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 (pHA) and the potential pH (pHP) 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 percent of the variability in pH values. This suggests that climatic conditions were responsible for current soil pH values. The pHA was 1.14 points higher tan pHP in all studied sites (p less than 0.01), indicating that a generalized natural acidification process existed. In soils of drier environments, differences between both pHA and pHP 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 pHA and pHP were higher than 1.10, being pHA values (6.17 and 5.80) acidic enough to affect the microbial activity and the development of pH sensitive crops. Fertilization with urea decreased pHA between 0.18 and 0.32 points compared to non-fertilized treatments (p less than 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.
Iturri, L. A., Buschiazzo, D. E., & Díaz Zorita, M. (2011). Acidification evidences of no-tilled soils of the central region of Argentina. Ciencia del Suelo : Revista de la Asociación Argentina de la Ciencia del Suelo,29, (1),p.13-19
Iturri, Laura Antonela, Buschiazzo, Daniel Eduardo, Díaz Zorita, Martín. 2011. "Acidification evidences of no-tilled soils of the central region of Argentina". Ciencia del Suelo : Revista de la Asociación Argentina de la Ciencia del Suelo 29, no.1:13-19.
Recuperado de http://ri.agro.uba.ar/greenstone3/library/collection/arti/document/2011Iturri