Diversifying and perennializing plants in agroecosystems alters retention of new C and N from crop residues. Issue 2 (11th January 2023)

• Record Type: Journal Article
• Authors: McDaniel, Marshall D.; Bird, Jeffrey A.; Pett‐Ridge, Jennifer; Marin‐Spiotta, Erika; Schmidt, Tom M.; Grandy, A. Stuart
• Is Part Of: Ecological applications. Volume 33:Issue 2(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2023-01-11
• Subjects: biodiversity -- decomposition -- dual‐labeled litter -- microbial biomass -- regenerative agriculture -- soil organic matter -- stable isotope -- sustainability; Ecology -- Periodicals; Environmental protection -- Periodicals; Biology, Economic -- Periodicals; 577.05
• DOI: 10.1002/eap.2784
• Languages: English
• ISSNs: 1051-0761

Abstract

Abstract: Managing soils to retain new plant inputs is key to moving toward a sustainable and regenerative agriculture. Management practices, like diversifying and perennializing agroecosystems, may affect the decomposer organisms that regulate how new residue is converted to persistent soil organic matter. Here we tested whether 12 years of diversifying/perennializing plants in agroecosystems through extended rotations or grassland restoration would decrease losses of new plant residue inputs and, thus, increase retention of carbon (C) and nitrogen (N) in soil. We tracked dual‐labeled ( 13 C and 15 N), isotopically enriched wheat ( Triticum aestivum ) residue in situ for 2 years as it decomposed in three agroecosystems: maize–soybean (CS) rotation, maize–soybean–wheat plus red clover and cereal rye cover crops (CSW2), and spring fallow management with regeneration of natural grassland species (seven to 10 species; SF). We measured losses of wheat residue (Cwheat and Nwheat ) in leached soil solution and greenhouse gas fluxes, as well as how much was recovered in microbial biomass and bulk soil at 5‐cm increments down to 20 cm. CSW2 and SF both had unique, significant effects on residue decomposition and retention dynamics that were clear only when using nuanced metrics that able to tease apart subtle differences. For example, SF retained a greater portion of Cwheat in 0–5 cm surface soils (155%, p = 0.035) and narrowed the Cwheat to Nwheat ratio ( p < 0.030) compared to CS. CSW2 increased an index of carbon‐retention efficiency, Cwheat retained in the mesocosm divided by total measured, from 0.18 to 0.27 (49%, p = 0.001), compared to CS. Overall, we found that diversifying and extending the duration of living plants in agroecosystems can lead to greater retention of new residue inputs in subtle ways that require further investigation to fully understand.