Europ. J. Agronomy 84 (2017) 84–94 Contents lists available at ScienceDirect European Journal of Agronomy j ourna l ho me page: www.elsevier.com/locate/eja Forage production, quality and water-use-efficiency of four warm-season annual crops at three sowing times in the Loess Plateau region of China Zhixin Zhang a,b,c , Jeremy P.M. Whish c , Lindsay W. Bell c , Zhibiao Nan a,b,∗ a The State Key Laboratory of Grassland Agro-ecosystems, Lanzhou University, Lanzhou, Gansu 730020, China b College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, Gansu 730020, China c CSIRO Agriculture Flagship, PO Box 102, Toowoomba, QLD 4350, Australia a r t i c l e i n f o Article history: Received 3 May 2016 Received in revised form 26 November 2016 Accepted 13 December 2016 Keywords: Forage Water use Crude protein North-west Loess Plateau Semi-arid cropping system a b s t r a c t Increasing demand for livestock products is driving development of livestock systems worldwide. That requires improved and new forage production options. The Loess Plateau region in central-northern China is an important area for livestock production, as it supports11% and 19% of the country’s cattle and sheep, respectively (China statistical yearbook 2014). The rain-fed semi-arid environment of the Loess Plateau means that maximizing the water-use-efficiency (WUE) of forage production is vital to guarantee enough fodder supply the livestock demand. A three-year field experiment in north-west Loess Plateau compared forage production, water use and water-use-efficiency as well as crude protein (CP) content of forage maize, Sudan grass, foxtail millet and Japanese millet sown at three sowing dates according to the opening rain during 2011–2013. On average, forage maize produced the highest biomass (12.1 t ha −1 ) and had the highest WUE (43.4 kg DM ha −1 mm −1 ). This was followed by Sudan grass (7.8 t ha −1 ; 26.5 kg DM ha −1 mm −1 ), Japanese millet (6.7 t ha −1 ; 26.2 kg DM ha −1 mm −1 ) and foxtail millet (6.7 t ha −1 ; 24.6 kg DM ha −1 mm −1 ). Optimizing sowing date played an important role in maximizing forage production and WUE of all tested forages. Compared to the earliest sowing date, a delay of two weeks reduced forage production by 17% in maize, 35% in foxtail millet, and 16% in Japanese millet. A delay of four to six weeks reduced biomass yield by 58% in maize, 57% in foxtail millet, and 56% in Japanese millet. Late sowing also greatly reduced WUE of forage maize and foxtail millet by 33% and 42%, respectively, when compared to early sowing. The middle sowing date maximized forage production and WUE of Sudan grass in two of the three growing seasons, which was 20% and 38% higher than the early and late sowing, respectively. Late sowing in all forages reduced crop water use by 42–57 mm compared to the early sowing. Among four test crops, CP of Sudan grass (7.9%) and forage maize (7.7%) was higher than foxtail millet (6.8%) and Japanese millet (6.7%). Compared with early sowing, CP f in late sowing significantly increased in Sudan grass and decreased in Japanese millet, in contrast, no evident sowing date effect was found in forage maize and foxtail millet. This study showed that all four warm-season annual grasses had high forage production potential, forage maize was the most reliable and efficient option. Forage maize and the millets could easily be integrated into existing cropping systems and provide opportunities as both grain and forage-producing crop to provide added flexibility for farmers. © 2016 Elsevier B.V. All rights reserved. 1. Introduction Sustainable development of animal production systems is defined as balancing the needs of animal production of the cur- ∗ Corresponding author at: The State Key Laboratory of Grassland Agro- ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, PO Box 61, Lanzhou, Gansu 730020, China. E-mail address: zhibiao@lzu.edu.cn (Z. Nan). rent generation and those of future generations and securing what is biologically and physically achievable in the long run (Gamborg and Sandøe, 2005). Population growth is increasing the demand for food and animal products worldwide. To meet this increased demand and to maintain a steady growth in animal numbers, while ensuring sustainable development of animal production, forages well adapted to the local environments with high yielding and rich nutrition are needed. Arid and semi-arid zones take up approxi- http://dx.doi.org/10.1016/j.eja.2016.12.008 1161-0301/© 2016 Elsevier B.V. All rights reserved.