"Molybdenum blue method, using ascorbic acid as reductant after heating of soil to 550 C and extraction with 6M sulphuric acid. Particularly used for Total P." . . . "Total_tp06"@en . . . . "Leenaars J.G.B., A.J.M. van Oostrum and M. Ruiperez Gonzalez, 2014. Africa Soil Profiles Database, Version 1.2. A compilation of georeferenced and standardised legacy soil profile data for Sub-Saharan Africa (with dataset). ISRIC Report 2014/01. Africa Soil Information Service (AfSIS) project and ISRIC - World Soil Information, Wageningen, the Netherlands. See Annex 4." . "Total_tp06" .