The agronomic challenges associated with acid soils have brought plant breeders into a research arena often considered a principal concern of soil fertility and plant nutrition specialists. Their approaches, while quite different, have the same intent: to bring actual crop yields closer to potential yields by modifying the plant genotype or the soil environment. Soil acidification places productivity of currently cultivated lands at risk. As cultivation continues, the likelihood increases that nutrient toxicities and deficiencies associated with low pH will erode yield potential. Nowhere is this more apparent than in the surface-acidified areas of the U.S. southern Great Plains, site of some of the world’s most intensive wheat (Triticum aestivum L.) production. As in other wheat-growing areas, such as Australia and South Africa, natural soil acidification is accelerated by removal of basic cations through the harvesting of vegetation and grain. Even during a period of the most intensive liming application in the U.S. Great Plains, the proportion of wheat fields with strongly acidic pH has actually increased, while those with neutral or

creased soil acidification faster than the addition of lime has diminished it.