Linked from
The 6 pages that link to Seedbed, each with the reason it gives.
Direct seedingRelated: A suitable seedbed gives sown seeds reliable contact with moist soil.
TillageRelated: Tillage often creates a seedbed with suitable depth, firmness, and surface texture.
SowingRelated: A suitable seedbed supports contact between seeds and moist soil.
OlericultureRelated: Seedbeds support early growth before seedlings are transplanted or field-grown.