Management systems in southern South America

BUSCHIAZZO, D.E.

Dryland Agricuture

Am. Soc. Agron.

Año: 2006; p. 395 - 426

Dryfarmed cropland in the southern part of South America covers about 2,500,000 km2. Approximately 60% of this surface belongs to the semiarid part of  Argentina, 25% to the Bolivian High Plains, and 15% to the Paraguayan Chaco. This region has been under dryland farming since early 1900. Cultivation has been mostly with methods adopted from more humid environments, which has resulted in major soil degradation, mainly between 1930 and 1970. In the semiarid parts of Argentina and Paraguay, the most important dryfarmed lands are on loess soils, with wind and water erosion being the main soil degradation processes. Depending on local climatic, edaphic and management conditions, physical and chemical degradation are also important. Soil compaction is a major soil degradation process in some soils of Argentina (Quiroga et al., 1999) and Bolivia (Barber, 1994; Barber and Díaz, 1992). Chemical degradation and wind erosion occurs in large areas of the Bolivian High Plains (Benites et al., 1994). Since 1990 the incorporation of no-till systems in some areas of the region tended to decrease some of the most important soil degradation processes like erosion and organic matter (OM) losses, but created new soil degradation processes like soil compaction and contamination hazards, and the introduction of new plant disease and weeds, which require new control systems. This chapter describes the main climatic and edaphic characteristics of these regions, the management systems used, their influence on soil properties, and the present and future trends on soil management in this area.