Agroforestry: a viable alternative to modern agricultural practices?

For this week’s blog I discuss how implementing agroforestry across Africa could alleviate many issues the agricultural sector faces. 

Globally, conventional agriculture is highly reliant on synthetic fertilisers. This is a practice increasingly espoused as the ‘best’ solution to increase yields across Africa. Undeniably, the use of synthetic fertilizer has greatly increased agricultural production over the past century, but that has come with a serious cost to the environment. This made me question if there are alternative practices that could minimise the environmental damage of conventional agriculture and improve Africa’s food security? Practices which are not reliant on techno-scientific fixes, such as GMOs or synthetic fertilizers (which already price out most smallholder farmers)? Agroforestry practices may be the answer I am looking for!

What is agroforestry and how does it work?

Simply put, the World Agroforestry Centre (ICRAF) defines agroforestry as ‘agriculture with trees’. It is a sustainable agricultural system based on traditional and indigenous knowledge practices which has the potential to simultaneously address the negative environmental impacts of modern agriculture and increase production in a way which is more resilient to future climatic changes. Agroforestry systems (AFS) encompass a range of practices from alley cropping and hedgerow systems to more complex multi-layered systems of food forests (see this incredible one in New Zealand).

The impacts of Agroforestry (blue arrows) and conventional agriculture (red arrows) for smallholders, intensive farmers and global society. Arrows pointing away from the centre equal a positive impact. Arrows towards the centre indicate a negative impact (Worldren et al., 2017).

This wonderful graphic from Worldren et al (2017) demonstrates the advantages of AFS (blue arrows) compared to conventional agriculture (red arrows). With all arrows pointing away from the centre, the overwhelmingly positive impact of AFS is clear. On a global scale, AFS improves biodiversity, has been recognised as a greenhouse gas mitigation strategy under the Kyoto Protocol, and improves water security by reducing evapotranspiration rates which in turn reduces the need for irrigation and could potentially alleviate droughts (Mbow et al., 2014). On a local-scale AFS offers many ecosystem services from enriching soils organic matter and nutrient levels, sustaining a richer soil microbial diversity to improving soil structure and stability preventing soil erosion. AFS also directly increases yields, some systems show a 100% increase (Pretty and Bharucha, 2014)!

Once established, AFS creates resilient livelihoods by diversifying household incomes through additional tree products which can mitigate against year-on-year uncertainties. Below are three African AFS which fascinated me during my research.

Faidherbia albida in Zambia

A farm in Zambia - The difference in Maize grown under Faidherbia
 albida (right side) versus away from the tree (left side) can be
visibly seen. Both crop plots had the same management
practices with zero inorganic fertilizer. (Garrity et al., 2010).

With the soil quality across Zambia declining every year, the Zambian Conversation Farming Unit (CFU) decided to take action by encouraging farmers to incorporation Faidherbia albida trees into their farms instead of promoting fertilizer-use. Faidherbia is a nitrogen-fixing acacia tree indigenous to Africa which becomes dormant and sheds its foliage during the rainy season when field crops are established. This means that they do not compete with crops for light, nutrients or water during the growing season but provides sufficient leaf biomass to improve soil quality (Garrity et al., 2010). The introduction of Faidherbia has been a huge success with reports of yields increasing from 6% to over 200%, as seen in the image below. The CFU estimates over 300,000 hectares use Faidherbia in AFS across Zambia (ibid.).

Chagga homegardens on Mount Kilimanjaro

Chagga homegardens on the slopes of Mount Kilimanjaro are excellent examples of highly diverse multi-layered food forests which provide a livelihood for farmers on a very limited amount of land. As seen in the video below from the FAO, the Chagga homegardens are chaotically organised but no growing space is wasted providing food, fodder, medicines, firewood and construction wood. The Chagga homegardens have managed to sustain a growing population (which was multiplied 10 times over the last 90 years) all without degrading the landscape (Hemp and Hemp, 2008). Indeed, as a result of their success, the homegardens are now protected as a Globally Important Agricultural Heritage Systems (GIAHS) because of their capability to protect biodiversity and ensures food security in a changing climate.

Video: The workings of Chagga homegardens on the slopes of Mount Kilimanjaro.

Parklands in Niger

Example of a Parkland in Niger with millet being
cultivated under Faidherbia (Garrity et al., 2010).

For many generations, farmers across the Sahel have maintained traditional agroforestry parklands. The Parklands are cultivated land where trees have been deliberately retained to provide additional food, fuel, fodder, medicines and cash commodities much needed during the long Sahelian dry season. However, in Niger during the 1970s and 80s, droughts and population pressures caused huge tree losses and resulted in widespread desertification of agricultural land (Garrity et al., 2010). Legislative bans on tree felling and fines for pruning trees were introduced to preserve the remaining trees which also meant that farmers could no longer harvest the trees for additional products so interest in growing new trees diminished. As a result, many of the environmental benefits of the parklands were lost such as the protection from wind-blown sand they provided crops.

In the 1990s, the laws were relaxed when government officials were shown successful farmer-managed natural regeneration (FMNR) projects which encouraged the natural regeneration of useful tree species allowing farmers once again to benefit from the parklands. Once the laws were dropped tree densities and cover dramatically increased, from 2003-2008 4.8 million hectares of new AFS were generated through FMNR. The success of the parklands in Niger has encouraged other countries across Africa to use FMNR and has recently amalgamated into the Regreening Africa Project which aims to improve livelihoods, food security and climate resilience in 8 countries by restoring ecosystem services through agroforestry.

Although agroforestry isn’t a new practice in Africa, the continent has ample capacity to expand its current AFS, with over 1550 million hectares of suitable land (Unruh et al., 1993). Hopefully, these examples have shown that AFS is a system which requires low external inputs making its implementation ideal for African smallholder farmers as a cost-effective transition towards a more sustainable and climate resilient agricultural system while addressing many of the UN SDGs.