In a short-term laboratory study C mineralization potentials were dete
rmined on soil samples obtained from some representative agricultural
soils in Tuscany, Italy. All the kinetic models tested to describe the
mineralization process provided a good fit to the experimental data.
A modified first-order model best described C mineralization in the so
il. Both potentially mineralizable C and the mineralization rate (k) v
aried considerably among soils, reflecting the differences in soil pro
perties. Potentially mineralizable C was positively related to C evolv
ed as CO2 and to the exchange capacity. Normalized values (potentially
mineralizable C divided by organic C), representing on average about
2% of the total soil C, was positively correlated to soil pH and negat
ively to the soil C pool, the soil N pool, and total microbial activit
y. Values for k ranged between 0.050 and 0.104 day(-1), being higher i
n fine-textured soils and in soils with a large free Fe content. A low
C:N ratio was indicative of a high k value. Turnover times for minera
lized C were relatively rapid, ranging from 10 to 20 days.