Determining farm-scale site-specific monetary values of “soil carbon hotspots” based on avoided social costs of CO₂ emissions

Figures & data

Figure 1. The building blocks of a systems approach to describing atmosphere and pedosphere ecosystem services exchange (based on Groshans et al., 2019) from which agriculture (e.g., farms etc.) receives ecosystem services (e.g., provisioning: food, fiber etc.) flows, and transforms them into various commodities with identified market value. This transformation can be accompanied by greenhouse gas emissions (e.g., CO₂ etc.), which can be valued based on social costs of carbon dioxide emissions (SC-CO₂).

Table 1. Example of agricultural users, scale of use, and probable uses of SC-CO₂ values associated with soil organic carbon (SOC), soil inorganic carbon (SIC), and total soil carbon (TSC) in relation to Sustainable Development Goals (SDGs) (based on Tugel et al., 2005)

User	Scale of use	Probable uses
Agricultural producers	Field, farm or ranch, watershed	- Minimize negative environmental impacts.
		- Manage for short-term economic profit and long-term sustainability (cost-benefit analysis etc.).

Figure 2. The “soil carbon hotspot” concept—an intersection between high soil carbon and disturbance (based on Bétard & Peulvast, 2019).

Table 2. Soil types within Willsboro Farm, Willsboro, NY

Soil order/Soil series	Taxonomic class	Map unit symbol	Total area (m^2)
Slight weathering
Entisols			378,691
Claverack loamy fine sand, 3% to 8% slopes	Sandy over clayey, mixed, superactive, nonacid, mesic Aquic Udorthents	CqB	64,230
Cosad loamy fine sand, 0% to 3% slopes	Sandy over clayey, mixed, superactive, nonacid, mesic Aquic Udorthents	CuA	168,530
Deerfield loamy sand, 0% to 3% slopes	Mixed, mesic Aquic Udipsamments	DeA	331
Stafford fine sandy loam, 0% to 3% slopes	Mixed, mesic Typic Psammaquents	StA	145,600
Inceptisols			157,764
Amenia fine sandy loam, 2% to 8% slopes	Coarse-loamy, mixed, active, mesic Aquic Eutrudepts	AmB	3,185
Massena gravelly silt loam, 3% to 8% slopes	Coarse-loamy, mixed, active, nonacid, mesic Aeric Endoaquepts	McB	8,479
Nellis fine sandy loam, 3% to 8% slopes	Coarse-loamy, mixed, superactive, mesic Typic Eutrudepts	NeB	39,030
Nellis fine sandy loam, 8% to 15% slopes	Coarse-loamy, mixed, superactive, mesic Typic Eutrudepts	NeC	107,070
Intermediate weathering
Alfisols			937,940
Bombay gravelly loam, 3% to 8% slopes	Coarse-loamy, mixed, active, mesic Oxyaquic Hapludalfs	BoB	270,615
Churchville loam, 2% to 8% slopes	Fine, illitic, mesic Aeric Endoaqualfs	CpB	36,900
Covington clay, 0% to 3% slopes	Very-fine, mixed, active, mesic Mollic Endoaqualfs	CvA	49,076
Howard gravelly loam, 2% to 8% slopes	Loamy-skeletal, mixed, active, mesic Glossic Hapludalfs	HgB	58,680
Kingsbury silty clay loam, 0% to 3% slopes	Very-fine, mixed, active, mesic Aeric Endoaqualfs	KyA	480,679
Kingsbury silty clay loam, 3% to 8% slopes	Very-fine, mixed, active, mesic Aeric Endoaqualfs	KyB	41,990
Totals			1,474,395

Figure 3. Map of Willsboro Farm, Willsboro, NY (Essex County) with the following soil types: Entisols (Claverack loamy fine sand, 3% to 8% slopes, CqB; Cosad loamy fine sand, 0% to 3% slopes, CuA; Deerfield loamy sand, 0% to 3% slopes, DeA; Stafford fine sandy loam, 0% to 3% slopes, StA), Inceptisols (Amenia fine sandy loam, 2% to 8% slopes, AmB; Massena gravelly silt loam, 3 to 8% slopes, McB; Nellis fine sandy loam, 3% to 8% slopes, NeB; Nellis fine sandy loam, 8% to 15% slopes, NeC), and Alfisols (Bombay gravelly loam, 3% to 8% slopes, BoB; Churchville loam, 2% to 8% slopes, CqB; Covington clay, 0% to 3% slopes, CvA; Howard gravelly loam, 2% to 8% slopes, HgB; Kingsbury silty clay loam, 0% to 3% slopes, KyA; Kingsbury silty clay loam, 3% to 8% slopes, KyB).

