a b s t r a c tEfficient use of energy in agroecosystems will reduce environmental problems, prevent destruction of natural resources and serve to promote sustainable agriculture as an economical production system. The aim of this study was to investigate the energy use efficiency in four double cropping systems including: wheat-silage corn (W-SC), barely-silage corn (B-SC), barely-grain corn (B-GC) and barely-rice (B-R) in the arid regions of Isfahan province, Iran. Data used in this study were collected from 73, 45, 38, 18, 18 wheat, barley, silage corn, grain corn and rice farms, respectively, personal interview using semistructured questionnaire during 2010. The results indicated that the total energy consumed were 140,422, 128,979, 121,360 and 172,962 MJ ha −1 for the W-SC, the B-GC, the B-SC and the B-R cropping systems, respectively. The share of diesel fuel by 43.36% (W-SC), 43.93% (B-GC), 42.82% (B-SC) and 49.40 % (B-R) was the highest input. This was followed by fertilizer (W-SC: 24.70%, B-GC: 25.12%, B-SC: 27.05 and B-R: 16.11) and water (W-SC: 10.54%, B-GC: 11.76%, B-SC: 10.73 and B-R: 13.85), respectively. The energy use efficiency was found as 1.70 for W-SC, 1.65 for B-GC, 1.64 for B-SC and 1.03 for B-R double cropping systems, respectively. According to the research results the W-SC, B-SC, B-GC and B-R double cropping systems were more efficient in terms of energy, respectively.

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This experiment was conducted to evaluate the effects of two irrigation regimes (control and water stress) and two nitrogen (N) levels (0 and 112.5 kg/ha) on forage yield and silage quality in millet. Bastan (Setaria italica (L.) P. Beauv) and Pishahang (Panicum miliaceum) were sown at two different dates during 2015 and 2016. Both cultivars exhibited reduced dry‐matter (DM) yields (45% and 51% in Bastan and Pishahang respectively) due to drought stress. Proline and phenolic contents increased as a result of drought and were significantly and negatively correlated with DM yield and digestibility. Moreover, Pishahang had a reduced acid detergent fibre (ADF) content but improved leaf/stem ratio, digestible dry matter (DDM), relative feed value (RFV), net energy for lactation (NEL), digestibility and silage quality as a result of drought stress, while no significant effects on these traits were observed in Bastan. Silage quality was greatly cultivar‐dependent. Both cultivars had higher levels of DDM, RFV and NEL at early sowing dates. Nitrogen supply had greater positive effects on increasing ash, crude protein (CP) content and DM yield under normal irrigation than under water‐stress conditions. In summary, given the importance of the energy received per unit of forage from an animal husbandry viewpoint and the significance of DM yield per unit area from an agricultural viewpoint, the obtained results might help farmers in choosing not only the best sowing dates but also proper irrigation and N management practices to achieve their quantitative and qualitative objectives in forage production.

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