THE AGRONOMIC AND ECONOMIC-PERFORMANCE OF BANANA, BEAN AND TREE INTERCROPPING IN THE HIGHLANDS OF BURUNDI - AN INTERIM ASSESSMENT

To meet their wood, fodder and fruit needs, resource-poor farmers with only small land holdings are forced to mix trees in their food crop plots. An experiment was conducted to study the effect of nine tree species planted at 312.5 trees ha(-1) (4 x 8 m) on the yield of bananas planted at 625 stools ha(-1) (4 x 4 m) and beans (80000 plants ha(-1)) as well as the wood production of the trees when intercropped. In addition, an economic analysis was done to compare the different tree/banana/bean associations. After three and one-half years, wood volume (in m(3) ha(-1)) of Grevillea robusta (18.1), was highest and that of Erythrina poeppigiana (2.7), Cedrela odorata (2.4) or Markhamia lutea (0.8) was the lowest. Volume of Cedrela serrata (13.7) was not significantly different from that of Albizia chinensis (12.8) but was significantly higher than that of Leucaena diversifolia (6.8), Acrocarpus fraxinifolius (6.7) or Calliandra calothyrsus (6.0). None of the tree species had a significant influence on the yields of the bananas and none affected the yield of the bean crops until the seventh cropping season, three years after the trees were planted. In that year, Grevillea reduced bean yield by 29%, Albizia by 34% and Leucaena by 36%. From the economic analyses, all the treatments except Leucaena and Markhamia had positive net benefits relative to the control (banana/bean) but the results were highly variable. C. serrata was found to be the best tree to be intercropped in a banana/bean system.