Harvest management is especially important to obtain high-quality field pea to be marketed as human food or seed. High-quality product is needed to receive a premium price for the crop. If the crop has quality problems, including bleached, split, cracked or earth-tagged seed, the livestock feed market likely will be the only option. Earth-tagged seed has dirt attached that cannot be removed.
The decision to start the harvest process will depend on three factors:
- Crop maturity (stage of uniformity): Look for a large majority of plants with tan pods on the bottom, yellow to tan pods in the middle, and yellow-green pods on the top.
- Seed moisture content: Swath or desiccate field pea when the seed moisture content has reached 25% to 30%. Straight combine field pea when the seed moisture content has reached 18% to 20%.
- Presence of weed growth: Do not wait for green weed growth to dry down.
Field pea can be swathed to preserve quality if crop maturity is uneven or heavy weed pressure is present.
When swathing pea, the seed needs to be at physiological maturity. At this stage of growth, the majority of pods should have turned from green to yellow. The crop matures from the bottom pods upward. Swathing normally will result in increased harvest losses, but swather modifications make the procedure easier and will reduce harvest loss.
Vine lifters enable producers to get under the pea vines and lift them over the cutting knife. Many growers use a pickup reel to help in moving plant material off the cutter bar onto the canvas.
Field pea should be swathed in the early morning or late afternoon when the humidity is high and the pods are tough to reduce shattering losses. Combining should not be delayed after swathing because pea swaths are susceptible to movement by wind.
Many short to medium vine and semi leafless pea cultivars have characteristics that allow straight harvesting compared with cultivars with indeterminate and prostrate vine growth. For example, semi leafless pea has a more open canopy, remain erect longer and dry down more rapidly after a rain or heavy dew than the indeterminate long vine type.
Straight combining will eliminate the possibility of windrow damage caused by high winds and reduce losses at the cutter bar. A desiccant may be used to enhance crop drying prior to combining.
Maintaining a low cutter bar height is essential to reduce losses. Floating cutter bars or flex-heads and raking-type pickup reels are available to reduce losses and increase harvest efficiency. To reduce seed shattering, the combine reel should be adjusted to a low speed.
Field pea should be combined with seed moisture of 17% to 20% to reduce splitting and seed coat cracking. Breakage increases at moisture contents below 14% to 16%. At this moisture range, the seeds are firm and no longer penetrable with a thumbnail.
Losses from shattering may be reduced by harvesting field pea before all pods are dry. Field pea does not ripen as uniformly as other crops, therefore harvesting while green leaves and pods remain may be necessary.
Pea vines must be dry or harvest will be extremely slow and difficult. However, seed that is too dry will be susceptible to seed coat breakage or peeling. Harvest should occur during humid conditions, such as at night or early morning, when pods are wet with dew, to minimize seed shatter.
Correct combine settings and operation are important to maintain seed quality. Reel speed should be slow to minimize seed shatter. Low cylinder speeds, normally 350 to 600 rpm, should be used to minimize seed cracking or splitting. The cylinder speed should be reduced as harvest seed moisture decreases.
Initial concave settings of 0.6-inch clearance at the front and 0.3 inch at the rear, with the chaffer at 0.6 inch and sieve size at 0.4, are suggested. Use high airflow for good separation. Adjust combine settings as crop and weather conditions change.