Plants need nitrogen, but they don’t like it.
And if phosphate fertilizer is placed with the nitrogen, plants will be reluctant to access it as well.
Garry Meier of Meier Farms at Tisdale, Sask., said the issue of nitrogen placement rises along with the rates being placed in the soil. In a single pass system where the nitrogen is planted in the soil at the same time as the seed, there is a period of time when the fertilizer is highly toxic to the young plants.
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The plants’ root systems avoid the area where the nitrogen is placed and if the phosphate fertilizer is in the same band, plants will avoid it too, said Meier.
“Anhydrous is the most toxic due to the fact it is the most concentrated form of (nitrogen). Yet we often place it right beside the seed. You need better seedbed utilization than that,” he said.
As well as farming, Meier is the corporate agronomist for farm equipment maker Bourgault Industries of St. Brieux, Sask.
Fertilizer placement is a selling point for Bourgault because of the company’s mid-row banding system, however the science is sound for carefully placed nitrogen.
Ross McKenzie, of Alberta Agriculture and the University of Lethbridge, told producers attending Alberta Southern Applied Research meetings to consider their equipment choices carefully when placing seed too close to fertilizer, or exceeding rates that are considered safe, depending on soil type and available moisture.
Research at the Alberta Machinery Research Centre dating back to the mid-1990s has shown that very narrow fertilizer bands created by disc openers that focus fertilizer in small regions next to or below the seed, impede plant growth and delay maturity.
Meier said mid-row banded crops show the fertilizer rows are often weed-free, while the spaces between crop plants are filled with annual weeds.
“The fertilizer band is an area where plants, wanted or unwanted, have germination problems,” he said at a Bourgault-sponsored agronomy event in St. Brieux, June 25.
“You want to avoid that band with your $6 (per pound) canola (seed),” he said.
Agronomists say producers can lose the initial pop-up effect of phosphorus when it is placed with the nitrogen and this will remain an issue until the nitrogen-placed region becomes more hospitable to plant roots.
McKenzie’s research up to 2007 showed that coated urea products that delay the release of nitrogen, such as Agrium’s ESN, allow plants to access nitrogen and phosphorus when seed placed and also reduce toxicity damage.
Ray Dowbenko of Agrium told producers at a Saskatchewan Soil Conservation Association meeting that side-band placement of urea and the ESN coated urea performed nearly equally. As expected, the coated product outperforms the uncoated when seed placed.
Whether side-banded or mid-row placed, making both nitrogen and phosphorus available to the plants as early as possible in the growing season increases yield, said Rigas Karamanos, of Westco Fertilizers.
“Plants need to be able to get to the phosphate fertilizer and the sulfur. If they can’t until the (nitrogen) is more dispersed or the area isn’t as hostile, then they won’t have the uptake when they need it,” he said, making a case for phosphorus placement with the seed.
Meier said it typically takes three or four weeks for plant roots to access the areas of the soil where the nitrogen is placed.
Meier said side-banded phosphate fertilizer doesn’t provide the same results as placing it with the seed or at least away from the nitrogen fertilizer.
“With (phosphorus) doubling in price in the past three seasons and (46-0-0 nitrogen) up 50 percent, the need to make the best use of your inputs is getting more and more important,” he said.
“With commodity prices up even more, you can see the benefit on the yield side as well as any efficiency and savings you might make,” said Meier.
Dowbenko said the research shows that when it comes to ideal placement, banding of urea nitrogen ahead of planting remains the strongest technique overall for getting nitrogen to the plants in an available form as early as possible. Coated delayed-release products perform nearly as well or, in some cases, equally.
However moisture loss, soil disturbance and the time and cost of another application mean the practice isn’t practical for many growers.
Meier said for many producers the single pass seeding application has moved from convenience to necessity because of large seeded acreage, lack of labour and increased equipment operating costs.
