Gerald Holmes, California Polytechnic State University at San Luis Obispo, Bugwood.org
No-till alfalfa should be part and parcel of a no-till system. The threat of soil erosion is very substantial if alfalfa is established in tilled soil. A stand can be partially lost due to erosion, or rills and gullies can form in a new seeding. These rills and gullies will be present for many years and can compromise operation of field equipment, damage it, and present danger to the operator.
Because of the protection provided by mulch, crusting problems are avoided. No-till also saves moisture, which can help improve success with late summer seedings of alfalfa. The stubble provides protection for the young, tender alfalfa seedlings from direct intense sunlight and possible damage from blowing sand or soil particles.
On rocky soils, use of no-till helps eliminate the need to pick rocks. Additional benefits include reduced fuel, labor and time requirements for no-till alfalfa establishment compared with alfalfa establishment in tilled soil.
Finally, lower seeding rates can be used because with a well-adjusted no-till drill seeding depth and metering is much better controlled than in conventional seed drills. However, if you just start thinking about no-till alfalfa now you are way behind the eight-ball. It would be better to start preparing for future no-till planting if you have not taken the necessary precautions or you could be disappointed and fighting the aftermath for the entire duration of the alfalfa stand. Preparation means addressing soil unevenness, weed control, soil fertility, soil pH, herbicide residues, etc. This is more than we can cover here where we assume you have done all the necessary homework so you are ready to plant alfalfa.
Make sure all weeds are killed. Use gramoxone or glyphosate to kill established and emerging weeds. However, it may not be necessary to apply herbicide if your field is clean, so check before you spray.
Any no-till drill can work as long as the seed can be placed within ¼ to ½ inch deep. The greatest threat is to place the seed too deep! Seeding depth is more critical than seeding rate. So the equipment needs to be able to place the seed at the right depth and uniform spacing across all units, and press the seed into the soil gently so it is covered and has good seed-to-soil contact.
Make sure the drill is well-maintained. Drill units should be tight and not wobbly-check bearings and parallel linkages. Make sure all units are in the same plane. Coulters, if present, need to cut through residue. It is best to have narrow coulters that do minimal soil disturbance-wide coulters may leave a lot of bare soil showing, and they also bring up moist soil which can stick to the coulters and depth wheels. By using narrow coulters such as rippled coulters or even bubble coulters you can work in a wider range of soil conditions. This is very important for spring establishment of alfalfa which often happened when the soil is on the wet side. The coulters should not run deeper than the planting depth to avoid dropping seeds too deep.
Double disk or single disk openers are the most common for no-till alfalfa seeding. Shoe types can also be used but tend to not handle residue as well, do more soil disturbance and can easily place the seed too deep. Make sure the double disk openers are not worn too much and have the right point of contact (check by placing two business cards between the disks to the point of contact-there should be something like an inch between them depending on the drill type).
The depth gauge wheel is often also the press wheel. It is very critical to set it to the right depth. There are also often 'dough-nut' shaped washers controlling seeding depth on the hydraulic cylinders. Play with the number of doughnuts and the settings on the press wheel to come to the right depth. Two inch wide closing wheels seem to work best-they cover the seed firmly while still controlling depth well. Narrower wheels lose to ability to control depth well, while wider wheels do a poor job closing the seed slot.
To determine seeding rate, use the seed charts on the drill as a first approximation. However, it is best to check calibration of the drill using our fact sheet. You should also keep track on the acres planted and quantity of seed used. It is easy to use too much seed and then you are just wasting money!
After planting, continue to monitor the stand and address any issues. Guidance is available in the Penn State Agronomy Guide for weed and pest control. After about 5 weeks the alfalfa should be 3-5 inches tall. Good luck!