Winter wheat fall-winter forage yield and grain yield response to plantingdate in a dual-purpose system

Previous published research suggests that if fall-winter grazing of winter wheat is properly managed, it will not reduce grain yield. However, highly aggregated state average data suggest that fall-winter grazing is associate d with lower grain yields. This study was undertaken to determine the trade -off, or substitution in production, between winter wheat fall-winter forag e yield and grain yield across planting dates. Data from experiment station trials were used to estimate response functions and to determine optimal p lanting dates. The estimated response functions suggest relatively large di fferences in expected fall-winter forage yield and expected grain yield acr oss planting date. Optimal planting date is sensitive to the value of fall- winter forage relative to the value of wheat grain. Producers will optimall y plant wheat intended for dual-purpose use earlier than wheat intended for grain-only. The expected yield from the earlier planted dual-purpose wheat is lower than the expected yield of the later planted grain-only wheat as a result of the earlier planting date. (C) 2000 Elsevier Science Ltd. All r ights reserved.