Variability and stability of different fallow seed mixtures

In a six year experiment in the Swiss lowlands of the Canton of Bern the development of single sown species, their competitive ability towards spontaneous species and flowering diversity were studied for four fallow seed mixtures (rotational fallow and wildflower strip mixtures of the companies UFA Winterthur and Schweizer Samen). The wildflower strip mixtures of both companies produced qualitatively good canopies rich in different species which remained competitive for the whole duration of the study. The mixture of Schweizer Samen distinguished itself by the high flower density and good canopy structure. From the fifth year onwards, Tanacetum vulgare started to dominate, especially on the UFA rotational fallow plots. Other species like e.g. Centaurea jacea developed differently in the mixtures of the two companies too. Both rotational fallow mixtures produced stable swards during four years. Towards the end of the experiment, the UFA rotational fallow mixture consistently deteriorated and was no longer competitive towards spontaneous species and species invading from adjacent wildflower strips. During the sixth year the quality of all mixtures deteriorated considerably.