| Sumario: | Global warming is a challenge the world is facing today. All countries won’t have
the same potential to adapt to future climate. The economic situation is determining
on how well the country can adapt. Therefore, this will be a bigger challenge
for developing countries. Many of these countries are situated near the equator and
are relatively dry. They are also predicted to become warmer and dryer in the future.
Due to high weathering rates and erosion soils in these countries are poor in
nutrients. Fertilizers are expensive and therefore in limited use. In many areas also
infrastructure is limiting the availability of fertilizers. Rapid decomposition of organic
matter causes carbon content rarely to be maintained in soils. Carbon is important
for water and nutrient holding capacity and is therefore affecting crop
yields. If crop residues are combusted in absence of oxygen a part of that carbon
remains as biochar. This biochar is more stable than crop residues and can thereby
be added to soil for improving soil properties. Research on biochar is conducted in
many countries over the world, inspired by the black Terra Preta soils in Amazonas.
Several field studies are run by Swedish University of Agriculture in collaboration
with International Center for Tropical Agriculture, Tropical Soil Biology
and Fertility (CIAT-TSBF) in Kenya. I performed my field studies in one of these
experiments, at Embu, close to Mount Kenya. I studied the effects of biochar on
plant growth and decomposition of crop residues under varying soil moisture levels.
This study was conducted in pots in a greenhouse. The results indicate a positive
effect of added biochar on plant water supply and nutrient availability after
application of biochar. Plants grown in soils not containing biochar suffered from
nitrogen deficiency and drought. Plants grown in presence of biochar had higher
biomass and showed less signs of nutrient deficiency and drought stress. Biochar
could be produced on the farms using organic materials that are commonly available.
Therefore, biochar could be an option for improving soil fertility. The implementation
of this technology could even become more important for food security
in the future due to climate change.
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