Variations in the number (10⁴ CFUs g⁻¹ dry soil) of aerobic bacteria, anaerobic bacteria, actinomycetes and fungi in a paddy soil under different cropping systems.

R-R-Ry: rice–rice–ryegrass cropping system; R-R-Mv: rice–rice–Chinese milk vetch cropping system; R-R-Ra: rice–rice–rape cropping system; R-R-Fa: rice–rice cropping system with winter fallow. TS: tillering stage; BS: booting stage; FS: full heading stage; MS: maturity stage. Values are presented as mean ± SE (n = 3). Means in each column with different letters are significantly different at the P<0.05 level.