Zinc is an essential nutrient required for proper plant development and a prime example of why the “micro” in micronutrient does not mean insignificant. It’s considered a micronutrient because it’s needed in much lower concentrations than macronutrients like nitrogen and phosphorous. The fact that it’s needed at lower rates does not mean it’s any less important to the plant.
When making a fertilizer recommendation I’ve learned to keep macro and micronutrients balanced based on the crop’s needs.
Zinc works alongside phosphorous to promote proper root development. The benefit is that the more surface area on a root system, the more nutrients and moisture the plant can take up. The plant will also pull in more zinc as flowers are fertilized and seeds begin to develop. I recommend soil and tissue samples to help make sure nutrients are balanced properly at these stages.
Availability vs Deficiency
If soil tests reveal deficient levels of zinc, an agronomist can make an informed fertility recommendation, but first you need to understand what is deficient and what is sufficient.
When you send soil samples for testing, ask about the extraction methods that your lab uses. There are two main extraction methods for zinc: DTPA and HCl. Both extractions can tell you the story of your zinc reserves, but only if you know how to read them.
A result of 2.0 ppm using a DTPA extraction method indicates your soil has sufficient zinc levels, but that same result using an HCl extraction shows your soils have deficient zinc levels. Talk to your lab about their extraction methods to help you understand the results.
Even when soil tests show sufficient levels of zinc in the soil for proper plant development, that’s only part of the story. Do you know if the zinc in the soil is actually available to the crop? The following three factors may be keeping your crop from taking up zinc:
1. Too much phosphorous
High phosphorous levels can keep plants from taking up zinc efficiently. Growers using manure or who are increasing phosphorous rates should look at adding some zinc in the seed row as well. High levels of zinc will increase uptake of phosphorous and calcium by the plant.
2. Seeding into cold soils
When you seed into cold soils, plant roots will search for nutrients less vigorously. At the same time, because zinc is not mobile in the soil, it can’t travel to the roots to be taken up. Unfortunately, zinc is key to proper root growth and must be available in early development.
3. High pH and low organic matter
Studies show that as pH increases, zinc uptake decreases. Organic matter provides zinc to the plant, and as a result, when organic matter decreases, so does available zinc.
When you confirm zinc deficiency, you have plenty of options for application at all stages of plant growth.
YaraVita™ Procote™ Zn is an oil-based micronutrient product that is applied to and coats granular fertilizer. It is very plant safe, equipment safe and reduces dust. Using Procote will get zinc applied right at seeding and makes it available at the root zone. Another option to get zinc to your plants at seeding is to use MicroEssentials® SZ™, an all-in-one nutritionally balanced granule that combines nitrogen, phosphorous, sulfur and zinc.
Further into the season, you can choose from a range of foliar products that can be mixed in the spray tank. YaraVita products such as Flex™, Zintrac™, or Glytrel ZnP™ are excellent in-crop options. These products have been developed with wettable agents, spreading agents and sticking agents to increase plant safety and uptake.
If you have any questions regarding how micronutrients could impact your crop, or about these products, contact your nearest Cargill retailer.
YaraVita, Procote, Flex, Zintrac, and Glytrel ZnP are trademarks of Yara Canada, Inc.
MicroEssentials is a registered trademark and SZ is a trademark of The Mosaic Company.