Ground cover by three crops cultivated on marginal lands in Southwestern Nigeria and implications for soil erosion

Abstract

Resource-poor farmers in developing nations cultivate marginal lands, thereby exacerbating the problem of soil degradation through poor plant growth and ground coverage. An assessment of ground cover under such a practice will provide a guideline for soil conservation. Ground cover by leguminous cover crops (e.g., Mucuna pruriens, Pueraria phaseoloides and Vigna unguiculata), associated with yam, maize and rice was measured in three different experiments in southwestern Nigeria using beaded-string method while leaf area was measured using a flat-bed scanner. The leaf area was used in obtaining equivalent of ground cover fraction from the leaf area index. Ground cover by yam was <15% at 10 wap (weeks after planting) in the second year of cropping and was <25% at 25 wap in the fourth year of cropping. Maize+legume ground cover was <40% at harvest (14 wap) in the third year of cropping. At 10 wap, rice "WAB 189" had significantly higher ground coverage (43.8%) than "ITA 321" (32.5%) and "WAB 450" (33.2%). Both the beadedstring and scanning methods were close in the values of ground cover fractions for upland rice, but not for maize, indicating that prediction equation cannot be generalized for crops with different morphology. Cover cropping and residue mulching are good practices for low-intensity cultivation of marginal lands to achieve soil conservation effectiveness.