Calculating pH in Pig Manure, Carefully

The Davies equation plays a featured role in this take on pig manure

Calculating pH in Pig Manure Taking into Account Ionic Strength,” A. M. Nielsen, H. Spanjers and E. I. P. Volcke, Water Science & Technology—WST Vol 57 No 11 pp 1785–1790. Doi:10.2166/wst.2008.099. (Thanks to Adam Eyring for bringing this to our attention.) The authors, at the University of Aarhus in Horsens, Denmark and at Ghent University, in Belgium, and at Lettinga Associates Fdn in Wageningen, The Netherlands and at INRA, in Narbonne, France, report:

In this study a model, implementing a procedure for calculating pH, was developed to analyse the effect of ionic strength on pH in a pig manure. By adding KCl to samples of pig manure, experimental results could be analysed with help from the model. A modified form of the Davies equation was found to give the most accurate prediction of pH in the pig manure studied in this paper with changing ionic strength