Effects of substituting mineral nitrogen fertilizer with organic manure on nitrogen transformations and nitrous oxide emissions from tobacco (<i>Nicotiana tabacum</i> L.) fields

Bingxue Wang; Xiaopeng Deng; Zhonglong Wang; Bin Wang; Ruibao Wang; Yali Zhang; Zhengqin Xiong; Bingxue Wang; Xiaopeng Deng; Zhonglong Wang; Bin Wang; Ruibao Wang; Yali Zhang; Zhengqin Xiong

doi:10.48130/nc-0026-0008

Figures (4) Tables (2)

Figure 1.
(a) N₂O fluxes, and (b) cumulative N₂O emissions via four pathways in tobacco fields under organic substitution treatments. SN: synthesized chemical fertilizer; NC: commercial organic manure substituting 15% synthesized N; NF: farmyard manure substituting 15% synthesized N; NT: bio-organic (Trichoderma viride Pers.) manure substituting 15% synthesized N. Significant differences among treatments are denoted by different letters (one-way ANOVA, Duncan's multiple range test, p < 0.05).
Figure 2.
N₂O emission pathways and their average contributions in tobacco fields under organic substitution treatments. SN: synthesized chemical fertilizer; NC: commercial organic manure substituting 15% synthesized N; NF: farmyard manure substituting 15% synthesized N; NT: bio-organic (Trichoderma viride Pers.) manure substituting 15% synthesized N.
Figure 3.
Log₁₀-transformed gene copy numbers of soil functional genes (AOA-amoA, AOB-amoA, nirS, nirK, fungal-nirK, nosZI, and nosZII) after 144 h of incubation under different organic substitution treatments. SN: synthesized chemical fertilizer; NC: commercial organic manure substituting 15% synthesized N; NF: farmyard manure substituting 15% synthesized N; NT: bio-organic (Trichoderma viride Pers.) manure substituting 15% synthesized N. Significant differences among treatments are denoted by different letters (one-way ANOVA, Duncan's multiple range test, p < 0.05).
Figure 4.
Heatmap of Pearson's correlation matrix between soil biochemical characteristics and gross NH₄⁺ and NO₃⁻ (a) production and consumption rates, and (b) cumulative N₂O emissions via pathways in tobacco soils. SN: synthesized chemical fertilizer; NC: commercial organic manure substituting 15% synthesized N; NF: farmyard manure substituting 15% synthesized N; NT: bio-organic (Trichoderma viride Pers.) manure substituting 15% synthesized N. * indicates significance at p < 0.05; ** indicates significance at p < 0.01; *** indicates significance at p < 0.001.

Treatment	pH	SOC (g kg⁻¹)	TN (g kg⁻¹)	C/N ratio	DOC (mg kg⁻¹)	DON (mg kg⁻¹)
SN	5.87 ± 0.02^a	20.05 ± 2.25^b	1.44 ± 0.09^b	15.42 ± 2.06^ab	21.29 ± 1.06^b	24.37 ± 1.67^a
NC	6.41 ± 0.50^a	22.83 ± 0.99^ab	1.80 ± 0.16^a	12.78 ± 1.44^b	25.68 ± 0.13^ab	28.93 ± 4.48^a
NF	6.45 ± 0.49^a	23.57 ± 2.08^ab	1.42 ± 0.05^b	16.56 ± 1.33^a	28.73 ± 1.06^a	27.62 ± 0.58^a
NT	6.33 ± 0.52^a	25.79 ± 0.20^a	1.99 ± 0.14^a	13.03 ± 0.84^b	25.54 ± 4.26^ab	25.98 ± 0.58^a
pH: soil potential of hydrogen; SOC: soil organic carbon; TN: total nitrogen; C/N ratio: SOC/TN ratio; DOC: dissolved organic carbon; DON: dissolved organic nitrogen; SN: synthesized chemical fertilizer; NC: commercial organic manure substituting 15% synthesized N; NF: farmyard manure substituting 15% synthesized N; NT: bio-organic (Trichoderma viride Pers.) manure substituting 15% synthesized N. Significant differences among treatments are denoted by different letters (one-way ANOVA, Duncan's multiple range test, p < 0.05).

Table 1.

Soil physicochemical characteristics (mean ± SD) under different organic substitution treatments

N transformation rate	SN (mg N kg⁻¹ soil d⁻¹)	Contribution	NC (mg N kg⁻¹ soil d⁻¹)	Contribution	NF (mg N kg⁻¹ soil d⁻¹)	Contribution	NT (mg N kg⁻¹ soil d⁻¹)	Contribution
Gross NO₃⁻ production	6.00 ± 0.04^d		6.43 ± 0.14^c		7.43 ± 0.13^a		7.21 ± 0.04^b
Autotrophic nitrification	3.90 ± 0.13^c	65.0%	4.07 ± 0.02^c	63.4%	4.68 ± 0.14^b	63.0%	5.39 ± 0.01^a	74.8%
Heterotrophic nitrification	2.10 ± 0.17^c	35.0%	2.35 ± 0.15^b	36.6%	2.74 ± 0.07^a	37.0%	1.82 ± 0.03^d	25.2%
Gross NO₃⁻ consumption	2.88 ± 0.05^b		3.14 ± 0.10^b		3.18 ± 0.38^b		3.58 ± 0.01^a
DNRA	0.32 ± 0.08^c	11.1%	0.47 ± 0.05^b	15.1%	0.52 ± 0.03^b	16.5%	1.25 ± 0.02^a	34.9%
NO₃⁻ immobilization	2.54 ± 0.04^a	88.1%	1.82 ± 0.10^c	57.8%	2.19 ± 0.05^b	68.7%	2.27 ± 0.05^b	63.3%
Gross NH₄⁺ production	0.88 ± 0.04^d		1.21 ± 0.04^b		1.01 ± 0.03^c		1.37 ± 0.01^a
DNRA	0.32 ± 0.08^c	36.4%	0.47 ± 0.05^b	39.3%	0.52 ± 0.03^b	51.8%	1.25 ± 0.02^a	90.9%
Mineralization	0.56 ± 0.04^b	63.6%	0.73 ± 0.03^a	60.7%	0.49 ± 0.06^c	48.2%	0.13 ± 0.00^d	9.1%
Gross NH₄⁺ consumption	6.14 ± 0.10^d		6.50 ± 0.03^c		6.96 ± 0.02^a		6.81 ± 0.02^b
Autotrophic nitrification	3.89 ± 0.14^c	63.5%	4.07 ± 0.02^c	62.6%	4.68 ± 0.14^b	67.3%	5.39 ± 0.01^a	79.2%
NH₄⁺ immobilization	1.30 ± 0.03^a	21.0%	1.16 ± 0.12^ab	17.9%	1.07 ± 0.05^b	15.4%	1.17 ± 0.04a^b	17.2%
Nitrate nitrogen: NO₃⁻; ammonium nitrogen: NH₄⁺; dissimilatory nitrate reduction to ammonium: DNRA; SN: synthesized chemical fertilizer; NC: commercial organic manure substituting 15% synthesized N; NF: farmyard manure substituting 15% synthesized N; NT: bio-organic (Trichoderma viride Pers.) manure substituting 15% synthesized N. Significant differences among treatments are denoted by different letters (one-way ANOVA, Duncan's multiple range test, p < 0.05).

Table 2.

The average gross NH₄⁺ and NO₃⁻ production and consumption rates, along with their percentage contributions to the total N pool production or consumption, under different organic substitution treatments at incubation times ranging from 0.5 to 144 h