These contour terraces, being built by women, yield 70 percent more potatoes per hectare than do the old sloping fields. - - Soil Conservation in the Andes. Terraced agriculture was practiced on the slopes of the Andes by the Incas, but with the passage of time these terraces fell into disrepair as ploughing was introduced. Farmers found it was easier to plough up and down a slope rather than following the la