Greater fungal and bacterial biomass in soil large macropores under no-tillage than mouldboard ploughing

Soil microorganisms inhabit pores of various shapes and sizes. No-tillage practices cause less disturbance and compaction of the soil profile than mouldboard ploughing, which could provide more habitat for soil microorganisms. The objective of this study was to determine how long-term no-tillage affected pore volume, microbial biomass and their relationship. Soil samples were collected from field plots that were continuously cropped with monoculture maize for 12 years under no-tillage or mouldboard ploughing in Dehui County, Jilin Province, China. No-tillage increased large macropore (> 100 mu m) volume in the 0-5 cm soil layer. Greater biomass of gram positive bacteria, gram negative bacteria, saprophytic fungi, and arbuscular mycorrhizal fungi was measured in the 0-5 cm soil layer of no-tillage than mouldboard ploughed plots. Microbial biomass expressed as PLFA was positively related to the soil large macropore (> 100 mu m) in the 0-20 cm soil layer in this field. We concluded that large macropores are better habitat for bacteria and fungi under no-tillage than mouldboard ploughing in this monoculture maize agroecosystem.