Abstract: Annual forage crops are important feeding sources in early spring and winter seasons in areas of the Loess Plateau, with water use efficiency being an important indication of crop adaptability to local climate environment. In a rainfed area of eastern Gansu, dry matter, soil water deficit and water use efficiency of annual forage crops were determined. Annual forage crops were maize (Zea mays), Sudan grass (Sorghum sudanense), soybean (Glycine max), small millet (Setaria italica), millet (Panicum miliaceum), common vetch (Vicia sativa), pea (Glycine max), oat (Avena sativa) and spring wheat (Triticum aestivum). The results showed that soil water deficit of annual forage crops presented a ‘V’ curve, with the exception of Sudan grass; water use efficiency of spring wheat was higher than other crops at 6 weeks after emergence, whereas maize was the most efficient at 15 weeks after emergence. Variable amplitude of water use efficiency in millet and small millet was low. The crops of maize, spring wheat, small millet and millet were optimum under spring-sown condition in the Loess Plateau.

Key words: annual forage crops, spring-sown, soil water deficit, water use efficiency, Loess Plateau