Seed persistence of nine weed species in silage, manure, and slurry and implications for dispersal through organic fertilizers

Weed seed contamination of cattle feed can contribute to weed dispersal within crop–livestock systems when viable seeds survive digestion and are returned to fields through manure or slurry applications. However, the persistence of weed seeds from feed preservation to waste recycling remains poorly understood. This study aimed to evaluate the viability of common agricultural weed seeds after exposure to silage fermentation, simulated rumen digestion, and storage in cattle manure and slurry. Seeds of nine weed species ( Abutilon theophrasti , Alopecurus myosuroides , Amaranthus retroflexus , Avena sterilis , Chenopodium album , Datura stramonium , Echinochloa crus-galli , Lolium multiflorum , and Sorghum halepense ) were incubated for one, four, and six months in three silage types (maize, sorghum, and grass) and subsequently incubated in cattle manure and slurry following simulated rumen digestion. Silage fermentation significantly reduced seed viability, although the response varied among weed species and silage types. During storage in cattle waste, seed viability declined progressively, with slurry degrading seeds faster than manure. Nevertheless, seeds of C. album , D. stramonium , A. retroflexus , and E. crus-galli remained viable after six months in manure. These findings suggest that cattle manure may be an important pathway for weed seed persistence and dispersal in agricultural soils, whereas slurry may pose a much lower risk. The results provide practical guidance for manure management strategies aimed at reducing weed spread while supporting sustainable crop–livestock production systems.