Dual-purpose use of winter wheat in western China: cutting time and nitrogen application effects on phenology, forage production, and grain yield L. H. Tian A,B , L. W. Bell C , Y. Y. Shen A,B,D , and J. P. M. Whish C A The State Key Laboratory of Grassland Agro-ecosystems, Lanzhou 730020, China. B College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730020, China. C CSIRO Ecosystems Sciences/APSRU, PO Box 102, Toowoomba, Qld 4350, Australia. D Corresponding author. Email: yy.shen@lzu.edu.cn Abstract. Conventional rainfed mixed crop–livestock systems of western China lack high-quality forage and restrict livestock production. This study explored the forage potential from wheat and its effects on subsequent grain yield. Different cutting times were imposed on winter wheat (Triticum aestivum) at Qingyang, Gansu Province, in two growing seasons, and the effect of nitrogen (N) topdressing rates (0, 60, and 120 kg N/ha) on grain yield recovery was explored. Results showed the potential to produce 0.8–1.6 t DM/ha of wheat forage with high nutritive value when cut before stem elongation (GS 30). In the wetter year, cutting before stem elongation did not delay crop development significantly (<3 days at anthesis and 5 days at maturity), but grain yields were reduced by 17–28% compared with the uncut crop (5.8 t DM/ha), mainly due to reductions in number of spikes per m 2 and, consequently, number of grains per m 2 . In both seasons, more forage biomass was available if crops were cut later than GS 32, but this came with large reductions (>62%) in grain yield and delays in crop development (>9 days or 131 degree-days). Crops cut later than GS 30 had greatly reduced harvest index, tillers per m 2 , and total N uptake but higher grain protein content. There was no significant effect of N topdressing rate on grain yield, although provided the crop was cut before GS 30, higher rates of N increased maturity biomass and crop N uptake by replacing N removed in cut biomass. This study showed that physiological delay of wheat due to cutting was not significant. The forage harvested from winter wheat before stem elongation could be a valuable feed resource to fill the feed gap in western China. Additional keywords: defoliation, kernels, phenology, nitrogen. Received 20 March 2012, accepted 20 July 2012, published online 18 September 2012 Introduction The dual-purpose use of wheat crops for grazing during their vegetative phase and allowing the crop to regrow to harvest grain is practiced in many countries including Argentina, Morocco, Pakistan, Syria, Uruguay, Australia, and Mediterranean countries (Rodríguez et al. 1990; Francia et al. 2006). In particular, wheat forage has historically played an important role in agricultural production areas of the Southern Great Plains in the United States, with at least 2.4 Mha, 50% of the wheat-planting area, used for dual-purpose (Pinchak et al. 1996). Grazing of cereals has also been effective for filling feed gaps in mixed farming systems in Australia (Moore 2009). Dual-purpose crops are an attractive management option for farmers because the forage is of high nutrition, which is conducive to livestock weight gain, it provides an alternative source of feed during a feed gap period, the reduced stubble load can benefit the sowing operation of the following crop, and the dual incomes from grain and livestock improve farm profit compared with a grain-only system (Harrison et al. 2011a). Various studies around the world have shown that wheat can be grazed without reducing grain yield (Holliday 1956; Christiansen et al. 1989; Redmon et al. 1995). To this end, Harrison et al.(2011a) report from their review of 276 dual- purpose crop experiments that defoliation has a positive effect on grain yield (7  25%); however, the timing of the defoliation is critical and more important than the rate or type of defoliation (including clipping, crash, or long-term rotational grazing) in achieving this increase. Removing livestock before the development of the first hollow stem (GS 31) (Zadoks et al. 1974) reduces the likelihood of grain yield losses compared with ungrazed crops (Harrison et al. 2011a). If grazing is extended past this critical time, then larger grain yield reductions occur (Redmon et al. 1996; Virgona et al. 2006). The main reason for this yield reduction is removal of the crop growing points (Sprague 1954; Pumphrey 1970). Alternatively, under certain conditions, grazing can increase grain yield by reducing lodging in tall varieties (Christiansen et al. 1989; Winter and Musick 1991) or by reducing crop leaf area and water Journal compilation Ó CSIRO 2012 www.publish.csiro.au/journals/cp CSIRO PUBLISHING Crop & Pasture Science, 2012, 63, 520–528 http://dx.doi.org/10.1071/CP12101