Separating competition-related factors limiting crop performance in an agroforestry parkland system in Burkina Faso |
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Authors: | H R Bazié J Bayala G Zombré J Sanou U Ilstedt |
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Institution: | 1.Département Productions Forestières,Institut de l‘Environnement et de Recherches Agricoles,Ouagadougou 03,Burkina Faso;2.World Agroforestry Centre (ICRAF), ICRAF-WCA/Sahel Node,Bamako,Mali;3.Université de Ouagadougou,Unité de Formation et Recherche en Sciences de la Vie et de la Terre,Ouagadougou 03,Burkina Faso;4.Department of Forest Ecology and Management,Swedish University of Agricultural Sciences,Ume?,Sweden |
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Abstract: | To address tree–soil–crop interactions in the Sahel, we examined the growth-limiting factors (water, light and mineral nutrients)
of Sorghum bicolor growing under trees in agroforestry parklands of Burkina Faso. Growth and yields of sorghum were measured after (1) pruning
crowns of Vitellaria paradoxa and Parkia biglobosa trees, and (2) applying mineral fertilizers (nitrogen and/or phosphorus) and supplemental irrigation during normal wet cropping
seasons in 2007 and 2008. Irrigation treatments led to non-significant 29% and 23% gains in grain and dry matter yields (from
control values of 455 and 1,140 kg ha−1), respectively. The fertilizer showed variable but in general significant increases in grain and straw yields and more consistently
in the height of sorghum plants. The crown pruning increased the values of these variables much more strongly, by 520% and
348% (from control, no-pruning values of 282 and 612 kg ha−1), respectively. The growth and production of S. bicolor were also >56% higher under V. paradoxa than under P. biglobosa. The same trends were observed in both cropping seasons, although rainfall was much heavier in 2008 than in 2007, and the
mean sorghum grain yield was approximately twice as high in 2008. The results clearly indicate that competition for light
limits sorghum growth more than competition for other resources in the studied system, suggesting that parkland management
should aim at either increasing light availability (by reducing tree density or pruning) or growing shade-tolerant crops under
the trees. However, use of a poorly soluble phosphorus source during the first year, modest amount of water applied through
the supplemental irrigation (48 mm) and the wetness of the rainy season in 2008 (which led to abandonment of the irrigation
treatments and floods in the experimental plots) may have masked possible effects of the applied fertilizers and irrigation.
Therefore, more prolonged analyses of the effects of fertilizers and deficit irrigation are required before robust recommendations
can be made to farmers. |
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