Carbon Flux Estimation for Potato Production: A Literature-Based Study

Abstract

This study reviews and synthesizes published data to estimate the net carbon flux associated with the complete potato production process. It identifies the key components that contribute to this flux and explores potential mitigation strategies, including both cultivation and post-harvest storage. Data were compiled from field-scale studies (primarily using eddy covariance) and life cycle assessment studies. The results indicate that potato production can act as a carbon sink or a carbon source, depending on the production scenario. In Scenario 1, which represents the worst-case scenario, potato production acts as a carbon source, with a carbon flux of 13,874.816 kg CO₂ eq ha⁻¹ season⁻¹. In contrast, in Scenario 2, the best-case scenario, potato production acts a carbon sink with a carbon flux of −12,830.567 kg CO₂ eq ha⁻¹ season⁻¹. Similarly, in Scenario 3, which is the average scenario, potato production acts as a carbon sink, though a minor one, with a carbon flux of −90.703 kg CO₂ eq ha⁻¹ season⁻¹. Notably, the growing phase has the most significant impact on potato production’s overall carbon flux, as it is the period in which the highest levels of carbon sequestration and emissions occur. Fertilization is the primary carbon source among all potato production operations, averaging 1219.225 kg CO₂ eq ha⁻¹ season⁻¹. Optimizing farming practices, including fertilization, irrigation, tillage methods, and cultivar selection, are essential to enhance carbon sequestration and reduce greenhouse gas emissions. Additionally, further research through controlled experiments is recommended to deepen the understanding of the relationships between various farming factors and carbon flux, ultimately supporting more sustainable potato production practices.

1. Introduction

The provincial government of Prince Edward Island (PEI) in Canada, has set a goal to achieve net zero by 2040 [1]. This objective cannot be realized without a comprehensive understanding of strategies to mitigate the carbon flux associated with potato production. This is particularly important given the significant role of the potato industry in the island’s economy, which accounts for 74.3% of the province’s total crop receipts, totaling CAD 409.1 million [2]. Furthermore, potato production has the potential to generate substantial greenhouse gas emissions [3,4]. Therefore, the carbon flux of potato production on PEI needs to be understood.

Carbon flux refers to the net exchange of three greenhouse gases—carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O)—within a system, expressed in terms of carbon dioxide equivalent (CO₂ eq) over a specific period. While no research specifically focuses on the carbon flux of potato production, emissions and sequestration data related to potato cultivation and storage have been examined in various studies. However, these studies often overlook certain components or fail to address both stages of potato production and can be grouped into two overall categories. The first type of study focuses on field-scale carbon flux measurements, primarily derived from eddy covariance (EC). In some cases, chamber techniques are employed within EC-based studies to support flux partitioning or provide complementary gas measurement. These studies do not consider emissions from operational diesel use and exclude the post-harvest potato storage stage. The second type of study employs life cycle assessment (LCA) to estimate emissions from operations activities, such as irrigation and potato storage, from a life cycle perspective. However, this approach does not account for greenhouse gas emissions and sequestration from the soil and potato plants.

The objectives of this literature review are (1) to estimate the carbon flux of potato production, (2) to identify the components that contribute most significantly to this flux, and (3) to explore potential mitigation methods. To address these objectives, we synthesized data from both field-based and LCA studies.

2. Methods

The literature was selected based on three criteria: (1) it must be open access or accessible through the University of Prince Edward Island’s institutional subscriptions, (2) it must be in English, and (3) it must provide data on carbon fluxes related to potato production. The literature was identified through searches in PubMed, Scopus, and Google Scholar, as well as by manually adding relevant sources. While the total number of studies screened was not systematically tracked, 48 studies (including peer-reviewed articles and gray literature) met the inclusion criteria and were included in the analysis.

There are several phases in potato production, from seed and seedbed preparation to potato storage, as illustrated in Figure 1. These phases involve many farming operations, including soil management, seed preparation, planting, irrigation, fertilization, crop protection, transportation, and harvest. In the storage phase, there are two sources of greenhouse gas emissions: storage operations and tuber respiration.

