Waste sulfur from biogas desulphurization: a supplement of Brassica napus L. nutrition

Figures & data

Table 1. Agrochemical properties of soil used in both experiments.

Soil parameter	Value	References
pH (CaCl2)	6.09	Zbíral, Malý, and Váňa (2011)
Soil oxidizable carbon (Cox)	0.80%
Clay	20%
Silt	27%
Sand	53%
Bulk density	1.28 g cm^-3
Cation Exchange Capacity	164 mmol kg^-1
N total	0.19%
N-NH4 (K2SO4)	1.48 mg kg^-1
N-NO3 (K2SO4)	17.2 mg kg^-1
S (water soluble)	8 mg kg^-1
P	36.4 mg kg^-1	Mehlich (1984)
K	400 mg kg^-1
Ca	2720 mg kg^-1
Mg	214 mg kg^-1
B	0.42 mg kg^-1	Berger and Truog (1939)
Mn	15.7 mg kg^-1	Lindsay and Norvell (1978)
Zn	1.25 mg kg^-1
Cu	0.65 mg kg^-1

Table 2. Experimental treatments of waste sulfur in combination with another nutrients.

Pot experiment	Treatment	Waste S (mg pot^−1 S)	B (mg pot^1)	HS (mg pot^−1)	AS		AN (mg pot^−1 N)
					mg pot N^−1	mg pot^−1 S
Plant-growth experiment	Control
	S	0.79
	S + B	0.79	0.01	0.01
	S + B + HS	0.79	0.01	0.01
	S + B + HS + AS	0.59	0.01	0.01	0.18	0.20
	S + B + HS + AN	0.59	0.01	0.01			0.18
Plant-yield experiment	Control
	S	3.16
	S + B	3.16	0.04	0.04
	S + B + HS	3.16	0.04	0.04
	S + B + HS + AS	2.36	0.04	0.04	0.72	0.80
	S + B + HS + AN	2.36	0.04	0.04			0.72

1. unfertilized control (Control), 2. waste elemental sulfur (S), 3. S + boron (B), 4. S + B + humic substances (HS), 5. S + B + HS + ammonium sulfate (AS), 6. S + B + HS + ammonium nitrate (AN).

Figure 1. The average daily temperature (°C) and relative humidity (%) in the vegetation hall during the experiment.

Table 3. The average content of N and S in the plants and their uptake by AGB of 1 plant with the N:S ratio.

Treatment	Average N content (%)	Average S content (%)	N:S ratio	N uptake (mg)	S uptake (mg)
Control	3.55^c ± 0.02	2.31^c ± 0.12	1.53	11	7
S	3.50^c ± 0.04	1.75^d ± 0.18	2.00	15	7
S + B	3.71^c ± 0.03	3.09^b ± 0.36	1.20	11	9
S + B + HS	4.44^b ± 0.19	3.87^a ± 0.30	1.15	16	14
S + B + HS + AS	5.68^a ± 0.55	2.53^c ± 0.14	2.24	40	18
S + B + HS + AN	5.34^a ± 0.42	2.61^c ± 0.18	2.05	35	17

Different letters indicate significant differences p < 0.05 (Fisher’s LSD test); the ± values mean standard deviation; 1. unfertilized control (Control), 2. waste elemental sulfur (S), 3. S + boron (B), 4. S + B + humic substances (HS), 5. S + B + HS + ammonium sulfate (AS), 6. S + B + HS + ammonium nitrate (AN).

Figure 2. The average N-tester values (BBCH 19, October 24, 2019). Columns marked by different letters indicate significant differences p < 0.05 (fisher’s LSD test). The error bars present the mean standard deviation. 1. unfertilized control (control), 2. waste elemental sulfur (S), 3. S + boron (B), 4. S + B + humic substances (HS), 5. S + B + HS + ammonium sulfate (AS), 6. S + B + HS + ammonium nitrate (AN).

Figure 3. The average DM weight of AGB (g 1 plant⁻¹; BBCH 19, October 24, 2019). Columns marked by different letters indicate significant differences p < 0.05 (fisher’s LSD test). The error bars present the mean standard deviation. 1. unfertilized control (control), 2. waste elemental sulfur (S), 3. S + boron (B), 4. S + B + humic substances (HS), 5. S + B + HS + ammonium sulfate (AS), 6. S + B + HS + ammonium nitrate (AN).

Table 4. Average content of nutrients in plants at the start of bud formation (April 14, 2020).

