Tithonia and senna green manures and inorganic fertilizers as phosphorus sources for maize in Western Kenya |
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Authors: | C N Gachengo C A Palm B Jama C Othieno |
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Institution: | (1) Tropical Soil Biology and Fertility Programme (TSBF), P.O. Box 30592, Nairobi, Kenya;(2) Moi University, P.O Box 1125, Eldoret, Kenya;(3) International Centre for Research in Agroforestry (ICRAF), P.O. Box 30677, Nairobi, Kenya |
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Abstract: | Efforts to overcome declining soil fertility on small holder farms in western Kenya must be consistent with the reality of
low utilization of inorganic fertilizers. Likewise organic inputs alone cannot supply adequate nutrients. The use of two organic
resources, Tithonia diversifolia (tithonia) and Senna spectabilis (senna) leaves, and their combination with inorganic P for
improving soil fertility and maize yields was investigated on a P limiting soil in Western Kenya. Treatments included: 1)
control, no inputs; 2) 5 t ha−1 (dry matter) tithonia leaves; 3) 5 t ha−1 senna leaves; 4) 5 t ha−1 tithonia leaves + 25 kg P ha−1 as triple superphosphate (TSP); 5) 5 t ha−1 senna leaves + 25 kg P ha−1 (as TSP); and 6) 25 kg P ha−1 of TSP. Maize was used as a test crop. Decomposition and P and N release of tithonia and senna leaves were determined in
a litterbag study. Tithonia + TSP applications tripled maize yields compared to the control, senna + TSP and tithonia sole
application doubled yields, while senna sole applications did not increase yields substantially. A large residual yield was
produced in the tithonia treatments in a subsequent crop. These yield results were consistent with the higher quality and
faster release of N and P from the tithonia leaves compared to senna. The tithonia biomass transfer system can improve yields
in the short term but has limitations because of the large amount of biomass and the associated labor requirements.
This revised version was published online in June 2006 with corrections to the Cover Date. |
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Keywords: | biomass transfer decomposition mineralization nitrogen |
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