African Journal of
Agricultural Research

  • Abbreviation: Afr. J. Agric. Res.
  • Language: English
  • ISSN: 1991-637X
  • DOI: 10.5897/AJAR
  • Start Year: 2006
  • Published Articles: 6576

Full Length Research Paper

Using universal soil loss equation and soil erodibility factor to assess soil erosion in Tshesebe village, north east Botswana

Trust Manyiwa and Oagile Dikinya*
Department of Environmental Science, University of Botswana, Private Bag 00704, Gaborone, Botswana
Email: [email protected]

  •  Accepted: 01 July 2013
  •  Published: 08 August 2013

Abstract

Soil erodibility (K) factor in the Universal Soil Loss Equation (USLE), defines the resistance of soil to 
detachment by rainfall impact and/or surface flow force. Whilst there are a number of factors of erosion, 
this study aims to use erodibility factor and related length slope factor to assess soil erosional loss at 
field scale. To quantify soil erodibility the following properties were measured; texture, organic matter 
content and structural properties of the soil samples in eroded and non-eroded sites. Sub sampling was 
conducted in both eroded and non-eroded site and a total of six samples were collected in each site. In 
addition, slope length and slope angle were determined to evaluate the slope effect on the degree of 
soil loss associated with the K-factor. The measured or estimated K-factor value compared with the 
USLE K-based nomograph. The average soil erodibility (K-factor) was 0.031 and (t ha h ha-1 MJ-1mm-1
for eroded and non-eroded area, respectively. The high K-factor value in eroded area (almost doubled) 
was associated with low organic matter content (0.75%) compared to high organic matter in non-eroded 
(1.18%) as well as the significant slope (3°) in eroded than non-eroded areas (1°). The results also show 
that K-factor significantly (P<0.05) correlates with soil texture and organic matter due to their strong 
binding effect on aggregate stability and water infiltration hence enhanced particles’ resistant to 
detachment. Interestingly there was no significant difference in K- factor values between eroded and 
non-eroded areas. Further, the K-factor based nomograph over-predicted the measured K-factor value 
by 10 times in eroded and 19 times in non-eroded soil, with a strong correlation in eroded (r2
=0.77) than 
in non-eroded (r2
=0.10).
Key words: Universal soil loss equation (USLE), soil erodibility, soil erosion, soil properties, eroded and noneroded areas.