Field Pea Production
A-1166 (Revised), MARCH 2003
Kent McKay, Area Extension Specialist/Cropping Systems
Blaine Schatz, Carrington Research Extension Center Director/Research Agronomist
Gregory Endres, Area Extension Specialist/Cropping Systems
Introduction
Uses
Adaption
Varieties, Types and Performance
Field Selection
Seeding
Seeding Rate
Seed Treatements
Inoculation
Fertilization
Weed
Control
Diseases
Insects
Harvest
and Storage
Markets
Field pea is a cool-season legume crop that is
grown on over 25 million acres worldwide. Field pea or "dry pea" is marketed as
a dry, shelled product for either human or livestock food. Field pea differs from fresh or
succulent pea, which is marketed as a fresh or canned vegetable.
The major producing countries of field pea are Russia and China, followed by Canada,
Europe, Australia and the United States. Europe, Australia, Canada and the United States
raise over 4.5 million acres and are major exporters of peas. In 2002, there were
approximately 300,000 acres of field peas grown in the United States.
Historically, field pea was primarily grown in the Palouse region of Washington and
Idaho. In the 1990s, North Dakota, South Dakota, Montana and Minnesota began producing dry
peas. In 1991, approximately 1,600 acres of dry peas were planted in North Dakota; in 2002
157,000 acres were planted. The majority (over 70 percent) of the dry pea produced in the
United States is exported.
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Field pea is primarily used for human consumption or as a livestock feed. Field pea is
a grain legume commonly used throughout the world in human cereal grain diets.
Field pea has high levels of amino acids, lysine and tryptophan, which are relatively
low in cereal grains. Field pea contains approximately 2125 percent protein. Peas contain
high levels of carbohydrates, are low in fiber and contain 8687 percent total digestible
nutrients, which makes them an excellent livestock feed. Field pea contains 5 to 20
percent less of the trypsin inhibitors than soybean. This allows it to be directly fed to
livestock without having to go through the extrusion heating process. Field pea is often
cracked or ground and added to cereal grain rations.
Research has shown that field pea is an excellent protein supplement in swine,
cow, feeder calf, dairy and poultry rations.
Field pea is often used in forage crop mixtures with small grain. Field pea forage is
approximately 18 to 20 percent protein. Pea interseeded at 60 to 100 pounds per acre with
a small grain such as oat can increase the protein concentration of the mixed forage by
two to four percentage points and increase the relative feed value by 20 points over oat
seeded alone.
Field pea also may be grown as a green manure or green fallow crop. With either option,
soil and future crop productivity will be maintained or improved. Use of field pea for
green fallow instead of black fallow protects the soil from erosion, improves soil
quality, substitutes water loss by evaporation or leaching from black fallow with
transpiration through plant growth and exploits rotational benefits. Costs of tillage and
idled land in black fallow are substituted with costs of field pea establishment
and termination (at early flowering) in green fallow.
Field pea in a green fallow system yielded 3,425 pounds per acre of biomass and 103
pounds per acre of accumulated nitrogen in above-ground biomass at the Carrington Research
Extension Center during 19901992. Spring wheat averaged 39 bushels per acre over a two-year
period at Carrington when grown without additional N fertilizer following green fallow as
field pea or following black fallow. This demonstrates that wheat following pea green
fallow can be as productive as wheat grown on black fallow, plus the numerous rotational
benefits of the legume can be utilized.
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Field pea is an annual cool-season grain legume (pulse) crop. There are two main types
of field pea. One type has normal leaves and vine lengths of three to six feet; the second
type is the semi-leafless type that has modified leaflets reduced to tendrils, resulting in
shorter vine lengths of two to four feet. Pea normally has a single stem but can branch
from nodes below the first flower.
Most varieties of pea produce white to reddish-purple flowers, which are
self-pollinated. Each flower will produce a pod containing four to nine seeds. Pea
varieties either have indeterminate or determinate flowering habit.
Indeterminate flowering varieties will flower for long periods and ripening can be
prolonged under cool, wet conditions. Indeterminate varieties are later in maturity
ranging from 90 to 100 days. Determinate varieties will flower for a set period and ripen
with earlier maturity of 80 to 90 days. Field pea is sensitive to heat stress at
flowering, which can reduce pod and seed set. Indeterminate varieties are more likely to
compensate for periods of hot, dry weather and are more adapted to arid regions.
Determinate, semi-leafless varieties that have good harvestability are more adapted to the
wetter regions.
Pea roots can grow to a depth of three to four feet; however, over 75 percent of the
root biomass is within two feet of the soil surface. A relatively shallow root system and
high water use efficiency make field pea an excellent rotational crop with small grains,
especially in arid areas where soil moisture conservation is critical.
Field pea is well adapted to cool, semiarid climates. Field pea seed will germinate at
a soil temperature of 40 degrees F. Emergence normally takes 10 to 14 days. Field pea has
hypogeal emergence in which the cotyledons remain below the soil surface. Seedlings are
tolerant to spring frosts in the low 20s and if injured by frost, a new shoot will emerge
from below the soil surface.
Flowering usually begins 40 to 50 days after planting. Flowering is normally two to
four weeks, depending on the flowering habit and weather during flowering.
Field pea has shown to be well adapted to most regions of the Northern Great Plains.
Field pea yields are similar to or exceed spring wheat on a pound or bushel basis within a
specific region. A six-year average (19931998) of `Profi' field pea yield on re-crop at the
North Central Research Extension Center at Minot was 2,784 pounds per acre or 46 bushels
per acre, compared to spring wheat on re-crop at 2,148 pounds per acre or 36 bushels per
acre.
