Camelina

Camelina (Camelina sativa), sometimes marketed as “winter camelina” when fall‑seeded, is a cool‑season oilseed brassica used increasingly as a cover crop across the Upper Midwest and other temperate regions. Growers choose camelina for its winter hardiness, very early spring growth, strong nutrient scavenging, notable early‑season weed suppression, and the option to harvest it as a short‑season “cash cover crop” for oilseed revenue. (cropsandsoils.extension.wisc.edu, extension.oregonstate.edu)

Benefits of Camelina as a Cover Crop

• Erosion Control: In Upper Midwest field trials of winter oilseed cover crops (camelina and pennycress) relay‑cropped with soybean, winter oilseeds reduced runoff and sediments during high‑intensity spring rains; total suspended solids (a proxy for soil loss) were cut by 75% during the intercrop phase in pennycress, with camelina plots likewise reducing runoff and sediments during storms. This highlights the erosion control potential of winter oilseed cover systems compared with fallow. (acsess.onlinelibrary.wiley.com, ui.adsabs.harvard.edu)
• Weed Suppression: Winter camelina consistently suppresses early‑season weeds. Across Minnesota sites, camelina reduced weed biomass by 85–88% compared with mono‑crop soybean; pennycress achieved 97–100%. These reductions occurred during the critical early competition window. (acsess.onlinelibrary.wiley.com)
• Soil Structure Improvement: As a brassica with a strong taproot and dense fibrous root system during establishment, camelina improves soil aggregation and creates channels that enhance infiltration; recent reviews also highlight its allelopathic potential that can further suppress competitors without herbicides. (mdpi.com)
• Water Management: Keeping living roots over winter and into early spring increases infiltration and moderates runoff; university guidance notes that cover crops (including brassicas) improve soil pore structure and water‑holding, leading to drier field conditions after rains in spring. Winter oilseed covers also reduced runoff and sediments during spring events in Upper Midwest studies. (extension.umn.edu, ui.adsabs.harvard.edu)
• Disease/Pest Break: Camelina contains glucosinolates; decomposition and exudates can be suppressive to certain soilborne pathogens and nematodes, contributing to a disease‑break effect reported in the literature for brassicas, with camelina specifically flagged for integrated pest management potential. (mdpi.com)
• Nitrogen Management: As a non‑legume, camelina does not fix N but is an efficient N scavenger. In USDA‑ARS lysimeter studies, soil‑water nitrate during the cover/intercrop phases averaged 4 mg/L under cover crops (including camelina) versus 31 mg/L under fallow; spring N uptake by overwintering oilseeds (camelina/pennycress) reached 28–49 kg N/ha (≈25–44 lb N/ac) before soybean planting, reducing leachable N. (pubmed.ncbi.nlm.nih.gov)
• Biomass Production: In NRCS performance ratings for Iowa, winter camelina produced 2,500–6,000 lb/ac of dry matter (year and timing dependent), providing meaningful residue and living cover into spring. (nrcs.usda.gov)

