The impact of different types of organic mulches on Cirsium arvense emergence

Abstract

The two - factor field experiment was carried out in the Pomological Garden of Lithuanian University of Agriculture (54°53'N, 23°50'E) in 2004-2007. The soil type - Cak(ar)i-Endohypogleyic Luvisol. Experimental scheme: Factor A - organic mulch: 1) no mulching; 2) wheat straw, 3) peat, 4) sawdust, 5) grass. Factor B - thickness of mulch layer: 1) 5 cm; 2) 10 cm. The aim of this investigation was to evaluate the influence of different organic mulches and different thickness of mulch layer on the emergence of creeping thistle Cirsium arvense (L.) Scop. All the examined organic mulches decreased total weed density. The diverse influence of mulches on C. arvense was established. After two years from the beginning of the experiment (2006-2007) plots mulched with straw, peat and sawdust had significantly higher density of C. arvense sprouts compared with unmulched plots and plots mulched with grass. During the investigation period (2004-2007) the number of C. arvense sprouts decreased. In the first year of the experiment density of C. arvense sprouts in plots mulched with wheat straw, sawdust and grass, in the second year in plots mulched with wheat straw, peat and grass was lower compared with no mulched plots. There was no significant difference in C. arvense emergence between the plots mulched with 10 cm thickness mulch layer and 5 cm thickness mulch layer, but in 2006-2007 higher amount of C. arvense sprouts emerged in plots covered with 10 cm thickness mulch layer. Strong negative correlations between number of C. arvense sprouts and soil shear strength, between number of C. arvense sprouts and crop yield were calculated. As mulch after harvesting was inserted into the soil by ploughing, soil shear strength decreased. Heavy crop in plots mulched with grass and no mulched plots smothered weeds as well. An increase in the prevalence of C. arvense was observed as weed density and annual weed density decreased.