Peas

Cool-season peas (Pisum sativum; field pea/Austrian winter pea) are fast-growing annual legumes used widely as cover crops for their reliable nitrogen fixation, spring biomass, and compatibility in mixes with small grains. Growers choose peas to jump-start spring growth, contribute meaningful nitrogen to the following crop, and provide flexible options for forage or green manure. (sare.org, nrcs.usda.gov)

• Erosion Control: Legume cover crops such as pea reduce soil loss 38–69% compared with bare fallow; across many systems, cover crops have cut sediment losses by an average of 20.8 tons/acre on conventional-till fields, with greater benefits when paired with reduced/no-till. This helps keep topsoil and nutrients on the field. (sare.org)
• Weed Suppression: Pea alone provides limited weed suppression (rated “Poor” in NRCS field performance), but adding a cereal (e.g., rye) can improve weed control about 50% vs. legume alone and increase total biomass about 50%, giving a thicker mulch. (nrcs.usda.gov, aaes.uada.edu)
• Soil Structure Improvement: Pea is rated a “Good” compaction fighter by NRCS; living roots and residue help stabilize aggregates and create macropores. More broadly, cover crops can increase rainfall infiltration by six-fold or more, reducing crusting and runoff. (nrcs.usda.gov, sare.org)
• Water Management: Cover crops paired with no-till can reduce water needs by an estimated 4–14% and buffer yields in dry years. Pea is particularly “water thrifty,” producing biomass efficiently per inch of water; in trials, Austrian winter pea fixed a high proportion of N2 per unit water early in the season. (usda.gov, sare.org)
• Disease/Pest Break: Pea is a poor host for soybean cyst nematode (SCN), helping interrupt SCN cycles before soybean. Note: in humid regions pea can be prone to Sclerotinia crown rot; use rotation and site selection to limit risk. (nrcs.usda.gov, sare.org)
• Nitrogen Management: As a legume, pea commonly contributes 90–150 lb N/acre (and up to 300 lb under exceptional conditions); specific studies report 96–207 lb N/acre depending on season and management. Its residue has a low C:N (about 13:1–29:1), so N becomes plant-available relatively quickly. (sare.org, nrcs.usda.gov)
• Biomass Production: Typical dry-matter production ranges from ~500–3,000 lb/acre in the Midwest; in long, cool seasons of the Intermountain West/Idaho, fall-planted Austrian winter peas often yield 6,000–8,000 lb DM/acre. (nrcs.usda.gov, sare.org)

• Seeding Rate (monoculture; adjust for Pure Live Seed where noted):
• Drilled: 40–80 lb/acre (Utah State). Mississippi State lists 60–90 lb/acre as a broadcast rate with a note that drilled rates can be reduced 20–30% (≈42–72 lb/acre PLS). Iowa NRCS provides a practical benchmark of 45 lb/acre PLS. Nebraska Extension field demonstrations commonly use 30–60 lb/acre when drilled. In mixes, SARE recommends reducing the pea rate by about one-quarter. (extension.usu.edu, extension.msstate.edu, nrcs.usda.gov, hal.unl.edu, sare.org)
• Broadcast (surface/aerial; incorporate lightly for best stands): 60–90 lb/acre (MSU Extension); 50–70 lb/acre is common in Nebraska demos. As a rule of thumb, increase broadcast rates 20–50% above drilled to offset poorer seed-to-soil contact. (extension.msstate.edu, hal.unl.edu, midwestcovercrops.org)
• Seeding Depth: 1.0–1.5 inches is typical; peas tolerate 1–3 inches depending on moisture and soil condition. Avoid surface seeding without incorporation due to the large seed size. (nrcs.usda.gov, extension.msstate.edu)
• Soil Type and pH: Best on well- to moderately well-drained soils; avoid waterlogged and saline areas. Field pea performs across a broad pH range and reaches maximum yield potential from about pH 5.5 to above 7.0; near-neutral, well-limed soils are preferred. (nrcs.usda.gov, ndsu.edu, sare.org)
• Planting Time (general U.S. windows; verify local dates):
• Upper Midwest/Corn Belt: Spring—early April to mid‑May; Fall—early to late August (Iowa NRCS). (nrcs.usda.gov)
• Northeast/Northern Plains: Early spring as soon as the top inch reaches ≈40°F; spring planting makes best use of stored soil moisture (SARE). (sare.org)
• Intermountain West (Zone 5 valleys): Fall—seed by about Sept. 15 for best winter survival; snow cover improves overwintering (SARE). (sare.org)
• Pacific Northwest/Idaho and other mild-winter West: Fall planting maximizes biomass; spring-planted winter peas there typically produce about half the biomass of fall sowings (SARE). (sare.org)
• Southeast (Zone 8 interior): Seed by about Oct. 1; late‑Oct plantings in South Carolina terminated mid–late April produced roughly 2,700–4,000 lb DM/acre (SARE). (sare.org)
• Termination (timing and methods):
• Winterkill: Pea winter survival is variable—plants tolerate short dips near 10°F but often winterkill without snow cover below about 18°F. Plan fall timing accordingly. (sare.org)
• Mechanical/Chemical: For dependable kill, mow or undercut at mid-bloom or later, or use a burndown herbicide; incorporate or leave as mulch depending on your system. SARE and NRCS guidance generally recommends terminating 10–14 days before planting to allow residue to mellow; roller‑crimping is most effective at flowering and is less reliable on pea than on cereals (rolled/crimped pea has shown regrowth and poor kill in trials). Always follow your NRCS Cover Crop (340) standard and state termination guidelines. (sare.org, projects.sare.org, nrcs.usda.gov)
• Rotational Considerations:
• Beneficial before soybean due to poor SCN host status. Avoid short legume‑to‑legume rotations: to minimize pea/lentil root rots, use at least a 4‑year interval before planting peas or lentils again; also monitor fields with a history of Sclerotinia in humid regions. Check residual herbicide restrictions before planting pea. (nrcs.usda.gov, ndsu.edu, sare.org)
• Water Requirements and Drought Tolerance:
• Relative to other cool‑season legumes, pea is rated “Fair” for drought tolerance by NRCS, and it does not tolerate waterlogging. That said, peas are efficient at producing biomass per inch of water and, as part of a cover‑crop/no‑till system, can help conserve soil moisture and improve infiltration. (nrcs.usda.gov, ndsu.edu, usda.gov, sare.org)

Notes to maximize success:

• Inoculate with the appropriate Rhizobium (R. leguminosarum) if peas haven’t been grown recently.
• For stronger weed suppression and lodging resistance, pair peas with a small grain (rye, triticale, barley, or oats); reduce the pea seeding rate by about one-quarter and the grain by about one-third in mixes. Recent work also shows that adding cereal rye to a legume increases biomass and weed control versus a legume alone. (sare.org, aaes.uada.edu)

This guidance reflects current extension and NRCS recommendations, plus recent research, to provide practical, numbers-forward management for cool-season peas as a cover crop.