Microbial population sizes and soil properties in topsoil and subsoil of two alley-cropping agroforestry systems in Germany

We quantified bacteria, fungi, and functional groups of microorganisms in the topsoil and subsoil of two alley-cropping systems using real-time PCR. Topsoil and subsoil samples were collected in the tree rows and at multiple distances from the trees within the crop rows of the agroforestry systems as well as at an adjacent monoculture cropland. Soil cores were divided into topsoil (0 – 15 and 15 – 30 cm soil depth) and subsoil (30 – 45 and 45 – 60 cm soil depth).

Research domain: Soil Sciences

Research question: This study aimed to recover microbial DNA from topsoil and subsoil of two temperate poplar-based alley-cropping systems and quantify soil bacteria and fungi as well as different functional groups of microorganisms (nitrifying, denitrifying, methanotrophic, and methanogenic microorganisms) at different soil depths using real-time PCR. We hypothesized that i) microbial abundance decreases with soil depth, ii) tree rows promote microbial communities in both the topsoil and subsoil, and iii) the promotion of microorganisms through the tree rows is stronger in the subsoil than topsoil.