Table 3. A conceptual overview of the accounting framework used in this study (adapted from Groshans et al., 2019)

Biophysical accounts (Science-based)	Administrative accounts (Boundary-based)	Monetary account(s)	Benefit(s)	Total value
Soil extent:	Administrative extent:	Ecosystem good(s) and service(s):	Sector:	Types of value:
Separate constitute stock 1: Soil organic carbon (SOC)
Separate constitute stock 2: Soil inorganic carbon (SIC)
Composite (total) stock: Total soil carbon (TSC) = SOC + SIC
			Environment:	Social cost of carbon (SC-CO2) and avoided emissions:
- Soil order - Soil series - Soil depth	- Farm - Soil map unit (SMU)	- Regulating (e.g., carbon sequestration)	- Carbon sequestration	- $42 per metric ton of CO2 (2007 U.S. dollars with an average discount rate of 3% (EPA, 2016))

Table 4. Total and area-normalized monetary values of soil organic carbon (SOC), soil inorganic carbon (SIC), and total soil carbon (TSC) storage by soil type and soil order from SSURGO (2015) at the Willsboro Farm (NY), based on a social cost of carbon (SC-CO₂) of $42 per metric ton of CO₂ (EPA, 2016)

		—- Mean SOC—–		——Mean SIC——		—- Mean TSC—-
Soil order/ map unit symbol	Total reported depth (cm)	Total value ($)	Value per area ($ m^−2)	Total value ($)	Value per area ($ m^−2)	Total Value ($)	Value per Area ($ m^−2)
Slight weathering
Entisols (total)	183 ± 0^a	768,460	2.03	523,600	1.38	1,292,060	3.41
CqB	183	106,722	1.66	155,540	2.42	261,800	4.08
CuA	183	338,800	2.01	368,060	2.19	706,860	4.19
DeA	183	650	1.96	0	0	650	1.96
StA	183	321,860	2.21	0	0	321,860	2.21
Inceptisols (total)	183 ± 0	251,020	1.59	562,100	3.57	813,120	5.16
AmB	183	4,528	1.42	14,599	4.59	19,096	6.01
McB	183	21,714	2.56	38,962	4.60	60,676	7.16
NeB	183	60,060	1.54	135,982	3.49	195,580	5.02
NeC	183	164,780	1.54	372,680	3.49	537,460	5.02
Intermediate weathering
Alfisols (total)	201 ± 27	1,503,040	1.60	3,711,400	3.97	5,220,600	5.57
BoB	183	406,560	1.50	896,280	3.31	1,302,840	4.81
CpB	183	63,140	1.71	183,260	4.97	246,400	6.70
CvA	183	146,916	2.99	122,738	2.50	269,500	5.50
HgB	183	55,594	0.95	96,096	1.64	151,844	2.59
KyA	236	763,840	1.59	2,217,600	4.63	2,987,600	6.22
KyB	236	66,682	1.59	194,040	4.63	261,800	6.22
Totals		2,522,520		4,797,100		7,325,780

Note: ^aMean ± standard deviations for the reported depths in the soil order.

Table 5. Total and area-normalized values of soil organic carbon (SOC), soil inorganic carbon (SIC), and total soil carbon (TSC) storage by soil type and soil order from averaged soil core results (original data from Mikhailova et al., 1996) at the Willsboro Farm (NY), based on a social cost of carbon (SC-CO₂) of $42 per metric ton of CO₂ (EPA, 2016)

