In West Africa, many farmers move to the cities, where they cultivate soils, many of which are not very fertile. The international team involved in the "Urban FoodPlus" project, coordinated by Prof Dr Bernd Marschner from the Ruhr-Universität Bochum (RUB), is looking for ways of boosting crop yields. In their experiments, they have identified biochar as an effective agent. It can be manufactured from crop residues at low costs. Their report has been published in the science magazine RUBIN.
Larger lettuce heads on biochar-enriched soils
"In West Africa, water is the number one limiting factor for agriculture," says Dr Volker Häring from the Chair of Soil Science and Soil Ecology. The second-largest is soil fertility; generally, the sandy subsoil does not store nutrients well. Biochar works as a soil conditioner; it ensures that nutrients are better absorbed and it improves the water balance. In a field experiment under controlled conditions in Ouagadougou, Burkina Faso, the researchers compared crops from biochar-enriched soils and untreated soils. Lettuce heads grown on enriched soils reach a greater weight.
Climate benefits from stable storage of greater carbon volumes
Another advantage of the soil conditioner: in the manufacture of biochar, at least fifty per cent of the carbon generated from the organic material is stored in a stable manner. Typically, crop residues are burned or they decay naturally over time. In the process, most of the carbon escapes into the atmosphere, is lost as a resource to the soil, and damages the environment in the form of CO2.
Next step: biochar in field trial
The team is now attempting to find out if farmers in Ghana and Burkina Faso would be able to handle biochar in practice. They supply the farmers with furnaces for biochar production that can be procured at low costs. No-cost plant waste such as rice husks or corn cob residues can thus be transformed into biochar in low-oxygen atmospheres and introduced to the fields. After the harvest, the researchers will assess if biochar likewise generates higher crop yields under these conditions.
Farmers in West Africa often irrigate their fields with wastewater, which is heavily polluted with bacteria and worm eggs. RUB researchers from the Department of Sanitary Engineering and Environmental Engineering test biochar as filter material, in order to eliminate pollutants. The "Urban FoodPlus" team is also testing ways of eliminating pollutants from the filter material and to subsequently use it as soil conditioner. The RUB Chair of Development Research is involved in the project as well; its team analyses if the measures are economically reasonable and, consequently, truly sustainable. In the course of the project, the Bochum team collaborates with partners at universities in Kassel, Göttingen and Freiburg, as well as with 14 African institutions and two international agronomic research organisations.
A detailed article with pictures can be found in the online magazine RUBIN, the RUB's science magazine: http://rubin.rub.de/en/more-lettuce-thanks-biochar.