Field pea (Pisum sativum L.), a native of southwest Asia, was among the first crops brought under cultivation by man. The largest acreages of field pea in the US are in Washington, Idaho, Oregon and North Dakota. The green- and yellow-seeded varieties are used for human consumption as dry split field pea. Field peas are used as protein concentrates for livestock and are popular pigeon feeds. In Northwest Minnesota pea yields are comparable with yields obtained by hard red spring wheat.

Pea Research Plot in NW Minnesota

Field pea may be grown as a forage crop, for hay, pasture or silage. Field pea grown in a mixture with oat, barley or triticale yields more dry matter per acre than monoculture pea crop. A mixture of 2/3 field pea and 1/3 oat can be seeded with alfalfa or clover as a companion crop. Harvest is recommended when field pea is in full bloom and oat is in the late boot stage.

Field pea stems grow to a length of 2 to 4 feet. A leaf consists of one to three pairs of leaflets with a terminal, branched tendril. Field pea is of the indeterminate (climbing) type or determinate (bush or dwarf) type. Flowers are reddish-purple or white. Pods are about three inches long and contain four to nine seeds.

A cool growing season is necessary for optimum pea yields (a mean temperature of 55 to 65 degrees F). Hot weather during flowering may result in reduced seed set. In Minnesota and North Dakota, field pea is a spring annual with a maturity of 95 to 100 days. Field pea requires the same length of growing season as wheat. On average, it requires 60 days from planting until bloom.

The moisture requirement for field pea is similar to that for cereal grains. Field pea can be grown on a wide range of soil types, but in any soil, there must be good drainage, as field pea does not tolerate soggy or saturated conditions. Field pea is capable of utilizing bacterially-fixed atmospheric nitrogen. The specific bacterial association for nitrogen fixation in field pea and lentils is with the bacterium Rhizobium leguminosarium. If field pea is to be grown in a field for the first time, or has not been grown recently, inoculation of the seed with the proper Rhizobium prior to planting may increase nodulation. Pea seed germination rate increases with increasing temperature, but at temperatures greater than 64 degrees F, the percentage of seed germinating decreases. Seed treatment with a fungicide can significantly improve emergence. Fungicide labels should be checked to see if a particular fungicide can be used on field pea. The cool-season legume crop fits well into small grain rotations.

Pea Flower and Developing Pod

Pea growers need to carefully monitor the crop as it nears maturity in order to harvest on a timely basis. Harvest time is especially important if the crop is to be marketed as seed, or to meet contract specifications for human food or specialty feed markets.

Field pea generally reaches maturity about the same time as wheat. Field pea may be swathed before combining or straight (direct) combined. Peas are normally swathed if a variety with prostrate type of growth is grown, or if there is uneven crop maturity or heavy weed pressure. When swathing peas, vines and pods should be a yellow to tan color. The crop matures from the bottom pods upward. Yellow peas should have seed that has turned yellow in color.

Swathing will normally result in increased harvest losses. Modifications like vine-lifters enable producers to get under the pea vines and lift them over the cutting knife. Many growers use a pickup reel as well. Peas should be swathed in the early morning or early evening when the pods are tough to reduce shattering losses. A roller is recommended to push the swath into the stubble for protection from wind.

Field peas should be combined when the seed contains 15 to 20% moisture, to reduce splitting and cracking of the seed coat. At this moisture level, the seeds are firm and no longer penetrable with a thumbnail. Also, pea vines must have turned yellow (no green color present) otherwise harvest will be extremely difficult.

Short-vine and semi-leafless pea varieties have characteristics that are adaptable to straight harvesting compared to varieties with indeterminate and prostrate-vine growth. For example, semi-leafless peas have a more open canopy, remain erect longer, and dry down more rapidly after a rain or heavy dew compared to long vined varieties.

Direct harvesting can be accomplished using an aggressive pickup attachment on a standard combine. Another option is use of a combine header with a floating cutterbar. Also, attachments such as a lifter guard and pickup reels reduce losses and improve harvest efficiency.

Correct combine settings and operation are important to maintain seed quality. Also, adjust combine settings as weather and harvest conditions change.

For more production information and pea trial results see http://www.smallgrains.org/Hans/Dry_Field_Peas/dry_field_peas.htm

Before planting field peas, it is advisable to identify potential buyers to see what cultivar recommendations and quality standards they may have.

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