Leaching of fungicides from golf greens: Quantification and risk assessment

Project outcome

The objectives of this project were to i.) assess the leaching risk associated with fungicide use on golf greens in Scandinavia, ii.) gain a better understanding of the processes controlling fungicide leaching from golf greens, and iii.) identify, recommend and encourage the adoption of green construction and management practices that minimize leaching. Leaching of Iprodione was monitored at the research green at Fullerö GK, Västerås, while degradation and sorption properties were measured in laboratory experiments on root zone material taken from Fullerö. This data was used to calibrate and validate the pesticide leaching model MACRO. The calibrated model was then used as a basis for a leaching risk assessment. ‘Scenario’ simulations were run to demonstrate the effects of root zone organic matter content on the leaching risk. The main findings and recommendations were as follows:

• Degradation of iprodione was initially very rapid (half life < 1 day), which was attributed to microbial adapation due to repeated applications of the compound. After this initial phase lasting c. 5 days, degradation proceceeded at a slower rate (half-lives 22-38d). Iprodione was moderately strongly adsorbed to the green soil. The isotherm was linear with a Koc value of 400 cm3 g-1. 
  
  
• Despite the rapid breakdown, concentrations in drainage water from the Fullerö green exceeding the surface water quality guideline value (0.2 mg L-1) were occasionally found. 
  
  
• The model matched the hydrological observations reasonably well, but could not match the peak concentrations of iprodione found in drainage water. This was attributed to preferential flow in the green, due to water repellency. 
  
  
• The simulations showed the great potential for minimizing losses of fungicides by appropriate green construction practices. Increasing the organic matter content in the root zone from 2 to 3% virtually eliminated leaching, while decreasing it to 1% increased leaching by a factor 20.