Starter fertilizer probably doesn't pay in tilled cornfields. But it usually boosts yield under no-till.
In three years of University of Missouri research, starter fertilizer increased no-till yields an average of 13 bu/acre.
The trials were conducted from 1996 to '98 by extension agronomist Peter Scharf and his colleague, Tom Anderson. The researchers applied starter fertilizer at a medium rate for both nitrogen and phosphorus.
For one set of experiments, they sought the help of Richard and Jack Elliott and their father, Jim. The Elliotts rotate no-till corn and soybeans near Versailles, in south-central Missouri.
They plant corn into slow-warming silt loam with a high clay content, usually in late April. The Elliotts' planters were already equipped with starter fertilizer attachments.
"We have used starter for several years - long enough for me to learn that I cannot afford to not put starter in the row when I plant," says Richard Elliott. "We use 10-34-0 liquid fertilizer directly in the planter furrow as a starter."
In fact, the Elliotts put most of their fertilizer on with the planter. They apply 5 gallons/acre of the liquid starter on top of the seed, directly in front of the press wheels, plus 100 lbs of N, 50 lbs of P and 8 lbs of K in the coulter furrow in front of the planter.
They keep fields fertilized to soil test. However, no-till soils stay cooler longer, which may limit the availability of phosphorus to seedling corn, they reason. Thus, the boost of starter in the row at planting.
They also sidedress an additional 100 lbs of N in the form of anhydrous ammonia when corn plants are about 6" tall.
"We've focused more on postemergence weed control," says Richard. "Since we're going over the field a second time with the sprayer, we put down anhydrous at the same time."
In 1997, Scharf and Anderson compared several starter treatments on the Elliott farm. All formulations increased ear length and boosted yield by an average of 23%.
The next year, starter fertilizer gave less dramatic yield boosts. For their 1998 trials on the Elliott farm, Scharf and Anderson again used several starter fertilizer recipes, applied when the Elliotts planted on Apr. 24.
Yields were 138.1 bu/acre for 15-39-39 starter, 149.4 bu/acre for 33-33-33 starter, and 149.6 bu/acre for 40-0-0 starter. The Elliotts' standard 10-34-0 starter gave similar results. Plots not receiving starter fertilizer averaged 140.6 bu/acre.
"That's not a great difference in yield," says Richard. "And it's probably typical. With fields fertilized to soil test, we don't always see a measurable response from starter fertilizer - at least not a definite year-in, year-out increase.
"And the way we do it, using starter takes more time at planting," he adds. "But we think the benefits of starter justify the cost of running to fill planter boxes. It's good enough yield insurance that we'll continue to use it."