|Bewick, Laylah - WASHINGTON STATE UNIV|
|Alldredge, Richard - WASHINGTON STATE UNIV|
|Young, Douglas - WASHINGTON STATE UNIV|
Submitted to: Crop Protection Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 16, 2007
Publication Date: February 1, 2008
Repository URL: http://hdl.handle.net/10113/11385
Citation: Bewick, L.S., Young, F.L., Alldredge, R.J., Young, D.L. 2008. Agronomics and economics of no-till facultative wheat in the Pacific Northwest, USA. Crop Protection Journal. 27:932-942. Interpretive Summary: The winter wheat/summer fallow (WW/SF) system of the arid and semi-arid region of the Pacific Northwest (PNW) is characterized by winter annual grass weeds, soil borne diseases, intensive tillage, and severe wind erosion. Computer models have predicted that reduced-tillage fallow and supplemental cropping systems of no-till annual spring crops may reduce soil erosion susceptibility by an estimated 55% and 95%, respectively. In 1995 a multi-, inter-disciplinary, long-term field study was initiated to evaluate the agronomic and economic feasibility of no-till spring cropping systems to replace or supplement the century-old WW/SF system. In 2002, two new rotations including facultative wheat were incorporated into the project replacing poor-performing spring cropping systems. These rotations included no-till facultative wheat/chemical fallow (FW/ChF) and no-till facultative wheat/no-till spring wheat (FW/SW). Facultative wheats, developed from WW by SW crosses, generally have less cold tolerance, a shorter period for vernalization, and start growing and flowering earlier compared to true winter wheats. In our study, WW was planted in early-September, FW was planted in early-November, and SW was planted in mid-March. Facultative wheat following ChF out-yielded all other crops the first year of the study and out-yielded the FW following SW and the SW for the 4-yr average. Facultative wheat had better grain quality as measured by test weight compared to WW and SW. In addition, FW reduced stripe rust incidence compared to SW and decreased soil borne pathogens compared to WW. The FW in combination with ChF shows promise as a sustainable system in the PNW by reducing weed infestations and subsequent herbicide inputs and achieving yields that may maintain or improve farm profitability.
Technical Abstract: Since the 1900’s, winter wheat rotated with dust-mulch summer fallow(WW/SF) has been the dominant production practice in the low-precipitation zone (<305 mm) of the Pacific Northwest. The WW/SF system has developed several problems including reduced crop yields and quality caused by increased weeds and diseases, severe wind erosion, and increased costs of production. Economically and agronomically feasible, as well as environmentally sustainable cropping system options need to be developed for this growing region. One proposed alternative is production of no-till facultative wheat (FW). The general objective of this research was to examine the performance of FW rotated with chemical fallow (FW/ChF) or no-till spring wheat (FW/SW), with both rotations being contrasted with WW/SF. The project was incorporated in 2002 into a long-term, multi-, inter-disciplinary project initiated in 1995. General planting dates for FW, SW, and WW were early-November, mid-March, and early September, respectively. During the first 3 years precipitation was 8 to 30% below, and the fourth year was 19% greater, than the long-term average for the site. The 4-yr average grain yield was WW greater than FW/ChF which was greater than FW/SW. It was noted that during 2006 and possibly 2005, FW/ChF was injured by residual sulfentrazone that was applied the previous year in ChF to control Salsola tragus. Test weight of FW was always higher than WW or SW, implying better grain quality. By harvest, WW extracted more soil moisture at the 1.2-1.8 m-depth than in either of the facultative wheats or SW. Insect pests were not yield-limiting for any crops in the study. In addition, the complex of soil borne pathogens was less in FW/ChF than WW/SF and stripe rust infections were less in FW than SW.