INLAND ACID SULFATE SOIL SYSTEMS ACROSS AUSTRALIA Hicks Warren and Rob Fitzpatrick. 2008. Acid Sulfate Soil Formation in Turfgrass in a Sports Stadium from Applications of Excess Elemental Sulfur as a Soil Amendment, In Inland Acid Sulfate Soil Systems Across Australia (Eds. Rob Fitzpatrick and Paul Shand). pp 149-150. CRC LEME Open File Report No. 249. (Thematic Volume) CRC LEME, Perth, Australia. CHAPTER 7 ACID SULFATE SOIL FORMATION IN TURFGRASS IN A SPORTS STADIUM FROM APPLICATIONS OF EXCESS ELEMENTAL SULFUR AS A SOIL AMENDMENT W. S. Hicks 1 and R.W. Fitzpatrick 2 1 CRC LEME, CSIRO Land and Water GPO Box 1666, Canberra, ACT 2601 2 CRC LEME, CSIRO Land and Water Private Bag 2, Glen Osmond, SA 5064 INTRODUCTION As documented in this monograph, the reactive nature of sulfur as it responds to changes in its redox environment can be troublesome. Here we report on one of the more unusual examples that resulted in considerable damage to a major sports ground’s turf grass and a civil lawsuit in excess of 1 million dollars. Superintendents may often apply elemental sulfur when soil pH exceeds 7.5 simply because they are frequently reminded that the optimum pH for turfgrass performance is between 6 and 7. This may be, in part, because they are concerned that a hidden micronutrient deficiency may occur when soil pH is relatively high. Visible iron deficiencies, exhibited as leaf chlorosis, are common when soil pH approaches 8 (Christians, 1998), although they were not observed in this instance. Attempts to reduce the pH of calcareous sand under turfgrass with elemental sulfur or ammonium sulfate, under conditions similar to those evaluated in this case, would be a waste of time and money. A better approach would be to use fertilizer applications to address potential nutrient deficiencies. During routine end-of-season ground’s maintenance, elemental sulfur was applied to reduce the slightly alkaline pH value. The pre-maintenance inspection report of the soil and turf grass noted “A conglomeration of soil types including sand and loamy sand. These conditions could affect drainage and needs regular surface and sub-surface aeration to reduce its impact”. There was also a “dense thatch layer” and “A thin layer of dead plant material and fine material existed on the surface”, indicating that the playing field had a range in soil texture, organic matter and permeability. The soil testing laboratory recommended an application of 0.1 t ha –1 of granulated sulfur. However the actual application was 2 t ha – 1 , some 20 times greater. Magnesium sulfate, molasses (50L per hectare) and “Dynamic Lifter” (3 tonnes per hectare) were also applied, adding to the readily available source of organic carbon that already existed in the thatch and providing a labile energy source for soil bacteria. Records of the resulting changes in the soil and turf grass condition indicate that in well drained areas the oxidation of the elemental sulfur caused the pH to drop to around 3.8, however in poorly drained areas waterlogging resulted in reducing conditions and the formation of black material with “strong putrid smell and anaerobic conditions”. DISCUSSION Sulfur is applied as an amendment to reduce the pH via its oxidation to sulfuric acid by soil bacteria. However Nelson (1982) found that excess sulfur may result in patchy reaction and that unreacted sulfur can accumulate in the soil profile in narrow bands of 2 to 3 cm of affected soil. This appears to have been the case at this sports ground where unreacted sulfur was present and the already variable soil conditions became worse. The excess sulfur application created two problems. In well drained areas excess acid Page 149