Reinforcement Effect of Plant Root System on Collapse of Earth Canals and Levee Slopes in Ghana

Abstract

In inland valleys of Ghana, where the development of paddy fields has been promoted, the earth canals and levees have not been functioning satisfactorily due to frequent heavy rainfall and poor maintenance. Thus, we have been working on the development of reinforcement technology by planting cover plants in the levees and irrigation canals. The above-ground part of cover plants is associated with the cover effect and the under-ground part is related to soil binding effect. The above-ground to under-ground ratio was 2.54 for Chrysopogon aciculatus, 4.17 for Cynodon dactylon, and 4.93 for Stenotaphrum secundatum. Based on the lowest ratio obtained for Chrysopogon aciculatus, it was verified that the development of under-ground part must be prioritized. The results of pull-out strength test revealed that the root system takes more than one year to develop in order to bind the soil. Measurements at 15 months after planting showed a significant difference between no planting work plot and planting work plots. Among the 3 plants, Chrysopogon aciculatus was the most superior and recorded the highest value of 410 N. Although the strength of soil binding per gram of root weight is weak, the dense growth of many roots enlarged the pull-out strength.