Second Helpings: The importance of post-plant nutrients

Picture this: you've just finished a hearty meal, but you're still hungry for more. You go back for seconds to get all the nutrients you need to feel satisfied. In many ways, side dressing nutrients for corn is like going back for seconds at the dinner table, providing a spoon feeding of a three course meal right to the crop before and during the growing season. It's about providing the crop with essential elements, ensuring it has everything it needs to thrive and reach its full potential.

Pre-plant fertilization lays the foundation for healthy growth, whereas post-plant (or in-season) nutrition plays a crucial role in supporting corn plants during critical development phases, setting the crop up for the best yield potential. Side dressing nitrogen and other nutrients is a great option to continue to spoon feed that crop into success.

Dr. Jake believes, generally, a planned side dress application is valuable. Planned applications allow you to adjust for economics and weather. For example, the early growing season often has low temperatures which slow down nitrogen mineralization and leave the corn crop vulnerable to nitrogen deficiencies. Economically nitrogen prices change throughout the year and side dressing nitrogen may or may not be a good value. Always check with your Liqui-Grow Sales Applicator to learn about up to date pricing.


Timing Matters: V5, V9, VT


Dr. Jake emphasizes the value of side dressing nutrients before V5 for a few reasons:

  1. Nutrients are limited because of slow mineralization early in the season, back to the cold soils again…
  2. Low nutrient availability and small root size means the roots often aren’t large enough to find the nutrients available. By side dressing nitrogen, you can increase your odds of keeping that plant on track to yield well.

If you are experiencing greater than normal spring rainfall, planning a V5 or before side dress nitrogen application can really benefit small corn plants. Rain can push nitrogen deeper into the soil, and the small roots are just often not large enough to keep up with the nitrogen moving through the soil profile. By V5, roots are established, facilitating nutrient uptake, including water, crucial for ongoing growth. Focusing on nutrient uptake during this phase sets the stage for effective plant development throughout maturation.

If you have low CEC soils or know you have low soil fertility because of soil tests taken, this could also be a great opportunity for side dressing. Check with your local Liqui-Grow Sales Rep to find out more!

Larson, E. (2023) V3 Growth Stage. Mississippi State Extension.


For Dr. Jake, "in-season application" ideally occurs before V5, but certainly before V9. The old way of thinking was to get that nitrogen on right before V9, so it’s there and later in the season, but there is lots of research to debate this theory. Beyond V9, there's a risk of stunting plant growth & yield, especially with a nutrient split of 75% before or at planting and 25% after - or any ratio that is less than 75% at or before planting. Typically, Midwest soils can adequately support nutrient uptake from V9 up to VT, depending on adequate soil moisture levels. By V9 through VT, the crop is at its peak nitrogen absorption rate per day, meaning delaying application until after V9 puts the crop at a disadvantage in terms of nutrition. Even though farmers have been across the fields “a lot” in a short amount of time, delaying the side dress pass can ultimately hurt yield, keep your equipment “warmed up” and ready to go again!

If you have questions about what this means, contact a Liqui-Grow Sales Applicator, or check out this video: Is Side-Dressing Nitrogen Worth It This Year?

Nielsen, R. (2000) V9 Growing Point & V9 Whole Plant. Purdue University.


Nitrogen uptake will peak at VT, and by this time the soil will provide enough nitrogen through mineralization to carry the crop, as long as adequate soil moisture is present to carry the nitrates. Late season N applications will only be beneficial in certain conditions.

The Extras - Just like mashed potatoes are good, they are better with gravy.

Side dressing nitrogen is important but with today's hybrids available to us, the potential of these hybrids, and the modern day cropping practices farmers participate in, we can see a benefit in adding some potassium and sulfur. Oftentimes these added nutrients can help combat limiting factors for plant development. Boron and zinc can even be added to your side dress mixture for additional micronutrients in your application.

Potassium (K):

Potassium is essential for various physiological processes in corn plants, including water regulation, enzyme activation and stress tolerance. While pre-plant applications are often the only recommendation for potassium, there are situations where side dressing with K can provide additional benefits, especially in fields with specific challenges.

  • Jake’s recent research trials suggest that applying potassium solely at pre-plant results in stronger crops than a 75% up front followed by a side dress of 25% ratio. However, there are times you’ll see a “bang-for-your-buck” with additional K in your side-dress application those are:
    • fields experiencing dry springs, or sandy/droughty soils
    • low and limited soil potassium levels
    • compaction issues (where roots have been limited)

Applying 10 to 15 pounds of potassium during side dressing, particularly in sandy or low-potassium soils, can help address deficiencies and promote optimal crop growth. Liqui-Grow manufactures its own 0-0-12 product to be used during the side-dress season. Just so you know, adding potassium to the tank can be tricky. It’s important to have the correct N to K ratio, and your Liqui-Grow team is knowledgeable and ready to help.

Sulfur (S):

Corn needs sulfur for proper development and over the past 10-15 years we have seen an increase in crop need for sulfur, here in the Midwest. To delve into why corn needs sulfur, check out this blog post from Jan! An extra benefit to using Sulfur in with our side dress nitrogen is its ability to act like a nitrification inhibitor, because it slows the nitrification process, leaving more nitrogen available for uptake for a longer period.

Recommended ballpark sulfur rates vary depending on crop rotation and soil type. For corn on corn, applying 20 to 25 pounds of sulfur per acre is advisable, while corn after soybeans may require 15 to 20 pounds. In sandy/droughty soils, we like to see 30 pounds regardless of crop rotation. For more specific rates tailored to your operation, give us a call!

In cool early season soils, sulfur applications can be a huge benefit to the corn crop, especially since it’s just not readily available until the soils warm up. But if your crop is on track, and the economics make sense, adding additional sulfur into your side-dressing application can result in a positive ROI for your operation. Find out more in our video: Sulfur: When is Enough, Enough?

Finishing Touches

By incorporating potassium and sulfur into your nitrogen side dressing application, you can provide your crop with the extra nourishment it needs to thrive. With the right approach, side dressing nutrients become a recipe for success in corn production.

Your Liqui-Grow Sales Applicators are happy to discuss the best option for your operation. Liqui-Grow is proud to offer

  • custom side dress applications
  • bar rentals if you prefer to do your own application and
  • high-quality products like our 20-0-4-2
  • Delivery or pick-up of product as well

We pride ourselves on being able to work with your operation, and fill your crops needs.

Questions? Give us a shout!

Text us at 564-220-2508 or email