CATENA z ELSEVIER Catena 45 (2001) 185-207 www.elsevier.com/locate/catena Runoff and soil erosion under rainfall simulation of Andisols from the Ecuadorian zyx Púravlzo: effect of tillage and burning Jérôme Poulenard a,b, zyxwvut ‘ , Pascal Podwojewski b, Jean-Louis Janeau ’, Jean Collinet Ceiitre de Pédologie Biologique (CNRS), zyxwv 17, zyxwv rue ND des pauvres, zyx BP zyx 5, 54501 Vandoeuure zyxwvu les Nancy, France IRD 32, Au. H. Varagnat 93143, Bondy, France IRD Tunis, BP 434, 1004 Tunis, El k?ellZah, Tunisia \ zyxwvutsrqponmlkjihgfedcbaZY E IRD IBSRAM-MEC, Project. P.O. Box 9-109, Jatujak, Bangkok 10900, Thailand Received 8 November 1999; received in revised form 26 February 2001; acccpted 27 March 2001 zy Abstract In northern Ecuador, soils of high altitude grasslands ( púrumos) are mainly non-allophanic Andisols developed on Holocenic volcanic ash. These soils have a high water retention capacity and are the “water tank” of central Ecuador. To assess the effect of land use (buming and tillage) on soil hydrodynamic properties, rainfall simulation was conducted at two different sites. At Pichincha near Quito, the simulation was conducted on a recent volcanic ash soil comparing natural, tilled and bumed plots. At El Angel, the simulation was conducted on a mature non-allophanic Andisol comparing natural, recently tilled and formerly cultivated plots. On natural plots, the infiltration rate was very high and sediment loss very low. Results for infiltration rate and runoff indicated that land use change on púrumos increased runoff flow and reduced saturated hydraulic conductivity. Superficial reorganisation of the soil surfaces occurred on tilled plots at both sites. This crusting process was fast and resulted in surfaces with very low conductivity at Pichincha. The same processes seemed to be slower at El Angel. The soil surface . - __- _- of-recent Andisols-at-Pichincha was prone to crusting whereas the mature Andisol, at El Angel, J ‘II I ‘i I / , . -. I I I * Corresponding author. Cedtre de Pédologie Biologique (CNRS), 17, rue ND des pauvres, BP 5, 54501 - __ Vand~u~-lës~~~~FÍanc~ E-mail address: poulenard@wanadoo.fr (J. Poulenard). 0341-8162/01/$ - see front matter 02001 Elsevier Science B.V. All rights reserved. PII: S O 34 1 - 8 1 62( 0-1 > O0 14 8 - 5