THE EARTHSCAN READER IN SUSTAINABLE AGRICULTURE

EDITED BY JULES PRETTY

EARTHSCAN          2005

PART XIV

 

PART V: PERSPECTIVES FROM DEVELOPING COUNTRIES

Perspective 26: Benefits from Agroforestry in Africa, with examples from Kenya and Zambia by Pedro A. Sanchez

Agroforestry – integrating trees and other perennials into farming systems for the benefit of farm families and the environment – is an ancient practice that began moving from the realm of indigenous knowledge into agricultural research only about 25 years ago. During the 1980s, agroforestry was promoted widely as a sustainability-enhancing practice with great potential to increase crop yields and conserve and recycle nutrients, while producing fuelwood, fodder, fruit and timber. At that time, agroforestry was considered almost a panacea for solving landuse problems in the tropics. Many development projects pushed agroforestry technologies that were without foundations in solid research. During the past decade, however, agroforestry studies have become more empirical, based on process-oriented research.

Agroforestry is now recognized as an applied science based on principles of natural resource management (NRM). The application of such principles includes the following practices:

v  Participatory, multidisciplinary and analytical approaches;

v  Technical and policy research;

v  Working at and across different spatial and temporal scales;

v  Beneficiaries identified at the community, national and global levels;

v  Working along the whole research-development continuum;

v  Working in partnership with governmental and non-governmental organizations (NGOs);

v  Moving rapidly into on-farm research with a decreasing degree of researcher control;

v  Assessing impacts in economic, social and environmental terms;

v  Being a credible partner in development.

Agroforestry is in fact a very widespread practice, found from the Arctic to the southern temperate regions, but most extensive in the tropics. Approximately a fifth of the world’s population (1.2 billion people) depend directly on agroforestry products and services in rural and urban areas of developing countries.

Agroforestry products include fuelwood, livestock fodder, food, fruits, poles, timber and medicines. Agroforestry services include erosion control, soil fertility replenishment, improved nutrient and hydrological cycles, boundary delineation, poverty reduction and enhanced food security, household nutrition, watershed stability, biodiversity, microclimate enhancement and carbon sequestration. Many agroforestry systems are superior to other landuse systems at global, regional, watershed and farm scales because they optimise trade-offs among increased food production, poverty alleviation and environmental conservation. Being complementary to rather than competitive with arable or pastoral practices makes agroforestry an important part of strategies to produce sufficient food in the decades ahead in ways that meet both human and environmental needs.

• While the original impetus for agroforestry was very practical and empirical, it is supported increasingly by scientific foundations that permit its extension and extrapolation across the tropics.
• Much of the information for determining the biophysical performance, profitability and acceptability of agroforestry comes from on-farm trials.
• Three broadly defined partnerships for on-farm trials have been adopted by the International Centre for Research in Agroforestry (ICRAF): those that are researcher-designed and –managed (type 1); researcher-designed and farmer-managed (type 2); and farmer-designed and –managed (type 3).
• The collaborating farmers for these on-farm trials are selected through locally based institutions such as extension services or farmer groups.
• Researchers are involved mainly in technical backstopping for farmers in trials of types 2 and 3, and they help lay out type 2 trials.

Some agroforestry innovations that can be applied to meet the particular agricultural challenges in Africa are discussed here – how to assure food security, reduce poverty and enhance ecosystem resilience at the scale of thousands of smallholder farmers. There are many examples of successful agroforestry innovations in other parts of the world that could be cited.

Redressing soil fertility problems

When smallholding farmers throughout the sub-humid and semi-arid tropics of sub-Saharan Africa, hereafter referred to as Africa, are involved in diagnosis and design exercises, they invariably identify soil fertility depletion as the fundamental reason for declining food security in this region. Scientists concur. No matter how effectively other constraints are remedied, per capita food production in Africa will continue to decrease unless soil fertility depletion is effectively addressed.

During the 1960s, the fundamental cause of declining per capita food production in Asia was the lack of rice and wheat varieties that could respond efficiently to increases in nutrient availability. Food security was only effectively addressed with the advent of improved germplasm in this region for higher-yielding varieties. Then other key aspects of agricultural development that had been previously less important – enabling government policies, irrigation, seed production, fertilizer use, pest management, research and extension services – came into play in support of new varieties.

The need for soil fertility replenishment in Africa is now analogous to the need for Green Revolution germplasm in Asia three decades ago. A full description of the magnitude of nutrient depletion, its underlying socio-economic causes, the consequences of such depletion and various strategies for tackling this restraint are described elsewhere. Fortunately, strategies for soil fertility enhancement and agroforestry can be combined based on much research.

• Nitrogen and phosphorous are the most severely depleted nutrients in smallholder African farms.
• Africa has ample nitrogen and phosphorous resources – nitrogen in the air and phosphorous in many rock deposits.
• The challenge is to get these natural resources to where they are needed and in plant-available forms.
• For nitrogen, this can be achieved through biological nitrogen fixation by leguminous woody species utilized in fallows. For phosphorous, there can be beneficial direct application of reactive, indigenous rock phosphate combined with biomass transfers of non-leguminous shrubs.
• The provision of nutrients through such plant and soil management methods, which require hardly any cash, repays the labour invested very well.
• About 4000 farmers are currently trying these techniques in Western Kenya.
• Many farmers who have adopted tithonia biomass transfers to their fields have shifted now from maize to high value vegetables, which can be readily sold in nearby towns, effectively bringing them into the cash economy.
• These people now farming on replenished soils have achieved food security.

 

Opportunities

It would be unwarranted to generalize that all agroforestry interventions will have similar degrees of success. But there are surely many more innovations still to be identified and evaluated. Agrofoestry is not the best landuse option for all tropical areas, and some practices have met with widespread failure when they were not based on solid technical and policy research. Science-based agroforestry pursue in cooperation with farmers can, on the other hand, assuredly produce economically, socially and environmentally sound results. These examples and many others that are emerging and spreading throughout the world, where trees and other perennials are integrated with other farming components and practices, can raise productivity and security for several billion people who will benefit from combining ancient practices and modern science.

Perspective 27: Reducing Food Poverty by Increasing Agricultural Sustainability in Developing Countries by Jules Pretty, James Morison and Rachel Hine