SOIL (Jan 2022)

Synergy between compost and cover crops in a Mediterranean row crop system leads to increased subsoil carbon storage

  • D. Rath,
  • N. Bogie,
  • L. Deiss,
  • S. J. Parikh,
  • D. Wang,
  • S. Ying,
  • N. Tautges,
  • A. A. Berhe,
  • T. A. Ghezzehei,
  • K. M. Scow

DOI
https://doi.org/10.5194/soil-8-59-2022
Journal volume & issue
Vol. 8
pp. 59 – 83

Abstract

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Subsoil carbon (C) stocks are a prime target for efforts to increase soil C storage for climate change mitigation. However, subsoil C dynamics are not well understood, especially in soils under long-term intensive agricultural management. We compared subsoil C storage and soil organic matter (SOM) composition in tomato–corn rotations after 25 years of differing C and nutrient management in the California Central Valley: CONV (mineral fertilizer), CONV+WCC (mineral fertilizer and cover crops), and ORG (composted poultry manure and cover crops). The cover crop mix used in these systems is a mix of oat (Avena sativa L.), faba bean (Vicia faba L.), and hairy vetch (Vicia villosa Roth). Our results showed a ∼19 Mg ha−1 increase in soil organic C (SOC) stocks down to 1 m under ORG systems, no significant SOC increases under CONV+WCC or CONV systems, and an increased abundance of carboxyl-rich C in the subsoil (60–100 cm) horizons of ORG and CONV+WCC systems. Our results show the potential for increased subsoil C storage with compost and cover crop amendments in tilled agricultural systems and identify potential pathways for increasing C transport and storage in subsoil layers.