Getting Out of Alfalfa With Herbicides
Alfalfa is widely used in crop rotations to improve soil health, nitrogen levels, and weed control while providing an alternative income source. Traditionally, alfalfa remains in rotation for 3–5 years before removal. While tillage is the most common method, it is costly, time-consuming, and can negate many benefits of forage inclusion. Herbicide-based removal offers an efficient, soil-conserving alternative.
Challenges with Tillage
- Requires up to six passes, costing $20–$30 per acre.
- Increases erosion risk and soil drying.
- Brings dormant weed seeds to the surface.
- Reduces soil structure and snow-trapping residue.
- Increases nitrate leaching from forage residue.
Advantages of Herbicide Removal
- Soil & Water Conservation – Maintains soil cover and moisture.
- Quackgrass Control – Herbicides allow effective treatment; tillage can worsen spread.
- Better Seedbed – No-till results in firm seedbeds and improved seed-to-soil contact.
- Annual Weed Control – Avoids stimulating dormant weed seeds.
Alfalfa Removal with Herbicides – Effectiveness
Treatment |
Rate (L/ac) |
% Control May 25 |
% Control June 22 |
Notes |
Roundup + Banvel + 2,4-D |
0.75 + 0.50 + 0.40 |
95%+ |
90%+ |
Excellent control; targets alfalfa, quackgrass, suppresses dandelions. |
Roundup + Banvel |
0.75 + 0.50 |
95%+ |
90%+ |
Similar to above. |
Banvel + 2,4-D |
0.50 + 0.40 |
95%+ |
90%+ |
Good suppression; no grass control. |
Lontrel + 2,4-D |
0.60 + 0.40 |
95%+ |
90%+ |
Costly; no quackgrass control. |
Lontrel |
0.60 |
95%+ |
85–90% |
Costly; no quackgrass control. |
Roundup |
2.00 |
95%+ |
55–60% |
High rate only needed for sod-bound grasses. |
Roundup |
1.00 |
90%+ |
35–40% |
Reasonable; follow-up likely needed; poor on dandelions. |
Roundup + 2,4-D |
0.75 + 0.40 |
90%+ |
70–75% |
Good treatment; needs full litre of Roundup for grasses. |
Banvel |
0.50 |
90%+ |
70% |
No quackgrass control. |
Roundup + Lontrel |
0.75 + 0.16 |
90% |
25–30% |
Needs full litre of Roundup for grasses. |
Roundup |
0.75 |
80–85% |
10–15% |
Too low; ineffective alone. |
Roundup |
0.50 |
80–85% |
10–15% |
Way too low; ineffective. |
2,4-D |
0.40 |
50–55% |
15–20% |
Not recommended; poor control. |
Note: Banvel and Lontrel leave soil residues—check labels for recropping restrictions.
June 22 results based on trials without crop competition or in-crop herbicide.
June 22 results based on trials without crop competition or in-crop herbicide.
Points to Consider Before Removing Alfalfa
When planning herbicide removal of alfalfa, keep these factors in mind:
- Weed Spectrum
Identify weeds present in the field. - Quackgrass only: Roundup is effective.
- Mixed weeds (thistles, dandelions): Include Banvel for broader control.
- Next Crop in Rotation
Banvel and Lontrel leave soil residues that may affect sensitive crops. Always check product labels for recropping restrictions. - Soil Moisture and Seeding Timing
Alfalfa land tends to be drier. Plan to seed early in spring to take advantage of snowmelt moisture. - Regrowth Management
Expect some alfalfa regrowth in early summer. Be prepared for an in-crop broadleaf herbicide treatment.
Best Practices
- Timing: Spray after second cut when regrowth reaches 8 inches and plants are actively growing. September applications are effective if done 1–2 weeks before killing frost.
- Dry Conditions: If regrowth is poor after second cut, consider spraying after first cut.
- Follow-up: Expect some regrowth; plan for in-crop broadleaf control.
- Seeding: Sow early to use snowmelt moisture. Zero-till drills preferred for minimal disturbance.
Summary
Herbicide removal of alfalfa is cost-effective, conserves soil and improves seedbed conditions compared to tillage. Proper timing, product selection, and follow-up management are key to successful transition from forage to annual crops.