The Direct Seeding Factsheet series of Alberta Agriculture, Food and Rural Development defines direct seeding as a system where soil is not tilled in the spring before seeding and fall tillage leaves most of the crop residue on the surface, with at least half the stubble remaining upright and anchored. Fall tillage might include fertilizer banding with narrow knives or harrowing to spread residue.
Single shooting refers to an air seeder or air drill which has a single air delivery system.
Seed and fertilizer are placed in the same row. Double shooting refers to an air seeder or air drill which has a separate air delivery system for seed and for fertilizer. A double shoot opener creates a band of fertilizer between two seed rows or it may place fertilizer to the side of the seed, which is often called side-banding. Yes, more and more producers are adopting direct seeding. Most crops can be direct seeded as long as your planter will do the job.