Planting time is the perfect opportunity to replace micronutrients in the soil.
Starter fertilizers are intended to get plants growing faster after emergence and, ultimately, improve yields. However, it’s important to identify what your crops really need. With crop yields continually on the rise, nutrients such as nitrogen (N), phosphorus (P) and potassium (K) are being used up in growers’ soils—but so are micronutrients. Planting time is the perfect opportunity to replenish micronutrients, as well as primary nutrients, like NPK. We’ve updated this blog post in 2022 to provide more information about how to replace micronutrients and primary nutrients at planter time, using corn and soybeans as examples.
Identify Micronutrient Deficiencies
Micronutrient deficiencies can be difficult to recognize because they resemble other problems. For instance in corn, manganese deficiency produces yellowing, which can look like a sulfur deficiency or even be confused with nitrogen deficiency. Often tissue testing can determine the cause, but it is best to have a good soil test so any problems can be addressed ahead of seeing yellow leaves.
Grass crops like corn most heavily rely on zinc and boron. Zinc deficiency symptoms are often localized and result from specific soil conditions: high pH, free carbonates and eroded topsoil with subsoil exposed.
Manganese is important for soybeans because so many of the upper Midwest soils are short on it. Often in the summer, manganese shortages cause soybean fields to take on a yellow cast. (Note that while manganese deficiencies can cause problems, researchers have proven that recent yellow flashes appearing in some fields can be traced to a glyphosate breakdown product.
AgroLiquid’s experts can help you identify the right nutrients for an optimal planter fertilizer
Learn more about soil and tissue testing
Take a Complete Soil Test
If you are going to fertilize for a specific nutrient shortage, make sure it’s the right one. Images from the field below indicate a nutrient deficiency, but this was misdiagnosed at first as a sulfur deficiency. In fact, a complete soil test showed that sulfur levels were adequate, but a severe manganese deficiency was responsible for the yellowing corn and stunted growth.
This misdiagnosis was costly in two ways: extra fertilizer money was spent for something that wasn’t needed and there was a yield loss from not putting on the correct micronutrient the plants actually needed.
This crop’s manganese deficiency was misdiagnosed as a sulfur deficiency. This shows why a complete soil test is needed and how important micronutrients are.
Choose Planter Fertilizers Carefully
Planting is usually the best time to apply micronutrients because it is easier to prevent a problem than correct one. If you see symptoms, the damage is already done and yield losses have already occurred. Roots are the best avenue to feed a crop, and putting some nutrients in the root zone at planting can usually make up for shortages in the soil.
AgroLiquid is fortunate to have a 1000-acre research farm, the North Central Research Station, where replicated test plot experiments can be established in order to investigate fertility issues under a variety of conditions. Planter fertilizer opportunities have been investigated routinely at the NCRS since 1994. We’ve used this research to optimize corn and soybean planter time fertilizers, and replace micronutrients as well as primary nutrients.
Wondering about an optimal planter fertilizer program for your crops?
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Combining NPK and Micronutrients at Planter Time
To maximize the effectiveness of your planter time fertilizer, it’s important to choose the right nutrients. Many growers assume that a bit of nitrogen for an early push and a bit of phosphorus for roots is all that’s needed for a planter fertilizer. But, research at the NCRS shows that you can improve results if your starter fertilizer satisfies all the plant’s needs, as shown by the soil test.
Let’s take a look at an example. This field was low in potassium (K), and the addition of some K fertilizer to the nitrogen and phosphorus starter saw an increased yield over that with phosphorus fertilizer alone. In this experiment, we compared outcomes based on the use of our NPK fertilizer alone (Pro-Germinator) and an NPK fertilizer combined with a potassium fertilizer (Sure-K).
Sure-K® is a chlorine-free potassium solution
Further adjustment of the product mix ratio can have even greater results, particularly at higher fertilizer application rates. In another field with soil that is high in P (51 ppm) and low in K (71 ppm or 1.5% base saturation), a much higher yield was obtained when the 10 gallons per acre fertilizer mix was heavier to the K side (70% Sure-K vs 40% Sure-K). Same volume, just different P and K fertilizer content where increased fertilizer K in soil with low testing soil K increased yield by an average of over 13 bushels per acre.
Replacing Micronutrients at Planter Time
In corn, yields have shown the greatest increase with a combination of Pro-Germinator (a dual-form phosphate fertilizer with multi-form nitrogen), Sure-K (a chloride- and hydroxide-free potassium fertilizer) and Micro500.
Micro500 contains five main micronutrients: zinc, manganese, iron, copper and boron. Numerous tests show that Micro500 increases corn yields from five to nearly 20 bu/A, depending on the situation. These nutrients are synergistic. Growers get better uptake and response from a micronutrient in Micro500 than if they apply an equal volume of a nutrient alone. In addition, having this combination available is helpful in pockets of a field where a grower might be unaware that a particular nutrient is lacking.
Trials show that AgroLiquid micronutrients perform better than dry micros because applicators can place them in a root zone band (to the side and below the seed). Products also offer better results compared with other conventional EDTA-chelated micronutrients.
Effect of Micronutrients on Corn Yield |
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| Additive | Rate/A | Yield (Bu/A)* |
| No Micros | 192.2 | |
| Micro 500 | 1 qt | 204.4 |
| Micro 500 | 2 qt | 210.4 |
| Zn, Mn EDTA | 1 qt + 1 qt | 193.9 |
| Soil test. Zinc: 0.7 ppm; Manganese: 10 ppm | ||
| * – Data average of 4 replications | ||
Armed with a little knowledge on how to choose the right starter program, as well as knowing where you are and where you want to go with yields, will help make informed decisions for your farm. Learn more about tissue and soil testing on our page to make sure you’re identifying the right nutrients to include in your planter fertilizer. If you’re wondering what an optimal planter fertilizer program might look like according to your crops and goals, talk with our agronomists.
