Lucerne Advisor Series: Lucerne in rotation – how to know when it’s time

Lucerne is more than a feed crop — it’s a valuable part of your farm system. Whether you’re preparing to sow into lucerne stubble, rotating out of a long-term stand, or planning for a fresh sowing next autumn, how you manage lucerne in rotation has a big impact on long-term productivity.

Here’s how to make the most of lucerne in your rotation — and how to manage the transition out.

Why lucerne earns its place in rotation

Lucerne isn’t just about grazing or hay. Its benefits carry through into the next crop or pasture phase.

Key advantages:

• Nitrogen(N) fixation: Lucerne can fix 150–300kg N/ha/year, reducing the need for synthetic N in following crops
• Weed suppression: A dense lucerne stand can suppress broadleaf weeds and annual grasses, cleaning up paddocks before cropping
• Soil conditioning: Deep roots improve structure, reduce compaction, and enhance infiltration — particularly valuable ahead of cereals

When to rotate lucerne out

Lucerne doesn’t last forever. As tiller density declines and gaps form, production drops — and so does its value in the system.

Signs it’s time to rotate out:

• Yield drops below 60–70% of peak
• Crown rot, disease or weed burden increases
• Spring growth slows or becomes patchy
• Bare soil is visible between plants

Rule of thumb:

• Dormant/semi-dormant lucerne can last 7+ years with good management
• Winter-active types last 5–7 years
• Highly winter-active varieties may last 3–4 years, especially under cutting

What to plant after lucerne

Lucerne leaves soil in good shape — high in nitrogen, with improved physical structure. That makes it ideal for certain follow-on crops.

Common follow-up options:

• Cereals (wheat, oats, barley): Use fixed nitrogen and benefit from clean paddocks
• Brassicas (forage rape, turnip, kale): Take advantage of weed suppression and rotation break
• Annual pasture mix: Reset the system with ryegrass, clovers and herbs while monitoring for carryover

Lucerne stubble can also provide grazing during the rotation year if managed carefully.

Managing lucerne regrowth in following crops

Lucerne is persistent — and it doesn’t always die quietly.

If you’re planting a crop after lucerne:

• Terminate properly with knockdown herbicide and/or tillage
• Monitor for regrowth in early crop phases, especially under conservation tillage
• Avoid residual herbicides in the final lucerne season that could affect follow-up crop germination

Planning your next lucerne phase

Many producers return to lucerne after one or two rotations. If that’s your plan:

• Plan the paddock now — clean up weeds, manage soil fertility, and think about variety selection
• Refer back to Blog 1: setting up for lucerne success — same rules apply
• Choose a variety that suits your new system (cutting, grazing, or dual-purpose)
• Use Goldstrike XLR8® treated seed for a strong start in your next phase

Conclusion

Lucerne improves the soil it leaves behind — but only if you manage the transition well. Know when to rotate out, pick your follow-on crop wisely, and use the break to set up for your next successful lucerne stand.

Whether you’re rotating out or bringing lucerne back in, these guides can help you prepare for a stronger, more resilient stand next season:

• Getting lucerne right from the start
• How treated lucerne seed improves your stand

Thinking about bringing lucerne back into the system?
Talk to AlfaGen about the best variety for your next phase — and how to set it up for success from day one.