The value of trees in low input agriculture systems in Zimbabwe.
The objectives of this study, done at the Makaholi Experiment Station, Zimbabwe, were to evaluate the effects of organic inputs, applied at 5t ha-1, in various combinations with inorganic fertiliser on the growth and yield of maize over three seasons, beginning in 1990/91. The inputs included manure, leaf litter from Brachystegia spiciformis (miombo), senesced leaves of Lucaena leucocephala, and Compound D fertiliser (8N-14P-7K). Inorganic fertiliser in combination with miombo litter and/or manure gave a higher biomass and yield of maize in the third season compared to organic litter alone. A synergism seemed only to exist when inorganic fertiliser was included in the inputs. The positive response of maize to the application of litter suggests that trees contribute to crop production via the transfer of litter. The loss of soil fertility and the subsequent decline in crop yields supports these results and demonstrates the value of trees in providing nutrients to crops. Smallholder farmers in Masvingo collect woodland litter and termitaria soil in an effort to reverse the decline in the fertility of sandy soils.
Transactions of the Zimbabwe Scientific Association Volume 72 (Supplement) 1998, pp. 55-59