Changes of weed ecological groups under different organic mulches

The aim of the investigation was to evaluate the influence of different organic mulches and different thickness of mulch layer on weed ecological groups. The field experiment was carried out in the Pomological Garden of the Aleksandras Stulginskis University (54º53'N, 23º50'E). The soil type was Calc(ar)i-Endohypogleyic Luvisol (LVg-n-w-cc). Treatments of the experiment: factor A – mulching: 1) without mulch, 2) straw, 3) peat, 4) sawdust, 5) grass; factor B – thickness of the mulch layer: 1) 5 cm, 2) 10 cm. All investigated organic mulches decreased weed density by 2.7–10.3 times compared with non-mulched soil. The mulch layer of 10 cm thickness decreased the weed density better by 1.3–2.9 times compared with the 5- cm mulch layer. The highest amount of weeds belonged to species indifferent to soil pH, rich in nitrogen, moderately moist and moist soil. Organic mulches, not infected with weed seeds, decreased density of the mentioned weed ecological groups compared with no-mulching. On that score mulching with 10 cm thickness mulch layer was more effective than that with 5 cm thickness mulch layer. Qualitative distribution of weeds into ecological groups influenced by mulch and thickness of mulch layer was even, but the quantitative distribution was uneven