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Changes in Soil Organic Matter under Different Tillage and Rotation: Mathematical Modeling in ecosys
Author(s) -
Grant R. F.
Publication year - 1997
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1997.03615995006100040023x
Subject(s) - tillage , environmental science , conventional tillage , soil water , soil science , organic matter , agronomy , ecology , biology
Reductions in both tillage and fallowing may increase soil organic C. The effects of tillage and fallowing on soil C could be estimated under site‐ and climate‐specific conditions by mathematical modeling. The simulation model ecosys predicts changes in soil C by calculating C added through fixation by plant communities and C lost through oxidation by microbial communities. During a 14‐yr simulation of a field experiment in a semiarid environment, ecosys predicted that 18 and 20 g m −2 yr −1 more C would be sequestered in the upper 0.15 m of soil in continuous wheat (W‐W; triticum aestivum L.) than in wheat‐fallow (W‐F) under conventional tillage (CT) and no tillage (NT), respectively. During the same period, ecosys predicted that 14 and 12 g m −2 yr −1 more C would be sequestered in the upper 0.15 m of soil under NT than under CT in W‐W and W‐F, respectively. These increases were compared with those measured from the field experiment of 9 and 19 g m −2 yr −1 in W‐W than W‐F under CT and NT, respectively, and of 13 and 4.5 g m −2 yr −1 under NT than CT in W‐W and W‐F, respectively. The sensitivity of simulated changes in soil C to doubled atmospheric CO 2 and a 3 or 6°C increase in air temperature was then tested. Similarity in the direction and magnitude of simulated and measured changes in soil C lend initial support to model hypotheses. However, there are some issues concerning the modeling and measurement of soil C that require further clarification.