Weed populations are affected by tillage systems and fertilization practices in organic flax (Linum usitatissimum L.) crop

Abstract

Flax is a weak competitor against weeds. To obtain high yield of flax, good weed management practices must be implemented. Field experiments were conducted during 2009 and 2010 to determine the effects of tillage systems and fertilization on weed flora in organic flax crop (Linum usitatissimum L.). The experiments were laid out in a split-plot design with four replicates having three main plots (conventional tillage: CT, minimum tillage: MT and no-tillage: NT) and three sub-plots (compost, vetch and faba bean as green manure). The total weed densities were significantly different among the tillage systems. In NT plots, the presence of wheat residues clearly reduced weed number. Crop residues mainly affect light interception, temperature and moisture of the soil. Differences in nitrogen availability of the fertilizers had a large effect on weed density and biomass. The lowest weed density was found in compost plots. Moreover, the highest density of competitive weeds (Amaranthus retroflexus, Chenopodium album, Convolvulus arvensis, Cynodon dactylon, Cyperus rotundus, Datura stramonium, Setaria verticillata, Sinapis arvensis and Solanum nigrum) was found under MT and CT systems, while the lowest was found in NT plots. In addition, concerning the density of noncompetitive weeds, there were no significant differences among the tillage systems. Moreover, there were no significant differences in the density of non-competitive weeds between the organic fertilization treatments. No-tillage and low nitrogen fertilization appeared to contribute to the suppression of weeds.