Acknowledgements Trials and data collection were partially supported
by the Instituto Nacional de Tecnología Agropecuaria and the
Proyecto Forestal de Desarrollo. Thanks are due to all the landowner
associated with field trials involved in this study. Particular thanks to
Pedro Gelid for help in establishing, maintaining, and assessing the
trials. The authors are grateful to Vicente Nakama, Adelqui Alfieri,
Ricardo Moschini, and Graciela Cazenave from the Instituto Nacional
de Tecnología Agropecuaria, for providing information about the soil
and climate of the trial sites. Finally, we also wish to thank Alvin
Yanchuk and Professor Brad Potts for their comments and suggestions
and to the Associate Editor Dr. R. Burdon and two anonymous
referees for their insightful comments on an earlier version of this
manuscript.