Fig 1.
The average monthly rainfall (mm) and temperature (°C) in 2013–2014.
Table 1.
Main chemical properties of biogas slurry used in this study.
Table 2.
Amounts of organic carbon and nutrients added by chemical fertilizers and biogas slurry.
Fig 2.
Distribution of MSAs under different treatments.
Soil samples were collected at a depth of 0–20 cm after two years combined application of biogas slurry (BS) plus chemical fertilizer (CF). MSAs: mechanical—stable aggregates. T1: control (no BS or CF); T2: CF only; T3: 15% BS—TN plus 85% CF—TN, T4: 30% BS—TN plus 70% CF—TN; T5: 45% BS—TN plus 55% CF—TN; and T6: BS only. Values were mean (n = 3). vertical bars in the figures represent the standard deviation of mean (n = 3) and lower case letters indicate significant differences between treatments at the P < 0.05 level (LSD test). ANOVA source information is shown in S4 Table.
Table 3.
Soil properties included bulk density, porosity, MWD and GMD under different treatments.
Fig 3.
SOC concentration in MSAs under different treatments.
Soil samples were collected at a depth of 0–20 cm after two years combined application of biogas slurry (BS) plus chemical fertilizer (CF). SOC: soil organic carbon (g/kg); MSAs: mechanical—stable aggregates. T1: control (no BS or CF); T2: CF only; T3: 15% BS—TN plus 85% CF—TN, T4: 30% BS—TN plus 70% CF—TN; T5: 45% BS—TN plus 55% CF—TN; and T6: BS only. Values were mean (n = 3). vertical bars in the figures represent the standard deviation of mean (n = 3) and lower case letters indicate significant differences between treatments at the P < 0.05 level (LSD test). ANOVA source information is shown in S5 Table.
Table 4.
SOC storage in MSAs under different treatments (104 g/ha).
Fig 4.
TN concentration in MSAs under different treatments.
Soil samples were collected at a depth of 0–20 cm after two years combined application of biogas slurry (BS) plus chemical fertilizer (CF). TN, total nitrogen (g/kg); MSAs: mechanical—stable aggregates. T1: control (no BS or CF); T2: CF only; T3: 15% BS—TN plus 85% CF—TN, T4: 30% BS—TN plus 70% CF—TN; T5: 45% BS—TN plus 55% CF—TN; and T6: BS only. Values were mean (n = 3). vertical bars in the figures represent the standard deviation of mean (n = 3) and lower case letters indicate significant differences between treatments at the P < 0.05 level (LSD test). ANOVA source information is shown in S6 Table.
Table 5.
TN storage in MSAs under different treatments (104 g/ha).
Table 6.
Relationship among the measured soil attributes and parameters under different treatments.