Abstract. Subsurface carbon stocks are a prime target for efforts to increase soil carbon storage for climate change mitigation and improving soil health. However, subsurface carbon (C) dynamics are not well understood, especially in soils under long term intensive agricultural management. We compared subsurface C dynamics 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 + cover crops) and ORG (composted poultry manure + cover crops). Our results showed a ~19 Mg/ha increase in SOC stocks down to 1 m under ORG systems, no significant SOC increases under CONV+WCC or CONV systems, and the accumulation of carboxyl rich C in the subsurface (60–100 cm) horizons of all systems. Systems also had greater amounts of aromatic carbon in the order ORG>CONV+WCC>CONV. We identified a potential interaction between cover crops and compost, theorizing that increased macropores from cover crop roots facilitate the transport of soluble C and nutrients into the subsurface, thereby increasing stocks. These results demonstrate the potential for subsurface carbon storage in tilled agricultural systems and highlight a potential pathway for increasing carbon transport and storage in subsurface soil layers.

中文翻译：

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堆肥和覆盖作物之间的协同作用导致地下土壤碳储量的增加

摘要。地下碳储量是努力增加土壤碳储量以缓解气候变化和改善土壤健康的主要目标。然而，地下碳（C）的动力学还没有被很好地理解，特别是在长期集约化农业管理下的土壤中。我们比较了加利福尼亚中央谷地25年不同的碳和养分管理后番茄玉米轮作下的地下碳动态：CONV（矿物肥料），CONV + WCC（​​矿物肥料+覆盖作物）和ORG（家禽粪便+覆盖作物） ）。我们的结果表明，在ORG系统下，至1 m时，SOC储量增加了约19 Mg / ha，在CONV + WCC或CONV系统下，SOC没有显着增加，并且富含羧基的C在地下（60-100 cm）地层中积累所有系统。系统还具有较大数量的芳族碳，顺序为ORG> CONV + WCC> CONV。我们确定了覆盖作物和堆肥之间的潜在相互作用，理论上认为，覆盖作物根部增加的大孔隙促进了可溶性碳和养分向地下的运输，从而增加了种群。这些结果证明了耕作的农业系统中地下碳储存的潜力，并突出了增加地下土壤层中碳迁移和储存的潜在途径。