Effects of different long-term fertilization on rhizosphere soil nitrogen mineralization and microbial community composition under the double-cropping rice field

Figures & data

Table 1. Effects of different long-term fertilizer treatments on rhizosphere soil N transformation rates in the double-cropping rice fields.

Items	Treatments
	IF	RF	OM	CK
GMR (mg N kg^−1 d^−1)	1.56 ± 0.05b	1.70 ± 0.05b	1.86 ± 0.05a	1.35 ± 0.03c
GACR (mg N kg^−1 d^−1)	2.28 ± 0.06c	2.47 ± 0.07b	2.65 ± 0.07a	2.04 ± 0.06d
GNR (mg N kg^−1 d^−1)	0.45 ± 0.02c	0.62 ± 0.02b	0.85 ± 0.02a	0.25 ± 0.01d
GNCR (mg N kg^−1 d^−1)	0.33 ± 0.01c	0.43 ± 0.01b	0.56 ± 0.02a	0.21 ± 0.01d
NMR (mg N kg^−1 d^−1)	0.32 ± 0.01c	0.50 ± 0.02b	0.61 ± 0.02a	0.11 ± 0.01d
NNR (mg N kg^−1 d^−1)	0.36 ± 0.01c	0.53 ± 0.02b	0.65 ± 0.02a	0.14 ± 0.01d
RR (mg N kg^−1 d^−1)	6.42 ± 0.21b	7.05 ± 0.20a	7.23 ± 0.18a	4.26 ± 0.12c

IF: inorganic fertilizer; RF: rice straw and inorganic fertilizer; OM: 30% organic manure and 70% inorganic fertilizer; CK: without any fertilizer input as a control.

GMR: gross N mineralization rate; GACR: gross ammonium consumption rate; GNR: gross nitrification rate; GNCR: gross nitrate consumption rate; NMR: net mineralization rate; NNR: net nitrification rate; RR: respiration rate.

Values were presented as mean ± standard error.

Different lowercase letters in the same line were indicated significantly at difference in 0.05 levels.

The same as below.

Figure 1. Effects of different long-term fertilizer treatments on rhizosphere soil enzyme activities in a double-cropping rice field (a) was soil urease; (b) was soil protease; (c) was soil β-glucosaminidase; (d) was soil arginase.

IF: inorganic fertilizer; RF: rice straw and inorganic fertilizer; OM: 30% organic manure and 70% inorganic fertilizer; CK: without any fertilizer input as a control.

Different lowercase letters indicated significant differences at p < 0.05 among different fertilizer treatments.

Figure 2. Effects of different long-term fertilizer treatments on rhizosphere soil relative abundances of Proteobacteria, Acidobacteria and Actinobacteria in the double-cropping rice fields (a) was Proteobacteria; (b) was Acidobacteria; (c) was Actinobacteria.

IF: inorganic fertilizer; RF: rice straw and inorganic fertilizer; OM: 30% organic manure and 70% inorganic fertilizer; CK: without any fertilizer input as a control.

Different lowercase letters indicated significant differences at p < 0.05 among different fertilizer treatments.

Table 2. Effects of different long-term fertilizer treatments on abundance of sub, npr, chiA and ureC in rhizosphere soil under the double-cropping rice system.

Abundance of genes	Treatments
	IF	RF	OM	CK
sub (copies × 10^7 cells g^−1 soil)	2.87 ± 0.11b	3.73 ± 0.11a	3.96 ± 0.08a	2.35 ± 0.06c
npr (copies × 10^5 cells g^−1 soil)	2.48 ± 0.07b	2.77 ± 0.08a	2.95 ± 0.08a	2.24 ± 0.07b
chiA (copies × 10^8 cells g^−1 soil)	2.55 ± 0.07b	2.86 ± 0.08a	3.01 ± 0.07a	2.21 ± 0.06c
ureC (copies × 10^7 cells g^−1 soil)	8.79 ± 0.31b	9.64 ± 0.27b	10.74 ± 0.25a	7.69 ± 0.22c

IF: inorganic fertilizer; RF: rice straw and inorganic fertilizer; OM: 30% organic manure and 70% inorganic fertilizer; CK: without any fertilizer input as a control.

sub: subtilisin; npr: neutral metalloprotease; chiA: chitinase; ureC: urease.

Figure 3. Effects of different long-term fertilizer treatments on alpha diversity of rhizosphere soil bacterial community in the double-cropping rice fields (a) was Chao 1; (b) was observed OTUs; (c) was Shannon.

IF: inorganic fertilizer; RF: rice straw and inorganic fertilizer; OM: 30% organic manure and 70% inorganic fertilizer; CK: without any fertilizer input as a control.

Different lowercase letters indicated significant differences at p < 0.05 among different fertilizer treatments.

Figure 4. Nonmetric multidimensional scaling (NMDS) ordination (stress = 0.1) of the weighted UniFrac distance for rhizosphere soil bacterial community with different long-term fertilizer treatments.

IF: inorganic fertilizer; RF: rice straw and inorganic fertilizer; OM: 30% organic manure and 70% inorganic fertilizer; CK: without any fertilizer input as a control.

Figure 5. Log₂-fold change in relative abundance of OTUs compared with those of the control treatment in rhizosphere soil.

IF: inorganic fertilizer; RF: rice straw and inorganic fertilizer; OM: 30% organic manure and 70% inorganic fertilizer.

Each circle represents a single OTU with an adjusted p value of < 0.1.

Figure 6. Effects of different long-term fertilizer treatments on relative abundance of rhizosphere soil bacterial community in the double-cropping rice fields (a) relative abundances of the dominant phyla (>1%) for bacterial ureC. (b) Nonmetric multidimensional scaling (NMDS) ordination (stress = 0.09) of the weighted UniFrac distance for bacterial ureC under four fertilizer treatments. (c) Relative abundances of the dominant phyla (>1%) for bacterial chiA. (d) Nonmetric multidimensional scaling (NMDS) ordination (stress = 0.05) of the weighted UniFrac distance for bacterial chiA under four fertilizer treatments.

IF: inorganic fertilizer; RF: rice straw and inorganic fertilizer; OM: 30% organic manure and 70% inorganic fertilizer; CK: without any fertilizer input as a control.

Figure 7. Maximum-likelihood tree of top 50 most abundant partial ureC OTUs.

Different branches indicated different phyla of ureC.

Figure 8. Maximum-likelihood tree of top 50 most abundant partial chiA OTUs.

Different branches indicated different phyla of chiA.