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Selecting the appropriate field pea variety should be based on review of the many
differences that exist among varieties. Factors to consider should include market class,
yield potential, harvest ease, vine length, maturity, seed size and disease tolerance.
The first criterion for selecting a variety should be market class. The green and
yellow cotyledon types are the primary classes. All field pea varieties may be considered
feed peas, but only selected varieties are acceptable for either the green or yellow human
edible market.
After market type is determined, growers should review the field pea performance test
information from trials conducted across the state with particular attention paid to those
trials reflective of their farming area.
Crop harvestability is a very important factor in variety selection and is often noted
by harvest ease scores in trial results. Most growers prefer a variety that will stand
upright at harvest since it allows a faster harvest, minimal equipment modification and
higher quality seed. The newer varieties that have shorter vines and are semi-leafless will
be easier to harvest. It is important to review harvest ease data since varieties within
this plant type differ greatly in standability.
Another factor to consider in variety selection is the producer's location. The
indeterminate nature of the long-vined normal leaf type varieties may make them a preferred
type in western North Dakota where moisture stress is more prevalent. Indeterminate
varieties tend to express more stable seed yields when moisture and heat stress impact
crop development. This type of variety will normally be heavily lodged at harvest and
require special harvest procedures.
Most growers will select among the semi-leafless varieties that are more determinate in
development. Selection within these semi-leafless types should consider the impact of vine
length. In areas with higher rainfall and cool summers, the shortest-vined varieties may be
best, while in the drier regions, a grower should choose a semi-leafless type with longer
vines.
A wide selection of field pea varieties exists for producers across the region. A good
source of information to aid in variety selection is field trial evaluations conducted by
the various NDSU research extension centers across the state. These trials include the
most promising varieties with information recorded on the important traits necessary for
making proper variety selection.
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Field pea can be grown on a wide range of soil types, from light sandy to heavy clay.
Field pea has moisture requirements similar to those of cereal grains. However, peas have
lower tolerance to saline and waterlogged soil conditions than cereal grains. Peas most
often will die after 24 to 48 hours in a waterlogged condition. Poorly drained and saline
soils should be avoided when growing peas.
Field peas are most often grown on re-crop following small grain. Being a legume, field
pea will fix the majority of required nitrogen if the seed is properly inoculated.
Residual nitrogen will also be present for the succeeding crop.
Fields that have a history of perennial weed problems such as quackgrass, Canada
thistle, perennial sowthistle and field bindweed should be avoided. Check field records
for prior use of herbicides with soil residual. Consult the current
North Dakota Weed
Control Guide (NDSU Extension Service circular W-253) and herbicide labels for rotational
restrictions prior to seeding field pea.
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Field pea can be grown in a no-till or conventional-till cropping system. Avoid
excessive tillage in the spring to avoid drying out the seedbed. Pea seed requires
considerably higher amounts of moisture for germination than cereal grains. Field peas are
typically seeded in narrow row spacings of 6 to 12 inches. A conventional grain drill or
air seeder that is capable of handling large seed without cracking is essential.
Field pea should be seeded early, April to mid-May, so flowering will occur during
potentially cooler weather in June and early July. Seeding date studies conducted in North
Dakota indicate that field pea yields decrease significantly when seeding is delayed
beyond mid-May. Seeding peas beyond mid-May will result in the crop beginning flowering in
mid-July, which increases the risk of heat stress and disease problems, such as powdery
mildew, reducing yields.
Maintaining firm seed-to-soil moisture contact is critical. Seeding pea well into
moisture is critical and seeding peas into dry soil should be avoided. Seeding depth of
one to three inches is recommended, with a rule of thumb that pea should be seeded at
least a half inch into moisture and never seeded onto the interface where soil moisture
meets dry soil.
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The seeding rate will depend on the size of the seed. Field pea varieties will range
from 1,600 to 5,000 seeds per pound. A plant population of 300,000 plants per acre or
seven to eight plants per square foot is recommended. Always select high-quality,
disease-free seed. When seeding pea, always adjust for germination. Planting equipment
should be calibrated or modified to allow for seed and inoculant to flow properly without
cracking the seed or plugging the opener.
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Seed treatments are not commonly used with field pea; however, there are seed-borne and
soil-borne diseases such as Fusarium, Rhizoctonia, Alternaria and Pythium that can cause
significant stand reduction. Field pea is often seeded early into cool or cold soil
conditions. In 2002, there were numerous reports of seed rot in field pea caused by
Fusarium, Pythium and/or Rhiztoctonia. This resulted in significant stand loss, which
caused weed control and harvest problems later in the growing season. Preventing seed rot
or seed decay with the use of fungicide seed treatments in pea is recommended when field
pea is planted into cold soils and is seeded close in rotation with other broadleaf crops.
Large-seed field pea varieties appear to be more susceptible to Pythium; therefore, seed
treatments such as Apron or Allegiance that control Pythium should be considered.
For a listing of registered seed treatments and specifics on disease control, consult
the most current version of NDSU Extension Service circular PP622,
North Dakota Field Crop
Fungicide Guide. It is very important to consult the seed treatment label for its effect
on rhizobial inoculants. Most seed treatments have little or no effect on rhizobial
inoculants and nodulation; however, there are seed treatments that are very toxic to all
formulations of inoculants. Allowing the seed treatment to fully dry and adding inoculants
just prior to planting is always recommended.
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A-1166(Revised), March 2003
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