Making a fertilizer plan that works for your conditions is imperative for a good yield. Wet conditions leave a little more room for error than dry conditions do, but both require some foresight to ensure you get the most out of your crop.
If you’re dealing with excessively dry or excessively wet conditions, Marla Riekman, Soil Management Specialist with Manitoba Agriculture, recommends holding back on fertility in the spring.
“If we’re dealing with really dry conditions and predictions show we may have a dry summer, then not putting down that full fertility amount in the spring may allow us to follow along and see how the crop is progressing before putting extra or the full amount of input costs into the crop,” she said, noting that growers may still want to put some fertilizer down. “But if there’s any inkling you won’t get to that full yield potential, you don’t want to put your full fertilizer amount down.”
Dry soil conditions often leave the crop with a lower yield potential. Riekman said a common thing to watch out for when fertilizing a dry field is seed injury, or seed burn, which can happen when too much is put on near the seed, becoming toxic to it. If predictions are calling for a dry summer and you’re unsure if your crop will reach its full yield potential, you can look at top-dressing later.
Wet conditions are more forgiving. Riekman said often, most fertilizer is put down in the fall, so spring is for topping it up. It’s more difficult for phosphorus to move in the soil when it’s cooler and wet, so getting that seed-placed phosphorus is critical when conditions are moist. That way, your crop will take advantage of it early in the growing season. In wetter conditions, there’s also a lower risk of seedling injury, so putting down more fertilizer or putting it down at a higher rate is less of a concern.
Riekman recommends downloading the IPNI Canada tool for determining your seed-placed fertilizer rate. Because it’s developed by South Dakota State University, the conditions aren’t exact for Manitoba, but the tool is a good starting point for growers.
“It looks at crop type, fertilizer type, soil type, and if the soil you’re putting it in has ideal, dry, or wet conditions,” she said. “You then enter your acceptable stand loss due to fertilizer. Recognizing you might push the rates a bit and have some stand loss due to seedling injury, you determine how much you’re willing to give up. Then, it tells you what rate your application could be to achieve that.”
When it comes to stand loss, verifying it is important. Riekman said often, growers will know they have stand loss, but they won’t actually know why. She recommends verifying stand loss each year so growers can try to prevent it the next. To do that, shut down the seed-placed fertilizer while seeding for a small part of the crop. Mark that area out and go back to it over the growing season to do stand counts. Based on your results, you can then tweak your fertilizer plan.
Riekman added that crop rotation is also an important part of the fertility puzzle. When changing the crop type, it’s important to apply phosphorus to match the removal rates by crop, meaning put down more phosphorus (P) than you need when growing crops like cereals so when you grow a more sensitive crop like canola or pulses, you have more stored P fertilizer in the soil for them.
“Ultimately, it’s a two-part thing,” said Riekman. “You’ve got this ‘what do I worry about if it’s really dry’ and the seed injury potential.”
For more information about creating your fertilizer plan for your conditions, talk to your local agronomist or Certified Crop Advisor.
