Fig 1.
Monthly precipitation and mean air temperature over a two-year period (2012–2013).
Table 1.
Enzymes with corresponding commission number (EC), corresponding substrate, and the abbreviation used in this study.
Table 2.
Variations in soil chemical properties under different fertilizations in 2012 and 2013.
Fig 2.
Variations in Microbial Biomass Carbon (MBC) and Nitrogen (MBN) under different fertilizations in 2012 and 2013.
Vertical bars represent the SE (n = 3) and different letters above bars indicate significant differences between fertilizations at P<0.05.
Fig 3.
Radar graphs illustrating the relative responses of enzyme activity to different fertilizations in 2012 and 2013.
To make a clear comparison when characterizing the organic amendments, the CK and NPK treatments were shown in two shadings. * and ** indicate significant differences between fertilizations at P<0.05 and P<0.01, respectively. Abbreviations: αG, α-glucosidase; βG, β-glucosidase; CBH, cellobiohydrolase; NAG, N-acetyl-glucosaminidase; Perox, peroxidase; Pho, phosphomonoesterase; PhOx, phenol oxidase; Sul, sulfatase.
Fig 4.
Principal Component Analysis (PCA) of enzyme activities in soils different fertilizations in the late rice season of 2012 (a) and the early rice season of 2013 (c), and Redundancy Analysis (RDA) results of the correlations between soil variables and enzyme activity in the late rice season of 2012 (b) and the early rice season of 2013 (d).
The red arrows indicate the soil parameters that had a strong and significant impact on the enzyme activities (P<0.05), and the corresponding explained proportion of variability is shown in the lower right corner. Abbreviations: Abbreviations: Avail., available; MBC, microbial biomass carbon; MBN, microbial biomass nitrogen; SOM, soil organic matter.
Fig 5.
Variations of the total PLFA, relative abundance of bacteria, ratio of gram-positive to gram-negative bacteria, and relative abundances of fungi and actinomycetes under different fertilizations in the late rice season of 2012 and the early rice season of 2013.
Vertical bars represent the SE (n = 3) and different letters above bars indicate significant differences between fertilizations at P<0.05.
Fig 6.
Principal Component Analysis (PCA) of microbial community composition (relative content of individual PLFA molecules) in soils under different fertilizations in the late rice season of 2012 (a) and the early rice season of 2013 (c), and Redundancy Analysis (RDA) of the correlations between soil parameters (chemical properties and microbial biomass C/N) and microbial community composition in the late rice season of 2012 (b) and the early rice season of 2013 (d).
The red arrows indicate the soil parameters that had a strong and significant impact on the microbial community composition (P<0.05), and the corresponding explained proportion of variability is shown in the lower left corner. Abbreviations: Avail. available, MBC microbial biomass carbon, MBN microbial biomass nitrogen, SOM soil organic matter.
Table 3.
Variations in rice yield under different fertilizations in 2012 and 2013.
Fig 7.
Variations in Soil Quality Index (SQI) under different fertilizations in the late rice season of 2012 (a) and the early rice season of 2013 (b).
Fig 8.
Relationships between Soil Quality Index (SQI) values and rice yields in 2012 and 2013.