The effect of farmyard manure anaerobic treatment on weed seed viability.
Farmyard manure and other organic fertilizers can be major sources of weed seeds that get into the soil. One of the methods for eliminating weed seed germination is the technology of anaerobic treatment of the farmyard manure with the simultaneous production of biogas (the Olomouc method). Germination tests were conducted on seeds of 11 weed species (Tripleurospermum maritimum [Matricaria perforata], Echinochloa crus-galli, Plantago major, Chenopodium album, C. strictum, Thlaspi arvense, Avena fatua, Rumex obtusifolius, Amaranthus retroflexus, Agropyron repens [Elymus repens] and Polygonum lapathifolium), after which the weed seeds were either used as feed for milking cows or were subjected to the process of anaerobic fermentation. Before anaerobic fermentation or being used for feed, seeds of all 11 weed species manifested high germination rates (74-98%). The seeds positioned in the lower layers of the fermentation unit (1800 mm) lost their germination power after 1 month of treatment. In the sub-surface layers (400 mm) of the farmyard manure, there was only a small proportion of viable seeds belonging to 4 species (E. crus-galli, C. album, R. obtusifolius and Amaranthus retroflexus with germination rates of 36, 9, 19 and 4%, resp.) after 1 month of treatment. Seed germination after passage through the digestive tract of cows was reduced to 3-91% compared to seed germination before being used as feed. The greatest reduction in seed viability was observed in the 2 Chenopodium spp., and the least reduction in R. obtusifolius.