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Applied and Environmental Soil Science
Volume 2012, Article ID 616383, 11 pages
http://dx.doi.org/10.1155/2012/616383
Review Article

Agroforestry and the Improvement of Soil Fertility: A View from Amazonia

1National Institute for Research in Amazon, INPA/CPCA, Agrarian Sciences Research Center, Avenue André Araújo, 69038-000 Manaus, AM, Brazil
2United Nations Development Program, (PNUD), Cj SHIS QI 25 Cj 03 C, 71640-220 Brasília, DF, Brazil

Received 16 October 2011; Revised 28 January 2012; Accepted 28 January 2012

Academic Editor: Robert L. Bradley

Copyright © 2012 Rachel C. Pinho et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

This paper discusses the effects of trees on soil fertility, with a focus on agricultural systems in Amazonia. Relevant literature concerning the effects of trees on soil physical and chemical properties in tropical, subtropical, and temperate regions is reviewed, covering both natural ecosystems and agroecosystems. Soil carbon, in the form of organic matter, is considered as an indicator of biological activity as well as in relation to policy issues such as carbon sequestration and climate change. In the case of tropical soils and Amazonia, information on the effects of trees on soils is discussed in the context of traditional agriculture systems, as well as in regard to the development of more sustainable agricultural alternatives for the region. Lastly, attention is given to a case study in the savanna region of Roraima, northern Brazil, where a chronosequence of indigenous homegarden agroforestry systems showed clear effects of management practices involving trees on soil fertility. The use of diverse tree species and other practices employed in agroforestry systems can represent alternative forms of increasing soil fertility and maintaining agricultural production, with important practical applications for the sustainability of tropical agriculture.