The performance of subterranean vetch (Vicia sativa ssp amphicarpa) in a cereal/pasture rotation in north-west Syria

The aim of this study was to determine if subterranean vetch can persist in a cereal-legume ley farming system and to determine when it is most susceptible to grazing. Grazing treatments were applied to a series of plots containing subterranean vetch during the establishment year. Thereafter the plots were alternately sown to barley or left for the vetch to regenerate. Early grazing caused a seed yield reduction of about 75%. Later grazing treatments had no effect on seed yield, which were between 1000 and 1400 kg/ha. The first cereal phase caused a 6-10-fold reduction in seed bank size. During the 2 years following the first barley year, the seed bank increased to about 900 kg/ha. The second barley year caused a 4-fold reduction in the soil seed bank. Although subterranean vetch managed to persist for 5 years, the dramatic reduction in the seed bank after the barley years indicates that subterranean vetch will not persist at a useful density in a system where 2 or more cropping years run successively. However, other studies have shown that there are enough genotypes with the necessary levels of hardseededness to fit the ley system.