Nitrogen and water balances under vetch-Barley, fallow-barley and continuous barley cropping systems in Cyprus

Due to limited water and nitrogen (N) resources in the rainfed areas of Cyprus, it is important to apply a sustainable cropping system which is environmentally non-degrading, technically appropriate and economically viable. The system should maintain or increase productivity, with maintenance and efficient use of natural resources. Four rainfed agricultural systems i.e. Vetch (Vicia sativa) for hay-barley for grain (Hordeum vulgare), fallow-barley for grain, barley for hay-barley for grain and continuous barley for grain were evaluated with regard to their N and water balance. The 15N methodology and neutron probe were used for evaluation of the N and water status, respectively. Water studies were done at the Laxia area and N studies at the Dromolaxia area. The N balance outcome showed that vetch fixed 80% of its nitrogen. Using barley of the continuous barley system as reference crop the residual N value of vetch, fallow and barley-hay to the percentage of the N in the subsequent barley crop was 36, 25 and 9%, respectively. The water balance outcome showed that significant moisture was conserved by fallowing only in the first year of the study when rainfall was 226 mm, while very limited moisture was conserved in the second season when rainfall was 202 mm. A significant amount of moisture was lost during summer especially in the top 30 to 40 cm soil zone. At both sites the highest productivity of barley was obtained in the vetch-barley system except at Laxia in the dry year when the moisture conserved by fallowing boosted the productivity of barley in this system. However, rainfall use efficiency of the fallow-barley system was the lowest among the cropping systems studied. It was concluded that vetch-barley is the most sustainable system under rainfed conditions in Cyprus. (author). 20 refs, 1 fig., 10 tabs