CHAPTER 6 Management Impacts on Carbon Storage and Gas Fluxes ( C 02 , CH . Jin Mid - Latitude Cropland
نویسندگان
چکیده
Agriculrural ecosystems comprise an estimated 113 of the land surface of the earth (Houghton ec al .. 1983) a.nd include some of the mosc productive and carbon-rich soils. As a result they play a significant role in the storage and release of C within the terresrrial carbon cycle. At the same time these ecosystems are higllly impacted through human activities and thus processes determining net carbon fluxes to the aunosphere are co a large degree influenced by I.and managemenc practices. In the context of global change, three major issues dealing with soil C balance and the emission of greenhouse gases from soil have come to the fore. These are (i) the potential for increased C~ emissiom from soil under conditions of global wanning, giving rise co a positive feedback on the greenhouse effect (Jenkinson el al., 1991), (ii) increased emission of other radiatively-active trace gases from soil as a consequence of land management practices [(e.g .. greater N10 emission and less CH. consumption with increased N fcrtili~cr use (Bronson and Mosier, 1993; Robenson, 1993)], and (iii) the potential for increasing C storage in soils to explain wh.ac appears co be a contemporary midlatirude C01 sink of 1.3-2.4 Pg yr· ' C (rans et al., 1990) and to help ameliorate furure increases of C02 in the atmosphere (Barnwell Ct al., 1992). In this paper we will examine processes determining the carbon balance in agriculrural soils. focusing in particular on the role of land managemem practices in influencing these processes. Our objectives are co provide a perspective on which practices are ~ost likely to be important for shifting the balance cowards greater storage of catbon ln soils and reducing the net emission of C01 and maximizing the net capture of ~ in soil, and w examine the interactions bccween managemeot and environmental controls on soil C ~r conditions of global clima.te change. ,:,. \ .:: tJ. Historical P erspective on Temperate Zone Agriculture and Soil C
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