Abstract
The rate of CO2 evolution Y (g CO2-C/m2/day) was studied in situ of the several soils such as naked and farm land. The Y of all soils was strongly controlled by soil temperature T (°C) and increased exponentially with it. But the Y of every soils showed considerable differences even when T showed the same value. For example, when T of all soils was almost the same of 22.5±0.5, there was about sixfold difference between Y of 0.49 in naked land formed on Kanto-roam in Fuchu city and Y of 2.83 in forest land adjacent to the naked land. The differences of the Y were not attributable to the difference of soil water content, microbial number or nutritional minerals.
While, there were large differences in water soluble organic compound expressed in terms of carbon C (mg C/kg dry soil) from the smallest of 3 in naked land to the largest of 89 in farm land formed on alluvial land in Hachioji city. The Y increased linearly with the increase of C upto 50 in every soil, in which the regression equation obtained was Y=0.022C+0.51 at 18±2°C. When C was over 50, the Y was within the range between 1.5 and 1.7.
Namely, in spite of the difference of soil type, human impact and vegetation, it was concluded that the Y could be determined by the two environmental factors in soil of T and C.
