Nitrous oxide and carbon dioxide emissions from two types of soil amended with manure compost at different ammonium nitrogen rates

Figures & data

Table 1. Initial properties of two types of soil and compost.

	Soil type		Compost type
	Kochi soil	Ushimado soil	Cattle manure compost	Mixed compost
Total N (g-N kg^−1)	3.9	1.4	16.3	26.0
Total C (g-C kg^−1)	62.6	14.7	301.6	273.3
C/N ratio	15.9	10.2	18.5	10.5
NH4^+-N (mg-N kg^−1)	109.5	9.5	30.5	893.2
NO3^−-N (mg-N kg^−1)	463.7	19.2	18.1	58.6
pH (H2O)	5.5	8.5	9.4	9.2
EC (dS m^−1)	0.8	0.1	7.6	7.5
CEC (cmolc kg^−1)	28.3	7.5	-	-
Texture	Sandy clay loam	Sandy loam	-	-

NH₄⁺-N: Ammonium N content, NO₃⁻-N: Nitrate N content, EC: Electrical conductivity, CEC: Cation exchange capacity

Table 2. Cumulative N₂O and CO₂ emissions in the incubation experiment.

Soil type	Treatment	Cumulative N2O emissions (mg-N kg^−1)			Cumulative CO2 emissions (g-C kg^−1)
		NH4^+-N rates (mg-N kg^−1)
		160	200	400	160	200	400
Kochi	K-	13.6 ± 2.6^g†	121.6 ± 18.1^d	62.8 ± 8.4^e	4.9 ± 0.2^de	5.5 ± 0.5^cd	4.5 ± 0.2^e
	KCC-	24.9 ± 7.5^fg	140.3 ± 10.5^d	46.5 ± 1.2^ef	5.8 ± 0.3^c	6.0 ± 0.1^c	4.3 ± 0.3^e
	KMC-	412.6 ± 3.3^a	260.6 ± 21.1^b	196.0 ± 4.4^c	10.4 ± 0.3^a	10.6 ± 0.9^a	7.8 ± 0.5^b
Ushimado	U-	3.9 ± 0.3^e	30.1 ± 2.1^c	18.9 ± 1.9^d	2.6 ± 0.5^f	2.8 ± 0.2^ef	2.6 ± 0.3^f
	UCC-	11.4 ± 0.3^d	46.7 ± 4.8^b	12.2 ± 2.2^d	3.3 ± 0.4^d	3.3 ± 0.1^d	3.2 ± 0.3^ed
	UMC-	58.7 ± 6.5^a	54.0 ± 2.7^ab	49.6 ± 9.2^b	6.6 ± 0.3^a	5.7 ± 0.1^b	4.9 ± 0.1^c

^†Means with the same letters are not significantly different at p >0.05 within the same soil type × gas.

K: No compost-amended Kochi soil, KCC: Cattle manure compost-amended Kochi soil, KMC: Mixed compost-amended Kochi soil, U: No compost-amended Ushimado soil, UCC: Cattle manure compost-amended Ushimado soil, and UMC: Mixed compost-amended Ushimado soil. The numbers (160, 200, and 400) indicate NH₄⁺-N application rates to soil (mg-N kg⁻¹).

Table 3. Responses of cumulative N₂O and CO₂ emissions to compost type, soil type, and NH₄⁺-N rates by three-way ANOVA.

Factor	Cumulative N2O emissions	Cumulative CO2 emissions
	p	p
Compost type	4.63×10^−13	<2×10^−16
Soil type	9.23×10^−13	<2×10^−16
NH4^+-N rates	0.0119	2.02×10^−11
Compost type×Soil type	2.79×10^−9	7.09×10^−8
Compost type×NH4^+-N rates	0.0076	4.25×10^−6
Soil type×NH4^+-N rates	0.0309	2.24×10^−5
Compost type×Soil type×NH4^+-N rates	0.014	0.31

Figure 1. N₂O emissions in the incubation experiment.The left (a)–(c) show results for Kochi soil (K) and the right (d)–(f) do for Ushimado soil (U). The upper (a) and (d) show results for no compost-, the middle (b) and (e) for cattle manure compost (CC)-, and the lower (c) and (f) for mixed compost (MC)-amended soils. The numbers (160, 200, and 400) indicate NH₄⁺-N application rates to soil (mg-N kg⁻¹). Error bars indicate ± standard deviation (n=3).

