The influence and residual effect of organic mulches on weed germination

Many researchers established, that organic mulch sprayed on the soil surface reduces incidence of weeds, especially in organic farms. The aim of our investigation was to evaluate the influence and residual effect of different organic mulches and different thickness of mulch layer on the germination of weeds. The field experiment on organic mulches was carried out in the Pomological Garden of Aleksandras Stulginskis University (54°53'N, 23°50'E) in organic certified field. The soil type - Calc(ar)i-Endohypogleyic Luvisol. Treatments of the experiment: factor A - mulch: 1) without mulch; 2) straw; 3) peat; 4) sawdust; 5) grass. Factor B - thickness of mulch layer: 1)5 cm; 2) 10 cm. The influence of organic mulches was investigated in 2004-2009, the residual effect of mulches - in 2010-2012. In the article the data of 2009-2012 are presented. All organic mulches significantly (2.6 - 10 times) reduced germination of annual and perennial weeds in 2009. Previously used and inserted into the soil organic mulch suppressed germination of weeds in 2010. It was investigated that the residual effect of the previously used and inserted sawdust mulch had tendency to reduce weeds germination in the 3nd year after mulch was used. The tendency of increased weed germination in plots were previously was inserted peat, straw and grass mulch was established only in 2012. The thicker (10 cm) mulch layer significantly (by 16.5 - 27.3 percent) suppressed the weeds germination compared with 5 cm mulch layer during 2009 and 2011Vytauto Didžiojo universitetasŽemės ūkio akademij