Abstract

ITURRI, Laura Antonela; BUSCHIAZZO, Daniel Eduardo  and  DIAZ-ZORITA, Martín. Acidification evidences of no-tilled soils of the central region of argentina. Cienc. suelo [online]. 2011, vol.29, n.1, pp.13-16. ISSN 1850-2067.

Empiric evidences indicate that agricultural soils of Argentina tend to acidify. The objective of this study was to determine the pH values of no-tilled and urea-fertilized-agricultural soils of Argentina during several years. Results indicated that both the actual pH (pH_A) and the potential pH (pH_P) values were lower in humid than in dry environments. The ratio between «mean annual precipitation:mean annual temperature» of the sites explained between 60 and 80% of the variability in pH values. This suggests that climatic conditions were responsible for current soil pH values. The pH_A was 1.14 points higher tan pH_P in all studied sites (p<0.01), indicating that a generalized natural acidification process existed. In soils of drier environments, differences between both pH_A and pH_P were, on average, higher than 1.21, indicating a more intense acidification process. However, pH values were not low enough to affect the normal growth of crops and soil organisms. In soils of humid environments, differences between pH_A and pH_P were higher than 1.10, being pH_A values (6.17 and 5.80) acidic enough to affect the microbial activity and the development of pH sensitive crops. Fertilization with urea decreased pH_A between 0.18 and 0.32 points compared to non-fertilized treatments (p<0.05), indicating that fertilization contributed to a decrease in pH values in the studied soils. In conclusion, fertilization with urea slightly increased the natural tendency to soil acidification in most of the studied soils.

Keywords : Soil acidification; Nitrogen fertilizers; Soil degradation.

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