Agroforestry Systems

, Volume 26, Issue 3, pp 185–203 | Cite as

Comparative performance of seventeen upperstorey tree species associated with crops in the highlands of Uganda

  • J. Okorio
  • S. Byenkya
  • N. Wajja
  • D. Peden


Trials were established at three sites in Uganda to test the suitability of multipurpose trees (MPTs) as upperstorey in crop lands to provide poles, small timber and fuelwood. The three sites were Kachwekano District Farm Institute (1°16′ S, 29°57′ E, 2000 m.a.s.l.) in Kabale District, Kabanyolo University Farm (0°28′ N, 32°27′ E, 1250 m.a.s.l.) in Mpigi District and Bushenyi District Farm Institute (0°34′ S, 30°13′ E, 1610 m.a.s.l.) in Bushenyi District. The MPTs were planted in single rows at intra spacing of 2 m and each plot contained seven or nine trees. On both sides of the tree row, crops were raised. Data on crop yields were collected every season, while data on the growth of the trees were collected four times each year.

In terms of tree growth,Grevillea robusta, Casuarina cunninghamiana andAlnus acuminata performed well with height growth of 1.8–2.4 m per year at Kachwekano, while at BushenyiGrevillea robusta, Casuarina junghuhniana, Cupressus lusitanica andCedrela serrulata averaged 1.6–2.0 m height per year. At Kabanyolo,Melia azedarach, Cassia siamea, Jacaranda mimosifolia, Grevillea robusta andMaesopsis eminii had height increments ranging from 1.8–2.7 m annually. Crop yields were affected by the presence of the MPTs, withMaesopsis eminii being the most competitive (averaging 60% reduction, over five seasons). The crop rows nearest to the tree line were the most affected. OnlyAlnus acuminata seems to have had a positive effect on crop yields. The installation of a root mesh to reduce tree root competition for nutrients and water in four species increased yields in plots with MPTs by 5% (Melia azedarach) to 152% (Maesopsis eminii), but the control plot still had significantly higher bean yields, suggesting that shading could also be important. In the case of maize, suppression seems to be due mainly to root competition because after its elimination yields obtained thereafter did not differ significantly from those of the control except for the Maesopsis plots. The negative influence of the MPTs could, therefore, be minimized by periodically pruning the tree crowns and roots.

Key words

agroforestry crop yields highlands intercropping MPTs species tree growth Uganda 


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Copyright information

© Kluwer Academic Publishers 1994

Authors and Affiliations

  • J. Okorio
    • 1
  • S. Byenkya
    • 1
  • N. Wajja
    • 1
  • D. Peden
    • 1
  1. 1.Afrena Agroforestry ProjectKabaleUganda

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