THE WEED SEED BANK ASSESSMENT IN TWO SOIL DEPTHS UNDER VARIOUS MINERAL FERTILISING

The field trial at the experimental station of Slovak Agricultural University in Nitra - Koliňany (Slovak Republic, maize growing region, Haplic Luvisol and Stagni-Haplic Luvisol) in 1997 year was established. Experiments were based on 14 ha area (424 x 432.2 m) by long strips method. The impact of different mineral fertilisers on six model crops was observed: winter wheat, spring barley, sunflower, winter oilseed rape, maize and sugar beet. Weed infestation of winter wheat, spring barley, maize and sugar beet as well as weed seed bank composition since 2000 year till 2002 year were detected. Three variants of mineral fertilisation were applied: variant 1 - without fertilisers, variant 2 - N-P-K fertilisation, steady state soil nutrients balance, variant 3 - high doses of N-P-K fertilisers (positive soil nutrients balance). Soil weed seed bank was analysed once per year before crop germination (on February) from depths 0-0.05 m and 0.20-0.25 m in five replicates. From the depth 0-0.05 m 26 weed species were found, from the depth 0.20-0.25 m 23 weed species, from late spring group mainly. Chenopodium album, Stellaria media and Amaranthus spp. (77.57 % from intact seeds in total) were the most occurred weeds in both depths. The year, depth of soil sampling and fertilisation did not have statistically significant impact on weed seeds number in the soil.