Spent coffee grounds (SCG) represent a significant food waste residue. Value-added uses for this material would be beneficial. Gritty agricultural residues, such as corncob grit, can be employed as abrasive air-propelled agents for organically-compatible and selective shredding of weed seedlings within established crops. SCG were tested and compared with corncob grit for their ability to injure seedlings of two important weeds: waterhemp and velvetleaf. Waterhemp seedlings were controlled completely with as little as 0.5 g of SCG at an air pressure of 690 kPa. Velvetleaf seedlings were much larger than those of waterhemp at the time of grit application, better tolerated SCG abrasion, but still were damaged appreciably by 1 to 2 g of grit. SCG were at least as effective for abrading weed seedlings as corncob grit, whose value for this purpose in organic crops was demonstrated previously.
Nomenclature: Tall waterhemp, Amaranthus tuberculatus (Moq.) Sauer; velvetleaf, Abutilon theophrasti Medik.