Interaction between N and C in Soil has Consequences for Global Carbon Cycling

• Energy—yielding processes in the N—cycle form important links with the global C—cycle. One example is demonstrated with the supply of nitrogen to soils, initially resulting in lowered CO2 emissions. This well known effect has mostly been interpreted as hampered or delayed soil respiration. When added in surplus, however, nitrogen supply does not stabilize the minimum emissions initially obtained, but gradually results in increased CO2 emissions. Specific inhibition of the CO2 consuming process nitrification in soils, with surplus ammonium supply or with acetylene, mostly results in additional CO2 emissions. The difference between this disclosed gross heterotrophic respiration (GHR) and the net CO2 emission (NHR) is the result of a within—soil CO2—sink. Soil respiration solely determined as CO2 emitted as NHR (the common situation) therefore may lead to misinterpretations of the function of the soil system, especially in areas with high N—deposition. As a consequence, the interpreted ‘acclimation’ of the soil respiration response in a warmer world should be reconsidered. The concept of respiration inhibition by nitrogen supply may also be questioned. Disregard of these processes, including the indicated N—driven within—soil CO2—sink, may prevent adequate measures counteracting climate change.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences (hsv//eng)

Nyckelord

soil respiration

carbon sink

CO2 emissions

temperature response

climate change

N—supply

Earth sciences

Geovetenskap

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