Soil C changes and size estimates of different organic C fractions in a Swedish long-term small plot experiment
1988
Persson, J. | Mattsson, L. (Sveriges Lantbruksuniv., Uppsala (Sweden). Inst. foer Markvetenskap)
The development of soil organic C and the sizes of different organic C fractions were estimated from data obtained in a 28 years old, Swedish small plot experiment. Treatments with crop residues and mineral fertilizer N were investigated. A treatment with continuous fallow was also included. In the fallow the soil organic C declined from 1.48% to 1.13% during the experimental period. Annual cropping without N addition counteracted the C decline. Addition of straw and supply of N (80 kg ha-1 year-1) increased the C content to 1.79% after 28 years. Based on the C content in the fallow treatment, the size of the active+slow C fraction was estimated to range between 11-37%. This correlated well with simulated values for the experiment. The size of the active+slow fraction determined from mineralization data indicated that there may be a further C fraction with a turn-over time somewhere between 30 and 1200 years. The relevance of this is discussed.
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