Maximize Fertilizer Investment With Proper Weed Management

Input costs are always a concern, especially when planning for the upcoming growing season. While recent tariff exemptions offer some price relief, there’s still plenty of sticker shock, especially relative to crop prices.

Because growers don’t want to see their fertilizer investments go to waste, it’s important to protect the input cost. By removing early-season weed competition, growers can maximize fertilizer inputs — helping their crops, not weeds, take up essential nutrients.  

Feed the Crop, Not the Weeds

Growers may be tempted to reduce spending on inputs, like herbicides, to offset the cost of fertilizer. However, a strong weed management program is essential to reach yield goals.

Consider the amount of fertilizer that weeds steal from your corn and the impact that it has on your crop. A Syngenta study across 20 locations found that weeds as small as 2 to 4 inches consumed 13.4 pounds of nitrogen, 0.85 pounds of phosphorus and 16.8 lbs. of potassium¹. In 2025, this equates to roughly $15.15 per acre in lost fertilizer nutrients alone. The current impact is even greater with increased fertilizer prices. 

That’s a costly situation since it takes: 

• 1.85 pounds of phosphate to replace the .85 pounds of phosphorus  

• 28 pounds of muriate of potash to replace the 16.8 pounds of potassium  

• 29.13 pounds of urea to replace the 13.5 pounds of nitrogen  

“If that’s not enough, those weeds can rob 2% of your yield,” says Kevin Gesse, head of herbicide product marketing at Syngenta. “That’s 4.34 bu/A, based on an average Illinois corn yield of 217 bu/A².”  

Gesse recommends that growers leverage investment in variable expenses — like fertilizer, crop protection and seed — to increase yield potential. “While fertilizer prices have increased 2.4% on average each year for the last seven years, the cost of crop protection products has remained stable,” he says. 

Know Your Soil Before Investing

In addition to using a quality preemergence herbicide, knowing when and where to place fertilizer helps unlock the full potential of the investment. It’s also important to know which nutrients already exist in the soil and in what quantities before making decisions on fertilizer investment. 

A soil test indicates nutrient levels, including those of potassium and phosphorus, which helps growers avoid overspending on fertilizer. That knowledge helps inform growers on how to best spend their hard-earned dollars on a high-performance herbicide program that will help ensure the crops benefit from these valuable nutrients.

How to Discover More Profit Potential

When tackling tough weeds, implementing a full-season approach is important. Starting with a high performance residual preemergence herbicide containing multiple sites of action and following up with a post-emergence herbicide with overlapping residual control helps ensure weeds don’t get established and rob nutrients from the crop. 

Gesse reiterates the importance of using multiple active ingredients (AI) in an herbicide program. “Acuron corn herbicide contains four AIs — including bicyclopyrone — for broad-spectrum weed control,” he says. “Growers can protect their fertilizer investment by controlling weeds before they emerge with this herbicide either used pre-emergence at a full rate or in a split-shot application with a portion of the rate applied pre-emergence followed by the remainder of the rate post-emergence.” 

Storen^® corn herbicide is another tool that helps maximize residual control and minimize fertilizer loss. It uses four active ingredients – including bicyclopyrone – to provide consistently clean rows up to three weeks longer than other leading corn residual herbicide products.

If growers can’t control weeds before emergence, Gesse suggests eliminating weeds before they reach 1 to 2 inches to minimize damage. However, by that point, the weeds are already cutting into a grower’s fertilizer investments and stealing vital nutrients. It’s also important to check labels for application directions and best practices for herbicide–resistance management.

¹Weed Nutrient Uptake Source: Approximately 20 Syngenta Learning Center Research locations between 2006-2008. Nutrients measured from samples taken from weeds 1”-2” and 2”-4” in height. Analysis completed by Midwest Labs, Omaha, NE. Period from weed emergence to removal at 1”-2” in height was 10 days and 2”-4” in height was 20 days. Cost of Weed Uptake Source: https://blogs.worldbank.org/opendata/fertilizer-prices-rise-moderately-2021. Calculations used 28% UAN as the nitrogen source, DAP-(18-46-0) as the phosphorus source and muriate of potash-(0-0-60) as the potash source. 

²2 Data Source: USDA NASS 2024 IL yield estimates