THE EFFECT OF FARMYARD MANURE ANAEROBIC TREATMENT ON WEED SEED VIABILITY

Weed encroachment is a serious problem of contemporary agriculture. Fa rmyard manure and other organic fertilizers can be major sources of we ed seeds that get into the soil. One of the methods for eliminating we ed seed germination is the technology of anaerobic treatment of the fa rmyard manure with a simultaneous production of biogas, the so called ''Olomouc method''. Before anaerobic fermentation seeds of all 11 spec ies under study (i.e. Tripleurospermum maritimum, Echinochloa crus-gal li, Plantago major, Chenopodium album, Chenopodium strictum, Thaspi ar vense, Avena fatua, Rumex obtusifolius, Amaranthus retroflexus, Agropy ron repens and Polygonum lapathifolium) manifested a high germination power. The seeds positioned in the lower layers of the fermentation un it (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 ge rmination rate of Echinochloa crus-galli, Chenopodium album, Rumex obt usifolius and Amaranthus retroflexus was 36%, 9%, 19% and 4%, respecti vely.