Tithonia diversifolia: variations in leaf nutrient concentration and implications for biomass transfer |
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| Authors: | T S George P J Gregory J S Robinson R J Buresh B A Jama |
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| Institution: | (1) Department of Soil Science, The University of Reading, PO Box 233, Whiteknights, Reading, RG6 6DW, UK;(2) International Centre for Research in Agroforestry (ICRAF), PO Box 30677, Nairobi, Kenya;(3) Present address: International Rice Research Institute (IRRI), MCPO Box 3127, 1271 Makati City, Philippines |
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| Abstract: | Green leaf biomass of Tithonia diversifolia is high in nutrients and recognised as a potential source of nutrients for crops. We conducted a field survey in western Kenya to determine the variation in leaf nutrient concentrations in tithonia grown in naturalised hedges and agricultural fields, and to examine whether leaf nutrient concentrations were related to soil nutrient status. Leaf P and K concentrations were higher in naturalised hedges (3.2 g P kg–1 and 35 g K kg–1) than in unfertilised fields (2.2 g P kg–1 and 23 g K kg–1). The critical level of 2.5 g P kg–1 for net P mineralisation was exceeded by > 90% of the leaves from hedges, but by only 14% from unfertilised fields. Leaf P and K concentration increased linearly with increasing natural logarithm of anion resin extractable soil P and exchangeable soil K, respectively. However, at the same levels of soil available P and K, field-grown tithonia consistently produced lower leaf P and K concentrations than that grown in hedges. This study indicates that biomass from tithonia planted on nutrient-depleted soils would be a less effective source of P and K, via biomass transfer, than tithonia from naturalised hedges.This revised version was published online in November 2005 with corrections to the Cover Date. |
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| Keywords: | nutrient cycling naturalised hedges phosphorus planted stands potassium |
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