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Effects of Ground Rock Phosphate and Elemental S on Yield and P Uptake of Maize in Western Kenya

Published online by Cambridge University Press:  03 October 2008

A. R. Bromfield
Affiliation:
Kenya Agricultural Research Institute, PO Box 30148, Nairobi, Kenya
I. R. Hancock
Affiliation:
Kenya Agricultural Research Institute, PO Box 30148, Nairobi, Kenya
D. F. Debenham
Affiliation:
Kenya Agricultural Research Institute, PO Box 30148, Nairobi, Kenya

Summary

The effect on maize yields of ground rock phosphate, alone or mixed with sulphur in either of two proportions, and of single-superphosphate, was measured at five consecutive harvests. At the first harvest single-superphosphate increased yield by 1.54 t and the best of the mixtures by 0.56 t grain/ha. Ground rock phosphate alone had no effect on yield. At the third harvest there were no yield differences between sources; because yields produced by rock phosphate and the mixtures improved. The cumulative increase in yield produced by single-superphosphate was 3.58 t/ha and by rock phosphate 2.69 t grain/ha, but because the fertilizer cost ratio was 3:1, additional grain produced by rock phosphate cost half as much. The apparent P recovery ranged from 5.40 to 8.28 kg/ha, with most from single-superphosphate and least from the mixture containing most elemental-S.

Type
Research Article
Copyright
Copyright © Cambridge University Press 1981

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References

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