Effect of phosphorus fertilizer application on some forms of phosphorus in selected Ghanaian cocoa-growing soils

Abstract

Changes in the forms of phosphorus present in Ghanaian cocoa- growing soils incubated at 25 oC for up to 56 days in the presence of added cocoa leaf litter and/or phosphorus fertilizer are described. The addition of organic litter alone had little effect on bicarbonate-extractable inorganic phosphorus but large initial increase of the inorganic phosphorus occurred with the litter and phosphorus fertilizer added in combination, followed by a decrease especially in the phosphorus deficient soils. The addition of the litter without phosphorus fertilizer increased microbial biomass phosphorus content in all the soils, the increase being between 15 and 70 per cent in the soils without the litter addition and thus suggesting that the litter, among others, might be a possiblesource of the increased microbial biomass phosphorus in these soils. When litter and phosphorus fertilizer were added together, there was an initial rapid incorporation of phosphorus into the microbial biomass in the soils with low initial available phosphorus content. The phosphorus content of the microbial biomass should, therefore, be considered in determining the trend of organic phosphorus mineralization in soils.


(Ghana Journal of Agricultural Science, 1997, 30(1): 23-30)