No, you didn’t read that title wrong — fertilizer impregnation is a real thing. In fact, it isn’t even a new concept and many will have heard of this before but likely in the context of added pesticide products to fertilizer prills. The type of impregnation I want to talk about today is impregnating fertilizer with more fertilizer. It may seem like a strange idea, but let’s explore the agronomic benefit to this practice.
Soil samples are coming back in full force this time of the year and often you will see some fields running low in more than just macronutrients, like nitrogen and phosphorous, but micronutrients, such as zinc and copper, as well. Many are saying how in the world do I get copper to my crop efficiently? Impregnation is one of the options.
Impregnating your granular fertilizer, such as urea or your seed-placed blend, with a micronutrient means coating fertilizer granules with a micro, say copper for example, which is either in dry or liquid form depending on the company. This way, wherever there is a fertilizer granule there will also be a tiny amount of micronutrient, meaning the actual distribution of the micronutrient is far more evenly spread across the root zone.
If you are applying a micronutrient as a granular by itself, it is generally in small amounts; it takes only 5 pounds per acre, for example with a 20% copper product, to achieve one pound of actual nutrient per acre. That means on a 9” row spacing you are getting one granule placed every 6 inches roughly (varies by product/weight)! This means those plant roots have to scavenge that much further to find the copper they need. Granular micronutrient products still work, yes, but the math shows that feeding sites increase with impregnation.
The agronomic benefit of this is very simple — better distribution means more feeding sites for the roots. When you have an immobile nutrient like copper your placement becomes incredibly important. On pure volume alone, small amounts of product spread on your macronutrient sources means you get a more even distribution of fertilizer across the field and therefore more sites for that crop to access the copper.
Micronutrient dressings come in liquid or dry formulations. With liquid products there is generally a pump that takes the liquid to the top of the fertilizer blender and then it is mixed until even coverage is achieved. The process is similar with dry products except proper rates are dumped into the blender. This leaves each granule to be put into the ground doused in a little bit of copper, in this example, for that crop to access
There are a number of other ways to get your crops’ micronutrient needs covered, from foliar, to liquid soil applications, but impregnation is one way to feed your crops’ needs this year and build levels in following years.
— Shane Thomas’s column appears courtesy of G-Mac’s Ag Team