This article appears in the September 2021 issue of Potato Grower.

Independent of the type and variety of potatoes grown, micronutrients are essential in potato production. Most potato growers understand the need for complete and efficient micronutrient nutrition to achieve maximum yield and quality potential. However, micronutrient fertilization and management in potato production is a very complex process that requires understanding multiple interactions between nutrients, soils, plants, fertilizer sources and distribution.

Micronutrient Rate Challenges

Even though micronutrients are required in smaller amounts when compared to macronutrients and secondary nutrients, they are essential for proper crop performance. According to research from the University of Idaho, a 400- to 500-hundredweigth-per-acre potato yield removes the following rates by nutrient:

• Iron: 2.8 pounds per acre
• Zinc: 0.2 pounds per acre
• Manganese: 0.3 pounds per acre
• Copper: 0.1 pounds per acre
• Boron: 0.18 pounds per acre

In comparing those removal values to recommended application rates by land-grant universities in potato production states, we see differences between recommended rates and the amounts required by the crop. For example, most universities recommend one pound per acre of elemental boron, or 455 percent more than the actual amount of boron required by a 500-hundredweight potato crop. In most cases, recommended rates are higher to account for source and distribution inefficiencies. For zinc, the gap is larger, as recommended rates vary between one and 10 pounds of elemental zinc per acre, which represents 500 to 5,000 percent more than the actual required amount of zinc by a 500-hundredweight crop. These types of applications can have unfavorable economic and agronomic effects like crop micronutrient toxicity.

If crop nutrient requirements are met, the key to micronutrient management is not in the total amount put into the crop, but rather the distribution, availability and efficiency of micronutrient fertilizers. These factors play crucial roles in the successful nutrition and uptake of micronutrients in potatoes.

Are Petiole Tissue Tests Enough?

While in-season petiole tissue testing has become a common management tool in potato production, it is not the ideal approach to manage micronutrients. Low levels of a determined micronutrient in a tissue test can be addressed with a subsequent in-season application. However, damage may already be done and yield potential reduced. Some micronutrients, because of the chemical nature of each one, are inefficient when applied in-season since they cannot be rapidly taken up by potato plants. These factors make tissue testing a good measuring tool but not an ideal management tool for micronutrient nutrition when it comes to in-season adjustments. Petiole tissue tests are good to evaluate crop status and, in some cases, assist with making adjustments for future crops, but this management strategy could lead to reduced yield potential that cannot be recovered even after in-season applications are made.

Manage Micronutrients & Improve Efficiencies

A micronutrient management strategy for potatoes is implementing 4R Nutrient Stewardship: the right source, right rate, right time and right placement of nutrients. Wolf Trax innovative micronutrients from Koch Agronomic Services can help maximize micronutrient nutrition efficiency and is a solution aligned with the 4R Nutrient Stewardship framework.

Wolf Trax, which features dry dispersible powder (DDP) technology, can be coated onto dry fertilizer blends and are designed to adhere to the dry fertilizer prill and provide a uniform distribution across fields. This uniform distribution promotes better root interception and increased potential for nutrient uptake.

The Wolf Trax lineup of DDP nutrients can help meet nutritional needs of primary, secondary and micronutrients necessary for potato production. In addition to the increased potential for nutrient uptake and more even distribution, growers can experience Wolf Trax’s agronomic advantages of the dual-action availability. Each solution is formulated with at least two forms of a mineral, providing immediate nutrient uptake by the plants, as well as continuous feeding over time. This means nutrients are available to the plant at the right time, and deficiencies are corrected during critical growth stages.

To learn more about Wolf Trax or to connect with a Koch representative, visit www.kochagronomicservices.com.

Wolf Trax and DDP are trademarks of Koch Agronomic Services, LLC. Koch is a trademark of Koch Industries, Inc.