Construction of a carbon budget model of soil ecosystems for measures to prevent the global worming

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The annual carbon fixation in forests and agricultural lands in Hokkaido was 10.61 × 10^6 tC and the annual budget was 9.09 × 10^6 tC emission due to the large consumption of fossil energy. And for the balanced budget, the population should decrease to 59 % of the present population (3.34 × 10^6 population) and the population density be 40 persons km^<-1>. The CO_2 emission from the forest floors in Hachijoji, Kanto District was 501 mgCO_2 m^<-2> h^<-1> for a deciduous oak (Quercus serrata) forest and 319 mgCO_2 m^<-2> h^<-1> for an evergreen needle-leaved Japanese cypress, respectively, during 2000 and 2002. CO_2 fluxes from the forests under different conditions of climate, parent materials, and vegetation were known to be influenced by not only soil temperature but also seasonal physiological status of forest trees, which was estimated from the laboratory experiment of carbon mineralization.Root system of orchard grass in pasture was concentrated in the uppermost layer most in stron … More gly-acidic non-allophanic Andisols, and least in low-humic allophonic Andisols, respectively. The application of slowly-released fertilizers at the time of land preparation significantly decreased the accumulation of root system of orchard grass in the uppermost layer in comparison with split application of conventional fertilizers.CO_2 flux to the subsoil by water percolation was estimated to amount to several percents of total carbon content in the plow layer of a paddy field, and the percolated CO_2 to the subsoil was temporally retained during the flooding period.A improved method for determining carbonate ions adsorbed to soils was applied to allophonic Andisols under the 4 % CO_2 atmosphere changing the pH condition. The amount of adsorption increased with the increase in pH without showing the adsorption maximum near pH 7. The CO_2 emission after the application of organic material (yeast extract) increased in the order of alluvial soil < diluvial soil < paddy soil < Ando soil. The microbial community in the alluvial soil metabolized carbohydrate fractions least, and that in the Ando soil maintained the high decomposing activity to long-chain carbonaceous organic materials, resulting in the Ando soil decomposing organic matter most in the long-term. Less