John Deere - Drill and Air-Seeder
The image to the right illustrates the John Deere single disc seeder seed slot when viewed from above. Within moist no-till conditions (and when using a new disc blade), the seed slot frequently measures between 5/8 and 3/4” of an inch in width, with a slight tapered furrow wall opposite the disc blade. As the disc blade (and boot) wear, the width of the seed slot decreases in width and the angle of the taper increases. Close inspection of the image to the right will reveal that the factory installed John Deere 1” firming wheel (which was sold until summer 2006) was too wide to fit down within the seed slot to effectively press seeds into moisture. Pressing seeds into moisture is very important, especially when trying to obtain a stand in lower moisture soil conditions.
The image to the right illustrates the John Deere single disc seeder seed slot when viewed from the end. This image was obtained by lifting up the seed firming wheel and closing wheel with string and driving forward with the seeder engaged in the soil. Notice the profile of the seed slot within a moist silt loam soil type in a no-till system. Also notice how the seeds are loosely dropped into the bottom of the seed slot. Pushing these seeds in the base of the seed slot (we call it imprinting) is critical within low moisture conditions to create uniform emergence. Most commercial seed firming wheels on the market are too wide and the wrong shape to accomplish this task consistently across different soil types and moisture conditions.
The image to the right illustrates some of the many concrete seed slot molds Phil Needham utilized in the wheel design process. Different soils, seeding speeds, seeding depths and moisture levels all have an influence on seed firming wheel performance and most seeding environments across the US have been tested.