No-tillage (NT) system contributes for the increase of soil organic matter (OM) contents, changing the ratio between exchangeable and non-exchangeable Al due to cation complexation. This study was carried out to evaluate the effect of lime and gypsum application in the contents of exchangeable aluminum (Al-KCl), exchangeable + non-exchangeable aluminum (Al-CuCl2), and non-exchangeable Al from samples of a dystrophic clayey Rhodic Hapludox under NT for 55 months, in Ponta Grossa - PR. The NT system was implemented on a native pasture between July and October of 1998. Three methods of lime application were evaluated: a single application of 4.5 t ha-1, either incorporated down to 20 cm or surface applied, and 1.5 t ha-1 applied in each of three years. In the subplots, 3, 6 or 9 t ha-1 of gypsum were applied. The liming decreased contents of Al-KCl, Al-CuCl2 and non-exchangeable Al. Both Al forms related negatively with soil pH. Even with large soil acidity, exchangeable Al contents were low, and non-exchangeable Al was the predominant form, representing 98, 95, 91, and 89 % of total Al, at 0-0.05; 0.05-0.1; 0.1-0.2, and 0.2-0.4 m, respectively. Gypsum application did not affected Al-KCl, Al-CuCl2 and non-exchangeable contents.
soil acidity; surface liming; lime incorporation; gypsum; Al-KCl; Al-CuCl2
