Farmscape for May 4, 2009   (Episode 3173)

A researcher with the University of Manitoba says the management of phosphorus applications to crop land will vary according to the source of the nutrient.

The Manitoba government has imposed strict limits on phosphorus applications to reduce the risk of excess amounts ending up in waterways.

Dr. Don Flaten, a soil fertility researcher with the University of Manitoba and chair of the National Centre for Livestock and the Environment, says the source as well as rate, placement and timing of application are fundamental to managing phosphorus.

Clip-Dr. Don Flaten-University of Manitoba

If you're working with a synthetic fertilizer source you're probably going to go with something like an application rate that's modest and it's applied near the seed row at planting.

That's going to be good agronomically, good environmentally.

On the other hand, if you're working with some of these other forms of phosphorus that are maybe less available, let's say liquid pig manure phosphorus is not quite as available as synthetic fertilizer phosphorus, you may have to go agronomically at a slightly higher rate.

Once again though we would recommend, if possible, try to inject or band the liquid manure phosphorus underneath the soil surface to make it more agronomically efficient and also to reduce the risk of run-off losses.

Then, in terms of solid manures and compost, those types of sources of phosphorus are less available to crops than the liquid manures or the synthetic fertilizers but they're also very difficult to band underneath the soil surface so in those sorts of cases, we're dealing with a source of phosphorus that's not as environmentally risky but it's also harder to manage in terms of the rate and the placement and the timing is a little bit more awkward.

Dr. Flaten says because of the difficulty of banding solid manures and composts under the soil surface, it's actually fortunate that phosphorus from these sources is less of a risk, environmentally.

For Farmscape.Ca, I'm Bruce Cochrane.

       *Farmscape is a presentation of Sask Pork and Manitoba Pork Council