Tree-crop interactions in hedgerow intercropping with different tree species and tea in Sri Lanka: 1. Production and resource competition |
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Authors: | Email author" target="_blank">W?A?J?M?De?CostaEmail author P?Surenthran |
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Institution: | (1) Department of Crop Science, Faculty of Agriculture, University of Peradeniya, 20400 Peredeniya, Sri Lanka |
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Abstract: | Incorporation of tree hedges along contours has been proposed as a means of reducing soil erosion and increasing soil fertility
of tea (Camellia sinensis (L.) O. Kuntz) plantations on sloping terrain in high-rainfall zones of Sri Lanka. Tea yields in these hedgerow intercrops
are determined by the balance between the positive (i.e., increased soil fertility) and negative (i.e., resource competition)
effects of hedgerows. Therefore, the objectives of the present study were to determine: (a) the net effect of six different
hedgerow species (Calliandra calothyrsus Meissner, Senna Cassia] spectabilis (DC.) H. Irwin and Barneby, Euphatorium innulifolium (R.M. King and H. Rob.) H.B.K., Flemingia congesta Aiton F., Gliricidia sepium (Jacq.) (Kunth.) Walp. and Tithonia diversifolia (Hemsl.) A. Gray) on long-term tea yields; (b) the effect of incorporating hedgerow prunings as mulch; and (c) the relationship
between hedgerow characteristics (i.e., biomass production, canopy and root growth) and tea yield variation. Tea yields, measured
over one complete pruning cycle from October 1998 to September 2001, showed reductions relative to a sole tea crop under all
hedgerow species except Euphatorium. The yield reductions ranged from 22 to 40%. Tea yields under Euphatorium showed increases up to 23% relative to the sole crop control. Addition of hedgerow prunings as mulch increased tea yields
in all hedgerow intercrops. The yield increases ranged from 11 to 20%, with the highest being under Euphatorium. Tea yields showed a negative relationship (R2=0.38) with the pruned biomass of hedgerows. Limitation of environmental resources (e.g., water and light) and hedgerow characters
which intensified resource competition (i.e., greater canopy lateral spread and height and greater root length densities,
especially in the top soil layer) were responsible for observed tea yield reductions in hedgerow intercrops. |
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Keywords: | Hedgerow intercropping Tea Mulching Resource competition |
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