Rev. Bras. Ciênc. Solo.2008;32(5):1987-95.
Organic phosphorus in soils under cocoa agrosystems
01/Oct/2008
DOI: 10.1590/S0100-06832008000500020
Understanding the soil organic P (Po) cycle is important to improve the P fertilization management in low-input tropical agricultural systems. The aim of this study was to evaluate Po content and labile P fractions, and microbial biomass P in soils under different cocoa agroecosystems. Mean total Po was 193 mg kg-1 and accounted for 7.8 to 36.3 % of the total extracted P. Mean labile Po was 15 mg kg-1 and accounted for 33.1 to 81.9 % of the total labile P. In cocoa agrosystems, the total Po, labile Po and microbial P contents were lower in the Oxisol than in the Inceptsol group. In the Oxisol group, in soils under cocoa agrosystems, the total Po, microbial P and available P contents were higher and the labile Po lower than in the soil under natural forest. Available P was positively correlated with Po (total, labile and microbial), and total Po was positively related to microbial P. The labile Po fraction was far higher in the labile inorganic fraction, especially in the Oxisol group.
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