Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/21/2018
Publication Date: 8/31/2018
Citation: Franco Jr, J.G., Duke, S.E., Hendrickson, J.R., Liebig, M.A., Archer, D.W., Tanaka, D.L. 2018. Spring wheat yields following perennial forages in a semiarid no-till cropping system. Agronomy Journal. 110(5):1-9. https://doi.org/10.2134/agronj2018.01.0072.
Interpretive Summary: The inclusion of a perennial forage phase in rotation with annual crops can have multiple benefits for producers. Yield benefits, often associated with enhanced soil quality by perennial forages, can vary depending upon climate, tillage management, and length of time in the perennial phase. Few studies have examined the impact of perennial forages on subsequent crop yields under no-till management in semiarid environments. In addition, there’s limited information on how long yield benefits last following the perennial phase under these conditions. Results suggest a minimum of three years of a perennial alfalfa or alfalfa-grass phase are required to see increased yields the first annual crop year compared to fertilized continuously cropped wheat. For yield benefits to persist into the second and third crop year, perennials should be in rotation for four and five continuous years. The results from this study can help inform management recommendations that are lacking for producers interested in diversifying their farm by including a perennial phase in their annual crop rotation.
Technical Abstract: Perennial forages have the potential to diversify annual crop rotations and provide yield benefits to subsequent cash crops. Little is known about the duration of and extent to which yield benefits are observed in semiarid no-till systems following perennial forages, which may depend upon the perennial crop type and duration of the perennial phase. Five perennial forage and forage combinations, alfalfa (Medicago sativa L.; PALF), intermediate wheatgrass [Thinopyrum intermedium (Host) Barkw. & D.R. Dewey subsp. Intermedium; IMWG], switchgrass (Panicum virgatum L.; SWG), alfalfa-intermediate wheatgrass mixture (PALF+IMWG), alfalfa-switchgrass mixture (PALF+SWG), and an annual cropping system of continuous wheat (Triticum aestivum L.) fertilized with 67.2 kg N ha-1 (CWF) were evaluated for their impacts on wheat yields in a seven-year study conducted near Mandan, ND USA. Spring wheat yields following three years of alfalfa were comparable to CWF. Following four and five years of alfalfa, wheat yields were 19 and 41% higher than CWF, respectively. Spring wheat yields following four and five years of PALF+SWG, comprised primarily of alfalfa, were 7 and 23% higher than CWF and 6% higher after five years of PALF+IMWG. Compared to CWF, yield benefits persisted for up to three years following five years of a perennial forage phase. Alfalfa and alfalfa-perennial grass mixtures showed the greatest promise for enhancing yields. These results suggest the addition of perennials as a rotation in annual no-till crop production systems in semiarid environments may provide yield benefits, but benefits may only be realized after three years of a perennial phase.