mounted models are better for large seeds. For best results, broadcasted seed should be followed by a second operation (e.g., light tillage, dragging chain-link fencing, or rolling) to press it into the soil. A seed drill is the preferred method as it requires less seed, places seed at a consistent depth, and ensures excellent seed to soil contact, typically resulting in a better stand. A conventional grain drill works for cover crops, but a no-till drill is better for hard soils or minimal seedbed preparation. How to Calibrate Your Equipment Calibrating a broadcast seeder is similar to calibrating a boom sprayer and requires measuring time, area and output. For additional reference, Project Apis m . has a helpful cover crop planting video on their YouTube channel which provides calibration tips. Determine Speed: First, find a safe and realistic operating speed under field conditions. For example, 400 feet per minute equals 4.5 MPH. Since spinner plate RPM is often fixed, speed is the easiest way to adjust the application rate; slowing down applies more seed, while speeding up applies less. Determine Swath Width: The seeder throws seed in an arc, often at 180 degrees. The width can be narrowed either by slowing down or using improvised or manufacturer-provided deflector plates or fenders. Collect and Calculate a Sample: At your desired speed, drive over a tarp or hard surface. Measure the width and length of the seeded area. Gather the seed and weigh it in ounces. Calculate the area in square feet (length x width). Multiply this area by your target seeding rate (lbs./acre). Divide that result by 43,560 (sq. ft. per acre) to find the pounds of seed that should have been applied. Convert pounds to ounces by multiplying by 16. Compare this calculated weight to your measured sample weight to determine if you need to adjust your speed or the seeder's gate setting.
Most drills can be calibrated off field. The owner’s manual usually provides a chart with suggested settings for different seed types and how to calibrate the unit. Setup: Safely lift the drive wheel off the ground and brace the drill to protect both you and the machinery. Measure the wheel's circumference. Place catch containers under three seed cups (often by pulling the ends of the seed tubes out and placing them in a container). Simulate Planting: Put seed in the hopper. Turn the drive wheel a predetermined number of revolutions (e.g., 20 turns). The distance simulated is the number of revolutions multiplied by the wheel's circumference (e.g., 20 revs x 5 ft/rev = 100 ft). Weigh and Calculate: Weigh the total amount of seed collected from all catch containers. Divide this by the number of cups (e.g., three) to get the average per cup, then multiply by the total number of cups on the drill. This gives the total seed released over the simulated distance. Compare and Adjust: Calculate the seed weight that should have been applied for that area using the method described for broadcasters. Compare this to your measured weight and adjust the drill's seed metering lever as needed. Cover crops can be a simple and rewarding addition to orchard management systems if set up correctly. They provide a variety of benefits including improved water infiltration, reduced soil compaction, and many more functions. Seed planter calibration is an important component which can often determine the success of the cover crop.
Tom Johnson, Seeds for Bees ® Grower Relations Manager, Project Apis m.
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SEPTEMBER–OCTOBER 2025
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