What is in this article?:
- Zinc deficiency can reduce sorghum yields, lower test weights
- Essential for plant growth
- Liquid zinc products
• The usual suspects include nitrogen deficiency, disease, or even herbicide burn, but last year in North Carolina some of the yellowing problems came from zinc deficiency, and in some cases on soils that showed adequate amounts of zinc, based on soil samples.
EARLY-SEASON zinc deficiency can hurt grain sorghum yield and lower test weights at harvest time.
Liquid zinc products
Liquid zinc products include chelates, lignin sulfonates plus polyflavonoids, and zinc-ammonium complexes.
In tests in the Midwest Zinc chelate (EDTA) banded as a starter was more efficient than other sources, and zinc rates can be reduced by half or three-quarters compared to the full recommended rates with similar performance.
Grain sorghum probably gets a bad rap for its inability to take up and use nitrogen. Research in other parts of the U.S. has shown the crop to be an excellent scavenger of available nitrogen. In many cases nitrogen deficiency has clearly been confused with zinc deficiency.
Heiniger says he saw some grain sorghum fields last year that also had sulphur deficiencies. In most grain sorghum producing areas, sulphur is adequate for best sorghum yields, but on some lighter, sandy soils, characteristic of the coastal areas of the Upper Southeast, deficiencies may be a limiting factor in grain sorghum production.
In some of the sandy soils in the Carolinas, Heiniger says 10-12 pounds of additional sulfur per acre may be needed to produce a top yielding crop.
The North Carolina State specialist says other factors, not associated with crop nutrition, can likewise be limiting factors in grain sorghum production in the region.
“Grass can be the Achilles Heel of grain sorghum production,” Heiniger says. “Grain sorghum is just not a fast grower — it’s slow and spindly — and doesn’t do a good job of covering rows and shading out grass and weeds. This can be an especially big problem on wider row spacings,” he adds.
Though grain sorghum has been widely promoted by Murphy-Brown and other grain buyers as a good double-crop with wheat, Heiniger says about 65 percent of the crop last year in North Carolina was grown as a conventional, May-planted crop.
The better results, he says, came from later-planted sorghum, planted behind wheat. “Grain sorghum is a lot like corn, if you knew when it would rain, you could consistently produce 100 bushels per acre,” he says.
“Choosing the right hybrid — one that is best suited to your particular farming operation and by all means planting hybrids with good disease resistance — are other keys to growing high yields of grain sorghum with high test weights,” Heiniger adds.
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