Publications by Colleges and Departments (MSU - Bozeman)
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Item Long‐term cover crop effects on biomass, soil nitrate, soil water, and wheat(Wiley, 2023-05) Miller, Perry R.; Jones, Clain A.; Zabinski, Catherine A.; Tallman, Susan M.; Housman, Megan L.; D'Agati, Kristen M.; Holmes, Jeffrey A.Cover crops during summer fallow have been rarely researched in the semiarid northern Great Plains. This study was conducted during 2012–2019 at four Montana locations and included four functional groups (Brassica family, fibrous-rooted crops, legumes, and tap-rooted crops). Eleven treatments included sole functional groups, a Full Mix, the Full Mix minus each functional group, pea, and chemical fallow. Wheat (Triticum aestivum L.) was grown after each cover crop year with three nitrogen (N) fertilizer rates. Cover crops were terminated with herbicide at first flower stage of pea (Pisum sativum L.) 57 to 66 days after planting. Shoot biomass averaged 2.0 Mg ha−1 over eight site-years representative of dryland farming in Montana. Using equal overall plant densities, treatments with six species averaged 13% greater biomass than two species. Measured at termination to a 0.9-m depth, Fallow held greater soil water than cover crop treatments, with Fallow averaging 57 mm greater than the Full Mix. Soil nitrate averaged 49 kg N ha−1 greater after Fallow than the Full Mix; the Legume treatment averaged 26 kg N ha−1 greater than the Minus Legume treatment. Wheat yield on Fallow averaged 0.85 Mg ha−1 greater than the Full Mix in 5 of 10 site-years, mainly at the driest site-years. The Legume treatment elevated wheat protein over the Minus Legume treatment by an average of 15 g kg−1. Cover crops grown during summer fallow reduced soil nitrate-N, soil water, and wheat yields compared with chemical fallow, especially in the major wheat growing region of north central Montana.Item Cover crops to improve soil health in the North American Great Plains(Wiley, 2021-09) Obour, Augustine K.; Simon, Logan M.; Holman, Johnathon D.; Carr, Patrick M.; Schipanski, Meagan; Fonte, Steven; Ghimire, Rajan; Nleya, Thandiwe; Blanco‐Canqui, HumbertoRotating cereal crops (e.g., wheat [Triticum aestivum L.] with a 10- to 21-mo summer fallow period [fallow]) is a common farming practice in dryland (rainfed) agricultural regions. Fallow is associated with several challenges including low precipitation storage efficiency, depletion of soil organic carbon (SOC), loss of soil fertility, little crop residue retention and soil erosion, and few control options for herbicide-resistant (HR) weeds. The inability to effectively control HR weeds poses a major challenge to maintaining soil and water conservation practices such as no-tillage, as some producers are considering tillage to control weeds. Cover crop (CC) integration into wheat-based production systems to replace portions of the fallow period provides an opportunity to increase SOC, improve soil fertility, suppress weeds, and increase profitability of dryland crop production, especially when CCs are used as forage. This forum paper used the North American Great Plains as a model region to review information on (a) challenges of dryland agriculture; (b) integrating CCs in dryland agriculture; (c) benefits, challenges, and limitations of CCs in dryland crop production; (d) management options for CC integration in dryland grain systems; and (e) recommendations for future research efforts.