An apparatus is described which under laboratory conditions permits sampling of water and gases from a waterlogged soil throughout the experimental period. A cultivated soil supplied with 6% straw is waterlogged during 97 days and the sequence of some redox reactions is shown. After one day of waterlogging the redox potential declines and reaches negative values after six days. pH declines from 7.5 to 6.5 after 17 days of waterlogging and then slowly increases to about neutral again. NO3− is the first compound to be reduced and within two days all NO3 has disappeared. NO2 is only detected during the first two days. After NO3 has been reduced Mn2+ increases, followed by a large increase of Fe2+. S042−- has totally disappeared within the first three weeks of waterlogging. CO2 is produced during the whole experimental period. A large production of CH4 begins after three weeks of waterlogging. N2O was not detected.