Uni-Bayreuth grafik-uni-bayreuth



Bachelor Thesis

Quantification of the CO2 efflux from planted soil and separation into main biogenic carbon sources

Support: Yakov Kuzyakov

This study investigated the effects of roots on the soil carbon metabolism during a shortterm incubation, starting five days after germination. Plant residues, using the example of 14C-labelled Zea mays L., were incubated in soil of an Haplic Luvisol under controlled laboratory conditions for 22 days at 25¬įC. One third of all samples was cropped with wheat (Tritikum aestivum), the second third was cropped with maize (Zea mays L.). The last third of the samples was maintained bare that means without plants. Each of this thirds was composed of four parts. These were the addition of three different 14C-labelled plant residues: ground roots (1.4 mg C (g soil)-1), ground leafs, pieces of leafs (each 1.2 mg C (g soil)-1) and the control tubes with no plant residues. The total CO2 and 14CO2 efflux from soil were measured regularly. Plants increased the CO2 while decreasing the 14CO2 efflux. The particle size of labelled litter had a temporally differentiated effect on their decomposition. Pairs of cropped and bare soils were analysed and compared according to the amounts of C sources of the total CO2. It could be shown that additional carbon inputs by root exudates and additions of 14C-labelled litter resulted in priming effects. These were represented as the effect of plants on the decomposition of plant residues and the effect of plants plus plant residues on the decomposition of soil organic matter.

last modified 2009-03-10