'Nitrogen and Phosphorus in Solid and Liquid Manures: The Tortoise Versus the Hare' was among the topics discussed last week as part of Prairie Livestock Expo 2014 in Winnipeg.

Trevor Fraser, a technician with the University of Manitoba's National Centre for Livestock and the Environment notes the nitrogen and phosphorus levels in manure do change according to the different types of manure and also the different handling systems used in the barns, so you can have different nutrient levels as well as different nutrient availability to the plants over time.

Trevor Fraser - University of Manitoba:

Liquid pig manure has both nitrogen and phosphorus in it.

The nitrogen tends to be more in the ammonia form, which is readily available to plants, where as something like a solid pig manure or a solid dairy manure, the form of nitrogen would be mostly in the organic form and that organic form needs to mineralise before it becomes available.

We found that those liquid pig manures, they tend to be very quickly available for plants and the plants are readily able to pick up that ammonia.

Where as the solid manures, they take a much longer time before that nitrogen becomes available.
We saw that it took up to six years before we started to see nitrogen becoming available from yearly applications of solid manures.

We also found that those were very effective at increasing soil phosphorus levels but actually, even though we're importing lots and lots of phosphorus with those solid manures, the effect it had on soil phosphorus was lower than the effect that liquid manures had on soil phosphorus.

Mr Fraser suggests when planning manure application producers need to consider the type of manure, the form of manure (whether it is liquid or solid) and the cropping system to which it is being applied.