Grain quality and handling issues for 2006
The erratic rainfall patterns across Iowa have affected both yield and quality for corn and soybeans. Because more corn is likely to be stored for local use through the entire crop year, attention to harvest and storage management details will be very important.
Soybeans are uneven in maturity, even within the same field, with many instances of dry seed on green stalks. Areas that received late August rains will have fewer small seeds but may still be variable in maturity (and moisture). Seed beans from long-term drought areas will be small; otherwise, seed size should be average with a lot of variation.
The 2006 soybeans overall should be average or higher than average in protein because late-season rains occurred before the plants started to turn color. Conditions that lengthen the growing season increase protein levels. Normal protein content for Iowa soybeans is about 35%, and about 35.5% for the United States as a whole.
Oil content is likely to be about average, around 18.5% (on a 13% moisture basis). The major soybean processing issue will be nonuniformity within lots in seed size, moisture, and probably composition. Fall weather conditions will determine average moistures; first indications are that moistures will be low after the first week or so of harvest, when the effect of uneven maturity is most pronounced.
If bean leaf beetles were prevalent, there may be considerable mottling and brown staining. Discoloration does not affect oil and meal yields, but food-grade soybean users prefer normal-colored beans and have a higher percentage of cleanout from discolored lots.
The impact of aphids on soybean color and quality is not known.
Watch out for the "pumpkins," oversize beans from greener pods, in the first few days of harvest. Frost will magnify this effect, as will the uneven maturity. They will test two to three percent too low in electric moisture meters and will be a storage problem. Aerate as you would for corn. Moistures equalize well in soybeans, and most greenness from frost will subside after several weeks of aeration.
Corn quality is also affected by drought, but quality often recovers with August rainfall more than does yield. Protein and other quality traits are determined early in the growing season. Corn protein should be average (eight percent at 15% moisture) in most areas.
Areas with favorable growing conditions all summer should have lower protein with the high yields, but lower protein means higher starch. August weather reduced the threat of aflatoxin considerably in 2006, whereas in 2005, the heat persisted through early October, which was very favorable for mold growth.
Test weight is a good indicator of corn storability. Corn that is below 54 pounds per bushel after drying should not be stored into warm weather and should be dried to less than 14% moisture before storage of any duration. Lighter corn also will break more in handling.
Corn normally gains 0.25 pounds per bushel per percent of moisture removed, but drought-stressed corn normally does not experience as much, if any, test weight gain. Test weight is not likely to be a problem this year, but selection of corn to put in longer term storage based on test weight is a good management practice.