Alfalfa Seeding Recommendations

Timing is crucial for spring planting. Planting too early can expose young stands to damaging frost, while planting too late can lead to greater potato leaf hopper and weed pressures.  Establishing a vigorous alfalfa stand is pivotal for future production, forage quality, and minimizing weed pressures. Here are some recommendations to establish a vigorous alfalfa stand.

Field Site

Field site should be well-drained. Ponding and wet soils can be detrimental to alfalfa stands creating conditions for diseases. Aim for a pH that is greater than 6.5 but ideally would be closer to 6.8- 7.0. Soil fertility particularly phosphorus and potassium should be in the moderate range, for more details check the PM 1688 “A General Guide for Crop Nutrient and Limestone Recommendations in Iowa“. These nutrients can be applied at planting, but if your pH needs adjusted this needs to occur six months prior to planting. Ensure that there are not any residual broadleaf herbicides from the previous crop by double checking plant-back restrictions on the herbicide label.  If no-tilling ensure there is minimal surface residue as this can cause competition for the new seedlings. Lastly, do not plant into an old alfalfa stand to avoid suppression of the new seedlings from autotoxicity.

Field Preparation and Planting Rates

Alfalfa should be planted into a firm seed bed. If deep tillage occurs before planting, consider the use of a cultipacker or roller to firm up the seed bed (Figure 1). Ensure your footprint does not sink deeper than 0.5 inch into the seed bed. The deeper your foot print the more likely the seed will settle deeper into the profile potentially leading to poor and uneven germination. If no-till drill is used, minimize surface residue to reduce competition for new seedlings (Figure 2).

Alfalfa is recommended to be planted between 15- 20 lbs per acre pure live seed, variation can occur based on field site, seed coating, and field conditions. The goal should lead to 20-30 seedlings per square foot by the end of the first year (Figure 3). Research has not shown planting at a higher rate will give you a better stand. It generally leads to more seedlings dying out of the stand during the first year.  Alfalfa needs be planted between 0.25 to 0.5 inch deep. A good indicator that you did not plant too deep is ~10% of the seed will be visible on the top the soil. Additionally select an alfalfa variety with high disease resistance to ensure a good stand for multiple years.

Companion Crop or Herbicide

Alfalfa is commonly planted with a nurse cereal crop, such as oats, to help protect the young seedlings from frost and crowd out weeds. A companion crop is also beneficial on slopes to help reduce soil erosion. Although care needs to be taken to ensure the companion crop is not overcrowding the alfalfa. If being harvested for forage, harvest at or before the boot stage, and if not harvesting for forage, terminate before it reaches height of 6 inches. If using a companion crop it is important to plant the companion crop at a reduced rate, less than ½ bushel per acre, as a higher rate can decrease alfalfa production and stand the following years. The alfalfa should be planted at a full rate. Remember if planting a companion crop, we are planting it to protect and ensure a strong alfalfa stand not planting them together for a good single cut of the companion crop compared to potential 20 cuts of the alfalfa. High competition of the companion crop could lead to an increased risk of competition and declined yield and quality for subsequent years of the alfalfa stand. Additionally, the companion crop will compete for soil moisture. In areas faced with drought, soil moisture may be limited this spring.

Seeding without a companion crop is another option when proper weed control measures are taken. Pre-plant incorporated herbicide, like trifluralin, Balan, or Eptam will help control small broadleaf weeds, but larger broadleaf like sunflower and velvet leaf will not be controlled well. They can be controlled with mowing later in the season. Post-emergence herbicides like Buctril and Buctril 200 will control a wider range of broadleaves. Other herbicides such as Raptor and Pursuit control a combination of broadleaf and grass weeds. Similarly, Poast Plus and Select can also help control many grass weeds.  They can be effective if applied in a timely manner before the weeds get very tall and at the right stage of alfalfa to avoid injury. Additionally, the use of round-up ready alfalfa can help with weed control problems with the use of glyphosate. Overall, starting with a clean seed bed, and controlling the weeds in the seeding year, whether with a companion crop or herbicides, is very important for reducing competition in subsequent cutting and years.