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2024

Woody species alongside earth contour bunds enhance the soil water-infiltration capacity in the Sahel, West Africa

Ky-Dembele, C.; Savadogo, P.; Bengaly, A.; Bargues-Tobella, A.; Diarra, M.; Winowiecki, L. A.; Bayala, J.; et al.

Abstract

Land degradation, including the loss of tree, forest and vegetation cover, and its related  loss  of  water  availability  are  the  main  constraints  affecting  the  rainfed  agricultural systems in West African Sahel and dry savanna. Therefore, farmers are implementing various soil and water conservation techniques such as zaï pits, half- moons, contour stone and earth bunds to improve crop production through reduced erosion and enhanced water retention. This study explores the effect of woody and herbaceous vegetation established along earth contour bunds on soil infiltration  capacity  in  southern  Mali.  The  soil  infiltration  measurements  were  carried out from September to December 2019 using single ring infiltrometers up- slope and down- slope of the bunds built on contour lines in 2015 and 2016 with four  types  of  vegetation:  (1)  natural  annual  herbaceous  vegetation;  (2)  planted  Andropogon gayanus (perennial grass); (3) planted Gliricidia sepium (woody spe-cies) and (4) planted Acacia colei (woody species). The field- saturated hydraulic conductivity (Kfs) was estimated from the infiltration data and subjected to sta-tistical analysis to compare the effect of the four types of vegetation on soil infil-tration  capacity.  The  results  revealed  significant  differences  in  infiltration  rate  and Kfs between the four vegetation types. The highest infiltration rate and Kfs were observed for earth contour bunds reinforced with woody species G. sepium(299.5 ± 0.6;  45.3 ± 1.4 mm h−1), followed by A. colei (232.2 ± 2;  38.2 ± 1.6 mm h−1). These were followed by the grass A. gayanus (189.4 ± 2.5;  33.0 ± 1.7 mm h−1) and natural annual herbaceous vegetation (132 ± 2.3;  20.7 ± 1.9 mm h−1). In addition, soil water- infiltration rate and Kfs were higher for down- slope compared to up- slope  areas  for  the  two  woody  species.  In  practice,  it  is  appropriate  for  farmers  to  reinforce  contour  bunds  with  woody  species  and  perennial  herbs  given  the  beneficial effect on soil water infiltration and retention capacity and the expected socio- economic benefit they can get from them.

Keywords

field-saturated hydraulic conductivity; soil and water conservation practices; soil degradation; soil erosion

Published in

Soil Use and Management
2024, Volume: 40, number: 1, article number: e13035