Sulphur speciation and biogeochemical cycling in long‐term arable cropping of subtropical soils: evidence from wet‐chemical reduction and S K‐edge XANES spectroscopy

European Journal of Soil Science - Tập 56 Số 5 - Trang 621-634 - 2005
Daniel Solomon1, Johannes Lehmann1, I. Lobe2, Carmen Enid Martı́nez3, Steinar Tveitnes4, C. C. du Preez5, Wulf Amelung2
1Department of Crop and Soil Sciences, Cornell University, Bradfield and Emerson Hall, Ithaca, NY 14853, USA,
2Berlin University of Technology, Institute of Ecology, Department of Soil Science, Salzufer 12, 10587 Berlin, Germany,
3Department of Crop and Soil Sciences, 418 ASI Building, The Pennsylvania State University, University Park, PA 16802, USA,
4Department of Soil and Water Sciences, Agricultural University of Norway, PO Box 5028, 1432 Ås, Norway, and
5Department of Soil, Crop and Climate Sciences, University of the Free State, PO Box 339, Bloemfontein 9300, Republic of South Africa

Tóm tắt

SummaryAgriculture has claimed a large share of terrestrial environments in the tropics and subtropics through cultivation of native grasslands or forests. The impact of this anthropogenic change on speciation, dynamics, and ecological significance of sulphur (S) compounds is still poorly understood. We combined degradative wet‐chemical reduction and S K‐edge X‐ray absorption near edge structure (XANES) spectroscopy techniques to evaluate the impact of long‐term agricultural management of native grassland soils in South African Highveld on the amount, form and dynamics of S species. Sulphur XANES in the humic substances extracted by 0.1 m NaOH/0.4 m NaF solution showed the presence of strongly reduced (polysulphides, disulphides, thiols, monosulphides and thiophenes), intermediate (sulphoxides and sulphonates) and strongly oxidized (ester sulphates) organic‐S. It showed that strongly oxidized‐S is the predominant form (39–54%) of the total organic‐S in the humic substances, and organic‐S in the intermediate oxidation state represented 30–37% (78–93% of which was attributed to sulphonates). The strongly reduced organic‐S comprised only 17–24% of the total organic‐S. We did not find a close correlation between the results of a degradative wet‐chemical procedure and XANES spectroscopy conducted in both the bulk soils (ester SO4‐S from XANES versus HI‐fractionation, r = 0.27; P < 0.05) and the humic substance extracts (ester SO4‐S from XANES versus HI‐fractionation, r= 0.39; P < 0.05). The ratio of reduced‐S to strongly oxidized‐S (R‐S/O‐S) in the humic substances decreased from 0.61 to 0.21, while the ratio of intermediate‐S to strongly oxidized‐S (I‐S/O‐S) declined from 0.93 to 0.61 after 90 years of arable cropping of the native grassland soils. Hence, there was a shift in oxidation state towards strongly oxidized‐S (+6) and, thereby, a change in the relative proportion of the organic‐S moieties associated with each oxidation state following cultivation of the native grassland soils. Therefore, we conclude that changes in land‐use practice brought about not only quantitative change but also altered the composition of organic‐S functional groups in these native subtropical grassland soils.

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Tài liệu tham khảo

10.1097/00010694-198707000-00008

10.1046/j.1365-2389.2002.00428.x

10.2136/sssaj1973.03615995003700060034x

10.1080/02571862.1995.10634351

FAO–UNESCO, 1997, Soil Map of the World, Revised Legend.

Fitzgerald J.W., 1978, Sulfur in the Environment: Part II, Ecological Impacts, 391

10.1002/jsfa.2740200718

Hendershot W.H., 1993, Soil Sampling and Methods of Analysis, 167

10.1021/es000953x

10.2136/sssaj2001.653704x

10.1016/S0166-5162(96)00033-X

Kowalenko C.G., 1993, Soil Sampling and Methods of Analysis, 65

Kowalenko C.G., 1993, Soil Sampling and Methods of Analysis, 231

10.1046/j.1365-2389.2001.t01-1-00362.x

10.1046/j.1365-2389.2002.00469.x

10.1021/es011333e

10.1007/BF02181123

10.1016/0016-7061(81)90024-0

10.1111/j.1365-2389.1977.tb02252.x

10.1071/SR01001

10.1016/S0016-7037(97)00003-3

10.2136/sssaj1975.03615995003900010016x

10.1046/j.1365-2389.2003.00543.x

Schnitzer M., 1972, Humic Substances in the Environment

10.2136/sssaj1987.03615995005100030017x

10.1016/S0016-7061(00)00103-8

Solomon D., 2002, Soil organic matter composition in the sub‐humid Ethiopian highlands as influenced by deforestation and agricultural management, Soil Science Society of America Journal, 66, 68, 10.2136/sssaj2002.6800

10.2136/sssaj2003.1721

10.1016/0038-0717(91)90043-J

10.1002/(SICI)1522-2624(199910)162:5<511::AID-JPLN511>3.3.CO;2-I

10.1016/0016-7037(93)90020-W

10.1016/0016-7037(91)90343-4

10.2136/sssaj1998.03615995006200050014x

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European Journal of Soil Science

Tập 56 Số 5

621-634

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