Epsilon Archive for Student Projects

Abstract

The majority of the people living in sub-Saharan Africa earn their living mainly by
farming. Infertile soils and variable climate make it difficult to reach sufficient
crop yields every year and therefore food security can be low. Soil quality reduction
due to erosion and nutrient depletion due to limited addition and maintenance
of nutrients is a common problem. One feasible measure to increase soil fertility is
addition of biochar, charcoal produced during pyrolysis (organic material, usually
wood, heated under low oxygen conditions), which generally is used as fuel for
cooking.

This Minor Field Study is a BSc thesis based on studies of biochar as soil
amendment in Kenya. The project had three main objectives. The first aim was to,
through visits, describe smallholder farming systems in three areas in Western,
Central and Eastern Kenya. Interviews, observation and sampling of characteristic
organic materials were performed in each area. The second aim was to measure
whether biochar application to soil can increase crop yields and if so, if there are
any differences between biochar originating from different feedstock organic materials.
The third aim was to return to the involved farmers and discuss and present
the results as well as the possible practical benefits.

All the visited farms were small-scale systems with no or few external inputs.
The farming systems were similar in all three areas, though some differences were
found, e.g. dominating types of crops. Most of the farmers were interested in using
biochar as soil amendment- if it would be proven to have beneficial effects and be
economically viable.

The results from analyses showed that nutrient concentration correlated with the
yield from pot trials where three treatments stood out: biochar from cassava stems,
coffee leaves and fresh banana leaves. Biochar from these materials in general had
the highest nutrient concentration as well as pot trial crop yield, indicating a fertilizer
effect. Plant materials with different properties may be important for plant
growth, but biochar rate seems to be a more significant factor, confirmed by the
statistical test.

The great need of improvement in soil fertility and the farmers’ interest towards
biochar indicate that this approach might be possible to use in the future. However,
more research on the subject is necessary if it is going to be implemented in the
field, since these farmers cannot afford failures.