Buckwheat

Buckwheat (Fagopyrum esculentum) is a fast-growing, warm-season broadleaf cover crop that establishes in 3–5 days and flowers in about 4–6 weeks. Growers choose buckwheat to quickly cover open ground between cash crops, smother summer annual weeds, and scavenge nutrients—especially phosphorus—while providing excellent bloom for pollinators and beneficial insects (SARE—Managing Cover Crops Profitably: Buckwheat, UC Davis SAREP).

• Erosion Control: Cover crops can reduce soil loss dramatically; meta-analyses show non-legume covers lower erosion 31–100%, and average sediment losses decreased by 20.8 t/ac (conventional till), 6.5 t/ac (reduced till), and 1.2 t/ac (no-till) versus no cover. Buckwheat provides rapid soil cover in summer to protect bare ground, but its residue decomposes quickly, so follow with a soil‑holding cover (e.g., cereal rye) for continued protection (SARE—Erosion fact sheet, SARE—Buckwheat notes on residue/erosion, MU Extension).
• Weed Suppression: Buckwheat shades the soil within 2–3 weeks and is highly competitive; 60–70% early ground cover is typically sufficient to outcompete most weeds. Research also documents strong suppression via competition and short‑lived allelopathy, with weed density reductions up to 96% in systems using buckwheat living mulch under a competitive crop (Purdue Extension, SARE—Buckwheat, 2024 review—PMC, NC State Extension—allelopathy overview).
• Soil Structure Improvement: A dense, fibrous root system concentrated in the top ~10 inches (with a taproot that can reach 3–4 ft) helps loosen topsoil and promote aggregation; recent work classifies buckwheat among species that increase topsoil aggregate stability and porosity in compacted soils (SARE—Buckwheat, NDSU Extension—Production, Hudek et al. 2022).
• Water Management: Across systems, cover crops can increase rainfall infiltration more than six-fold and reduce runoff; buckwheat’s fast canopy also lowers soil surface temperatures and conserves moisture. Studies show buckwheat residues can increase soil moisture and moderate daily soil temperature swings compared with bare soil (SARE—Ecosystem Services, 2024 review—PMC).
• Disease/Pest Break: Buckwheat is non-host to many cereal diseases and can disrupt pest cycles; field observations in Ohio note buckwheat may alleviate symptoms associated with root‑lesion nematode (Pratylenchus penetrans) and verticillium wilt, and its blooms attract predators (e.g., hoverflies, parasitic wasps) that help suppress aphids and other pests (Ohio State Extension, UC Davis SAREP).
• Nitrogen Management: As a non-legume, buckwheat does not fix N but it scavenges residual N and rapidly recycles it. Early-flower stands (~1 ton DM/ac) can contain substantial total N that returns to the soil upon decomposition, though only a fraction becomes plant‑available in the first season (e.g., 10‑week PAN ≈ 10–40 lb N per dry ton depending on tissue N%) (NDSU Extension—Soil Fertility, 2022, OSU Extension PNW‑636). Bonus: Buckwheat is exceptionally effective at mobilizing phosphorus—nearly 3× barley and >10× rye—enhancing P availability to following crops (SARE—Buckwheat).
• Biomass Production: Typical dry matter is 1,500–2,500 lb/ac in many Mid-Atlantic/Northeast plantings; under favorable conditions buckwheat produces 2–3 tons/ac in just 6–8 weeks. Short windows or dry conditions can yield as little as 500–2,500 lb/ac (Penn State Extension, SARE—Buckwheat, Ohio State Extension).

