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For optimal foliar nutrition make hindsight 20-20

Read Time: 8 minutes

By the Cargill team July 23, 2020

Plan now to simplify next year’s in-season decisions

We’ve just come through the typical timing for application of foliar nutrients. So why write about it now? Because now is the right time to both look back at that decision and to think about next year’s in-season fertilizer application – as a potential part of your overall crop nutrition plan.

The same way we create that wholistic plan with the 4Rs (right source, right rate, right place, right time) as our guide, I like to think about the 4Rs for foliars: right product, right time, right conditions, right expectations. When we get these wrong – especially the proper conditions and timing for a nutrient application – farmers begin to distrust foliar products.

Right product

When it comes to foliar nutrition where you get the product is important. You can’t just get boron and dissolve it in water and try to spray it (and customers have asked me about this). The size of the molecule is important, and how well it mixes with water because if it’s too big the leaves will have a hard time taking it in. I recommend relying on companies that have proven themselves with research and take foliar products seriously.

Right conditions

Some companies call their products stress relief, but that’s not necessarily accurate. In dry conditions plants struggle to hold water in. The cuticle thickens to retain moisture – sometimes so thick it overlaps with stomates so the plant has trouble breathing. Look for drought stress before choosing to use a foliar. Under dry conditions, nutrients in the soil may not have had moved toward the roots, meaning a tissue test could show nutrient deficiency. However, once you get a rain, that could change nutrient uptake.

Right timing

It’s key to make sure your crop is at the right stage for an application of foliar nutrients. For example, additional boron can help improve flowers and roots in canola. However, if your canola is at 30% bloom and you want to apply boron to prevent flower blast it’s too late because it takes 5-6 hours to move through the leaf to be metabolized, then more time to translocate to the growing point. Boron has more chance to be effective applied at bolting.

Right expectations

You can’t pin your hopes on a yield bump from a foliar nutrient application in all situations. It’s important to have the right expectations of your foliar product to avoid disappointment. For example, last year I went into a customer’s wheat field and I could see a copper deficiency. (You know it’s bad if you can see it.) Together, we decided to do a side-by-side trial with an application of YaraVita® COPTRAC™ to see how effective it might be. We applied it at the 6-leaf/flag leaf stage. This was not the proper timing to boost yield, but we did see a protein boost of 1.3% in the treated crop over the untreated.

Fertilizer is never thrown away. It’s never going to be 100% perfect. Every time you push the envelope with one nutrient you make another one the limiting factor. But water or heat can also be the limiting factor.

Likewise, fertilizer is something we can change. Proper soil sampling this fall means we can address your needs and have fewer things to adjust in-season.

If you have questions about your fertility plan, or you’d like to book soil sampling for your farm, contact your Cargill representative.


YaraVita is a registered trademark and COPTRAC is a trademark of Yara Canada and Yara International ASA.