Planters
Traditionally, two types of planter row units are used-those with staggered (offset) double-disc openers and those with unstaggered (conventional) double-disc openers. While similar in design, the difference in the amount of soil they move can be significant, especially in fragile residues. The staggered double-disc openers typically disturb less soil and leave more residue cover after planting.
Seeding rates are usually higher for no-till planting than conventional tillage due to no-till's greater ability to sustain higher populations. (Seed hybrid selection should be based on early season vigor, emergence and high yield potential. Other factors to consider include disease and insect tolerance, standability, and residue production for erosion control.)

Drills
Two types of drills predominate in the United States. The majority are drills with staggered (offset) double-disc openers (with or without a coulter caddy). The other type has a single, angled disc opener.
Other types of seed furrow openers include the hoe and runner openers, used primarily in wheat production. They are slightly more aggressive in covering residues than disc openers.
Drills with a single, angled disc opener have fewer parts to move the residue and a smaller angle between the soil-contacting blade and direction of travel. That's why they usually leave more residue cover than drills with hoe, furrow, or double-disc openers.
Like planters, drills also offer the option of coulter attachments. Unlike planters, only one coulter per row is attached. The same types of coulters are used on both planters and drills, so depending on the machinery combination, the amount of cover left after drilling can vary widely. For more on coulters, see table 7 on the next page.

Figure 2. Points to ensure a level planter

In addition to properly adjusted press wheels, seed firming attachments like the one pictured here may help improve seed-to-soil contact.