NEWS for North Dakotans
Agriculture Communication, North Dakota State
University
7 Morrill Hall, Fargo, ND 58105-5665
April 9, 1998
To improve chances of success with corn, fertilize it properly, says Dave Franzen, soil science specialist for the North Dakota State University Extension Service.
"Applying phosphate fertilizer in a starter band, either with the seed or in a side-banded application, can increase early growth and vigor," says Franzen. "Doing this can help the corn avoid hot and dry weather during pollination, and can get it well on its way to tasseling and grain-fill during the long summer days of June and early July."
A side-banded application of phosphate is also important when growing corn following sugar beets, to avoid fallow-syndrome. Corn after beets can be noticeably shorter due to poorer growth, and can show leaf purpling characteristic of a phosphate deficiency.
"Although there is much to learn about why this happens," says Franzen, "it appears that helpful fungi called mycorrhizae are not present in high numbers following sugar beets, as they are after most other crops. Mycorrhizae are helpful to plants because they serve as supplemental roots. When they are not present, nutrient uptake is inhibited. Phosphate has a difficult time entering plants early in the season under normal circumstances because it moves poorly through the soil, but when the helpful fungi are not present, the situation worsens."
Side-banding a large amount of phosphate is the best way of reducing effects of fallow-syndrome, he says.
Nitrogen application should be based on yield goal, which may range from 70 bushels per acre on dry land to 150 bushels or more per acre on irrigated land in North Dakota. The yield goal multiplied by 1.2 will give the recommended nitrogen rate to use.
"Be sure to credit previous crop contributions from alfalfa, soybeans, peas, dry beans and green sugar beet tops, subtracting the previous crop credit from the recommended nitrogen rate," says Franzen. "Nitrogen can be applied before planting or side-dressed between the rows later in the season. Because corn plants make their yield potential decisions later in the season than small grains do, delaying application until the corn is 2 feet tall does not limit yields, so long as the nitrogen is applied during the side-dress application window."
Corn is relatively tolerant to seed-placed nitrogen. Up to 10 pounds of nitrogen plus potash (P) can be applied with the seed in a 30-inch row. If the fertilizer is side-banded, more fertilizer can be applied, says Franzen. But more than 50 pounds of nitrogen per acre may be too hot for plant roots to take immediate advantage of the P in the band, especially if urea-N is used.
Corn also requires zinc.
"Some varieties will respond to zinc more than others," says Franzen, "but newer growers, especially, should be aware of the potential for deficiency when soil test levels are below 1 part per million. Dry bean growers are well aware of their soil zinc levels and many have increased zinc soil test levels over the years, but small-grain growers may have little knowledge of zinc levels in their fields."
In applying zinc, he says, use a water-soluble source such as zinc sulfate. Chelates can be used, but at normal rates the application will need to be repeated for the next zinc-sensitive crop, since there will be little buildup of soil zinc.
"Potassium and sulfur may also be deficient in sandier soils in upland landscape positions," says Franzen. "Soil-testing these suspect areas separately may provide better information on potassium and sulfur than using a field composite sample in variable fields."
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Source: Dave Franzen (701) 231-8884
Editor: Barry Brissman (701) 231-7866