Scientific Research and Essays Vol. 2 (10), 446-453, October 2007          
ISSN 1992-2248 © 2007 Academic Journals

Full Length Research Paper

Green manure from prunings and mineral fertilizer affect phosphorus adsorption and uptake by maize crop in a gliricidia-maize intercropping

D. E. Mweta¹, F. K. Akinnifesi^2*, J. D. K. Saka¹, W. Makumba² and N. Chokotho¹

¹University of Malawi, Chancellor College, P. O. Box 280, Zomba, Malawi.

²World Agroforestry Centre (Malawi), Chitedze Agricultural Research station, P.O. Box 30798, Lilongwe 3, Malawi.

*Corresponding author. E-mail: fakinnifesi@africa-online.net, Tel.: +265.1.707.328, Fax: +265.1.707.323

Accepted 7 September, 2007

Abstract

Gliricidia sepium-maize intercropping has shown to be a suitable option for soil nutrients replenishment and for sustainable crop production in Southern Malawi. This study was carried out to understand the effect of green manure on phosphorus sorption and subsequent crop uptake under gliricidia (G. sepium)-maize intercropping. The experiment consisted of a factorial combination of two cropping practices (maize with and without gliricidia), three rates of inorganic N fertilizer (0, 46 and 92 kg N/ha), and inorganic phosphorous (P) fertilizer (0, 20 and 40 kg P₂O₅ ha^-1) combined. Application of gliricidia prunings and inorganic P fertilizers reduced the P sorption capacity of the soil and maize P uptake. Langmuir P affinity constant and the Freundlich P adsorption constant were significantly reduced with application of gliricidia prunings and inorganic P fertilizers. Combination of gliricidia prunings and inorganic P fertilizer further reduced the P sorption capacity of the soils compared to gliricidia prunings alone. The results indicate that addition of gliricidia prunings increases P availability through reduced P sorption capacity of the soil and recycling of P. combination of gliricidia prunings and inorganic P fertilizer has an added benefit compared to application of either gliricidia prunings or inorganic P fertilizers alone.

Key words: Agroforestry, organic and inorganic fertilizers, P sorption, P uptake.