Table of Contents
ISRN Soil Science
Volume 2014 (2014), Article ID 920541, 8 pages
Research Article

The Effect of Minjingu Phosphate Rock and Triple Superphosphate on Soil Phosphorus Fractions and Maize Yield in Western Kenya

1Kenya Forestry Research Institute, Maseno Regional Centre, P.O. Box 5199, Kisumu, Kenya
2Department of Soil Science, Maseno University, P.O. Box, Private bag, Maseno, Kenya

Received 29 November 2013; Accepted 1 January 2014; Published 4 March 2014

Academic Editors: J. A. Entry and W. Peijnenburg

Copyright © 2014 Robert Orangi Nyambati and Peter Asbon Opala. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


We tested the effects of triple superphosphate (TSP) and Minjingu phosphate rock (MPR), when applied at phosphorus (P) rates of 50 or 250 kg P ha−1 in a factorial combination with urea or Tithonia diversifolia green manure as nitrogen sources, on P availability and maize yields for two seasons at Nyabeda and Khwisero in Kenya. Phosphorus availability was determined by the Olsen method or sequential fractionation. There was no significant difference in Olsen P as influenced by TSP and MPR at 50 kg P ha−1 irrespective of the N source at both sites in both seasons. However, at 250 kg P ha−1, TSP gave significantly higher Olsen P than MPR. The labile P fractions generally followed the same trend as the Olsen P. Maize yields increased with increasing amount of P applied. Generally, there was no significant difference between TSP and MPR on maize yields irrespective of the N source. The Olsen-P, Resin-P, and sodium bicarbonate inorganic P correlated well with maize yields when TSP was used but the correlations between these P tests and maize yields for MPR were not consistent and therefore their use on soils treated with MPR should be exercised with caution.