Banded application of fertilizer at planting is a key management practice for achieving the best yields in strip-till, no-till and ridge-till systems, says George Rehm, a retired nutrient management specialist with the University of Minnesota.
“Using a banded fertilizer has a positive impact on production for the corn, where early corn growth is often hampered by lower soil temperatures associated with higher amounts of crop residue,” Rehm says. “With strip-till, no-till and ridge-till, the banded fertilizer is applied in the fall of the previous crop year. Since the location of the band is known, the subsequent corn crop can be planted directly above it.”
For these planting systems, rates of suggested phosphate and potash are adjusted based on soil-test levels, Rehm says. When considering phosphate, the rates suggested for banded placement in conventional tillage systems are appropriate.
In contrast to phosphate, higher rates of potash are needed for banded application in conservation tillage production systems.
“If the soil test for potassium is in the range of 120-160 parts per million (ppm) in these systems, an annual application of 40 pounds of potash per acre is suggested,” he says. “If the soil test for potassium is less than 120 ppm, an annual application of 80 pounds per acre potash is suggested.”
Annual applications of banded phosphate and potash are suggested when corn follows corn. In a corn-soybean rotation, they can easily be applied in the fall of the soybean year. The suggested rates can be doubled and applied for 2 years of production.
Banding vs. Starter
In the past, banded fertilizer was usually considered a “starter,” where fertilizer was placed 2 inches to the side and 2 inches below the seed at planting. Times have changed.
“Use of a banded fertilizer is still important, but the placement of the band can be positioned at several locations,” Rehm says. “The term “starter fertilizer” is disappearing from the fertilizer vocabulary.
Fertilizer-use guidelines from the past suggested that rates of phosphate and/or potash needed for optimum production can be halved, compared to broadcast applications, if those nutrients are applied in a band near the seed and soil test values are in the low and very low ranges.”
For corn, the rates are adjusted for soil test levels of phosphorus and potassium. Broadcast applications of phosphate and/or potash aren’t suggested when soil-test values are in the very-high range. Relatively low rates of these fertilizer materials are suggested if applied in a band (row application).
Although this placement may not guarantee higher yields when soil test values are high, this practice may reduce the risk of having reduced yields in some years. When banded fertilizer is placed near the seed, the early increase in corn growth is primarily the result of the combination of nitrogen and phosphate.
For non-sandy soils systems, the potash and other nutrients, such as zinc, might not be that important if soil-test values for potassium and zinc are in the very-high range. For sandy soils, sulfur should be added to the banded fertilizer.
There are limits to the amount of fertilizer that can be applied close to the seed at planting. Phosphate hasn’t been shown to have a negative effect on germination. There are concerns, however, about rates of nitrogen, potash and sulfur (if 12-0-0-26 is used).
“In general, as the rates of suggested potash increase, the distance between seed and fertilizer should increase,” Rehm says.
“So, if high rates of potash are suggested, place the fertilizer so there is at least 1 inch of soil between seed and fertilizer. The use of 10-34-0 is a good choice for placement close to the seed when soil test values for potassium are 160 ppm or higher in conventional tillage systems.”