The effect of fertiliser application on soil pH

Abstract

Lime induced chlorosis is a major concern for Maltese farmers. The calcareous nature and high pH of Maltese soils makes this condition inevitable. This study focuses on the effect some fertilisers and other soil amendments have on the pH of soils from Malta. Ammonium sulphate, N.P.K., aluminium sulphate and elemental sulphur were added to different soils with contrasting properties and the pH of these soils was monitored after treatment. A significant drop to pH 6.5 was obtained with aluminium sulphate however this was followed by a rapid increase to a pH value above 7.0.The same drop and rise pattern was obtained with N.P.K. however a pH drop to below 7.0 was only obtained in one of the soils. Sulphur and ammonium sulphate produced a gradual decrease in pH in all soils. Although with sulphur and ammonium sulphate the drop in pH was to the 7.3 - 7.7 region, the pH did not increase again during the experimental period.