New environmental rules due to take effect in Manitoba in November 2013 will limit the amount of manure that can be applied to the land based on the level of phosphorus in the manure and in the soil and winter spreading of manure will be banned.

John Carney, the executive director of the Manitoba Livestock Manure Management Initiative says if your farm has a high soil test phosphorus level it will be important to understand your soil test level and be working on strategies to adjust manure application: "I think a good way to think of it is thinking of it in terms of the phosphorus balance on a farm.

"If you think about all the sources of phosphorus imported onto your farm and whether that's phosphorus coming in in the feed that you bring into your livestock. If you buy commercial fertilizer it could have phosphorus in it. In some cases you may buy manure and bring it in from another operation and so if you bring in manure from another farm that would be a source of phosphorus.

"You would aggregate those inputs and then you would look at the phosphorus that you export from your farm through the year. It could come off your farm in terms of crops, it could come off in terms of livestock that you raise and market, it could be through the eggs and milk you produce.

"You can almost think of it as an equation where you start the year with a balance, you have inputs that increase the phosphorus level on your farm, you have exports that reduce the phosphorus level, at the end of the year you have a closing balance of phosphorus."

Mr Carney says strategies designed to reduce feed costs usually also offer an environmental benefit.

He says, if we can find ways for pigs to get more nutritional value out of the feed dollar, there's often an environmental benefit that comes along with it that may not be readily recognised.