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

Abstract

Gliricidia sepium-maize intercropping has shown to be a suitable option for soil nutrients replenish-ment 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 fertiliser. Combination of gliricidia prunings and
inorganic P fertiliser 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 fertiliser has an added benefit
compared to application of either gliricidia prunings or inorganic P fertiliser alone.