ISSN 2756-3863
International Journal of Manures and Fertilizers Vol. 3 (4), pp. 502-507 April, 2014. © International Scholars Journals
Full Length Research Paper
Use of trimming and mineral fertilizer affects soil phosphorus availability and fractionation in a gliricidia/maize intercropping system
Simon Calvin, Nduta Hanjari and Bedan H. Jacques
Department of Crop Science, Faculty of Agriculture, Egerton University, kenya. Email: simonicsl@yahoo.com
Accepted 16 March, 2014
Abstract
Leguminous tree species are known to replenish soil nutrients through biological N fixation, mulch effect and recycling of other nutrients from the deeper soil layer to the topsoil, when managed in agroforestry systems. The soil available phosphorus (P) status and inorganic P-forms (fractionation) in a long-term gliricidia-maize trial was studied to understand the effect of additions of gliricidia prunings combined with and without inorganic fertilizers (N and P). Addition of gliricidia prunings and inorganic N and P fertilizers significantly increased phosphorus uptake by maize. Bray P1 had strong correlation with P uptake by maize in gliricidia/maize intercropping (r = 0.81, p<0.001). Both the Olsen and Bray P1 methods of extraction were strongly correlated (r = 0.80) . Phosphorus fractionation data of the soils from the maize and gliricidia-maize plots indicated that the Fe-P fraction was the most dominant form of inorganic P. The addition of gliricidia prunings significantly reduced the Fe- P and Al-P forms. We conclude that iron phosphate acts as a sink for applied inorganic P in Lixisols and the increased soil organic matter through addition of gliricidia prunings solubilizes fixed P in the soil.
Key words: Agroforestry, fertilizer trees, available P, P-uptake, inorganic P fractions.