POVERTY AND THE DETERIORATION OF NATURAL SOIL CAPITAL IN THE PERUVIAN ALTIPLANO SCOTT M. SWINTON 1∗ and ROBERTO QUIROZ 2 1 Department of Agricultural Economics, Michigan State University, East Lansing, MI 48824-1039, USA; 2 International Potato Center, Apartado 1558, Lima 12, Peru ( ∗ author for correspondence, e-mail: swintons@msu.edu; fax: 517 432 1800; tel.: 517 353 7218) (Accepted in final form October 2001) Abstract. The Peruvian altiplano is a marginal agricultural region with limited infrastructure, climate con- straints, and high levels of poverty. Data were collected from 265 farms in four different agricultural regions, and data from three of those regions are analyzed here. Regressions were run with soil nutrient loss, soil depth loss, and yield loss over the past 20 years, as perceived by farmers. Location, topographical and management factors were considered. Additional regressions were run to examine the determinants of two agricultural management practices which were found to affect soil quality, namely fallowing and ploughing vertical fur- rows. Use of traditional fallowing (aynoca) was associated with helping to preserve soil quality, and was practiced by households with more education, with higher non-farm income, and in villages which had ben- efitted from natural resource development projects. Vertical furrowing similarly was associated with helping preserve soil quality, and was practiced by households with fewer unmet basic needs. These results have implications for the agricultural and development strategies to be followed in the region. Key words: Altiplano, erosion, intensification, natural capital, natural resource degradation, Peru, poverty, soil conservation, soil fertility. The most severe challenges to sustainable development occur where many poor people struggle to eke out a living from marginal lands. In some cases, high human populations on fragile lands have led agricultural productivity to deteri- orate (Garc´ ıa-Barrios and Garc´ ıa-Barrios, 1990; Mink, 1993; Zimmerer, 1993), but likewise intensification in some locales has led to sustainable productivity increases (Boserup, 1965; Tiffen et al., 1994). These mixed results beg closer inquiry, in order to understand how contrary outcomes can come about. For the context of Peru’s chilly high plain surrounding Lake Titicaca, this paper examines changes in the stock of natural capital in agricultural soils, how that came about, and what policy tools might contribute to sustaining this key natural capital stock and the agricultural productivity that it enables. 1. Conceptual framework Like other forms of capital, natural capital yields service flows over time, depreciates, and can grow through investment. It is distinguished by the natural Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue. Environment, Development and Sustainability 5: 477–490, 2003. © 2003 Kluwer Academic Publishers. Printed in the Netherlands.