To improve water quality in Lake Winnipeg Prairie farmers are being urged to balance crop nutrient applications with crop removal and to avoid winter application.
Research conducted in Manitoba’s South Tobacco Creek watershed shows about 80 percent of phosphorus loading and runoff occurs during spring snow melt.
Although phosphorus contained in eroded soil is a concern in many regions the main challenge for prairie farmers is dissolved phosphorus in runoff.
National Centre for Livestock and the Environment chair Dr. Don Flaten notes, although the concentration of phosphorus in runoff may not differ all that much, much of the runoff from summer rains soak into the soil but snow melt is different because it occurs when the soil is frozen.
In other parts of North America they really promote conservation tillage because they’ve got a big problem with erosion of soil particles being the main form of phosphorus loss.
In our environment we’re not wet enough or we don’t have steep enough slopes to really make erosion our big problem and we’ve got this dissolved phosphorus problem.
It’s going to take more than erosion control to really solve our problem so what we’re really promoting is making sure that you try to balance phosphorus addition at a rate that doesn’t exceed crop removal so you don’t build up excess phosphorus levels in your soil and avoiding winter application. But I don’t mean that that’s a simple challenge to address.
There are big challenges in areas where there is a very high livestock density.
There may not be sufficient land base for everybody to go on sort of a phosphorus balance based system.
Also for some small producers the storage costs for avoiding winter spreading of manure can be quite high and so we have some substantial technical and economic challenges that are built in within those two overall recommendations.
Dr. Flaten says our high proportion of dissolved phosphorus is difficult to intercept once it starts moving off the field, so we need to be careful about when and how much phosphorus is applied in the first place.
Source: Farmscape.Ca
