Cropping under the shade in the Sahel

The performance of different crops under shade in the parklands of Burkina Faso could hold important information for the future management of these vulnerable landscapes, according to two papers in the latest issue of Agroforestry Systems co-authored by Centre scientist, Jules Bayala.

Parklands are mixtures of trees and shrubs that farmers select for certain functions. In the Sahel, parklands are cultivated for a variety of foods - such as fruits, fats, oils, leafy vegetables, nuts and condiments - to complement their staple food crops. There is growing evidence that these parklands are degrading.

“We need to know more about the interactions between different trees and agricultural crops so that we can better manage the parklands in the future,” says Bayala.

The first paper reports on research into the effect of shade of two indigenous fruit trees: Baobab (Adansonia digitata) and Néré (Parkia biglobosa) on taro and millet. The scientists found that millet performed better under baobab and yields of taro were higher under néré.

There was a strong relationship between the amount of photosynthetically active radiation (PAR) intercepted by trees and crop yields under the trees.

“We found that as PAR decreased, millet yields decreased whereas taro yields increased,” explains Bayala. “from this, we conclude that parkland productivity could be enhanced by cropping shade tolerant crops such as taro under trees of heavy shade such as néré.”

In the second paper, research over two years shows the effect on eggplant, chill, taro and pearl millet when grown under Parkia biglobosa trees in south central Burkina Faso. The trees suppressed the growth and yield of pearl millet and eggplant, but chilli pepper yields increased by up to 150% when grown under the tree canopy. Taro yields were also higher when grown in the shade.

“If we can better understand what crops perform well when grown under what tree species, farmers will benefit from higher yields and they will have good reason to maintain a diverse range of trees in their fields, preventing further degradation of the parklands.”

A third article co-authored by Bayala in the journal looks at the wealth status of farmers in the cereal-based ‘Plateau Central’ and the cotton-based ‘Boucle du Mouhoun’ regions of Burkina Faso.

In the Plateau Central 70% of households managed to escape poverty, 9% remained poor and 2% fell into poverty. For the ‘Boucle du Mouhoun, 56% escaped poverty, 12% remained poor and 6% fell into poverty. Households were able to escape poverty through such things as subsidies for cotton and income from relatives working in town. The main causes of poverty included the death of a spouse, illness and a high number of people in the household.

The findings will help in the design of appropriate policies and options for sustainable management of agroforestry parklands under different land use systems.

Photo: Marco Schmidt