
%0 Journal Article
%A Tan, Z 
%A Mclaren, RG 
%A Cameron, KC 
%T Seasonal variations in forms of extractable sulfur in some New Zealand soils
%J Soil Research
%D 1994/10/01
%V 32
%N 5
%P 985-993
%K Carbon-Bonded Sulfur;Extractants;Hydriodic Acid Reducible Sulfur;Organic Sulfur;Seasonal Fluctuation;Sulfate;
%R https://doi.org/10.1071/SR9940985
%U https://www.publish.csiro.au/paper/SR9940985 
%X Seasonal variations in different forms of extractable sulfur (S) were examined in three New Zealand soils under permanent pasture. The concentrations of total extractable S, extractable inorganic sulfate-S (SO2-4-S), and extractable organic HI-reducible sulfur (HI-S) and carbon-bonded sulfur (C-S) were determined in field moist samples using four different extractants. During the course of the year, extractable SO2-4-S levels varied substantially. Concentrations of SO42--S in the soils peaked in the early spring and, for two of the soils, remained at relatively low levels throughout the rest of the year. The third soil, however, following a decrease in concentration in late spring, showed a continuous increase in SO2-4-S during the summer and autumn period. Concentrations of extractable organic C-S in soils were generally highest in the winter and declined significantly during the spring. Extractable organic HI-S concentrations fluctuated throughout the year with no clear trends. The proportions of the three forms of extractable S in soils also varied seasonally. The proportions of extractable organic HI-S in soils were more constant compared with the other two forms of S and generally accounted for less than 20% of the total extractable S. The seasonal changes in the proportions of SO2-4-S appeared to be inversely related to the changes in extractable C-S. This suggests that under the field conditions, the extractable organic C-S fraction is readily mineralized to sulfate when conditions are favourable for mineralization to take place. 