Figure 2. CO₂ emissions in the incubation experiment.The left (a)–(c) show results for Kochi soil (K) and the right (d)–(f) do for Ushimado soil (U). The upper (a) and (d) show results for no compost-, the middle (b) and (e) for cattle manure compost (CC)-, and the lower (c) and (f) for mixed compost (MC)-amended soils. The numbers (160, 200, and 400) indicate NH₄⁺-N application rates to soil (mg-N kg⁻¹). Error bars indicate ± standard deviation (n=3).

Figure 3. NH₄⁺-N contents in the incubation experiment.The left (a)–(c) show results for Kochi soil (K) and the right (d)–(f) do for Ushimado soil (U). The upper (a) and (d) show results for no compost-, the middle (b) and (e) for cattle manure compost (CC)-, and the lower (c) and (f) for mixed compost (MC)-amended soils. The numbers (160, 200, and 400) indicate NH₄⁺-N application rates to soil (mg-N kg⁻¹). Error bars indicate ± standard deviation (n=3).

Figure 4. NO₃⁻-N contents in the incubation experiment.The left (a)–(c) show results for Kochi soil (K) and the right (d)–(f) do for Ushimado soil (U). The upper (a) and (d) show results for no compost-, the middle (b) and (e) for cattle manure compost (CC)-, and the lower (c) and (f) for mixed compost (MC)-amended soils. The numbers (160, 200, and 400) indicate NH₄⁺-N application rates to soil (mg-N kg⁻¹). Error bars indicate ± standard deviation (n=3).

Figure 5. pH (H₂O) values in the incubation experiment.The left (a)–(c) show results for Kochi soil (K) and the right (d)–(f) do for Ushimado soil (U). The upper (a) and (d) show results for no compost-, the middle (b) and (e) for cattle manure compost (CC)-, and the lower (c) and (f) for mixed compost (MC)-amended soils. The numbers (160, 200, and 400) indicate NH₄⁺-N application rates to soil (mg-N kg⁻¹). Error bars indicate ± standard deviation (n=3).

Figure 6. Electrical conductivity values in the incubation experiment.The left (a)–(c) show results for Kochi soil (K) and the right (d)–(f) do for Ushimado soil (U). The upper (a) and (d) show results for no compost-, the middle (b) and (e) for cattle manure compost (CC)-, and the lower (c) and (f) for mixed compost (MC)-amended soils. The numbers (160, 200, and 400) indicate NH₄⁺-N application rates to soil (mg-N kg⁻¹). Error bars indicate ± standard deviation (n=3).

Figure 7. Cumulative N₂O emissions until day 7 or 21, narG, and nosZ gene copy numbers in the incubation experiment.The left (a)–(c) show results for Kochi soil (K) and the right (d)–(f) do for Ushimado soil (U). The upper (a) and (d) show results for no compost-, the middle (b) and (e) for cattle manure compost (CC)-, and the lower (c) and (f) for mixed compost (MC)-amended soils. The numbers (160, 200, and 400) indicate NH₄⁺-N application rates to soil (mg-N kg⁻¹). Error bars indicate ± standard deviation (n=3).

^†Means of N₂O emissions or each gene type with the same letters are not significantly different within the same treatment across NH₄⁺-N rates (p >0.05). In the original Kochi soil, narG and nosZ gene copy numbers were 0.13×10¹⁴ and 0.22×10¹⁴ copies g⁻¹ dry soil, respectively. In the original Ushimado soil, narG and nosZgene copy numbers were 0.91×10¹⁴ and 0.19×10¹⁴ copies g⁻¹ dry soil, respectively.

Figure 8. Relationship between cumulative N₂O emissions until day 7 and copy numbers of the narG gene in Kochi soil treatments.