Weed response to soil tillage, catch crops and farmyard manure in sustainable and organic agriculture

The influence of soil tillage, different catch crop species (Trifolium pratense L., Lolium multiflorum Lam., Sinapis alba L., Brassica napus L.) for green manure as well as farmyard manure on weed infestation in a barley stand under the conditions of sustainable and organic agriculture was investigated. Field experiments showed that weed density and dry matter mass in barley depended on tillage time, catch crops for green manure and farmyard manure application. Shallow rotovating of the catch crops and farmyard manure in spring increased the number and dry matter mass of weeds in sustainable agriculture compared to deep ploughing in autumn. Spraying of catch crops with glyphosate shortly after barley direct drilling in spring significantly reduced the number of weed seedlings in sustainable agriculture, compared to deep ploughing in autumn. In organic agriculture, shallow rotovating of catch crops in spring stimulated the occurrence of perennial weeds in 1999. Shallow ploughing in spring had no influence on weed density in 2000, but significantly reduceding it in 2001.