Table 1 Physicochemical properties of wheat straw and dairy manure biochars (500 °C and 700 °C) after oxidation.

Wheat straw

500 °C

CK

63.60 ± 1.87^a

3.12 ± 0.31^a

10.99 ± 2.02^c

0.59 ± 0.05^b

0.13 ± 0.03^c

17.40 ± 0.80^c

21.59 ± 2.63^b

61.01 ± 1.87^ab

73.68 ± 5.57^e

5%

64.69 ± 1.02^a

3.46 ± 0.01^a

13.85 ± 1.04^bc

0.64 ± 0.01^ab

0.16 ± 0.01^bc

21.54 ± 1.70^b

17.51 ± 0.63^b

60.95 ± 1.30^ab

380.69 ± 6.98^d

10%

65.18 ± 0.50^a

3.51 ± 0.01^a

13.96 ± 0.50^bc

0.65 ± 0.00^ab

0.16 ± 0.01^bc

21.56 ± 0.96^b

16.84 ± 2.74^b

61.59 ± 1.80^a

470.49 ± 7.14^d

15%

62.51 ± 0.21^a

3.10 ± 0.04^a

17.71 ± 0.23^ab

0.60 ± 0.01^b

0.21 ± 0.00^b

23.32 ± 0.66^b

16.16 ± 2.28^b

60.52 ± 1.74^ab

600.89 ± 26.51^c

20%

61.27 ± 0.97^a

3.10 ± 0.04^a

15.73 ± 0.98^b

0.61 ± 0.00^b

0.19 ± 0.01^bc

25.33 ± 0.13^b

19.60 ± 2.29^b

55.06 ± 2.37^b

1906.42 ± 40.24^b

30%

37.96 ± 1.32^b

2.13 ± 0.07^b

20.14 ± 1.36^a

0.67 ± 0.00^a

0.40 ± 0.04^a

29.25 ± 1.46^a

40.09 ± 2.43^a

30.67 ± 1.41^c

2116.45 ± 68.17^a

700 °C

CK

67.25 ± 0.61^a

1.89 ± 0.01^b

10.02 ± 0.60^ab

0.34 ± 0.00^d

0.11 ± 0.01^ab

12.48 ± 0.42^b

20.40 ± 1.41^a

67.13 ± 1.83^a

41.48 ± 3.04^e

5%

69.52 ± 0.32^a

2.00 ± 0.03^a

5.99 ± 0.36^c

0.35 ± 0.00^cd

0.06 ± 0.00^c

12.08 ± 0.14^b

22.06 ± 1.66^a

65.86 ± 1.52^a

72.28 ± 4.87^d

10%

68.14 ± 1.34^a

2.00 ± 0.04^a

9.63 ± 1.36^ab

0.35 ± 0.00^bc

0.11 ± 0.02^ab

13.67 ± 0.91^ab

19.83 ± 3.23^a

66.51 ± 2.88^a

86.64 ± 6.02^cd

15%

68.50 ± 0.24^a

2.06 ± 0.01^a

8.31 ± 0.23^bc

0.36 ± 0.00^ab

0.09 ± 0.00^bc

13.96 ± 0.54^ab

20.78 ± 0.31^a

65.27 ± 0.28^a

100.22 ± 4.43^bc

20%

68.22 ± 0.53^a

2.05 ± 0.02^a

9.35 ± 0.54^ab

0.36 ± 0.00^ab

0.10 ± 0.01^ab

14.65 ± 0.78^a

20.03 ± 2.68^a

65.32 ± 1.94^a

114.98 ± 4.55^b

30%

65.15 ± 0.36^b

2.00 ± 0.01^a

10.87 ± 0.36^a

0.37 ± 0.00^a

0.13 ± 0.00^a

15.77 ± 0.56^a

21.76 ± 2.51^a

62.47 ± 1.96^a

146.57 ± 5.51^a

Dairy manure

500 °C

CK

46.82 ± 1.43^a

2.56 ± 0.22^a

12.44 ± 1.58^ab

0.66 ± 0.05^c

0.20 ± 0.03^c

18.96 ± 0.88^b

37.56 ± 1.08^b

43.48 ± 1.04^a

77.09 ± 5.25^e

5%

46.79 ± 2.07^a

2.69 ± 0.37^a

10.39 ± 2.33^b

0.69 ± 0.08^c

0.17 ± 0.04^c

18.30 ± 0.76^b

39.68 ± 3.92^b

42.02 ± 3.17^ab

386.75 ± 3.71^d

10%

46.55 ± 1.01^a

2.90 ± 0.09^a

11.08 ± 1.12^b

0.75 ± 0.01^bc

0.18 ± 0.02^c

20.35 ± 1.49^b

39.24 ± 5.00^b

40.41 ± 3.50^ab

528.97 ± 10.68^d

15%

41.63 ± 1.22^b

2.67 ± 0.09^a

14.18 ± 1.34^ab

0.77 ± 0.00^bc

0.26 ± 0.04^bc

23.06 ± 1.05^ab

41.72 ± 2.25^b

35.21 ± 1.49^b

839.93 ± 17.35^c

20%

36.53 ± 0.58^c

2.52 ± 0.06^a

16.02 ± 0.66^a

0.83 ± 0.01^b

0.33 ± 0.02^b

26.98 ± 0.79^a

45.53 ± 2.40^b

27.50 ± 1.62^c

1317.89 ± 2.53^b

30%

25.18 ± 0.55^d

2.12 ± 0.06^a

16.40 ± 0.63^a

1.01 ± 0.01^a

0.49 ± 0.03^a

27.55 ± 2.38^a

57.60 ± 2.13^a

14.85 ± 0.26^d

4043.7 ± 152.80^a

700 °C

CK

50.18 ± 2.65^a

1.50 ± 0.08^bc

6.86 ± 2.76^a

0.36 ± 0.00^b

0.10 ± 0.05^a

10.00 ± 0.67^b

40.98 ± 3.39^a

49.02 ± 2.82^a

40.56 ± 4.25^a

5%

47.29 ± 0.68^a

1.41 ± 0.01^c

7.26 ± 0.69^a

0.36 ± 0.00^b

0.12 ± 0.01^a

9.46 ± 0.33^b

43.57 ± 3.26^a

46.97 ± 2.96^a

23.45 ± 9.61^a

10%

44.31 ± 1.12^a

1.38 ± 0.10^c

8.40 ± 1.16^a

0.37 ± 0.02^b

0.14 ± 0.02^a

10.04 ± 0.42^b

45.53 ± 3.60^a

44.43 ± 3.24^a

26.15 ± 9.09^a

15%

47.22 ± 1.27^a

1.51 ± 0.02^bc

7.22 ± 1.32^a

0.38 ± 0.00^b

0.12 ± 0.02^a

10.87 ± 0.74^b

43.72 ± 2.25^a

45.41 ± 1.54^a

22.48 ± 3.12^a

20%

48.28 ± 2.05^a

1.69 ± 0.08^ab

6.47 ± 2.12^a

0.42 ± 0.00^a

0.10 ± 0.04^a

11.13 ± 0.47^ab

43.15 ± 2.03^a

45.72 ± 1.61^a

28.01 ± 6.45^a

30%

47.62 ± 1.79^a

1.73 ± 0.06^a

9.56 ± 1.88^a

0.44 ± 0.00^a

0.15 ± 0.04^a

12.85 ± 0.57^a

40.91 ± 2.46^a

46.24 ± 2.02^a

28.55 ± 3.91^a