High-yielding forage grass cultivars increase root biomass and soil organic carbon stocks compared with mixed-species permanent pasture in temperate soil

A - Papers appearing in refereed journals

Gregory, A. S., Joynes, A., Dixon, E. R., Beaumont, D. A., Murray, P. J., Humphreys, M. W., Richter, G. M. and Dungait, J. A. J. 2021. High-yielding forage grass cultivars increase root biomass and soil organic carbon stocks compared with mixed-species permanent pasture in temperate soil. European Journal of Soil Science. https://doi.org/10.1111/ejss.13160

AuthorsGregory, A. S., Joynes, A., Dixon, E. R., Beaumont, D. A., Murray, P. J., Humphreys, M. W., Richter, G. M. and Dungait, J. A. J.
Abstract

Agricultural grass cultivars bred for increased forage yield commonly have extensive root systems. As roots are an important input of organic matter into the soil, it follows that such cultivars could lead to important increases in soil organic carbon (SOC), but this, and the mechanisms involved, are poorly understood with little empirical field evidence. We assessed the effect of two cultivars, Lolium perenne L. cv. ‘AberMagic’ and L. perenne L. × Festuca pratensis Huds. cv. ‘Prior’, in comparison with mixed-species permanent pasture (‘Pasture’) in a field experiment on temperate alluvial soil in the southwest UK. Root and SOC stocks, and specific plant-derived lipids as mechanistic biomarkers for shoot and root inputs of C, were measured on intact 1-m volumetric soil cores collected on four dates in 2013-2015. Total grass yields were greater for both grass cultivars (40-43 Mg ha–1) than Pasture (39 Mg ha–1), and by 2015 root stocks in the upper 0.1 m were significantly greater by more than 4.7 Mg ha–1. At 0.1-0.3 m depth, SOC stocks (per 0.1-m depth) were significantly greater under the two grass cultivars (24-50 Mg ha–1) compared to Pasture (18-32 Mg ha–1). In the full 1-m profile, mean SOC stocks were 137, 133 and 110 Mg ha–1 for AberMagic, Prior and Pasture, respectively, matching root biomass distribution. Odd-chain n-alkane concentrations were significantly greater for shoots than roots (274 vs. 64 mg kg–1, respectively), and roots had significantly greater concentrations than shoots of even-chain hydroxy fatty acids (1829 vs. 305 mg kg–1, respectively) and diacids (317 vs. 93 mg kg–1, respectively). This confirmed lipids as candidate biomarkers for distinguishing shoot and root inputs into the soil, with the latter being the dominant source of SOC. Based on the observations of increased forage yield and SOC stock, high-yielding forage grass cultivars can contribute to future strategies for climate-smart agriculture in grassland-dominated temperate regions.

KeywordsDiacid; Festuca pratensis Huds.; Festulolium; Hydroxy fatty acid; Lolium perenne L.; N-alkane; Nitrogen; Soil core
Year of Publication2021
JournalEuropean Journal of Soil Science
Digital Object Identifier (DOI)https://doi.org/10.1111/ejss.13160
Web address (URL)https://onlinelibrary.wiley.com/doi/abs/10.1111/ejss.13160
Open accessPublished as green open access
FunderBiotechnology and Biological Sciences Research Council
Funder project or codeMaximising carbon retention in soils
S2N - Soil to Nutrition - Work package 1 (WP1) - Optimising nutrient flows and pools in the soil-plant-biota system
Output statusIn press
Publication dates
Online17 Aug 2021
Publication process dates
Accepted09 Aug 2021
PublisherWiley
ISSN1351-0754

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