|THIVIERGE, MARIE-NOELLE - Agriculture And Agri-Food Canada|
|JEGO, GUILLAUME - Agriculture And Agri-Food Canada|
|BELANGER, GILLES - Agriculture And Agri-Food Canada|
|BERTRAND, ANNICK - Agriculture And Agri-Food Canada|
|TREMBLAY, GAETAN - Agriculture And Agri-Food Canada|
|Rotz, Clarence - Al|
|QIAN, BUDONG - Agriculture And Agri-Food Canada|
Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/12/2016
Publication Date: 3/4/2016
Citation: Thivierge, M., Jego, G., Belanger, G., Bertrand, A., Tremblay, G., Rotz, C.A., Qian, B. 2016. Predicted yield and nutritive value of an alfalfa-timothy mixture under climate change and elevated atmospheric carbon dioxide. Agronomy Journal. 108:585-603.
Interpretive Summary: Future climate change and elevated atmospheric carbon dioxide will affect the agronomic, economic, and environmental performance of dairy farms. The Integrated Farm System Model (IFSM) was used to explore the effect of projected climate on forage mixture yield and nutritive value on Canadian dairy farms through the remainder of this century. An adaptation strategy consisting of a modified harvest schedule with additional forage cuts was able to maintain today’s forage yield and nutritive value for all future climate scenarios in the warmer region of southwest Quebec and to improve both in the colder region of eastern Quebec. This indicates that changes in climate may provide an opportunity to improve whole-farm performance in this northern climate.
Technical Abstract: Modelling studies of the effect of climate change on forage crops have focused on individual species even though legume-grass mixtures are most common on dairy farms in northern areas of North America. Our objectives were (i) to assess the impact of future climate change (temperature and precipitation) and elevated carbon dioxide concentration (CO2), isolated or in combination, on the yield of alfalfa (Medicago sativa L.) and timothy (Phleum pratense L.), grown alone or in a mixture, and (ii) to assess the impact of an adaptation strategy to climate change (a modified schedule of harvest including additional cuts) on yield and nutritive value of an alfalfa-timothy mixture. The Integrated Farm System Model (IFSM) simulated forage yield and nutritive value for two contrasting climate areas in eastern Canada, under two representative concentration pathways (RCP 4.5 and RCP 8.5), and for a near future (2020-2049) and a distant future period (2050-2079). Alfalfa’s response to rising CO2 was more favorable than timothy’s. Only the warmer area was negatively affected by climate change alone. Forage first cut yield was enhanced while subsequent cuts suffered losses due to greater water and temperature stresses. Without adaptation of harvest dates and number, the combination of climate change and rising CO2 resulted in higher yield in the colder area, and under most scenarios for alfalfa and for the alfalfa-timothy mixture in the warmer area (+1.0 Mg/ha). However, under the more drastic scenario (RCP 8.5 in the distant future) in the warmer area, yield decreased for all species, and particularly for timothy (-2.2 Mg/ha). Nutritive value of the forage mixture also decreased under all future scenarios. Considering the adaptation strategy, forage mixture yield increased in all scenarios in the warmer area (+1.3 Mg/ha) and increased further in the colder area (+2.0 Mg/ha). Because of the increased proportion of alfalfa in the mixture and the high quality of additional cuts, nutritive value was not compromised by yield increase.