Broadcasting alfalfa seed is possible, but it requires specific conditions and techniques to achieve results comparable to traditional mechanical drilling. Alfalfa is a perennial legume forage crop, highly valued for its protein content and ability to fix nitrogen in the soil. While broadcasting offers speed and simplicity, the successful establishment of a dense, long-lasting stand depends on overcoming the challenges of placing a tiny seed correctly.
Ensuring Proper Seed-to-Soil Contact
The primary hurdle when broadcasting alfalfa is the necessity of firm, continuous contact between the seed and the soil particles. Alfalfa seeds are small and require moisture to initiate germination. If the seed remains on the soil surface, it is susceptible to desiccation or consumption by birds. Without mechanical placement, the broadcast seed lacks the security provided by a seed drill. If a seed germinates on the surface, the developing seedling root may struggle to penetrate the soil quickly enough to access moisture before drying out. Proper seed-to-soil contact is the most important factor for maximizing seedling survival before the plant develops its deep taproot system.
Essential Steps for Successful Broadcast Seeding
Successful broadcast seeding begins with meticulous seedbed preparation to create a firm, smooth surface. A properly prepared seedbed should be firm enough that a person’s footprint sinks no deeper than about a half-inch, often achieved by using a cultipacker or roller before application. This firmness helps regulate the seeding depth and ensures that subsequent packing can fully secure the seed.
Since alfalfa is a legume, the seed must be inoculated with the specific Sinorhizobium meliloti bacteria, which allows the plant to fix atmospheric nitrogen. Most commercial alfalfa seeds come pre-coated, but verify the seed has been treated or inoculate it yourself just before spreading.
The broadcast seeding rate must be higher than the rate used for drilling to compensate for anticipated losses. While drilling typically uses 12 to 15 pounds per acre, broadcasting often requires a 10 to 30 percent increase to ensure adequate final stand density. After the seed is spread, immediate post-seeding management is necessary, usually involving a second pass with a cultipacker or roller to press the seed into the soil surface. This action lightly covers the seed and firms the soil around it.
Comparing Broadcasting to Mechanical Drilling
Mechanical drilling remains the preferred method for alfalfa establishment because it offers superior control over both seeding depth and seed-to-soil contact. A drill places the seed precisely at the optimal depth, typically between one-quarter and one-half inch, which leads to a higher and more consistent establishment rate. This precise placement generally translates to better long-term yield consistency compared to broadcast stands.
Broadcasting, however, is significantly faster and requires less specialized or expensive equipment, making it a more accessible choice for smaller operations or when wet conditions prevent the use of heavy machinery. The trade-off is often a lower initial germination rate; while drilling can achieve close to 90% germination in ideal conditions, broadcasting without intensive packing may yield lower establishment success.
Another crucial difference is the impact on early weed competition. Drilling places the alfalfa seed deeper and gives it a slight head start over many shallow-germinating weeds. Broadcast seeding often results in a higher proportion of seeds remaining near the soil surface, which can lead to greater weed pressure during the vulnerable seedling stage. Therefore, effective weed management, often through the use of a companion crop or herbicides, becomes even more important when broadcasting alfalfa.