Pearl Millet

Pearl millet (Cenchrus americanus, syn. Pennisetum glaucum) is a fast-growing, warm-season annual grass widely used as a summer cover crop and grazing forage. Growers choose it for its exceptional drought tolerance, rapid canopy, strong fibrous root system, and ability to produce substantial biomass and scavenge residual soil nitrogen, especially on sandy or acidic soils where other grasses struggle (NRCS Iowa 2025 fact sheet; UGA Forages).

Benefits of Pearl Millet as a Cover Crop

• Erosion Control: Dense summer cover and residue reduce splash and runoff. Across global studies, cover crops have cut soil loss by up to 75% and reduced runoff by as much as 90% compared with bare fallow; grass covers with fibrous roots are among the most effective—making pearl millet well suited for this role (Univ. of Illinois farmdoc daily summary of meta-analyses, 2024). Field studies also report 50–75% erosion reduction and 23–77% runoff reduction under cover versus bare soil, depending on site and rainfall intensity (UC ANR).
• Weed Suppression: Pearl millet can “choke weeds” through quick canopy and residue; Ohio State rates it “Excellent” for choking weeds and “Very good” for allelopathy as a cover crop (OSU Ohioline, 2023). Recent lab research found extracts from pearl millet residues inhibited primary root growth of Ipomoea grandifolia by 41–72% at higher concentrations, supporting chemical (allelopathic) contributions to suppression alongside physical mulch effects (PubMed 2025; open-access summary: PMC 2025).
• Soil Structure Improvement: A vigorous, deep, fibrous root system creates macropores and stabilizes aggregates. Pearl millet roots can extend well beyond 1 m (up to ~3 m in long-duration types) with penetration rates of 3.5–4.5 cm/day in sandy soils; primary roots elongate rapidly (7–9 cm/day) during early growth, enhancing soil porosity and rooting channels for the next crop (Passot et al., 2016, PMC; Phenotyping review, 2012, PMC; 2023 drought review, PMC).
• Water Management: Cover crops improve infiltration and reduce runoff. Reviews and field monitoring show cover crops increase time to runoff by 10–40 minutes and cut runoff volume by ~50% in most experiments, improving water capture and reducing transport of sediment-bound nutrients (Univ. of Wisconsin Extension, 2024). Pearl millet’s quick canopy and root channels help keep summer fields trafficable after storms (NRCS Iowa 2025 fact sheet).
• Disease/Pest Break: Pearl millet is widely reported to suppress root-lesion nematode (Pratylenchus penetrans); in Quebec rotations, forage millet decreased P. penetrans and increased subsequent potato marketable yields by ~10% versus oats (Journal of Nematology, 2005). OSU also highlights pearl millet as “best-known” among covers for reducing P. penetrans, though varietal differences exist; some cultivars show resistance to root-knot nematodes while others can be susceptible, so variety choice matters (OSU Ohioline, 2023; Timper et al. syntheses, PMC).
• Nitrogen Management (scavenging): As a non-legume, pearl millet captures residual N in summer. Typical cover-crop biomass ranges from 3,000–7,000 lb dry matter/acre; harvested early, pearl millet forage contains about 8–11% crude protein (~1.3–1.8% N), implying roughly 40–125 lb N/acre tied up in biomass (biomass and CP sources: NRCS Iowa 2025; UGA Forages). Expect slow N release (high C:N ~50:1), so plan starter N for the following non-legume if planting soon after termination (NRCS Iowa 2025; UNL CropWatch—N release, 2020).
• Biomass Production: As a summer cover, dry matter commonly runs 1,500–4,000 lb/ac in Ohio and 3,000–7,000 lb/ac in Iowa; Upper Midwest trials have averaged ~3.4 tons DM/ac in some years, and Kentucky guidance cites 2.5–5.0 tons/ac when planted on time (OSU Ohioline, 2023; NRCS Iowa 2025; UMN cover crop yields; Univ. of Kentucky Grain Crops, 2025).

