Tillage effects on soil properties and crop production in the subhumid and semiarid Argentinean Pampas

Crops have been grown in the subhumid and semiarid Argentinean Pampas for over 50 years using tillage methods (intensive plowing) introduced from more humid regions. As a result, soil degradation due to erosion by wind and water has been moderate to severe. Experiments to control erosion through use of conservation systems were initiated at six semiarid and subhumid sites in the Argentinean Pampas between 1976 and 1990 and conducted for 5 to 11 years. In this paper, we summarize the effect of conventional and conservation tillage treatments on some soil properties and crop yields. Most soil physical, chemical, and biological properties were improved by conservation systems, but the rate of change differed due to climatic and soil differences among sites, with the difference due to tillage generally being greater at the more humid sites with loamy soils than at the drier sites with sandier soils. Crops with a large N requirement yielded less with conservation than with conventional tillage systems. Use of conservation tillage can improve or stabilize soil conditions in the region, but crop nutrient requirements must be met to achieve optimum crop yields when conservation tillage is used. Research regarding the plant nutrient requirements under conservation tillage is being conducted. Also, conservation tillage is gaining acceptance in the Argentinean Pampas region. (C) 1998 Elsevier Science B.V. All rights reserved.