Do Species Mixtures Increase Above- and Belowground Resource Capture in Woody and Herbaceous Tropical Legumes?

S.M. Gathumbi, J.K. Ndufa, K.E. Giller, G. Cadisch

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31 Citations (Scopus)


The rotation of crops with planted, N2-fixing legumes is a promising agroforestry innovation for replenishing soil fertility in the tropics. We postulated that woody and herbaceous legumes with different growth and rooting patterns could be mixed to optimize above- and belowground resource capture. The objective of this study was to evaluate the effect of species interactions on resource utilization by legumes grown in mixtures on a Kandiudalfic Eutrudox in western Kenya. Four woody legume shrubs—pigeonpea [Cajanus cajan (L.) Millsp.], sesbania [Sesbania sesban (L.) Merr.], crotalaria (Crotalaria grahamiana Wight and Arn.), and tephrosia (Tephrosia vogelii Hook F.)—grown in monoculture and mixed stands were evaluated for light interception, soil N and water uptake, and biomass production. Siratro [Macroptilium atropurpureum (DC.) Urb.] and groundnut (Arachis hypogaea L.) were undersown in woody legume stands. Total aboveground biomass production ranged from 9 to 13 Mg ha-1 for monoculture and 8 to 15 Mg ha-1 for mixtures of woody legumes. Total N in woody-legume stands ranged from 100 to 178 kg N ha-1. Biomass and plant N were not significantly different among woody-legume treatments. However, undersowing siratro as a supplement increased stand productivity and recycled biomass N. Species complementarity in topsoil and subsoil utilization of mineral N was observed in crotalaria sesbania and pigeonpea tephrosia mixed stands. Dense soil cover created by siratro led to better conservation of soil water. Results indicated that the tested mixtures provide a better risk management strategy through compensatory growth potential. Greatest opportunities for intensifying resource utilization appear to exist through undersowing a creeping legume with an open-canopy woody legume.
Original languageEnglish
Pages (from-to)518-526
JournalAgronomy Journal
Issue number3
Publication statusPublished - 2002

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