Kevin Tiessen, Macdonald Col.-McGill Univ., Dept of NRS, McGill University, 21 111 Lakeshore Road, Ste. Anne de Bellevue, QC H9X 3V9, CANADA, Freddy Sancho, Centro de Investigaciones Agronomicas, Facultad de Ciencias Agroalimentarias, Universidad de Costa Rica, San Jose, Costa Rica, David Lobb, University of Manitoba, Department of Soil Science, University of Manitoba, Winnipeg, MB R3T 2N2, Canada, and Guy Mehuys, CANADA,McGill U., Dep. of Natural Resource Sci., Macdonald Campus Mcgill University, Ste Anne De Bellevue, QC H9X 3V9, CANADA.
Soil erosion from cultivated lands is a problem that continues to threaten the sustainability of both commercial and subsistence agriculture in many parts of the Americas. Despite decades of soil conservation programs, soil losses due to erosive processes continue. Previous erosion studies have focussed primarily on rainfall-induced erosion and/or the action of wind. However, these are not the only erosion processes that threaten the sustainability of agricultural production around the world. Recent studies have demonstrated that the direct movement of soil by tillage operations is another significant erosive process.
Soil degradation by tillage erosion is of greatest concern in regions where intensively tilled crops, such as potatoes, are grown on topographically complex landscapes. Potatoes are a major crop throughout North, Central and South America. However, despite its global importance (and erosive nature), no research has been conducted on the potential for, and impact of, tillage erosion within potato production under steepland agricultural systems in Latin America. The primary objectives of this study were to: 1) measure tillage translocation and tillage erosion by the ‘arado disco’ (disc plough), the most common mechanized primary tillage implement used in Costa Rica; and 2) examine the relationship between tillage erosion and caesium-137, soil nutrient, and organic carbon distribution patterns. Preliminary results suggest that the arado disco is a highly erosive implement. Soil movement downslope was three times greater than that moved upslope, with large soil losses occurring at the boundaries of the field. A highly significant relationship was observed between the mass of translocated soil and slope gradient for both up and downslope cultivation and downslope cultivation only. We suspect that the threat of soil erosion to the sustainability of potato production in the volcanic highlands of Costa Rica has been greatly underestimated because only water erosion has been seriously considered to date.
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