| Summary: | In order to assess the sustainability of cultivating Jatropha curcas L. in rural areas in the Kinshasa region, four cropping systems were compared: cultivation of J. curcas as a sole crop with and without fertilisers, a combination of J. curcas with subsistence crops (maize Zea mays L., the common bean Phaseolus vulgaris L.) with and without fertilisers. The major attacks by pests (mainly Aphthona sp.) suffered by J. curcas plants in the region make it vital to conduct at least two insecticide treatments per year. Dry seed yields of J. curcas obtained in the 4th year of cultivation amounted to 753 kg ha1 when J. curcas was cultivated as a sole crop without fertilisers, 797 kg ha1 for intercropping without fertilisers, 1158 kg ha1 when J. curcas was cultivated as a sole crop with fertilisers and 1173 kg ha1 for intercropping with fertilisers. Yields from the two annual crops were not improved by the application of mineral fertilisers on the J. curcas plants. They amounted to an average of 815 kg ha1 for maize and 676 kg ha1 for the beans. It is more profitable to cultivate J. curcas with maize and beans than to cultivate it as a sole crop. By combining crops in this way, a one hectare farm can earn 1102 USD ha1 without fertilisers and 1049 USD ha1 with fertilisers. Sustainable cultivation of J. curcas under the test conditions requires the development of efficient weed/pest control methods and improved soil fertility management, in order to minimise the use of mineral fertilisers as well as strong improvement of labour productivity for seed harvesting.
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