FACTORS THAT AFFECT SEED PLACEMENT
Seed placement is key to producing an excellent harvest. Good seed placement consists of three factors: depth, seed spacing, and seed to soil contact. To meet these needs, you will have to strike the right balance with your direct seeding equipment.
Seeding to the Correct Depth
Uneven seed depth leads to varying germination rates across a field. Seeds that are planted too deep will germinate slowly and grow into weak seedlings. For accurate depth placement, your opener needs to have two things: good ground following capabilities, and depth gauges. Knife openers tend to have the best ground following capabilities because they have light, flexible frames that can adjust to uneven terrain. They also have packing wheels that double as depth gauges. Many disc openers also have depth gauges, but disc openers are much heavier than knife openers. In soft areas, they will often dig in too deep.
Dealing with Furrow Cave-In
Furrow cave-in is common after heavy rains. When more soil washes into the furrows, you are effectively increasing the planting depth. While it is impossible to account for the weather, you can lessen the risk of furrow cave-in by choosing a seeder that will provide the least amount of soil disturbance. Clay soil and heavy, wet soil tends to stick to disc openers, causing more disturbance than necessary. In this situation, you may have better luck with a knife opener. In contrast, knife openers often cause more soil disturbance in hard, dry soils.
Achieving the Right Seed to Soil Contact
Packing wheels play a key role in seed to soil contact. The packing wheels on your seeder should always be as wide as the furrows to ensure even soil compaction. If the soil isn’t compacted well enough, you could have slow germination rates. Loose soil also loses moisture quickly, which can turn into a big problem in dry weather. When the seedbed is compacted too much, seedlings will struggle to emerge, and often turn into weak, spindly plants.
How Seed Velocity Affects Spacing
Inaccurate seed spacing can lead to some serious losses at harvest time. When seeds are too close, competition from their neighbors weakens them. Meanwhile, the seeds that are farther apart grow vigorously, often crowding out the smaller, weaker seedlings. Disc and knife seeders will usually give you good seed spacing. Uneven spacing can become a problem if you are using an air seeder. When the air pressure is set too high, seeds bounce and scatter as they hit the seedbed. If you are using an air seeder, you will need to carefully adjust the delivery speed to prevent seed scatter.