower, and to evaluate
their potential for erosion control. For each plant species, mean root diameter (D), root
density (RD), root length density (RLD) and root area ratio (RAR) were assessed for six
plants in each species and relative soil detachment rate (RSD) predicted. Mean RD
values in the 0 - 0.4 m soil depth for Majulai village and Migambo village respectively
3
3
were 50.9 and 58.6 kg/m for Guatemala grass, 30.4 and 31.3 kg/m for Napier grass and
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3
22.1 and 23.0 kg/m for Tithonia shrub. RLD values were 35.9 and 45.0 km/m for
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3
Guatemala grass, 31.3 and 150.0 km/m for Napier grass and 10.5 and 6.4 km/m for
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-14
Tithonia shrub. Predicted RSD values were 4.43*10
and 1.20*10
for Guatemala
-5
-4
-3
-4
grass, 6.10*10 and 2.74*10 for Napier grass and 4.43*10 and 2.24*10 for Tithonia
shrub in the 0 - 0.4 m soil depth. The results indicate that Guatemala grass has a higher
potential to reduce soil erosion rates by concentrated flow as compared to Napier grass or
Tithonia shrub in the 0 - 0.4 m soil depth. These findings have implications on the
selection and use of appropriate plants for soil erosion control.