			——Mean SOC—		——- Mean SIC—–		——Mean TSC—-
Soil order/ map unit symbol	Number of cores	Core depth (cm)	Total value ($)	Value per area ($ m^−2)	Total value ($)	Value per area ($ m^−2)	Total value ($)	Value per area ($ m^−2)
Slight weathering
Entisols (total)	18	84 ± 21^a	531,300	1.40^b	96,250	0.25	626,780	1.66
CqB	4	84 ± 20	114,884	1.79	3,065	0.05	117,964	1.84
CuA	6	83 ± 31	229,460	1.36	90,860	0.54	318,780	1.89
DeA	1	91	691	2.09	0	0	691	2.09
StA	7	85 ± 15	187,880	1.29	2,402	0.02	189,420	1.30
Inceptisols (total)	4	63 ± 33	198,660	1.26	27,720	0.18	226,380	1.43
AmB	n/a^c	n/a	n/a	n/a	n/a	n/a	n/a	n/a
McB	n/a	n/a	n/a	n/a	n/a	n/a	n/a	n/a
NeB	3	74 ± 31	55,440	1.42	25,718	0.66	81,158	2.08
NeC	1	30	128,282	1.20	0	0.00	128,282	1.20
Intermediate weathering
Alfisols (total)	32	84 ± 29	1,516,900	1.62	421,960	0.45	1,940,400	2.07
BoB	10	68 ± 37	269,500	0.99	104,104	0.39	374,220	1.38
CpB	n/a	n/a	n/a	n/a	n/a	n/a	n/a	n/a
CvA	1	92	142,758	2.91	0	0	142,758	2.91
HgB	n/a	n/a	n/a	n/a	n/a	n/a	n/a	n/a
KyA	19	94 ± 19	882,420	1.84	267,960	0.56	1,150,380	2.39
KyB	2	115 ± 5	67,452	1.60	6,175	0.15	73,612	1.75
Totals			2,246,860		545,930		2,793,560

Note: ^aMean ± standard deviations for the reported depths in the soil order. ^bReported value omits areas of SMUs from which no soil cores were taken. ^cn/a: not applicable. No soil core was taken from the specific SMU.

Table 6. Total and area-normalized values of soil organic carbon (SOC), soil inorganic carbon (SIC), and total soil carbon (TSC) storage by soil type and soil order from interpolated soil core results (original data from Mikhailova et al., 1996) at the Willsboro Farm (NY), based on a social cost of carbon (SC-CO₂) of $42 per metric ton of CO₂ (EPA, 2016)

	——Mean SOC—–		——- Mean SIC—–		——Mean TSC—–
Soil order/ map unit symbol	Total value ($)	Value per area ($ m^−2)	Total value ($)	Value per area ($ m^−2)	Total value ($)	Value per Area ($ m^−2)
Slight weathering
Entisols (total)	546,700	1.44	76,230	0.20	622,160	1.64
CqB	108,878	1.69	7,715	0.12	116,424	1.81
CuA	234,080	1.39	61,754	0.37	295,680	1.76
DeA	687	2.07	4	0.01	691	2.09
StA	201,740	1.39	6,730	0.05	209,440	1.43
Inceptisols (total)	209,440	1.33	65,604	0.42	274,120	1.74
AmB	5,544	1.74	2,264	0.71	7,808	2.45
McB	10,734	1.27	1,848	0.22	12,566	1.48
NeB	63,294	1.62	27,258	0.70	90,706	2.32
NeC	129,668	1.21	34,188	0.32	163,240	1.53
Intermediate weathering
Alfisols (total)	1,438,360	1.53	411,180	0.44	1,848,000	1.97
BoB	329,560	1.22	103,334	0.38	432,740	1.60
CpB	65,450	1.77	24,332	0.66	89,474	2.43
CvA	62,986	1.28	35,728	0.73	98,560	2.01
HgB	73,150	1.25	715	0.12	79,926	1.36
KyA	848,540	1.76	231,000	0.48	1,079,540	2.25
KyB	58,520	1.39	8,917	0.21	67,452	1.60
Totals	2,194,500		553,014		2,744,280

Figure 4. Value of total soil carbon (TSC) (based on mean) by different pools (SOC=soil organic carbon, SIC=soil inorganic carbon) at the Willsboro Farm, Willsboro, NY: (a) based on SSURGO database (soil depth range: 183–236cm), (b) based on interpolated field measurements (soil depth range: 30–115cm) based on soil C numbers from Mikhailova et al. (2016) and a SC–CO₂ of $42 per metric ton of CO₂ (EPA, 2016).