Planting and Management Advice

• Seeding Rate (monoculture; Pure Live Seed where specified):
• Drill: 10–15 lb/ac PLS at 0.5–1.0 inch (OSU Ohioline, 2023); NRCS Iowa lists 10 lb/ac PLS at 0.5–1.0 inch (NRCS Iowa 2025). Many forage/cover references also allow 15–20 lb/ac when drilled, especially for weed suppression or grazing (Virginia Tech Extension).
• Broadcast: 11–17 lb/ac PLS with shallow incorporation (OSU Ohioline, 2023); some regional guides use 20–30 (up to 40) lb/ac when broadcasting to ensure a quick canopy in drier or rough seedbeds (Virginia Tech Extension; Univ. of Kentucky, 2025).
• Seed size and mixes: ~80,000 seeds per lb; reduce rate proportionally when used in multi-species mixes (NRCS Iowa 2025; MU Extension).
• Seeding Depth: Target 0.5 inch; acceptable range 0.25–1.0 inch depending on soil moisture/texture. Stay shallow on fine/firm seedbeds and slightly deeper in dry, sandy soils (OSU Ohioline, 2023; Virginia Tech Extension).
• Soil Type and pH: Best on well‑drained, light to medium-textured soils; performs on sands and tolerates acidity. Preferred pH roughly 5.5–7.5 (tolerant to ~5.0 in some guides). Avoid ponded/flooded sites and shade (NRCS Iowa 2025; OSU Ohioline; MU Extension; Mississippi State Extension).
• Planting Time (soil ≥65°F; by region):
• Upper Midwest/Northern Plains: Late May to late July (best May 20–July 25) (UMN Extension, 2024).
• Ohio Valley/Midwest: State-average reliable window May 20–Sept 6 (earlier planting yields more biomass; late seedings risk heading/seed set) (OSU Ohioline, 2023).
• Mid-Atlantic: Plant when soils reach ~65°F—typically late May to June; millets are more cold‑sensitive than sorghums, so wait for warm soils (Virginia Tech Extension).
• Southeast: April–June once 2-inch soil temps are ≥65°F (UGA Forages).
• Termination (before viable seed set to avoid volunteers):
• Winter‑kills with the first hard frost; cold tolerance about 32°F (NRCS Iowa 2025).
• Mechanical: Mowing after heading or mowing >2 ft tall stands to <2 inches can terminate; tillage may require multiple passes (OSU Ohioline, 2023).
• Chemical: Nonselective herbicides terminate quickly when vegetative; follow local NRCS termination guidelines for program compliance (OSU Ohioline, 2023).
• Rotational Considerations:
• High C:N (~50:1) residues can immobilize N; if planting a non‑legume cash crop shortly after termination, consider 30–50 lb N/ac starter and/or terminate 1–2 weeks before planting to reduce tie‑up (NRCS Iowa 2025; UNL CropWatch—N release, 2020).
• Nematodes: For root‑lesion nematode (P. penetrans), pearl millet can lower populations and benefit the next crop, but choose varieties carefully where root‑knot nematodes are an issue (resistance varies among hybrids) (OSU Ohioline, 2023; J. Nematology—millet rotation benefits; resistance variability, PMC).
• Avoid allowing seed set; millets grown for grain can contribute to volunteer weeds the following season if not terminated on time (OSU Ohioline, 2023).
• Water Requirements and Drought Tolerance:
• Pearl millet is among the most drought‑tolerant summer annual grasses used in U.S. systems, maintaining growth on hot, sandy or acidic soils where maize or small grains falter (UGA Forages; Mississippi State Extension). Deep, rapidly elongating roots help sustain water use efficiency under deficits (Passot et al., 2016, PMC; 2023 drought review, PMC).
• Compared with other summer covers, it provides reliable cover and grazing during hot, dry periods without prussic acid concerns; monitor nitrates if heavily fertilized and drought‑stressed (UGA Forages).

Practical notes for success:

• Fertility: Although it tolerates low fertility, pearl millet responds to N—especially when cut or grazed—but avoid over‑fertilizing a pure cover stand to minimize nitrate accumulation and excessive C:N (Virginia Tech Extension; Mississippi State Extension).
• Traffic/grazing: Stands bear traffic well and graze readily once 20–24 inches tall; leave 6–9 inches stubble to promote regrowth if grazing before termination (OSU Ohioline, 2023; UGA Forages).
• Program compliance: If participating in NRCS programs, follow state Field Office Technical Guide seeding windows/rates and NRCS termination guidelines (OSU Ohioline, 2023; NRCS Iowa 2025).

SARE perspective and recent research:

• SARE’s national handbook notes millets (especially pearl millet) are vigorous, drought‑tolerant summer grasses useful for suppressing weeds and reducing nematodes when incorporated appropriately; sudangrass and pearl millet are specifically cited for nematode suppression potential, with varietal differences and a need to avoid letting covers host the target nematode (SARE—Building Soils for Better Crops, Ch. 10).
• Newer regional data underscore high-biomass potential of summer grasses, with pearl millet in Nebraska trials reaching up to ~9.1 tons/ac in favorable July–October windows and exhibiting high C:N ratios that provide longer-lasting mulch (UNL CropWatch 2022–2024 summary).

Typical performance snapshot (monoculture, timely planting):

• Biomass: 1,500–7,000 lb DM/ac (region/weather dependent) (OSU Ohioline; NRCS Iowa 2025).
• N scavenging: Roughly 40–125 lb N/ac tied in biomass (calculated from biomass and forage N content), with slow release due to C:N ≈ 50:1—plan starter N if planting a high‑N‑demand cash crop soon after (NRCS Iowa 2025; UGA Forages; UNL CropWatch N-release).
• Erosion and water: Expect 50–75% erosion reduction and ~50% runoff reduction compared with bare soil when adequate biomass/residue is achieved, with benefits scaling with biomass and cover duration (UC ANR; UW Extension; farmdoc daily).

Notes:

• If weed control is a primary goal, favor drilled seeding, timely planting, and higher broadcast rates to maximize early canopy and biomass; terminate prior to heading to avoid volunteer millet in the following crop (OSU Ohioline, 2023; Virginia Tech Extension).
• For nematode management, consult local diagnostics and select cultivars with documented resistance where root‑knot nematodes occur; pearl millet has shown strong suppression of root‑lesion nematode in rotations (OSU Ohioline, 2023; J. Nematology).