P tips from Manitoba Agronomists Conference

Instead of printing out hundreds of copies of its proceedings, the Manitoba Agronomists Conference videoed the whole conference, including the slides, and put it online. Click this link. Then click on "Webcast archive." The username and password are both "mac2008." This afternoon I watched a panel presentation on phosphorus fertilizer, which you'll find at around the 166th minute of the video.

The panel included Rigas Karamanos of Viterra, Geza Racz, now an Agri-Coach with Agri-Trend, Don Flaten, prof at U of M, and John Lee, agronomist with AgVise Labs. Here are a few highlights:

1. If you have good soil reserves of available phosphorus, you can cut rates in the short term. Don Flaten quoted a 1962 study that says if your soil test shows 15 ppm of available phosphorus in the soil, you may just need a starter rate of 10 pounds per acre of P2O5.

Geza Racz added that 10 pounds is reasonable for a one-inch opener. “If the seed row is wider than one inch, you’ll want to go to 15 pounds or more,” Racz says.

2. Racz emphasized the need for placement with the seed or right beside. “Phosphorus MUST be available to seedlings,” he says. “Delay in uptake equals lower yield.”

3. John Lee showed slides to demonstrate how far apart fertilizer granules or liquid droplets are at certain rates. For example, with seven-inch row spacing, phosphate granules applied at five pounds per acre will be 7.5 inches apart in the seed row. You need to get up to 20 pounds before the granules are two inches apart, on average. “That’s close enough for granules to be accessible to every seed,” he says. I hope to get these slides and post them on my blog in the near future.

4. Rigas Karamanos says you’ll get the maximum yield return from the first 15 to 20 pounds of phosphate applied. After that, you might as well save your money. http://youronlinechannel.com/mac/