Table 7. Comparison of mean area-normalized values of soil organic carbon (SOC), soil inorganic carbon (SIC), and total soil carbon (TSC) storage by soil order from STATSGO (based on numbers from Guo et al., 2006), SSURGO, and field sampling at the Willsboro Farm (NY), based on a social cost of carbon (SC-CO₂) of $42 per metric ton of CO₂ (EPA, 2016)

Soil order, Data source, Scale	Total reported depth (cm)	SOC value per area ($ m^−2)	SIC value per area ($ m^−2)	TSC value per area ($ m^−2)
Slight weathering
Entisols
- STATSGO (NY state)	200	1.23	0.74	1.97
- SSURGO (Farm)	183 ± 0^a	2.03	1.38	3.41
- Field cores (Farm)	84 ± 21	1.40	0.25	1.66
- Interpolated field cores (Farm)	84 ± 21	1.44	0.20	1.64
Inceptisols
- STATSGO (NY state)	200	1.37	0.79	2.16
- SSURGO (Farm)	183 ± 0	1.59	3.57	5.16
- Field cores (Farm)	63 ± 33	1.26	0.18	1.43
- Interpolated field cores (Farm)	63 ± 33	1.33	0.42	1.74
Intermediate weathering
Alfisols
- STATSGO (NY state)	200	1.16	0.66	1.82
- SSURGO (Farm)	201 ± 27	1.60	3.97	5.57
- Field cores (Farm)	84 ± 29	1.62	0.45	2.07
- Interpolated field cores (Farm)	84 ± 29	1.53	0.44	1.97

Note: ^aMean ± standard deviations for the reported depths in the soil order.

Figure 5. Value of total soil carbon (TSC) (based on mean) based on a SC-CO₂ of $42/metric ton of CO₂ at the Willsboro Farm, Willsboro, NY: (a) based on SSURGO database (soil depth range: 183–236 cm), (b) based on averaged field measurements (soil depth range: 30–115 cm).

Figure 6. Value of soil organic carbon (SOC) based on a SC-CO₂ of $42/metric ton of CO₂ at the Willsboro Farm, Willsboro, NY: (a) from SSURGO results averaged over SMUs, (b) interpolated from soil core sample results.

Figure 7. Value of soil inorganic carbon (SIC) based on a SC-CO₂ of $42/metric ton of CO₂ at the Willsboro Farm, Willsboro, NY: (a) from SSURGO results averaged over soil map units (SMUs), (b) interpolated from soil core sample results.

Figure 8. Value of total soil carbon (TSC) based on a SC-CO₂ of $42/metric ton of CO₂ at the Willsboro Farm, Willsboro, NY: (a) from SSURGO results averaged over soil map units (SMUs), (b) interpolated from soil core sample results.

Table 8. The proportion of the area occupied by different management zones according to the SSURGO database, and field data based on interpolation of soil core sample results for soil organic carbon (SOC), soil inorganic carbon (SIC), and total soil carbon (TSC)

Management zones
Soil carbon classes ($ m^−2)	Area (m^2)	Area (%)
SOC: SSURGO database
0–0.55	0	0
0.55–1.10	58,681	3.98
1.10–1.65	942,583	63.93
1.65–2.20	269,962	18.31
2.20–2.75	154,075	10.45
2.75–3.30	49,097	3.33
SOC: Interpolated from field soil core sample results
0–0.55	7,519	0.51
0.55–1.10	256,103	17.37
1.10–1.65	738,968	50.12
1.65–2.20	415,043	28.15
2.20–2.75	51,015	3.46
2.75–3.30	5,750	0.39
SIC: SSURGO database
0–0.85	145,818	9.89
0.85–1.70	58,681	3.98
1.70–2.55	552,752	37.49
2.55–3.40	0.00	0.00
3.40–4.25	145,965	9.90
4.25–5.10	571,182	38.74
SIC: Interpolated from field soil core sample results
0–0.40	1,005,834	68.22
0.40–0.80	306,380	20.78
0.80–1.20	103,355	7.01
1.20–1.60	38,039	2.58
1.60–2.00	18,872	1.28
2.00–2.40	1,917	0.13
TSC: SSURGO database
0–1.2	0	0
1.2–2.4	145,965	9.90
2.4–3.6	58,534	3.97
3.6–4.8	232,807	15.79
4.8–6.0	465,910	31.60
6.0–7.2	571,182	38.74
TSC: Interpolated from field soil core sample results
0–1.2	105,272	7.14
1.2–2.4	1,134,254	76.93
2.4–3.6	228,532	15.50
3.6–4.8	6.340	0.43

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