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[B-6.1.1 Quantitative Analysis of Carbon Cycle in Agro-ecosystems]

[Contact Person]

Section Director, Tomoyuki Hakamata
Department of Environmental Management,
National Institute of Agro-Environmental Sciences,
Ministry of Agriculture, Forestry and Fisheries
3-1-1 Kannondai, Tsukuba, Ibaraki 305, Japan
Tel +81-298-38-8224, Fax +81-298-38-8199
E-mail tomo@niaes.affrc.go.jp

[Total Budget for FY1990-1992]

26,082,000 Yen

[Abstract]

　The objectives of the study were to clarify quantitative carbon cycle in such agro-ecosystems as vegetable field, paddy field and agro-forest. (1) Carbon budgets of a sweet potato (Ipomoea batatas)-chinese cabbage(Brasica rapa) double-cropping field and an abandoned field were -168 and -187gC/m²/yr, respectively. The carbon budgets suggest that croplands act as a source of carbon dioxide. (2) Carbon cycle through solid phase or liquid phase was measured in a paddy field. About 90gC/m²/yr was assumed to be accumulated in the system. Carbon dioxide flux measured in paddy fields by the alkaline absorption method was appeared to be overestimated compared with IR analysis and chamber methods. (3) Net carbon absorptions of forest ecosystems from atmosphere in a managed agro-forest, an abandoned agro-forest and a 50 years old deciduous natural agro-forest were 3.7, 2.2, 3.9tC/ha/year, respectively. The results show that both a agro-forest and a natural deciduous forest perform as a carbon sink.

[Key Words]

Carbon cycle, Upland field, Paddy field, Agro-forest, Agro-ecosystems