Determining Field Harvest Order

Identifying fields that have standability, disease, stress, uneven maturity, or moisture content issues prior to the harvest season may help increase harvest efficiency and minimize in-field losses.

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Corn

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Consider monitoring corn for stalk quality as soon as black layer (physiological maturity) occurs. Scout different areas of the field and use the push or pinch tests (process stated in Stalk Rots and Lodging in Corn article) to identify weak stalks. Split lower portions of stalks to assess stalk strength and determine if the stalks are discolored, shredded, or hollow. If more than10% of the stalks in a field are rotted or prone to lodging, consider scheduling the field for early harvest. Also, inspect ears for rots and test ear shanks for weakness and potential ear drop.

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Drydown. Corn kernels are around 30% moisture content when physiological maturity (black layer) occurs. Several factors that influence field drydown after maturity include weather conditions and seed product characteristics. Kernel moisture content decreases faster with warm, dry weather and may decrease slowly in a wet and cool environment. Fuller season corn products, that require more growing degree units (GDUs) to reach black layer, may dry slower as generally there will be less GDUs per day after these products reach maturity.

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Typical drying rates after black layer range from 0.4% to 0.8% kernel moisture content loss per day.1 About 30 GDUs per point of moisture are required to dry corn from black layer to 25% moisture content and 45 GDUs per point of moisture to dry from 25 to 20% moisture content.2 A two-year University of Nebraska study reported a range from 0.60 to 0.64% moisture content loss per day from late August through October.

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Corn products differ from one another in drydown rates. Plant characteristics that can influence drydown rate include:4

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  • Number and Thickness of Husk Leaves. Fewer husk leaves and thinner leaves can lead to faster moisture loss.
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  • Husk Dieback. Earlier dieback of husk leaves can lead to more rapid grain drying.
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  • Ear Tip Exposure. Exposed ear tips may provide for quicker grain moisture content loss.
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  • Husk Tightness. Husks that are loose and open may help increase grain drying.
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  • Ear Angle. Drooping ears tend to lose moisture content more quickly. Upright ears can capture moisture from rainfall.
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  • Kernel Pericarp Properties. Thinner pericarps (outer layer covering a corn kernel) have been associated with faster field drying rates.
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Soybean Pod Shattering

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Consider these situations, when determining when to harvest your soybeans. Drought conditions during pod maturation may result in a weak pod structure. A pod has one shell which encloses the central cavity where the seeds are contained. Along the length of the pod are seams (sutures) on both sides, where the pod opens when maturity is reached. If mature pods are rehydrated from precipitation and dry again, they may open more easily because the seam attachment breaks down with the cycles of drying and re-wetting. Also, hail earlier in the season may lead to empty, twisted pods at harvest.

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Pod shatter may occur in areas of the field with poor fertility or severe pod-feeding from grasshoppers and bean leaf beetles. In addition, late-season spider mite infestations can accelerate soybean senescence and increase pod shattering.