Essentially an African view of how to improve soil productivity on smallholder farms, this book synthesizes results obtained by AfNet members and their collaborators. The book is based on three premises: that the fertility of tropical soils is controlled by biological processes and can therefore be managed by manipulating these processes; that soil fertility depletion is the major biophysical cause of declining per capita food supply on smallholder farms in sub-Saharan Africa; and that such depletion must be tackled in a holistic manner, that is, by solving nutrient deficiencies, ensuring appropriate germplasm materials and cropping-system designs, manipulating pest and disease interactions with soil, and resolving institutional failures. The book's 42 chapters, spread over three themes, reflect this approach. The first theme, integrated soil-fertility management, deals with the integration of green manures into farming systems; effects of organic and inorganic fertilizers as well as litter; tilling; and soil organic matter. The second theme, below-ground diversity, emphasizes soil macrofauna and inoculation with mycorrhizae. The third theme, participatory research and scaling-up of soil-fertility restoration technologies, covers the social context of soil fertility, rural development, economic analysis, and farmer evaluation of integrated nutrient management. The book is dedicated to Mike Swift, who helped establish AfNet and taught many of the scientists working in the field in Africa. The Rockefeller Foundation financed the AfNet conference that led to this book, and RELMA financed the publication.
Keywords: Soil fertility; Soil biology; Research networks; Cover plants; Fertilizer application; Soil chemicophysical properties; Soil conservation; Green manures; Innovation adoption; Africa South of Sahara
Methods of Payment
The savanna ecosystem of tropical Latin America (250 million hectares) is rapidly being incorporated into agricultural production, mostly monocropping and pastures, in response to population increase, demand for food, and, at the production level, demand for certain crops. In some savannas (e.g., the Brazilian Cerrados), such exploitation is degrading the land through erosion, soil compaction, loss of organic matter, inappropriate grazing, and pest and weed infestation at a rate of 2%-4% per year, which demonstrates unsustainability. This book presents agropastoral systems (zero and minimal cultivation, integration of crops and pastures) as alternatives to check the degradation of this tropical ecosystem throughout the entire region. Also described are the research, progress, and conclusions as expressed at meetings of the Agropastoral Network for the Savannas, held in Colombia, Brazil, Venezuela, and Bolivia between 1992 and 1996. Researchers, farmers, extension workers, students, and policy makers will all recognize the usefulness of this work. EMBRAPA (Brazil), CIAT, and the Consortium for Managing Acid Soils (MAS) of the Consultative Group on International Agricultural Research (CGIAR) made this work possible. 342 p. 16.5 ? 23.5 cm. Also available in Spanish.
Keywords: Agropastoral systems; Savannas; Sustainability; Planning; Rice; Oryza sativa; Arachis pintoi; Brachiaria brizantha; Acid soils; Soil management; Soil conservation; Zea mays; Maize; Technology transfer; Feed crops; Sustainability indicators; Participatory research; Orinoquia; Forage; Latin America; Brazil; Colombia
[Agroecology and Biodiversity in the Savannas of the Eastern Plains of Colombia] The Neotropical savanna ecosystem encompasses the plains of Colombia and Venezuela, the Brazilian Cerrados, and the savannas of Bolivia and Guyana. The 250 million hectares involved have been subjected to human intervention since the 1970s, including the introduction of improved grasses, development of 50% of the Brazilian cattle herd, and extension of soybean cultivation (converting Brazil into an important world exporter). The expansion of the agricultural and livestock frontier brings with it the development of road infrastructure and petroleum exploitation. The impact on the ecosystem deserves attention. For example, the Orinoquian Plains belong to the basin and delta of South America's third largest river by volume (the Orinoco) and the sixth by contribution of sediments. The development of this basin (900,000 km2) would have, without doubt, a scarcely imagined, effect of international dimensions. The intensification of production systems will affect native vegetation whose conservation implies integration with introduced species, especially forages. This collaborative work provides, over 12 chapters, an inventory of native species and their characterization, a description of experiments that measured the effects of fire and grazing in the savannas, a study of soil macrofauna, and recommendations for the intensive and rational use of native savanna. One of several appendices contains two illustrated synoptic keys (original and unique) identifying grass species in a representative section of higher lying savannas known as altillanuras. 302 p. 16.5 ? 23.5 cm.
Keywords: Savannas; Ecology; Plant communities; Biodiversity; Controlled burning; Ecological succession; Remote sensing; Soil fauna; Grassland management; Biomass; Eastern plains
This book compiles recent knowledge on soil macroinvertebrates, emphasizing the earthworms of the acid-soil savannas of Colombian Eastern Plains. An inventory of biological resources, including abundance and diversity of soil macrofauna, and their specific ecologies, were produced for natural and agricultural systems at "Centro Nacional de Investigacion Carimagua", together with an evaluation of the impact of those resources on soil and plants. In addition, the volume details the effects of the ecosystem engineers' functional group of earthworms on the soil's physical, chemical, and biological properties. Options for conserving and using the biological resources found in soils under different land management practices are presented. 389 p. 16.5 x 23.5 cm. Also available in Spanish.
Keywords: Soil biology; Biodiversity; Ecosystems; Lumbricidae; Population dynamics; Soil organic matter; Pastures; Acid soils
The increasing interest in local soil knowledge is largely due to the realization that farmer communities that have been interacting with their soils for a long time can provide many insights into the sustainable management of tropical soils. A participatory approach, in the form of a methodological guide, has been developed and used in Latin America and Africa to identify and classify local indicators of soil quality related to permanent and modifiable soil properties. This methodological tool aims to empower local communities to better manage their soil resources through improved decision making and monitoring of their environment. It is also designed to steer soil management towards developing practical solutions to identified soil constraints and monitoring the impact of the management strategies implemented to address such constraints. The methodological approach presented here constitutes one tool to capture local demands and perceptions of soil constraints as an essential guide to relevant research and development activities. A significant component of this approach is the collaboration between technical officers and farmers to build an effective communication channel with each other. The participatory process also places considerable emphasis on consensus building among farmers to determine those soil-related constraints that should be tackled first. Such consensus is an important step toward collective action by farming communities if improved soil management strategies are to be adopted at a landscape scale. 21.5 x 27.5 cm.
Keywords: Soil fertility; Quality; Monitoring; Methods; Soil chemicophysical properties; Soil genesis; Decision making; Soil management; Natural resources; Resource management; Africa; Participatory research.
© Centro Internacional de Agricultura Tropical 2001. All rights