Soil erosion under different management of coffee plantations in the Venezuelan Andes

In the Venezuelan Andes the traditional way of cultivating coffee has been beneath shade, using the variety Coffea arabica var. arabica. However, since 1975 the government has promoted a change from this type of cultivation to 'sun coffee' which implies the elimination of shade trees and the replacement of old coffee trees with varieties such as C. arabica var. bourbon and var. caturra. in order to analyze the possible consequences of this change to the soil erosion in the sloping coffee plantation, a study was carried on in the region of Canagua, in the State of Merida. The results were obtained from studying the successive loss of the mineral fraction and runoff, measured in plots situated in (1) a 16-17 year old shade plantation, (2) the same plantation in the first and second years following its transformation to a 'sun plantation', and (3) a seven to ten year old sun plantation. The results show that: (a) Despite the larger losses in the sun plantation, both types of management show very low erosion after the plantation has become established, (b) the loss of the mineral fraction less than 4 mm represents the greatest difference between erosion in the sun and shade plantation in full production, (c) the losses of < 4 mm fraction during the first year following implantation of sun coffee are four times greater than those found in the old shade plantation, and (d) there is a positive relation between erosion and human activities within the plantation, contrasting with a non significant correlation between erosion and runoff and rainfall erosivity.