Subsoil Nitrogen Capture in Mixed Legume Stands as Assessed by Deep Nitrogen-15 Placement
Stanley M. Gathumbia,
Georg Cadisch*,b,
Roland J. Bureshc and
Ken E. Gillerd
a MacArthur Agro-Ecology Research Center, 300 Buck Island Ranch Road, Lake Placid, FL 33852
b Department of Agricultural Sciences, Imperial College at Wye, University of London, Wye, Kent, TN25 5AH, UK
c International Rice Research Institute, DAPO Box 7777, Metro Manila, Philippines
d Plant Production Systems, Department of Plant Sciences, Wageningen University, P.O. Box 430, 6700 AK Wageningen, The Netherlands
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Fig. 1. Daily rainfall received from January through March 1998 during the period the 15N injection experiment was conducted in western Kenya.
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Fig. 2. Field layout of 15N-application subplots in two improved fallow systems in western Kenya.
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Fig. 3. Nitrogen-15 concentration in young leaves after application of 15N at two soil depths in western Kenya.
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Fig. 4. Young leaf 15N concentration for sesbania and crotalaria plants sampled at various distances from the 15N injection point at 9 wk after application in the field.
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Fig. 5. Residual soil atom% 15N excess at vertical distances below the 0.15- and 1.00-m depths for 15N injection at 9 wk after application.
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Fig. 6. Effect of soil depth on root length density (Lrv) of pure and mixed species.
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Copyright © 2003 by the Soil Science Society of America.
