By Kristy Nudds

Nutrients and bacteria that leach into groundwater from manure-treated soil is a significant environmental concern, but the way manure management practices influence this process is poorly understood. University of Guelph researchers have started a three-year study examining how contaminant's escape from soil is altered by the season of manure application, and various tillage practices.

Profs. John Lauzon, Gary Parkin, Michael Goss, Bill Deen and graduate student Steve Crittenden, departments of Land Resource Science and Plant Agriculture, are looking at how the transfer of nitrogen, phosphorus and E. coli from soil into groundwater differs between applying manure in the spring, compared to late summer and early fall.

This transfer can depend on how water moves through soil, so conventional tillage and no-till practices will also be compared for their impact on 'preferential' water flow, through worm burrows and dessication cracks.

The researchers' goal is to strike a balance between manure being a resource for producers, yet safer for the environment.

"One of the biggest challenges in the beef industry is minimizing environmental impacts and maximizing nutrient uptake in crops," says Parkin. "We hope to give producers the best possible option for manure application."

Research began in September on silt loam soil plots at a Guelph-area research station. Manure will be applied either in the fall or the spring, with or without tillage, then planted to crops in a standard rotation. For each seasonal manure application and tillage method, the amount of rainfall left in and between tile drains will be collected, and measured on a continual basis.

This data will be used to determine what differences exist in preferential water flow between seasons and management practices. More importantly, it will also indicate the time of year when the potential for nutrient and bacterial leaching is greatest, says Parkin. Phosphorus, nitrogen, and E. coli concentrations will be measured in the collected water samples.

"Understanding how different management practices affect soil water movement will allow us to quantify when the greatest risk for nutrient and bacterial leaching can occur," he says.

This research is sponsored by the Ontario Cattlemen's Association, the Ontario Ministry of Agriculture and Food, Ontario Pork, the Canada Foundation for Innovation and the Canadian Water Network.