02260naa a2200241 a 450000100080000000500110000800800410001910000190006024501010007926000090018052016080018965000120179765000150180965000150182465000130183965000130185265300150186570000180188070000200189870000220191870000180194077300600195819663202015-02-19       2013    bl uuuu     u00u1 u    #d1 aMORALES, M. M.  aSorption and desorption of phosphate on biochar and biocha-soil mixtures.h[electronic resource]  c2013  aThe term biochar refers to materials with diverse chemical, physical and physicochemical characteristics that have potential as a soil amendment. The purpose of this study was to investigate the P sorption/desorption properties of various slow biochars and one fast pyrolysis biochar and to determine how a fast pyrolysis biochar influences these properties in a degraded tropical soil. The fast pyrolysis biochar was a mixture of three separate biochars: sawdust, elephant grass and sugar cane leaves. Three other biochars were made by slow pyrolysis from three Amazonian tree species (Lacre, Inga and Embauba) at three temperatures of formation (400 °C, 500 °C, 600 °C). Inorganic P was added to develop sorption curves and then desorbed to develop desorption curves for all biochar situations. For the slow pyrolysis, the 600 ºC biochar had a reduced capacity to sorb P (4–10 times less) relative to those biochars formed at 400 °C and 500 °C. Conversely, biochar from Inga desorbed the most P. The fast pyrolysis biochar, when mixed with degraded tropical mineral soil, decreased the soil’s P sorption capacity by 55% presumably because of the high soluble, inorganic P prevalent in this biochar (909 mg P/kg of biochar). Phosphorus desorption from the fast pyrolysis biochar/soil mixture not only exhibited a common desorption curve but also buffered the soil solution at a value of ca. 0.2 mg/L. This study shows the diversity in P chemistry that can be expected when biochar is a soil amendment and suggests the potential to develop biochars with properties to meet specific objectives.  abiochar  adesorption  aphosphorus  asorption  aFósforo  aBiocarvão1 aCOMERFORD, N.1 aGUERRINI, I. A.1 aFALCÃO, N. P. S.1 aREEVES, J. B.  tSoil Use and Managementgv. 29, p. 306-314, Sept. 2013.