Fertilization strategy for strip-tillers can vary greatly, depending on when strips are built, soil type and health, and climate.
For Shell Rock, Iowa, strip-tiller Jeff Reints and his son, Clay, they’ve long subscribed to the philosophy that fertilizer needs to be placed where plants need it most — in the root zone.
“Why put fertilizer next to the crop?” Jeff says. “Whether you’re strip-tilling in the fall or spring, apply fertilizer where it’s going to provide the biggest benefit.”
Since adopting strip-till more than a decade ago on their 2,000-acre corn and soybean operation, the Reints have made numerous modifications to their system, including a switch from fall to spring strip-till in 2008 to improve crop flexibility and allow more time for residue to break down during winter.
This spring, they moved from a 16-row to a 24-row Harvest International UltraMax 60 series 60-foot toolbar with Dawn Pluribus coulter-style row units with Montag’s high output dry fertilizer delivery system.
“We upgraded from our 40-foot toolbar this year to cover more acres because we typically like to strip-till 24 hours ahead of the planter, seal in that moisture and have excellent seed-to-soil contact,” Jeff says. “With a 60-foot rig, we can run about 8¼ mph, which allows us to cover about 60 acres per hour, well a head of the 5½ mph we run our 24-row Case IH planter.”
The Zoning Effect
One constant for the Reints has been their commitment to banding fertilizer in the strip because it saves time, fuel and fertilizer costs.
For the last 6 years, they’ve yielded 10% above their county average for corn, and Jeff says their crop insurance agent tells them they have one of the highest actual production history (APH) numbers on farm ground that is several points below the county average. (CSR-corn suitability rating)
At the 2014 National Strip-Tillage Conference in Cedar Rapids, Iowa, the Reints shared research they conducted this past spring, comparing broadcast application of fertilizer in a conventionally tilled cornfield with banded application in strip-tilled field.
To illustrate their comparison, they pulled corn plants from the two different fields and mounted 8 plants on a board, 6 inches apart, to represent a 34,500 planting population. The Reints then weighed, on a gram scale, the exact amount of potassium, phosphorus and sulfur applied for a 200-bushel-per-acre yield goal.
For the broadcast application, they applied 160 pounds per acre of diammonium phosphate (18-46-0), 100 pounds per acre of potassium chloride (0-0-60) and 100 pounds per acre of ammonium sulfate (21-0-0-24). The total application (360 pounds) costs $74 per acre.
“We measured it out to 3.75 grams of fertilizer per square foot, which meant that this is what we’d see on the soil with a broadcast application by a floater,” Jeff says.
For strip-till, the Reints reduced application rates by 25%, banding the fertilizer in an 8-inch wide by 5-inch deep strip. They applied 120 pounds of diammonium phosphate, 75 pounds of potassium chloride and 75 pounds of ammonium sulfate.
Not only was banding a cheaper method — $18 less per acre than broadcast application — the concentration of fertilizer was higher with 10.5 grams per square foot. Overall, the Reints estimate a fertilizer application savings of more than $20,000 per year with banded application in strip-till, vs. broadcast application in conventional tillage practices.
“We know we can reduce application rates with strip-till and talking with agronomist Brian Hefty, he told me that broadcast rates have to be 50% higher than banded application to achieve the same effect on crops,” Jeff says. “In our example, what the root mass is seeing with strip-till is the equivalent of broadcasting 1,010 pounds per acre of fertilizer.
“If you call up your local co-op and order 1,010 pounds per acre, you will be getting a Christmas card from them because that would be one giant order.”
Strip-till is also saving the Reints more than $4,000 per year in fuel costs because they only make one pass in spring to place fertilizer, rather than multiple field preparation trips in a conventional tillage system.
“When our combine leaves the field, we are 0.40 of a gallon of diesel from planting the next crop,” Jeff says. “We only burn about 0.40 of a gallon per acre applying one-third of our nitrogen, all of our potassium and phosphorus and building the strip, all in one pass.”
The Funnel Effect
Another benefit of banding fertilizer is that it’s more accessible to moisture, Jeff says.
“The most important thing you need to get fertilizer going is moisture,” he says. “When I was in the field this spring, the light bulb went on in my head that corn plants are great funnels of moisture to the root mass.”
One experiment the Reints plan to conduct in the future is to measure how much water falls between the corn row compared to the amounts that filter down to the roots.
Jeff says he may put a corn plant in a coffee can to try and record the amount that is captured in the can, using a sprayer to apply water.
“Our best estimate is that about two-thirds of moisture reaches the root mass and only about one third lands in between the rows,” Jeff says. “I’d like to get a more accurate measurement, but it makes sense to place our fertilizer where the most moisture is going to reach it.”