Studies in the variation of soil reaction. III. Variations at the Waite Agricultural Institute

Abstract

Variations in reaction and total soluble salts of a red-brown earth from South Australia have been assessed. Seasonal changes are discernible for reaction but are largely masked by spatial variations even over small areas. The amplitude of the seasonal changes is of the order of 0.15 of a pH unit, the soil returning to the same pH value during the succeeding season. Spatial variations have been found for organic carbon, nitrogen, clay, and exchangeable cations over small areas. Data have been presented to show that while the mean soil reaction does not vary widely, there is a variation in the variance of the reaction values about the mean with season. The change of the reaction status of the soil with time over a small area does not consist of a uniform increase and decrease of 911 the reaction values in the area but rather of a reorganization of all hydrogen ion contributing factors to give difference in dispersion about the mean value.