Urease and β-glucosidase activity enhanced the transformation of functional groups of humin amended by straw and straw-derived biochar

Chemical and Biological Technologies in Agriculture

Table 2 Relative distribution (%) of signal area over chemical shift regions (ppm) in CPMAS ¹³C NMR spectra of Hu incubated for 180 days

Treatments	160–190	145–160	110–145	60–110	45–60	0–45	Aromaticity (%)^a	Aliphaticity (%)^b	Hydrophobicity^c
Tobacco straw biochar	0	0	95.24	0	0	4.76	95.24	4.76	0
Tobacco straw	4.51	7.54	6.64	69.48	7.31	4.51	14.85	4.73	0.23
Wheat straw biochar	0	0	93.46	0	0	6.54	93.46	6.54	0
Wheat straw	3.30	4.30	3.64	75.55	6.15	7.07	8.21	7.31	0.18
Soil CA
Control	1.05	0	2.94	0.18	5.42	90.42	2.97	91.37	14.05
TB	0.20	0	64.70	4.09	0	31.00	64.83	31.06	22.28
WB	0.11	0	68.75	1.35	1.08	28.70	68.83	28.73	38.23
TS	1.77	4.97	14.78	33.99	6.08	38.41	20.10	39.10	0.49
WS	2.18	2.34	7.23	42.24	7.34	38.68	9.78	39.54	0.89
Soil UV
Control	10.98	3.40	25.58	22.94	4.83	32.27	32.55	36.25	1.49
TB	1.16	0	68.68	24.48	0	5.68	69.49	5.74	2.90
WB	2.35	0	76.55	5.69	0	15.42	78.39	15.79	11.44
TS	5.90	7.01	14.18	43.11	7.33	22.47	22.52	23.88	0.65
WS	6.43	6.24	11.06	51.70	5.40	19.16	18.49	20.48	0.48
Soil UA
Control	4.21	2.82	16.00	27.54	9.64	39.79	19.65	41.54	1.35
TB	2.82	0	62.92	7.20	1.04	26.02	64.75	26.77	8.04
WB	7.36	0	49.63	16.49	2.36	24.15	53.58	26.07	2.81
TS	6.77	6.70	12.12	38.52	9.75	26.13	20.19	28.03	0.69
WS	7.31	6.14	11.55	43.71	6.36	24.93	19.09	26.89	0.64

^aAromaticity is calculated as follows: aromaticity = aromatic C/(aromatic C + o-alkyl C + alkyl C × 100
^bAliphaticity is calculated as follows: aromaticity = alkyl C/(aromatic C+O-alkyl C+alkyl C)×100
^cHydrophobicity is calculated as follows: hydrophobicity = (aromatic C+ alkyl C)/(carboxyl C+ O-alkyl C+ methoxyl C)