Dry soils increase the risk of in-row fertilizer damaging early plant stands, but there are things farmers can do to make it safer, says John Heard, a soil fertility specialist with Manitoba Agriculture and Resource Development (MARD).
“We like to take as much nitrogen and sulphur out of the seed row as possible in order to protect the stand in a dry year,” Heard said in an interview April 14 following MARD’s weekly CropTalk webinar. “There is flexibility to apply nitrogen and sulphur in numerous other ways (such as mid-row and side band while seeding) or if they have to, after seeding, broadcast. It’s maybe not Plan A but it might be wiser than jeopardizing a plant stand.”
Why it matters: With dry soils most farmers are expected to disturb their fields as little as possible ahead of planting, but too much fertilizer with the seed risks crop injury.
About 45 per cent of Manitoba farmers apply their wheat and canola fertilizer in the fall, usually by tilling in anhydrous ammonia or banding urea.
“Those folks are ready to go (in spring) and that’s why they do that,” Heard said. “They have great flexibility in the spring.”
Those farmers can top up their nitrogen and add starter phosphorus with the seed, but those who want to do all their fertilizing while seeding in one pass risk damaging seed or seedlings when soils are dry unless they can place it mid-row or side band it.
However, only 15 to 20 per cent of Manitoba farmers have seeding equipment that can mid-row band fertilizer and 15 per cent can side band it, Heard said.
Such seeding equipment is more common in Saskatchewan and Alberta where more farmers zero till, he said.
Another option with nitrogen is replacing urea with a safer form such as ESN (Environmentally Smart Nitrogen), “but that’s contingent on the ESN being fairly intact. If it has been augered a lot, guys might want to be shy if they think they have injured the coatings.” he said.
When less fertilizer can go with the seed, phosphorus should be the priority.
“It is the essential nutrient that we should have on, with, or close to the seed,” Heard said.
If soil moisture was more plentiful many farmers would opt to broadcast urea and work it in. Since it’s dry they will be inclined to leave it on the surface but without timely rain urea will volatilize, which not only costs the farmer money because it won’t help the crop, but it also adds greenhouse gas to the atmosphere.
Another option if one didn’t fall fertilize, or lacks the equipment to band, is to put safe amounts of fertilizer with the seed and then apply more fertilizer later by broadcasting granular urea, safer forms of urea, or dribbling on 28-0-0 liquid urea ammonium nitrate.
“That comes with its own challenges because you’re still going to need water to get that into the root zone,” Heard said.
There’s no guarantee it will rain, but if that underfertilized crop is looking good in the early stages it’s something to consider, he said.
“If you were going to bet on the Winnipeg Jets winning a hockey game would you like to place your bet at the beginning of the game or would you like to bet at the end of the second period? This is what this about,” Heard said.
Research shows in wheat adding nitrogen up to the stem-elongation stage will boost yield and protein, “providing you got some base nitrogen on early,” and if it rains, he told the CropTalk webinar.
In canola, nitrogen should be applied before the full-rosette stage “because that canola plant is chugging a lot of nitrogen out of the ground as it goes from that full rosette to the bolting stage,” Heard said. “So you probably want to target it for before your canola bolts.”
Liquid urea ammonium nitrate is well suited for an in-crop application as it is less likely to get hung up in crop residue compared to urea granules, Heard said. And it’s less likely to volatilize.
“A good portion is already in the nitrate form so it’s not subject to surface loss like granular urea would be,” he said. “It’s subject to some loss, but reduced loss.”
Applying urea treated with urease inhibitors can also reduce the potential of volatilization loss on surface-applied nitrogen, Heard said.
Farmers have options, but it’s up to them to make the decision, he said.
Decision-making can be aided through soil tests and past experience, Heard said.
“I hope farmers go back into their records and put their highest rates of phosphorus on those fields that warrant it and they may be able to back off to starter rates under higher-testing fields,” he said. “I can’t call that shot. That’s for intelligent farmers who have soil tests. They’re the ones who can make those decisions. But when… it tends to be dry we would tend to want to reduce the amount of fertilizer with the seed.”
American tariffs on imported Russian and Moroccan phosphorus has driven prices higher this year. Farmers who built up their soil phosphorus levels in previous years when prices were more affordable have more flexibility now, Heard said.
Heard also recommends farmers assess how their seed-placed fertilizer is affecting their crops by shutting off the fertilizer for 50 to 100 feet while seeding.
“Then you simply use that area as a measure of how much injury are we causing,” he said. “The guys who did that last year learned something important for 2021. You might as well use 2021 to get smarter for 2022 and 2023. Do that and it will give you an assessment for your soil, your rates, your equipment and prepare you for future decisions.”