Chapter Six: Management of Soil Acidity of South American Soils for Sustainable Crop Production

• Published in: Advances in agronomy Vol. 128; p. 221
• Main Authors: Fageria, Nanda K, Nascente, Adriano S
• Format: Journal Article
• Language: English
• Published: San Diego Elsevier BV 01.01.2014
• Subjects: Agronomy; Soil sciences; Sustainable agriculture
• ISSN: 0065-2113; 2213-6789
• DOI: 10.1016/B978-0-12-802139-2.00006-8

A burgeoning global population is creating unprecedented demands on agriculture to produce ever-increasing amounts of food, fiber, and fuel. In this context, South America has the largest land area in the world that can be used to meet food and fiber demand. In addition, South America also has the largest amount of fresh or potable water globally and favorable climatic conditions throughout the year, which further enhances the role of this continent in providing world food supply. The Brazilian Cerrado, or savanna, a total area of about 205 million ha of acid soils is a good case in point. Similarly, Colombia, Bolivia, Venezuela, Peru, and Ecuador also have large land areas, which can be utilized for crop production. However, the major soils of this continent are acidic and infertile. Hence, liming and fertilizer application are essential. Soil acidity is mainly caused by leaching of bases from soil profile, soils may be acidified with acid deposition from the atmosphere, use of ammoniacal fertilizers, by proton generation in the soil, mineralization of organic matter, intensive crop cultivation, and from N2 fixation by legumes. Important indices that are used in correcting soil acidity for maximizing crop yields are pH, base saturation, aluminum saturation, acidity saturation, calcium saturation, magnesium saturation, and potassium saturation. Sometimes, calcium/magnesium ratio, calcium/potassium ratio, and magnesium/potassium ratio are also used as soil acidity indices in crop production. Optimal values of these soil acidity indices varied with type of soil, crop species, and cultivar or genotypes within species. Management practices that can be adopted in improving crop yields on acid soils are liming, gypsum application, and the use of an adequate rate of fertilizers and organic manures. The use of acidity tolerant crop species or cultivars within species is another important strategy in improving crop yields on acid soils.