Influence of tillage and rotation systems on distribution of organic carbon associated with particle-size fractions in Chernozemic soils of Saskatchewan, Canada |
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| Authors: | Tianyun Wu Jeff J Schoenau Fengmin Li Peiyuan Qian Sukhdev S Malhi Yuanchun Shi |
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| Institution: | (1) Soil Science and Fertilizer Institute, Gansu Agricultural Academy of Sciences, Lanzhou, 730070, PR China;(2) Department of Soil Science, University of Saskatchewan, 51 Campus Drive, Saskatoon, Canada, S7N 5A8;(3) State Key Laboratory of Arid Agroecology, Lanzhou University, Lanzhou, 730070, PR China;(4) Agriculture and Agri-Food Canada, Research Farm, P.O. Box 1240, Melfort, Saskatchewan, Canada, S0E 1A0 |
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| Abstract: | The effects of several dominant tillage and rotation systems on soil organic C content of different particle-size fractions
were studied in Chernozemic soils from southwestern and east-central Saskatchewan, Canada. In an Orthic Brown Chernozem in
southwestern Saskatchewan, 7 years of no-till cereal–fallow, imposed on a long-term tillage fallow–wheat rotation soil, resulted
in 0.1 Mg C ha−1 more organic C mass in the sand + organic matter (OM) fraction of the 0- to 5-cm layer, whereas organic C associated with
coarse silt (CS), fine silt (FS), coarse clay, and fine clay of 0- to 5- and 5- to 10-cm layers was less than that of the
comparable tilled cereal–fallow system. Conversion of tilled fallow–wheat rotation soil to continuous cropping had a slight
effect, whereas the organic C mass in all the size fractions was significantly increased in both 0- to 5- and 5- to 10-cm
layers after alfalfa was introduced on tilled fallow–wheat as perennial forage for 10 years. In an Orthic Black Chernozem
in east-central Saskatchewan that was cultivated and tilled using a cereal–fallow rotation for 62 years, organic C mass decreased
in sand + OM, CS, and FS of 0- to 10-cm depth. Conversion of the tilled cereal–fallow cropland soil back to seeded grassland
resulted in significantly more soil organic C in sand + OM fraction after 12 years of grass seed-down. The sand + OM fraction
appears to be the size fraction pool initially most sensitive to adoption of management practices that are liable to sequester
carbon in the soil. |
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| Keywords: | Soil organic carbon Particle-size fractionation Organo-mineral complex Tillage and rotation system |
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