The litter bag method is often used to study different aspects of deco
mposition of organic matter in soil or on the soil surface. Deposition
of surrounding soil into the litter bags makes determination of decom
position rates of organic matter and its nutrients particularly diffic
ult. This contamination has to be removed or determined for subsequent
correction of measured results. A common method to quantify soil cont
amination of litter bag material is the determination of ash residues
of organic matter, soil, and sample material. Later on, data like mass
losses can be corrected for the contamination. For straw samples with
predefined soil contaminations (10 % to 60 % soil in dry weight) we e
valuated the effects of grinding and subsampling on the estimation of
soil content, where ash residues are used as a marker to identify soil
. The possibility of using element contents (SiO2, Al, Fe, and Pb) of
litter bag material as internal standards to calculate soil contaminat
ion was also tested. Calculation of soil contamination with internal s
tandards from element analysis is generally possible. Results are comp
arable to the ones using ash residues. The aluminium content was the m
ost appropriate marker of soil in straw-soil samples. Subsampling caus
es large errors in determination of soil content in litter bag samples
. Errors can be reduced using subsamples from homogenized (ground) sam
ples or using the whole litter bag sample to determine ash residues.