The growing of crops for a few years on selected and cleared plots alternating with a lengthy period of vegetative fallow when the soil is rested. Cultivation consequently shifts within an area that is otherwise covered by natural vegetation. The intensity of rotation, expressed as R, is less than 33 percent. R is calculated as the years of cultivation multiplied by 100 and divided by the length of the cycle of land utilization. This indicates that less of 33 percent of the area which is available for farming, is under cultivation. In other words, the land is cultivated for less than 33 percent of the year.; A farming practice whereby a particular piece of land is cultivated for some years and then abandoned for a period sufficient to restore its fertility by natural vegetative growth before being re-cultivated.