Crops in the Peruvian coastal flatlands that have been ruined by flooding, the eroded and deforested mountain sides having been unable to hold the rush of waters. - - 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