The Effect of Farmyard Manure Anaerobic Treatment on Weed Seed Viability

Weed encroachment is a serious problem of contemporary agriculture. 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 a simultaneous production of biogas, the so called “Olomouc method”. Before anaerobic fermentation seeds of all 11 species under study (i.e. Tripleurospermum maritimum, Echinochloa crus-galli, Plantago major, Chenopodium album, Chenopodium strictum, Thlaspi arvense, Avena fatua, Rumex obtusifolius, Amaranthus retroflexus, Agropyron repens and Polygonum lapathifolium) manifested a high germination power. The seeds positioned in the lower layers of the fermentation unit (1,800 mm) lost their germination power after one month's 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. The germination rate of Echinochloa crus-galli, Chenopodium album, Rumex obtusifolius and Amaranthus retroflexus was 36%, 9%, 19% and 4%, respectively.