Get Off to the Right Start with Starter Fertilizer

Planting with starter fertilizer ( Darrell Smith )

With last year’s planting obstacles still fresh on your mind, you might be thinking about what you can do this planting season to get your fields off to the right start. For some farmers, excess moisture led to depleted nutrients, which might mean you need to take a closer look at your nutrient mix in 2020.

Review last year’s notes, perform soil sampling, look at the forecast and consider your overall nutrient management strategy before pulling the trigger on starter fertilizer.

“In all my research [a response from starter fertilizer] boils down to three different issues,” says Antonio Mallarino, Iowa State University Extension. “It depends on the nutrient, the cropping system and the weather.”

Some nutrients produce stronger crop reactions than others, each crop responds differently to starter fertilizer and ultimately weather controls everything. First examine if your fields need starter fertilizer with potassium, phosphorus and/or nitrogen.


Potassium (K) is responsible for vegetative growth and a shortage of this nutrient can lead to stunted plant growth, according to University of Minnesota Extension. K is also recognized for assisting early root growth.

While K is an important nutrient, says Mallarino, it might not need as much attention in starter fertilizer mixes.

“We seldom find it has an effect in terms of getting the crop started—no extra seedling or root growth—from that perspective, unless the soil is deficient you might not need to apply it with starter,” he explains. “The only reason I would use potassium is if it’s not too expensive as a safety net, and then try to use a low-salt mix.”

In areas where potassium soil test levels are low or leaching of potassium might be a problem (course textured soils with CEC of six or less or muck soils) there’s a greater chance you’ll see a positive response to 2x2 placement in soybeans, says Michael Staton, Michigan State University Extension soybean educator. “Early planting followed by dry, cold soil conditions will likely enhance the response.”


However, phosphorus (P) in starter could make a big difference this year—especially in prevent plant fields with no cover crop.

“Those acres with nothing growing means the phosphorus is bound pretty tightly and won’t be readily available for the crop,” says Jon Kohrt, Valent field market development specialist. “That fallow field syndrome means the beneficial microbes and mycorrhizal fungi that aid in converting phosphorus into a useable form are depleted or not there, so having starter where the plant can get it could help, especially in a cool, wet spring.”

Many farmers this year are already making plans to get in and plant as early as possible—2019 has left its scars and some farmers want to play it ‘safe’ and plant ahead of schedule. If that’s you, it might be more important to consider P at planting—even on non-prevent plant fields.

“Even if a farmer applied the right rate of phosphorus in the fall or early spring, cold  weather and early planting could mean phosphorus in starter makes a big jump in the early growth in seedlings,” Mallarino says. In fields with heavy residue cover, phosphorus can help the young crop overcome colder soils, he adds.


Because it’s been wet for months now, it’s likely nitrogen (N) leached or suffered gaseous loss. Consider what might have been lost and adjust your management plan accordingly.

“You should apply at least a portion of the nitrogen preplant. If April or early May is too wet and you can’t get any nitrogen down preplant, consider 2x2 planter attachments to apply 20 lb. to 50 lb. at planting time and sidedress the rest,” Mallarino says.

Consider salt content

With N and K, consider the risk of salt burn before applying starter, especially in-furrow applications.

“Finer, heavy OM soils have a higher capability of burring the impact of salt,” says Mike Zwingman, Verdesian senior technical service manager. “With low OM soils, you need to be careful with the rate and placement of the starter to make sure you don’t burn plants—especially in a dry year. But OM might be down in PP fields after last year so it’s important to think about either way.”

Learn more about starter fertilizer here:

Ken Ferrie Answers Your Questions About Starter Fertilizer