Assessment of long-term barley–legume rotations in a typical Mediterranean agro-ecosystem: grain and straw yields

Abstract

Traditional Mediterranean rainfed cereal/fallow systems are being replaced by cereal monoculture due to land-use pressure. Food or forage legumes in rotation with cereals are an alternative sustainable cropping system. Complex cropping systems can only be assessed by long-term trials. This 11-year rainfed barley-based rotation trial in northern Syria assessed rotation effects on yields of barley and legumes, with particular emphasis on the management of vetch. The mean order of barley grain yields from the rotations was: vetch for hay, vetch for grazing > fallow = medic = vetch for seed > lentil, and continuous barley. Straw yields followed a similar pattern. Nitrogen (60 kg ha⁻¹) increased grain (39%) and straw (65%) yields. The N fertilization of barley had no carryover effect on the alternative legume crops. Although there were no significant differences in seed or straw yield between lentil and vetch, seasonal rainfall influenced overall yields. Total biomass yields were in the order of vetch, medic and lentil. There is a compelling case for annual vetch paired with barley in rotations for the Mediterranean region. Thus, barley/vetch rotations can potentially enhance barley yields and improve soil quality, and provide valuable fodder for small ruminants as well in the region's agricultural systems.

Keywords:

• forage legumes
• lentils
• fallow
• continuous cereal cropping
• dryland cereals

Acknowledgements

We appreciate the intellectual contributions of Drs P.S. Cocks and A. Smith during the establishment of the experiment (wheat phase, period 1 and 2) and later Drs A.V. Goodchild, T.L. Nordblom and T. Treacher. We thank Nerses Nersoyan for the day to day management of the trial and A. Rajab, A. Antar, M. Touma and A. Badenjki for their conscientious attention to detail and standard methodology over all the years. Thanks are also extended to Dr G. Gintzburger for his support to the trial during his tenure as Leader of the Pasture, Forage and Livestock Program. We are particularly grateful to M. Bounejmate (deceased), who supervised the current barley trial for several years, and to Dr J. Diekmann, Station Manager, who handled the day-to-day management of the trial. We thank Dr Rolf Sommer for reviewing an earlier version of the manuscript.