Figure 1.
Respiration rate and microbial DNA in soil and rhizosphere.
Basal respiration rate (a), microbial DNA content (b), and ratio of basal respiration rate (Vbasal) to DNA content (c) of rhizosphere and root-free soil under Beta vulgaris at half (63 kg N ha−1) and full (126 kg N ha−1) rates of nitrogen fertilisation.
Figure 2.
Dynamics of microbial respiration after glucose addition to root-free and rhizosphere soil.
Glucose and nutrients induced respiration rate in root-free and rhizosphere soil under Beta vulgaris at half (a) and full (b) rates of N fertiliser. Experimental points and curves fitted by Eq. 3 for unlimited growth period are presented.
Table 1.
Biomass and kinetic parameters of the respiratory response of microorganisms growing on glucose.
Table 2.
Contribution of two factors: living roots (Roots) and N fertilisation rate (N) and their interactions (Roots x N) to the variance of microbial parameters.
Figure 3.
Microbial DNA dynamics and cumulative CO2 production in root-free and rhizosphere soil.
Dynamics of microbial DNA content and CO2 accumulation after glucose addition in rhizosphere (a) and root-free (b) soil collected from the plot fertilized with 126 kg N ha−1 year−1. Dynamics of specific CO2 production (VCO2-to-DNA ratio) are shown in the inserted graphs for rhizosphere and root-free soil, correspondingly.
Table 3.
The amount of produced CO2, DNA increment and carbon use efficiency (CUE) at different phases of microbial growth after glucose addition.
Figure 4.
The ratio of CO2 increment-to-DNA increment in rhizosphere and root-free soil.
Soil was collected from the plot fertilized with 126−1 year−1, (a) – rhizosphere soil, (b) – root-free soil. Horizontal arrows show the time period used for ΔCO2/ΔDNA ratio calculation. Vertical bars show standard deviations.