RRBC "Action Around the Basin"

Do grassed buffers along fields intercept nutrients?

As producers are coming under greater and greater scrutiny regarding the application of fertilizers, organizations such as Conservation Districts have a supportive role to play through the provision of advice and information to producers and the public at large. Recent regulations under the Water Protection Act has been enacted that restricts the application of chemical fertilizers within 8 m of a Provincial drain, creek or major wetland (i.e. >2 ha). This nutrient application set-back can be reduced to 3 m from the waterway’s edge if those three metres are permanently vegetated. This type of regulation is aimed at protecting the health of our waterways by minimizing the nutrient load to streams. The question is, will this work and does a vegetation strip filter out nutrients contained in field runoff? By tapping into research expertise at the University of Manitoba (Dr. Don Flaten) and with funding support from Manitoba and MCDA, CDs are trying to get to the bottom of this question. In addition, we are also examining how management of the vegetation affects the buffer’sability to hold nutrients.

The East Interlake Conservation District is the lead on this project and has one of the test sites. Two other sites are located in central and western Manitoba within the Pembina Valley CD and the Little Saskatchewan River CD. Combined, these sites represent the majority of the dominant agricultural landscapes within Manitoba.

Starting at snowmelt, staff from each site have been collecting the water that is running from the annually cropped field and through the buffer. This water is sent to Winnipeg for analysis from which we will be able to determine what effect buffer strips of 5 m in width have on water quality. Twice a year the buffers are harvested and the vegetation is removed to see how management of the vegetation within the buffer zone impacts its ability to remove nutrients. This process reflects what a producer would do when haying grassed areas.

Although we are testing the effectiveness of buffer strips in removing nutrients, buffer strips are known to provide a variety of other functions and are a critical part of a healthy watershed. Through the creation, restoration or protection of buffer strips you provide, among other benefits, wildlife corridors, stable stream banks, reductions in sedimentation, improved habitat for aquatic life, and reductions in bacteria; but, do they reduce nutrient loads to waterways?

PICTURE (Above): Spring runoff collection, A. Belanger, Manager, EICD.

PICTURE (Upper Right): Bufferstrip site, Willow Creek on the right, farmers field on the left.
SOURCE: East Interlake Conservation District (http://www.eicd.net/)