Most producers know that going into a wet field with equipment will cause soil compaction. But with the late harvest season and wet soil conditions, many operators will take compaction as the lesser evil.

Soils at field capacity will allow the greatest amount of compaction to occur. If compaction occurs this fall, it probably still will be noticeable during the next growing season in uneven plant growth, ponded areas in wheel tracks or evidence of dry-weather stress.

Duane Friend, natural resources management educator with University of Illinois Extension, says there are still some ways to reduce the amount of compaction that may occur including:

* Whenever possible, restrict traffic to specific tracks or lanes. The first trip through the field creates the greatest amount of compaction. Secondary trips over the same lanes do not significantly increase the amount of compaction in those areas.

* If you can't park the semi trucks on the adjoining road, keep them on the headlands. Research indicates that high surface contact pressure, such as from over-inflated tires, concentrates loads onto smaller areas and compacts soil.

Once soil is compacted, Friend said time will be needed to reduce it. Wetting/drying and freezing/thawing will diminish compaction over time, but Mother Nature should not be expected to correct problems by the next season.

Frost and forages

With fall frosts, precautions and management strategies may need to be taken with the harvesting and feeding of the sorghum family of annual grasses.

Sudan grass and sorghum-sudangrass hybrids contain a compound called dhurrin. When the plant tissue is frozen, enzymes in the plant convert dhurrin into hydrocyanic acid or hydrogen cyanide, also referred to as prussic acid. When a large amount of the substance is consumed in a short period of time by ruminants, the dose can be lethal.

Grasses in the sorghum family can be safely harvested or grazed after a frost if the crop was safe to harvest before the frost and the plant tissue is allowed to dry.

Safe harvest or grazing is based on the general height of the plant. University of Illinois suggests sudangrass be at least 18 inches tall, with hybrids at least 24 inches tall, before harvest.

At the proper height, frozen sudangrass and sorghum can be fed once the plant tissue has dried. Drying allows the prussic acid to dissipate from the plant material.

With a light frost, only the tops of the plants may be damaged, and one should delay harvest or grazing 4-5 days. With a killing freeze (28 degrees or colder), wait at least 8-10 days before harvesting.

-- Compiled by Herald-Whig Staff Writer

Deborah Gertz Husar