	Ca	P	K	Mg	N	S	B
Treatment	%						mg kg^-1
Control	1.50^a ± 0.07	0.25^a ± 0.02	3.40^ab ± 0.35	0.25^ab ± 0.02	2.43^b ± 0.02	1.46^d ± 0.34	29.5^d ± 1.2
S	1.46^a ± 0.01	0.20^c ± 0.06	2.64^d ± 0.10	0.23^c ± 0.01	2.17^c ± 0.03	1.83^c ± 0.20b	36.1^d ± 0.6
S + B	1.45^a ± 0.14	0.20^bc ± 0.03	2.74^d ± 0.11	0.23^bc ± 0.01	2.14^c ± 0.01	2.12^ab ± 0.09	44.4^c ± 7.1
S + B + HS	1.49^a ± 0.07	0.24^ab ± 0.03	2.81 ^cd ± 0.35	0.25^ab ± 0.01	2.08^c ± 0.02	1.65 ^cd ± 0.10	62.4^ab ± 2.0
S + B + HS + AS	1.50^a ± 0.02	0.31^a ± 0.01	3.67^a ± 0.01	0.26^a ± 0.01	2.77^a ± 0.17	2.24^a ± 0.29	67.7^a ± 5.3
S + B + HS + AN	1.40^a ± 0.03	0.29^a ± 0.01	3.16^bc ± 0.01	0.25^ab ± 0.01	2.54^b ± 0.16	1.02^e ± 0.01	57.2^b ± 1.8

Different letters indicate significant differences p < 0.05 (Fisher’s LSD test); the ± values mean standard deviation;1. unfertilized control (Control), 2. waste elemental sulfur (S), 3. S + boron (B), 4. S + B + humic substances (HS), 5. S + B + HS + ammonium sulfate (AS), 6. S + B + HS + ammonium nitrate (AN).

Figure 4. The average straw yield of oilseed rape (g pot⁻¹) (July 14, 2020). Columns marked by different letters indicate significant differences p < 0.05 (fisher’s LSD test). The error bars present the mean standard deviation. 1. unfertilized control (control), 2. waste elemental sulfur (S), 3. S + boron (B), 4. S + B + humic substances (HS), 5. S + B + HS + ammonium sulfate (AS), 6. S + B + HS + ammonium nitrate (AN).

Figure 5. The average seed yield of oilseed rape (g pot⁻¹) (July 14, 2020). Columns marked by different letters indicate significant differences p < 0.05 (fisher’s LSD test). The error bars present the mean standard deviation. 1. unfertilized control (control), 2. waste elemental sulfur (S), 3. S + boron (B), 4. S + B + humic substances (HS), 5. S + B + HS + ammonium sulfate (AS), 6. S + B + HS + ammonium nitrate (AN).

Table 5. Average post-harvest content of nutrients in straw of rape.

	Ca	P	K	Mg	N	S	B
Treatment	%						mg kg^-1
Control	0.99^a ± 0.33	0.12^a ± 0.05	1.74^b ± 0.06	0.13^a ± 0.07	0.58^a ± 0.24	0.30^b ± 0.08	24.40^c ± 1.4
S	0.90^a ± 0.14	0.07^b ± 0.01	2.03^a ± 0.20	0.09^a ± 0.01	0.32^b ± 0.04	0.39^a ± 0.06	26.93^c ± 4.8
S + B	0.91^a ± 0.14	0.10^ab ± 0.02	2.10^a ± 0.09	0.11^a ± 0.04	0.39^b ± 0.04	0.41^a ± 0.05	39.28^a ± 4.5
S + B + HS	1.02^a ± 0.28	0.09^ab ± 0.03	2.03^a ± 0.14	0.12^a ± 0.04	0.45^ab ± 0.09	0.42^a ± 0.05	40.48^a ± 3.1
S + B + HS + AS	0.87^a ± 0.05	0.09^ab ± 0.01	1.91^ab ± 0.12	0.09^a ± 0.01	0.41^ab ± 0.09	0.37^a ± 0.02	33.96^b ± 3.8
S + B + HS + AN	0.91^a ± 0.06	0.08^b ± 0.01	2.02^a ± 0.09	0.10^a ± 0.01	0.41^ab ± 0.09	0.39^a ± 0.02	37.90^ab ± 1.4

Different letters indicate significant differences p < 0.05 (Fisher’s LSD test); the ± values mean standard deviation; 1. unfertilized control (Control), 2. waste elemental sulfur (S), 3. S + boron (B), 4. S + B + humic substances (HS), 5. S + B + HS + ammonium sulfate (AS), 6. S + B + HS + ammonium nitrate (AN).

Figure 6. The average oil content of oilseed rape (July 14, 2020). Columns marked by different letters indicate significant differences p < 0.05 (fisher’s LSD test). The error bars present the mean standard deviation. 1. unfertilized control (control), 2. waste elemental sulfur (S), 3. S + boron (B), 4. S + B + humic substances (H), 5. S + B + HS + ammonium sulfate (AS), 6. S + B + HS + ammonium nitrate (AN).

Figure 7. The average production of oil (g pot⁻¹) (July 14, 2020). Columns marked by different letters indicate significant differences p < 0.05 (fisher’s LSD test). The error bars present the mean standard deviation. 1. unfertilized control (control), 2. waste elemental sulfur (S), 3. S + boron (B), 4. S + B + humic substances (HS), 5. S + B + HS + ammonium sulfate (AS), 6. S + B + HS + ammonium nitrate (AN).

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Data availability statement

Presented data in this study are available on request from the corresponding author.