Browsing by Author "Dafoe, Julia M."

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Introducing cover crops as a fallow replacement in the Northern Great Plains: I. Evaluation of cover crop mixes as a forage source for grazing cattle
(Cambridge University Press, 2021-09) Wyffels, Samuel A.; Bourgault, Maryse; Dafoe, Julia M.; Lamb, Peggy F.; Boss, Darrin L.
Crop-livestock integration has demonstrated that cover crops can be terminated using livestock grazing with minimal negative impacts on soil health, however, provides little information on system-level approaches that mutually benefit soil health and both crop and livestock production. Therefore, the objective of this research was to examine the effects of cover crop mixtures on biomass production, quality and the potential for nitrate toxicity on a dryland wheat-cover crop rotation. This research was conducted at the Montana State University-Northern Agricultural Research Center near Havre, MT (48°29′N, −109°48′W) from 2012 to 2019. This experiment was conducted as a randomized-complete-block design, where 29 individual species were utilized in 15 different cover crop mixtures in a wheat-cover crop rotation. Cover crop mixtures were classified into four treatment groups, including (1) cool-season species, (2) warm-season species dominant, (3) cool and warm-season species mixture (mid-season), and (4) a barley (Hordeum vulgare) control. All cover crop mixtures were terminated at anthesis of cool-season cereal species to avoid volunteer cereal grains in the following wheat crop. At the time of cover crop termination, dry matter forage production was estimated and analyzed for crude protein, total digestible nutrients and nitrates as indicators of forage quality. All mixtures containing oats (Avena sativa) had greater (P ⩽ 0.03) biomass production than other mixtures within their respective treatment groups (cool- and mid-season). Forage biomass was influenced by cover crop treatment group, with the barley producing the greatest (P < 0.01) amount of forage biomass when compared to cool-, mid- and warm-season cover crop treatments. Total digestible nutrients were greater (P < 0.01) in the barley control compared to the cool- and mid-season treatment groups. Crude protein was greatest in the warm-season treatment group (P < 0.01) compared to the barley control, cool- and mid-season treatment groups. The barley control produced fewer nitrates (P ⩽ 0.05) than the cool-, mid- and warm-season treatment groups; however, all cover crop mixtures produced nitrates at levels unsafe for livestock consumption at least one year of the study. The relatively high and variable nitrate levels of all cover crop mixtures across years in this study suggest that forage should be tested for nitrates before grazing. In conclusion, our research suggests that in a dryland wheat-cover crop rotation that requires early-July termination, cool-season cover crop mixtures are the most suitable forage source for livestock grazing most years.
Introducing cover crops as fallow replacement in the Northern Great Plains: II. Impact on following wheat crops
(Cambridge University Press, 2021-12) Bourgault, Maryse; Wyffels, Samuel A.; Dafoe, Julia M.; Lamb, Peggy F.; Boss, Darrin L.
Crop-livestock integration has demonstrated that cover crops can be terminated using livestock grazing with minimal negative impacts on soil health, however, provides little information on system-level approaches that mutually benefit soil health and both crop and livestock production. Therefore, the objective of this research was to examine the effects of cover crop mixtures on biomass production, quality and the potential for nitrate toxicity on a dryland wheat-cover crop rotation. This research was conducted at the Montana State University-Northern Agricultural Research Center near Havre, MT (48°29′N, −109°48′W) from 2012 to 2019. This experiment was conducted as a randomized-complete-block design, where 29 individual species were utilized in 15 different cover crop mixtures in a wheat-cover crop rotation. Cover crop mixtures were classified into four treatment groups, including (1) cool-season species, (2) warm-season species dominant, (3) cool and warm-season species mixture (mid-season), and (4) a barley (Hordeum vulgare) control. All cover crop mixtures were terminated at anthesis of cool-season cereal species to avoid volunteer cereal grains in the following wheat crop. At the time of cover crop termination, dry matter forage production was estimated and analyzed for crude protein, total digestible nutrients and nitrates as indicators of forage quality. All mixtures containing oats (Avena sativa) had greater (P ⩽ 0.03) biomass production than other mixtures within their respective treatment groups (cool- and mid-season). Forage biomass was influenced by cover crop treatment group, with the barley producing the greatest (P < 0.01) amount of forage biomass when compared to cool-, mid- and warm-season cover crop treatments. Total digestible nutrients were greater (P < 0.01) in the barley control compared to the cool- and mid-season treatment groups. Crude protein was greatest in the warm-season treatment group (P < 0.01) compared to the barley control, cool- and mid-season treatment groups. The barley control produced fewer nitrates (P ⩽ 0.05) than the cool-, mid- and warm-season treatment groups; however, all cover crop mixtures produced nitrates at levels unsafe for livestock consumption at least one year of the study. The relatively high and variable nitrate levels of all cover crop mixtures across years in this study suggest that forage should be tested for nitrates before grazing. In conclusion, our research suggests that in a dryland wheat-cover crop rotation that requires early-July termination, cool-season cover crop mixtures are the most suitable forage source for livestock grazing most years.
Warm-Season Forage Options in Northern Dryland Regions
(2020-06) Carr, Patrick M.; Boss, Darrin L.; Chen, Chengci; Dafoe, Julia M.; Eberly, Jed O.; Fordyce, Simon; Hydner, Roger M.; Fryer, Heather K.; Lachowiec, Jennifer A.; Lamb, Peggy F.; McVay, Kent A.; Khan, Qasim A.; Miller, Perry R.; Miller, Zachariah J.; Torrion, Jessica A.
Rotating summer fallow with wheat (Triticum spp.) is done in dryland grain farming at upper latitudes to stabilize yields over time and to prevent crop failure. However, summer fallow is costly since weeds must be controlled and crops are not grown. Replacing summer fallow with grain crops can generate low economic returns. Previous research indicated that annual cool‐season forages can be substituted for summer fallow in dryland cropping systems. Our objective was to determine if annual warm‐season species were suited for forage production in monocultures and polycultures in the U.S. northern Great Plains. Dry matter (DM) production by 20 warm‐ and cool‐season crop monocultures and 4 polycultures was determined across six environments during 2016, and by 25 warm‐ and cool‐season crop monocultures and polycultures across four environments from 2016 through 2018. Maize (Zea mays L.) monoculture produced forage DM in amounts equal to, or greater than, those produced by other warm‐ and cool‐season crop treatments (P < 0.05). Maize DM production averaged 2.5 to 5.7 Mg ha−1, depending on the study and environment. Sorghum (Sorghum bicolor L.), foxtail millet [Setaria italica (L.) P. Beauv.] and sunflower (Helianthus annuus L.) also produced relatively large amounts of forage DM. Polycultures failed to produce more DM than monocultures consistently (P > 0.40). These results indicate that maize and other warm‐season crops are adapted for dryland forage production in cool regions at upper latitudes. Additional research is needed to determine the impacts of annual warm‐season forages on grain yield in a forage‐wheat crop sequence.