STEFAN HAUSER1, MUSTAPHA NJAYOU1, LOUIS ZAPFACK2
1International Institute of Tropical Agriculture, Humid Forest Eco-regional Center, Cameroon
2University of Yaounde, Plant Biology,
The leguminous tree Calliandra calothyrsus was introduced to farmers in southern Cameroon for soil fertility and crop yield improvement in shortened fallow phases in 1989. On-farm trials by ICRAF and IITA used the alley cropping concept, and various spatial patterns and tree densities. Initially 2 year old fallow was cropped after slash and burn land preparation. This study reports farmers' perception of the effects of C. calothyrsus fallow in four areas and verifies if farmers used the system without researchers' involvement.
After the initial 2 years fallow, 95% of farmers cropped, after the second and third fallow 41% and 13% cropped, respectively. Labor requirements to clear and prepare land after C. calothyrsus was perceived as being larger than after natural fallow by 86% of farmers after the first fallow; and by 24% and 13% after the second and third fallow. Perceived and recorded labour requirements were closely correlated. Across all crops, 61% of farmers perceived yields being higher after C. calothyrsus than natural fallow; 17% did not report any difference. Perceived yield advantages after C. calothyrsus increased from 57% after the first fallow to 77% after the third fallow. Yield perception varied with location: in the south 45% of farmers believed C. calothyrsus produced higher crop yields, compared with 70% north of Yaounde. Maize was believed by 78% of farmers to produce higher yields in C. calothyrsus. Groundnut was believed to not respond positively to C. calothyrsus with 45% of farmers reporting higher yields in C. calothyrsus. Cassava yields were perceived by 62% of farmers as higher in C. calothyrsus. For sites where yields were measured by researchers, farmers either incorrectly perceived a yield advantage or overestimated the yield advantage of C. calothyrsus by a wide margin. The decline in the use of C. calothyrsus fallow indicates, that increased labour requirements for clearing and land preparation outweighed perceived and real yield advantages. Consequently, C. calothyrsus is virtually only used in the high population density area north of Yaounde. The species can neither be recommended for large areas nor for all crops.
Keywords: Adoption, alley cropping, labour requirements , tree based fallows