Use of labelled plant residues to study the impact of residue incorporation on soil carbon and aggregation

Soil structural and soil organic matter decline is a worldwide problem and the return of plant residues is being used in many areas to attempt to increase soil C, which can lead to an improvement in structure. Studying the impact of residue incorporation on soil C can be difficult because of the large background of residual C. The use of isotope-labelled plant material allows the investigation of the effects of newly incorporated residue on C dynamics. An experiment was conducted to evaluate the effect of plant residues - with differing breakdown rates, incubated at different temperatures and for various time periods - on the incorporation of C and the stability of the soil aggregates to wetting. No increase in total C within the soil aggregates was found, however, there were large increases in soil aggregate stability. The rate of incorporation of the C from the added residues differed between plant materials