Temporarily storing manure in farm fields can have damaging consequences on the surrounding environment if best management practices aren’t followed. Choosing the right location, say Ontario Ministry of Agriculture and Food (OMAF) researchers, can make a big difference in helping to lower environmental risk.

Dr. Chris Duke and Pamela Joosse, Environmental Management Unit and Kevin McKague, Engineering and Technology recently found high levels of potentially harmful nutrients – including nitrate and phosphorus, which can harm aquatic life and damage the environment – in water from in-field stockpiled manure runoff and leachate.

What’s more, there were also significant levels of potentially pathogenic bacteria, including E. coli. In fact, says Duke, both E. coli and ammonia nitrogen levels in these runoff samples exceeded the province’s water quality objectives to protect aquatic life.

“Location is very important with regards to temporary manure storage, because of where contaminated runoff or leachate might flow,” he says. “That’s why we need to know the impact stockpiling manure could have on the environment. We need to base regulations on real Ontario field characteristics.”

Duke’s study investigated how cattle manure was stored in farm fields, and took a closer look at how the water that runs off manure piles affects surrounding soil and water systems. The study was initiated to establish whether regulations from Ontario ’s voluntary Best Management Practices (BMPs) and mandatory Nutrient Management Act regulations sufficiently protect the environment. Temporary field storage is permitted under the Act; suitability of the site and duration of storage is a function of several soil and site characteristics.

To assess environmental effects from runoff and seepage, Duke studied five manure piles – placed in a typical field location – during a summer and winter period. Two piles were placed on plastic, allowing all runoff and seepage to be collected. One pile was covered with a plastic tarp while the final two piles were assessed under normal conditions. Following any precipitation, runoff and seepage samples were taken from the piles and nutrient and bacteria levels were measured.

Duke’s results showed that water samples from uncovered manure piles contained high levels of nutrients and bacteria, which can contaminate soil and waterways and pose risks to human, animal and environmental health. Covering the pile helped reduce runoff and the contaminants from manure piles.

Duke says a key element to responsibly stockpiling manure is to carefully choose a storage site. Manure piles should be located where runoff loaded with nutrients and bacteria won’t reach wells, tile drains or surface water. And the same stockpiling sites shouldn’t be used repeatedly – different locations of the field should be used from year to year.

Temporary manure piles are usually used for short-term manure storage before producers spread the material on fields, so there are very few studies assessing runoff from them. However, says Duke, temporary manure storage can adversely affect soil and water. He hopes this study will raise awareness of manure storage’s environmental and health impacts, and encourage producers to improve their storage practices. OMAF and other partners have also conducted similar studies on different materials under different soil characteristics.

This study was sponsored by OMAF, the Ontario Cattlemen’s Association and the Partners in Nitrogen Use Efficiency project.