Farm Seed & Cover Crop Comparison Chart. Compare the following criteria / purposes: Seed Type, Sowing Season, Minimum Germination Temperature, Hardiness Zone/Frost-Sensitivity, Growth Rate, Seed Sowing Rate/Square Area; Seeding Depth, Nitrogen Fixation, Ability to Attract & Sustain Beneficial Organisims, Compaction Control, Erosion Control, Weed Suppression, Green Manure, Forage, and Biomass (Organic Matter).