Changes in soil organic carbon under perennial crops

Authors: LEDO, ALICIA - University Of Aberdeen; SMITH, PETE - University Of Aberdeen; ZERIHUN, AYALSEW - Curtin University; WHITAKER, JEANETTE - Centre For Ecology And Hydrology; VICENTE-VICENTE, JOSE' LUIS - Leibniz Centre; QUIN, ZHANGCAI - Sun Yat-Sen University; MCNAMARA, NIALL - Centre For Ecology And Hydrology; ZINN LOPES, YURI - Federal University Of Lavras; LLORENTE, MIREIA - University Of Extremadura; Liebig, Mark; KUHNERT, MATTHIAS - University Of Aberdeen; DONDINI, MARTA - Thunen Institute Of Climate-Smart Agriculture; DON, AXEL - Thunen Institute Of Climate-Smart Agriculture; DIAZ-PINES, EUGENIO - University Of Natural Resources & Applied Life Sciences - Austria; DATTA, ASHIM - Indian Council Of Agricultural Research (ICAR); BAKKA, HAAKON - King Abdullah University Of Science And Technology; AGUILERA, EDUARDO - Technical University Of Spain; HILLIER, JON - University Of Edinburgh

Submitted to: Global Change Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/27/2020
Publication Date: 5/15/2020
Citation: Ledo, A., Smith, P., Zerihun, A., Whitaker, J., Vicente-Vicente, J., Quin, Z., McNamara, N.P., Zinn Lopes, Y., Llorente, M., Liebig, M.A., Kuhnert, M., Dondini, M., Don, A., Diaz-Pines, E., Datta, A., Bakka, H., Aguilera, E., Hillier, J. 2020. Changes in soil organic carbon under perennial crops. Global Change Biology. 26:4158-4168. https://doi.org/10.1111/gcb.15120.
DOI: https://doi.org/10.1111/gcb.15120

Interpretive Summary: Agricultural lands have the potential to sequester up to two-thirds of historical carbon loss if managed properly. Planting perennial crops has been offered as a strategy to increase soil organic carbon (SOC) while also enhancing food security. However, there is a lack of evidence documenting the capacity of perennial crops to increase SOC. Therefore, a global dataset of paired-comparison measurements was used to explore SOC changes under perennial crops. Results showed that: 1) a change from annual to perennial crops over 20 years led to an average 20% increase in SOC at 0-30 cm and a 10% increase at 0-100 cm, 2) among perennials, woody crops were most effective at increasing SOC over time, and 3) temperature was the main variable explaining differences in SOC changes, followed by crop age, soil bulk density, clay content and soil depth. This information is useful to policy makers and action agencies by demonstrating that growing perennial crops is a useful strategy for storing carbon in the soil.

Technical Abstract: This study evaluates the dynamics of soil organic carbon (SOC) under perennial crops across the globe. It quantifies the effect of change from annual to perennial crops and the subsequent temporal changes in SOC stocks during the perennial crop cycle. It also presents an empirical model to estimate changes in the SOC content under crops as a function of time, land use, and site characteristics. We used a harmonised global dataset containing paired-comparison empirical values of SOC and including different types of perennial crops (perennial grasses, palms, and woody plants) with different end-uses: bioenergy, food (including beverages), other bio-products (e.g., fibre) and short rotation coppice crops. Salient outcomes include: (1) a 20-year period encompassing a change from annual to perennial crops led to an average 20% increase in SOC at 0-30 cm (6 Mg/ha gain) and a total of 10% increase over the 0-100 cm soil profile. A change from natural pasture to perennial crop decreased SOC stocks by an average of 1% over 0-30 cm (-2.5 Mg/ha) and 10% over 0-100 cm. The effect of a land use change from forest to perennial crops did not have significant impacts, probably due to the limited number of plots; but the data indicated that while an increase in SOC was observed at 0-30 cm, a decrease was observed at 30-100 cm; (2) perennial crops generally accumulate SOC through time, especially woody crops; and (3) temperature was the main driver explaining differences in SOC dynamics, followed by crop age, soil bulk density, clay content and depth. We present empirical evidence suggesting that the FAO perennialization strategy is reasonable, underscoring the role of perennial crops as a useful component of land-based climate change mitigation strategies.