Fungal and bacterial colonization of maize litter during decomposition in a temperate arable and grassland alley-cropping system

Abstract Aims Alley-cropping systems (ACS) often increase soil organic matter and microbial biomass with unknown effects on the decomposition of harvest residues. The central objective of the current field study was to address microbial decomposition processes in two distinct ACS. Methods Litterbags with 15 N labelled C4-plant maize ( Zea mays ) root or stalk litter were placed at 5 cm depth for seven months in the tree rows and alleyways of an arable and grassland ACS in Germany. In the remaining litter, gene abundance of bacteria and fungi were quantified by real-time PCR. Ascomycota and Basidiomycota were additionally quantified as the two major decomposing fungal groups in soil. Results Recovery of maize-derived C and N in the litterbags was higher in the alleyway than in the tree row of the arable ACS, whereas no differences were observed at the grassland ACS. The C recovery did not differ between root and stalk litter, whereas more N was recovered from roots due to their higher C/N ratio. In the alleyway soil of both ACS, fungal gene abundance reached 11% of the bacterial gene abundance and in the tree row soil, fungi reached even 27%, due to the stronger presence of Basidiomycota. In the maize litter, the fungal gene abundance was even 8% higher than the bacterial gene abundance. Conclusions The current study reveals that q PCR is a useful and powerful tool for investigating decomposition processes, not only of harvest residues but most likely also of other litter types.