Planting and Management Advice

• Seeding Rate (cover crop use):
• Drill: 3–5 lb/ac PLS (NRCS Iowa). University of Wisconsin also recommends ~6–8 lb/ac for drilled winter camelina in WI systems. A practical drilled range across regions is 3–8 lb/ac depending on seedbed, drill type, and whether it’s a monoculture or mix. (nrcs.usda.gov, cropsandsoils.extension.wisc.edu)
• Broadcast/Aerial: 5–6 lb/ac PLS (NRCS Iowa); WI guidance uses ~8–10 lb/ac when broadcasting to offset lower placement uniformity. Light packing after broadcast improves establishment. (nrcs.usda.gov, cropsandsoils.extension.wisc.edu)
• Seeding Depth: Place very shallow—about 1/4–1/2 inch. Extension also advises “as shallow as possible,” with a few seeds on the surface acceptable due to the very small seed size (~400,000 seeds/lb). (nrcs.usda.gov, extension.psu.edu)
• Soil Type and pH: Camelina tolerates a wide soil range but performs best on well‑drained, lighter‑textured or droughty soils; avoid poorly drained/wet fields. Recent research summaries note adaptation across pH 5.5–8.0; maintain pH in the typical row‑crop range and correct severe acidity or alkalinity as needed. (extension.psu.edu, mdpi.com)
• Planting Time (seasonal windows by region):
• Upper Midwest (e.g., IA/MN/WI): For winter camelina, seed in late summer to fall. NRCS Iowa: mid‑August to late October; WI Extension: September–early October (drill preferred). These windows aim for fall rosette formation before winter. (nrcs.usda.gov, cropsandsoils.extension.wisc.edu)
• Northeast/Mid‑Atlantic: Spring camelina can be sown very early—when soils reach 38–40°F—because seedlings tolerate frost; Penn State notes no stand loss at 20°F. This makes camelina one of the earliest feasible spring covers. (extension.psu.edu)
• Southeast (e.g., North Florida): As a cool‑season oilseed/cover, best performance when planted in mid‑November; later planting reduces growth and yield potential. (edis.ifas.ufl.edu)
• Termination: For most systems, terminate 2–4 weeks before cash‑crop planting to avoid hairpinning and allow residues to mellow. In conventional programs, broadleaf‑active herbicides (e.g., glyphosate or 2,4‑D) effectively terminate camelina; use tillage for organic systems. Plan timing around bolting/early bloom if maximizing biomass without seed set; roller‑crimping alone is unreliable on brassicas. (sare.org, cropsandsoils.extension.wisc.edu)
• Rotational Considerations:
• Herbicide carryover: Camelina is sensitive to residual sulfonylurea and triazine herbicides. Colorado State Extension lists >24‑month intervals for several SUs; carryover risk increases on high‑pH (>7.0), low‑rainfall soils. Check prior herbicide history before planting. (extension.colostate.edu)
• Disease rotation: To limit buildup of brassica pathogens, avoid planting camelina back‑to‑back; Florida Extension suggests no more than once every three years in the same field due to risks like Sclerotinia/downy mildew in warm, humid regions. (edis.ifas.ufl.edu)
• Following crops: Camelina residues decompose quickly and typically do not immobilize N, making it a workable preceding cover before corn or soybean; manage residues and termination timing to minimize interference with planting. (cropsandsoils.extension.wisc.edu)
• Water Requirements and Drought Tolerance: Camelina is notably drought‑tolerant and suited to lower‑rainfall environments compared with many oilseeds; it has been used successfully in dryland systems of the Pacific Northwest and performs well on droughty soils. However, it should not be placed on poorly drained sites. (extension.oregonstate.edu, extension.psu.edu)
• Nitrogen Scavenging/Release Planning: Expect strong spring N uptake; ARS studies measured 28–49 kg N/ha (≈25–44 lb N/ac) in camelina/pennycress prior to soybean planting, and soil‑water nitrate reductions from ~31 to ~4 mg/L during the cover/intercrop phases. Adjust starter N for the following crop based on soil tests to capture this benefit without under‑fertilizing. (pubmed.ncbi.nlm.nih.gov)
• Biomass Targets: In the Upper Midwest, plan on roughly 2,500–6,000 lb/ac dry matter from winter camelina (driven by planting date, winter survival, and termination timing); mixes with winter rye can increase residue if more surface mulch is desired. (nrcs.usda.gov, cropsandsoils.extension.wisc.edu)

Notes to maximize success:

• Seed with a small‑seed (grass) box or a drill capable of metering tiny seed; firm seed‑to‑soil contact is critical. (extension.psu.edu)
• For more erosion control and spring mulch, consider blending camelina with a small grain (e.g., winter rye), then terminate the mix on schedule for your planting date. (cropsandsoils.extension.wisc.edu)
• Where the goal is weed suppression prior to soybean, relay systems with winter camelina have provided 85–88% early‑season weed reduction; use skip‑rows and timely termination to balance weed control with soybean light/water needs. (acsess.onlinelibrary.wiley.com)