F.X. Martinez, R. Casasayas, S. Burés, N. Cañameras
A methodology based on volumetric sampling and neutralization at constant volume for titration curves of acid and basic substrates is reported. Spanish black peat (Turbyg, pH-H20 = 4.58), german peat (Neuhaus, pH-H20 = 3.90), forest litter (Burés, pH-H20 = 7.90) and pine bark (I.M.C., pH-H20 = 7.31) are titrated with calcium hydroxide (approx. 0.04 N) or ferrous sulphate (approx. 2.5 %).

Pot amendment trials are performed by adding amounts of dolomite or micronized sulphur in relation with titration curves to achieve final pH of 5.5, 6.0 and 6.5.

According to titration curves, base demand of Turbyg peat was higher than Neuhaus due to its greater humic acid content. The superior acid demand for Burés forest litter versus I.M.C. pine bark can be attributed to differences in the base saturation of its exchange complex.

Amendment ability (%) was lower than 100 % for all substrates and desired pH. The lack of effectiveness of dolomite can be explained, in a great extent, by particle size effects while for micronized sulphur it seems to be due mainly to the kind of substrate and its own buffering capacity. The influence of other factors on amendment effectiveness are discussed.

Martinez, F.X., Casasayas, R., Burés, S. and Cañameras, N. (1988). TITRATION CURVES OF DIFFERENT ORGANIC SUBSTRATES. Acta Hortic. 221, 105-116
DOI: 10.17660/ActaHortic.1988.221.8

Acta Horticulturae