Effects of antimony on the soil enzymes, microbial, and rhizobial activity of legumes

Figures & data

Table 1. Basic physicochemical properties of test soil.

Physicochemical properties	Results
Soil type	Loam
pH	7.7
Sand	7%
Clay	40%
Silt	53%
Cation exchange capacity	8 cmol·kg^−1
Total organic content	19.20 g·kg^−1
Electrical conductivity	269 μs·cm^−1
Available phosphorus	56.7 mg·kg^−1
Total K	175.45 mg·kg^−1
Total Ca	6.04 g·kg^−1
Total Mg	1.01 g·kg^−1
Total Zn	11.57 mg·kg^−1
Total Fe	5.25 g·kg^−1
Total Cu	0.78 mg·kg^−1

Figure 1. Effects of Sb³⁺ on soil enzyme activity. Note a sucrase activity sucrase activity was expressed as milligrams of 1 g of soil glucose after 24 h); b Catalase promotes (Catalase activity was expressed as milliliters of 0.02 mol/L potassium permanganate consumed by lg soil); c urease activity (urease activity was expressed as milligrams of NH₃-N in lg soil after 24 h).

Figure 2. Effects of Sb³⁺ on soil nitrogen content. Note. a total nitrogen content in soil (mg·kg⁻¹); b ammonia nitrogen content in soil (mg·kg⁻¹).

Table 2. Physical indicators of mung bean root nodules.

	Soil Sb concentration (mg·kg^−1)	Average mass (g)	Average diameter (mm)	Bacterial count of plate coating culture
Sb^3+	0	0.0551 ± 0.0037	1.56 ± 0.071	16
	100	0.0478 ± 0.0067	1.53 ± 0.057	14
	200	0.0428 ± 0.0068	1.49 ± 0.069	12
	400	0.0434 ± 0.0092	1.49 ± 0.083	11
Sb^5+	0	0.0551 ± 0.0037	1.56 ± 0.071	16
	100	0.0466 ± 0.0034	1.52 ± 0.074	14
	200	0.0438 ± 0.0046	1.42 ± 0.058	14
	400	0.0442 ± 0.0084	1.40 ± 0.048	12
Sb^3++ Sb^5+	0	0.0551 ± 0.0037	1.56 ± 0.071	16
	50 + 50	0.0459 ± 0.0055	1.52 ± 0.067	15
	100 + 100	0.0471 ± 0.0039	1.44 ± 0.064	13
	200 + 200	0.0433 ± 0.0066	1.42 ± 0.049	12

Table 3. Physical indicators of kidney bean root nodules.

	Soil Sb concentration (mg·kg^−1)	Average mass (g)	Average diameter (mm)	Bacterial count of plate coating culture
Sb^3+	0	0.0511 ± 0.0052	1.67 ± 0.088	14
	100	0.0405 ± 0.0065	1.59 ± 0.047	14
	200	0.0396 ± 0.0058	1.52 ± 0.038	12
	400	0.0338 ± 0.0073	1.51 ± 0.054	10
Sb^5+	0	0.0511 ± 0.0052	1.67 ± 0.088	14
	100	0.0408 ± 0.0081	1.62 ± 0.066	13
	200	0.0395 ± 0.0053	1.58 ± 0.074	10
	400	0.0366 ± 0.0034	1.55 ± 0.051	10
Sb^3++ Sb^5+	0	0.0511 ± 0.0052	1.67 ± 0.088	14
	50 + 50	0.0432 ± 0.0077	1.62 ± 0.094	13
	100 + 100	0.0407 ± 0.0038	1.58 ± 0.038	13
	200 + 200	0.0353 ± 0.0054	1.53 ± 0.067	11

Table 4. Physical indicators of peanut root nodules.

	Soil Sb concentration (mg·kg^−1)	Average mass (g)	Average diameter (mm)	Bacterial count of plate coating culture
Sb^3+	0	0.0651 ± 0.0044	1.92 ± 0.053	18
	100	0.0604 ± 0.0022	1.85 ± 0.077	15
	200	0.0573 ± 0.0065	1.81 ± 0.039	12
	400	0.0411 ± 0.0084	1.79 ± 0.082	11
Sb^5+	0	0.0651 ± 0.0044	1.92 ± 0.053	18
	100	0.0618 ± 0.0088	1.83 ± 0.042	16
	200	0.0568 ± 0.0047	1.77 ± 0.088	13
	400	0.0427 ± 0.0063	1.75 ± 0.091	12
Sb^3++ Sb^5+	0	0.0651 ± 0.0044	1.92 ± 0.053	18
	50 + 50	0.0528 ± 0.0074	1.85 ± 0.067	15
	100 + 100	0.0469 ± 0.0031	1.79 ± 0.057	12
	200 + 200	0.0375 ± 0.0056	1.76 ± 0.085	10

Figure 3. Effects of Sb³⁺ on rhizobium activity. Note a mung bean’s rhizobium activity (rhizobium activity was calculated as C₂H₄ content consumed per minute, **: p < 0.01); b kidney bean’s rhizobium activity; c peanut’s rhizobium activity.

Figure 4. Statistical chart of the number of microbial taxonomic units at each level. Note. Sb0 represents CK, Sb1 represents soil with added Sb⁵⁺, and Sb2 represents soil with added Sb³⁺.

Table 5. Statistical table of the number of microbial taxonomic units at each level.

ID	phylum	class	order	family	genus	species
A0 (CK)	22	68	144	221	326	50
A1 (200 mg·kg^−1 Sb^5+)	21	66	140	207	283	47
A2 (200 mg·kg^−1 Sb^3+)	24	68	142	207	303	49

Figure 5. Venn diagram of the sample (group) ASV/OUT.

Figure 6. Abundance grade graph.

Figure 7. Heat map of species composition at the genus level for species clustering.

Figure 8. Heat map of species composition at the genus level for biclustering.

Figure 9. Bar chart of species composition. Note Sb0 represents CK, Sb1 represents soil with added Sb⁵⁺, and Sb2 represents soil with added Sb³⁺.

Figure 9. (Continued).

Figure 9. (Continued).