Plants and earthworms control soil carbon and water quality trade-offs in turfgrass mesocosms

• Published in: The Science of the total environment 2021-01, Vol.753, p.141884-141884, Article 141884
• Main Authors: Peach, Morgan E., Hicks Pries, Caitlin E., Friedland, Andrew J.
• Format: Article
• Language: English
• Subjects: Lawn; Nutrient leaching; Park; Sustainable design; Urban ecology; Woody plant
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2020.141884

Understanding how plants and earthworms regulate soil-based ecosystem services can guide design and management of built environments to improve environmental quality. We tested whether plant and earthworm activity results in trade-offs between soil carbon (C) retention and water quality. In a 2 × 2 factorial random block design, we introduced shrubs (Aronia melanocarpa) and earthworms (Lumbricus terrestris) to turfgrass (Lolium perenne) sandy loam mesocosms in a greenhouse. We measured soil respiration and soil microclimate every two weeks and leachate every two months. After 15 months, we assessed C and nitrogen (N) in bulk soil and aggregates (> 2000, 2000–250, 250–53 μm). Turfgrass mesocosms with earthworms retained less soil C (6.10 ± 0.20 kg/m2), especially when warmer. Soils planted with shrubs were drier and had 7% lower mean respiration rates than soils without shrubs. Turfgrass mesocosms with both shrubs and earthworms retained more soil C (6.66 ± 0.25 kg/m2), even when warmer, and held ~1.5 times more C in >2 mm aggregates than turfgrass-only mesocosms. Turfgrass mesocosms with shrubs and earthworms leached nitrate-N with increased respiration and retained phosphate-P and dissolved organic carbon (DOC) when wetter. In contrast, turfgrass mesocosms with only shrubs had the opposite response by leaching less nitrate-N with increased respiration, and more phosphate-P and DOC when wetter. Overall, shrub and earthworm activity in turfgrass mesocosms led to soil C-nutrient retention trade-offs. Our results reveal potential challenges in managing built environments to both retain soil C and improve water quality. [Display omitted] •Shrubs regulated soil C dynamics by drying soils, thus limiting decomposition.•Earthworms increased soil C loss when shrubs were absent and when soils were warmer.•Soils dried by shrubs leached more phosphate when earthworms were present.•Shrubs led to a soil C-nitrate retention trade-off.