Tree species and pruning regime affect crop yield on bench terraces in SW Uganda

Siriri, D.; Ong, C.K.; Wilson, J.; Boffa, J.M.; Black, C.R.. 2010 Tree species and pruning regime affect crop yield on bench terraces in SW Uganda. Agroforestry Systems, 78 (1). 65-77.

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Integration of trees on farms may exert complementary or competitive effects on crop yield. This four year study examined novel systems in which Alnus acuminata (alnus), Calliandra calothyrsus (calliandra), Sesbania sesban (sesbania) or a mixture of all three were grown on the degraded upper part of bench terraces in Uganda; beans or maize were grown on the more fertile lower terrace during the short and long rains. Three pruning treatments (shoot, root or shoot+root pruning) were applied to the tree rows adjacent to the crops; shoot prunings were applied as green manure to the woodlot from which they came. Pruning increased survival in calliandra and reduced survival in sesbania; alnus was unaffected. Pruning reduced tree height and stem diameter in alnus, but did not affect calliandra or sesbania. Maize yield adjacent to unpruned calliandra, alnus and sesbania or a mixture of all three was reduced by 48, 17, 6 and 24 % relative to sole maize. Shoot pruning initially sustained crop performance but shoot+root pruning became necessary when tree age exceeded two years; shoot+root pruning increased maize yield by 88, 40, 11 and 31 % in the calliandra, alnus, sesbania and tree mixture systems relative to unpruned trees. Bean yield adjacent to unpruned calliandra, alnus, sesbania and the tree mixture was 44, 31, 33 and 22 % lower than in sole crops and pruning had no significant effect on crop yield. The results suggest that sesbania fallows may be used on the upper terrace without reducing crop yield on the lower terrace, whereas pruning of alnus is needed to sustain yield. Calliandra woodlots appear to be unsuitable as crop yield was reduced even after pruning.

Item Type: Publication - Article
Digital Object Identifier (DOI):
Programmes: CEH Topics & Objectives 2009 - 2012 > Biodiversity
CEH Programmes pre-2009 publications > Biodiversity > SE01A Sustainable Monitoring and Management of Land Resources
UKCEH and CEH Sections/Science Areas: Watt
ISSN: 0167-4366
Additional Keywords: Alnus acuminata, Beans, Calliandra calothyrsus, Competition, Maize, Sesbania sesban
NORA Subject Terms: Agriculture and Soil Science
Ecology and Environment
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Date made live: 19 Jan 2010 14:20 +0 (UTC)

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