Just because nitrogen fertilizer is placed below the soil surface doesn’t mean it’s going to stay there for plants to use it. In fact, if it’s not buried deep enough, you might be better off broadcasting it on top of the soil, says the senior agronomist for Koch Agronomic Services.
Whether for equipment reasons, with more fertilizer being applied at seeding, or farmers wanting to drive faster, there’s more shallow banding of fertilizer than there used to be.
“Practices have changed with people for example side-banding their fertilizer. When you’re seeding canola at 1/2? or 1?, inadvertently your fertilizer is side-banded at 1? or 1 1/2?. As a result the depth of banding is not the same,” explains Rigas Karamanos. “People also mid-row band and although they’re supposed to go at a 3 or 4? depth, they want to go faster, so they lift the mid-row bander.”
By definition, banding urea or UAN leaves a concentrated band in the soil, which creates a microenvironment with high pH.
“As a result you have volatilization of nitrogen, but with deep banding there’s enough soil atop of the band to stop the diffusion of the ammonia gas that is being produced,” he says. “When you shallow band, unfortunately that doesn’t happen.”
Weather is a factor in how much volatilization occurs (rain may move it deeper into the soil profile,) but Karamanos recommends deep banding or the use of an enhanced efficiency fertilizer product to protect the fertilizer for the 10 to 12 days between seeding and the time when nitrogen uptake usually spikes in wheat or canola.
He shared the results from his 2014 trials in Manitoba, Saskatchewan and Alberta at the Farm Forum Event in Saskatoon earlier this month. Comparisons of broadcast, shallow-banded and deep-banded urea, as well as urea treated with Agrotain and Super U, will be repeated in 2015.