one of the 12 soil orders in the U.S. Soil Taxonomy (soil). Oxisols form principally in humid tropical zones under rainforest, scrub and thorn forest, or savanna vegetation on flat to gently sloping uplands. They are typically found on old landscapes that have been subject to shifting cultivation for millennia. Intensive plantation agriculture is possible if lime and fertilizers are applied with careful management to prevent erosion. Oxisols occupy 7 percent of the nonpolar continental land area on Earth, mostly in the equatorial regions of South America and Africa.