Agroforestry can lead to the sustainable intensification of tropical agriculture. Roger Leakey reports.

Roger Leakey

Numerous international reports (PDF) have concluded that ‘business as usual is not an option for agriculture’, but there seems to be no clear path forwards. Indeed there is a highly polarized debate in which biotechnology (GM) and organic agriculture are the two opposing candidates for most people’s affections and attention.

An analysis of the issues behind the state of tropical agriculture, especially in Africa, reveals a highly complex set of production, environmental and social factors which drive the downward cycle of land degradation and social deprivation that lie behind the low yields achieved by poor farmers, despite the high potential yields of modern cultivars.

A complex  'multifunctional agriculture' landscape with a wide mixture of crops in  southern Vietnam. Image: CABI, 2012.
A complex ‘multifunctional agriculture’ landscape with a wide mixture of crops in southern Vietnam. Image: CABI, 2012.

This difference between potential yield and actual yield is the ‘yield gap’. If we could fill this gap, food insecurity would be a thing of the past.

Simple solutions

In my book, Living with the Trees of Life – Towards the Transformation of Tropical Agriculture, I present agroforestry as a way to sustainably increase the productivity of modern crop varieties and conclude the discussion with a generic three-step model for a relatively simple and inexpensive process to fill the yield gap.

  • Step 1: adopt agroforestry technologies such as two-year ‘improved fallows’, in which natural land rest (fallow) is enriched with fast-growing trees, shrubs or vines. Another is ‘relay cropping’ where crops are planted in rows alongside nitrogen-fixing plants such as soybean that improve maize yields from around one tonne per hectare up to about 4-5 tonnes per hectare. This allows the farmers to both improve food security and reduce the area of their holdings planted with maize and so make space for other crops, perhaps cash crops such as some of the species being domesticated in Step 2, or coffee, tea, cocoa and bananas – all which would generate income. Leguminous shrubs also reduce parasitic weeds such as African witchweed Striga hermontica, and insects pests like the stem borers of maize.
  • Step 2: diversify the farming system by the inclusion of tree species producing traditionally important indigenous fruits, nuts and other marketable products which are currently being domesticated as new cash crops using participatory approaches involving local communities. These new cash crops empower communities towards self-sufficiency, generate income, improve nutritional security through diversified diets rich in micro-nutrients, enhance gender equity, and maintain culture and traditions. The sale of these products allows the purchase of fertilizers and pesticides and so, potentially, the increase of maize yields up to 10 tonnes per hectare. Consequently, the area under maize could be reduced further to allow more cash cropping. The integration of fodder trees and livestock into the farm is further element of diversification that could be part of this step.
  • Step 3: promote entrepreneurism in local communities to develop value-adding and processing technologies for the new tree crop products, so increasing availability of the products throughout the year, expanding trade and creating employment opportunities.

Furthermore, there are thousands of useful tree species around the tropics that can be used to implement these three steps, with over 50 currently being domesticated, allowing adaptation to the full range of biophysical and socio-economic environments.

From vision to ‘proof of concept’

I believe these three steps tick all the boxes for reversing the downward spiral of land degradation and social deprivation. This model is highly adaptable and applies equally well to the dryness of the Sahel as it does to the moist tropical lowlands and the highlands of the tropics, especially in Africa.

It represents a middle path between high-tech agribusiness and organic agriculture. It is a low-input system appropriate to the socio-economic conditions that prevail on so many smallholder tropical farms. But once the farmers are on a path out of poverty, malnutrition and hunger, it involves the purchase of inputs currently out of their reach.

This three-step model also involves the rehabilitation of degraded farmland in terms of soil fertility and agroecological functions; the generation of income from marketable products, and a return to many traditionally/culturally important foods from trees which also sequester carbon to mitigate climate change. This approach also empowers local people and creates new business and employment opportunities so that many can move out of near-subsistence farming and into the cash economy.

Too good to be true? I don’t think so, but it does require a change of mind set by many of the people currently driving agriculture in other directions.

This ‘convenient truth’ is that over the last 15 years the World Agroforestry Centre (ICRAF) has had a US Department of Agriculture-funded ‘Food for Progress’ project in Cameroon entitled the Agricultural and Tree Products Programme for which the RIBA Agroforestry Resource Centre (PDF) was awarded an UNDP  Equator Prize in 2010, so there is proof of concept. (More case studies can be found here.)

It is do-able. But it needs to be scaled up to hundreds of millions, or billions, of poor farmers. That’s the challenge.

Step 1: land rehabilitation with leguminous  trees and shrubs; step 2: domestication with indigenous trees producing  marketable products; step 3: marketing, processing and value adding indigenous  tree products.
Step 1: land rehabilitation with leguminous trees and shrubs; step 2: domestication with indigenous trees producing marketable products; step 3: marketing, processing and value adding indigenous tree products. Image: CABI, 2012.

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About Roger Leakey

Roger Leakey is a former Director of Research of ICRAF (now the World Agroforestry Centre), and Professor of Agroecology and Sustainable Development at James Cook University, Cairns Australia. He was a Coordinating lead author of the International Assessment of Agricultural Science and Technology for Development and is now Vice Chairman of the International Tree Foundation and Vice President of the International Society of Tropical Foresters.

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