Project properties
Title The use of soil amendments to reduce cadmium availability and uptake in cacao.
Group Soil Biology
Project type thesis
Credits 24-39
Supervisor(s) Mirjam Pulleman, Bert Jan Groenenberg
Examiner(s) prof.dr. Rachel Creamer (soil biology) or Prof. dr. Rob Comans (soil chemistry)
Contact info Mirjam.pulleman@wur.nl and Bertjan.groenenberg@wur.nl
Begin date 2020/01/01
End date
Description Cacao production in South America is strongly promoted and linked to important environmental and rural development goals. However, important market-related challenges include new EU food safety regulation setting limits to cadmium levels in chocolate products sold in Europe. Cadmium is a heavy metal that naturally occurs in soils and is easily taken up by cacao. This thesis topic focuses on important knowledge gaps at the interface of soil ecology and soil chemistry that need to be addressed to develop integrated management recommendations that allow smallholder cacao producers to reduce cadmium levels in cacao beans produced on their farms. One of the strategies to be evaluated is the use of different soil amendments that can reduce cadmium bioavailability in soils and/or cadmium uptake by cacao roots. Different field experiments have been implemented in Colombia and Ecuador where different (combinations) of soil amendments such as sources of organic matter, biochar, lime, gypsum, fertilizers among others, have been applied. The student working on this topic can either study the effectiveness of these amendments to reduce cadmium levels, as well as underlying mechanisms or, alternatively, focus on the the trade-offs and synergies between the use of cadmium reducing amendments and their effects on soil health and cacao yields. The research will require the student to work in the field and laboratory in one of the two South American countries. Local supervision will be available in these countries.
Used skills Cacao production in South America is strongly promoted and linked to important environmental and rural development goals. However, important market-related challenges include new EU food safety regulation setting limits to cadmium levels in chocolate products sold in Europe. Cadmium is a heavy metal that naturally occurs in soils and is easily taken up by cacao. This thesis topic focuses on important knowledge gaps at the interface of soil ecology and soil chemistry that need to be addressed to develop integrated management recommendations that allow smallholder cacao producers to reduce cadmium levels in cacao beans produced on their farms. One of the strategies to be evaluated is the use of different soil amendments that can reduce cadmium bioavailability in soils and/or cadmium uptake by cacao roots. Different field experiments have been implemented in Colombia and Ecuador where different (combinations) of soil amendments such as sources of organic matter, biochar, lime, gypsum, fertilizers among others, have been applied. The student working on this topic can either study the effectiveness of these amendments to reduce cadmium levels, as well as underlying mechanisms or, alternatively, focus on the the trade-offs and synergies between the use of cadmium reducing amendments and their effects on soil health and cacao yields. The research will require the student to work in the field and laboratory in one of the two South American countries. Local supervision will be available in these countries.
Literature review, writing proposal and thesis, field sampling and field measurements, chemical (and biological) laboratory analysis, data processing and statistics. Presentation skills
Requirements Required courses for MSc thesis Soil Biology or Soil Chemistry