chemical complexity, one being a sugar and the other an aromatic
aldehyde. This allowed us to determine whether there was any
interaction between the mineralisation of different types of organic
C and changes in soil structure. In order to verify the depth to which
the substrates penetrated into the samples, at the end of the incubation
depth profiles for 13C were established by measuring the
13C signature at 1 cm depth increments.
Immediately after amendment the samples were placed on
sample holders in 1 L air-tight jars with spring-lock catches. The
jars were sealed with rubber gaskets and a glass lid fitted with a
septum for headspace sampling. The jars had a wide opening to
enable the incubation of undisturbed cores. In order to keep the soil
moisture levels constant during the incubation, 20 mL water was
placed at the bottom of each jar. The samples were incubated at
20 C in the dark for 127 days.