Publication Abstracts

Hillel and Rosenzweig 2009

Hillel, D., and C. Rosenzweig, 2009: Soil carbon and climate change: Carbon exchange in the terrestrial domain and the role of agriculture. CSA News, 54, no. 6, 4-11.

The earth's ecosystem constitutes a bio-thermodynamic machine that is driven by solar energy and the exchanges of water, oxygen, carbon dioxide, and other components in the pedosphere-hydrosphere-atmosphere continuum. Green plants in the terrestrial domain perform photosynthesis by absorbing atmospheric CO2 and reducing it to forms of organic carbon in combination with soil-derived water, while utilizing the energy of sunlight. In the process, radiant energy is transformed into chemical energy that is stored in the molecular bonds of organic compounds produced by the plants. This in turn provides the basis for the food chain, which sustains all forms of animal life.

Roughly 50% of the carbon photosynthesized by plants is returned to the atmosphere as CO2 in the process of plant respiration. The rest, being the carbon assimilated and incorporated in leaves, stems, and roots, is deposited on or within the soil. There, organic compounds are ingested by a diverse biotic community, including primary decomposers (bacteria and fungi) and an array of mesofauna and macrofauna (nematodes, insects, earthworms, rodents, etc.). The ultimate product of organic matter decay in the soil is a complex of relatively stable compounds known collectively as humus. It generally accounts for some 60 to 80% of the total organic matter present, the balance consisting of recent organic debris of partially decomposed litter, dead roots, and the waste products of soil fauna.

Since the beginning of the Industrial Revolution in the late 1800s, the expansion of agriculture, the clearing of forests, and especially the burning of fossil fuels have led to a dramatic increase in the atmospheric content of carbon dioxide, from about 270 ppm to more than 380 ppm. Concurrently, there has been an increase in the content of other radiatively active gases (the so-called greenhouse gases), such as methane and nitrous oxide. The effect, so far, appears to be a rise of more than 0.6°C in the global average temperature. This warming trend is expected to increase markedly in the coming decades, unless strong measures are taken to mitigate it.

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BibTeX Citation

@article{hi05100g,
  author={Hillel, D. and Rosenzweig, C.},
  title={Soil carbon and climate change: Carbon exchange in the terrestrial domain and the role of agriculture},
  year={2009},
  journal={CSA News},
  volume={54},
  number={6},
  pages={4--11},
}

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RIS Citation

TY  - JOUR
ID  - hi05100g
AU  - Hillel, D.
AU  - Rosenzweig, C.
PY  - 2009
TI  - Soil carbon and climate change: Carbon exchange in the terrestrial domain and the role of agriculture
JA  - CSA News
VL  - 54
IS  - 6
SP  - 4
EP  - 11
ER  -

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