• Seeding Rate:
• Drill: 50–60 lb/ac in 6–8" rows (use heavier rates for faster canopy). Cornell and MU Extension commonly recommend 50–65 lb/ac for drilled cover crops (SARE—Buckwheat, MU Extension, Cornell—Cover Crop Guide 2024).
• Broadcast: 70–96 lb/ac onto a firm seedbed; incorporate lightly to improve establishment (SARE—Buckwheat, MU Extension).
• Note: Some states publish Pure Live Seed (PLS) rates (e.g., Ohio drills 20–35 lb PLS/ac; broadcast 22–42 lb PLS/ac); adjust bulk seed accordingly (Ohio State Extension).
• Seeding Depth: 0.5–1.5 inches; avoid >2 inches because emergence declines at deeper placement (SARE—Buckwheat, NDSU Extension—Production).
• Soil Type and pH: Prefers light to medium, well‑drained soils (sandy loams, loams, silt loams); performs poorly on heavy, wet, or high‑limestone soils. Best growth near neutral to slightly acidic pH (≈6.0–7.5), but tolerance has been reported from pH ~5.0 in the East to >8.0 in some Northern Plains soils (SARE—Buckwheat, Ohio State Extension, Penn State Extension, NDSU Extension—Production).
• Planting Time (seasonal windows by region):
• Upper Midwest/Great Lakes: After last frost through summer; reliable Ohio window ≈ June 11–Sept 28. For grain in the central/northern Plains, plant after frost risk (late May–mid June) or mid‑summer after small grain harvest; flowering prefers cooler nights (Ohio State Extension, NDSU Extension—Production).
• Northeast: Late May–early June or late July–early August ("short-niche" between vegetables) (UMass Extension).
• Mid-Atlantic/Southeast: Plant any time spring–summer–early fall before frost; terminate before seed set. Very frost sensitive (NC State Extension).
• Florida: Grows spring/fall in North FL and winter in South FL due to frost sensitivity (UF/IFAS Gardening Solutions).
• Termination (methods and timing):
• Timing: Kill at early bloom—typically 35–40 days after seeding, or 7–10 days after first flowers—to prevent volunteer seed. Allowing seed fill greatly increases volunteer risk (Cornell—Cover Crop Guide 2024, Penn State Extension).
• Mechanical: Mow (flail or rotary) at early bloom; residue desiccates quickly and can be incorporated or left as surface mulch. Tillage can be used if incorporation is desired (Cornell—Cover Crop Guide 2024, NC State Extension—Termination).
• Frost: Winter-kills easily; even light frost will terminate stands, so do not rely on winter residue for erosion control (SARE—Buckwheat).
• Herbicide (where appropriate): Broadleaf covers like buckwheat can be terminated with labeled nonselective or broadleaf herbicides; consult your state weed guide and always follow labels (MSU Extension—Termination, farmdoc Illinois).
• Rotational Considerations:
• Do not let buckwheat set seed; volunteers are highly competitive and can contaminate small grains and other crops. Kill on time, especially if a small‑seeded crop follows (Penn State Extension, Cornell—Cover Crop Guide 2024).
• Buckwheat is sensitive to herbicide carryover; residual trifluralin, triazines, and sulfonylureas can injure seedlings—test if in doubt (SARE—Buckwheat).
• On sloping ground, follow buckwheat with a soil‑holding fall cover (e.g., cereal rye) because its succulent residue decomposes rapidly (MU Extension).
• Water Requirements (and drought tolerance): Buckwheat thrives in cool, moist conditions and wilts under hot, dry afternoons (recovers overnight). It is less drought/heat tolerant than warm-season grasses like sorghum‑sudangrass and millets; several extensions rate its drought/heat tolerance as low to fair (SARE—Buckwheat, Penn State Extension). As a cash crop it uses roughly half the soil moisture of soybeans, reflecting overall modest water use but limited stress tolerance (eOrganic—Buckwheat for Cover Cropping).

Notes on recent research (for context):

• Root and soil physical properties: A 2022 trait-based analysis showed buckwheat’s fine root system increases topsoil aggregate stability and porosity in compacted layers, though infiltration responses vary by species and soil (Hudek et al. 2022).
• Weed suppression mechanisms: 2023 work highlights dose-dependent suppression of weed germination by incorporated buckwheat residues; a 2024 review summarized reports of up to 96% reductions in weed density in systems using buckwheat living mulch with competitive cash crops (McKenzie‑Gopsill 2023, 2024 review—PMC).

This guidance is based on U.S. university extension, NRCS/SARE publications, and recent peer‑reviewed research to provide practical, numbers‑based recommendations for using buckwheat as a cover crop.