These phases can be further categorized into cultivation and storage. The cultivation stage consists of 5 phases: seed preparation, seedbed preparation, planting, growing, and harvest. The storage stage involves only greenhouse gas emissions from operations conducted within the storage facilities and from tuber respiration without sequestration. The total carbon flux associated with potato production (FLUX_production) can therefore be defined as the sum of the carbon fluxes from the cultivation stage (FLUX_cultivation) and the storage stage (FLUX_storage):

$${\mathrm{F}\mathrm{L}\mathrm{U}\mathrm{X}}_{\mathrm{p}\mathrm{r}\mathrm{o}\mathrm{d}\mathrm{u}\mathrm{c}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}}={\mathrm{F}\mathrm{L}\mathrm{U}\mathrm{X}}_{\mathrm{c}\mathrm{u}\mathrm{l}\mathrm{t}\mathrm{i}\mathrm{v}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}}+{\mathrm{F}\mathrm{L}\mathrm{U}\mathrm{X}}_{\mathrm{s}\mathrm{t}\mathrm{o}\mathrm{r}\mathrm{a}\mathrm{g}\mathrm{e}}$$

(1)

The cultivation stage encompasses four key components: soil, potato plants (which includes the entire development from seed potatoes to mature plants and tubers), cultivation inputs (such as fertilizers and biocides), and energy use. To assess the carbon flux during this stage, data from two types of studies is extracted and analyzed: field-scale studies and life cycle assessment (LCA) studies.

Field-scale studies evaluate the ecosystem comprising soil, potato plants, and cultivation inputs, providing an estimate of the carbon flux for this ecosystem (FLUX_ecosystem). FLUX_ecosystem encompasses the net emissions of three greenhouse gases: CO₂ (FLUX_{ecosystem_CO2}), CH₄ (FLUX_{ecosystem_CH4}), and N₂O (FLUX_{ecosystem_N2O}), where:

$${\mathrm{F}\mathrm{L}\mathrm{U}\mathrm{X}}_{\mathrm{e}\mathrm{c}\mathrm{o}\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t}\mathrm{e}\mathrm{m}}={\mathrm{F}\mathrm{L}\mathrm{U}\mathrm{X}}_{\mathrm{e}\mathrm{c}\mathrm{o}\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t}\mathrm{e}\mathrm{m}\_\mathrm{C}\mathrm{O}2}+{\mathrm{F}\mathrm{L}\mathrm{U}\mathrm{X}}_{\mathrm{e}\mathrm{c}\mathrm{o}\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t}\mathrm{e}\mathrm{m}\_\mathrm{C}\mathrm{H}4}+{\mathrm{F}\mathrm{L}\mathrm{U}\mathrm{X}}_{\mathrm{e}\mathrm{c}\mathrm{o}\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t}\mathrm{e}\mathrm{m}\_\mathrm{N}2\mathrm{O}}$$

(2)

$${\mathrm{F}\mathrm{L}\mathrm{U}\mathrm{X}}_{\mathrm{e}\mathrm{c}\mathrm{o}\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t}\mathrm{e}\mathrm{m}\_\mathrm{C}\mathrm{O}2}={\mathrm{E}\mathrm{M}\mathrm{I}\mathrm{S}\mathrm{S}\mathrm{I}\mathrm{O}\mathrm{N}}_{\mathrm{e}\mathrm{c}\mathrm{o}\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t}\mathrm{e}\mathrm{m}\_\mathrm{C}\mathrm{O}2}\times {\mathrm{G}\mathrm{W}\mathrm{P}100}_{\mathrm{C}\mathrm{O}2}$$

(3)

$${\mathrm{F}\mathrm{L}\mathrm{U}\mathrm{X}}_{\mathrm{e}\mathrm{c}\mathrm{o}\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t}\mathrm{e}\mathrm{m}\_\mathrm{C}\mathrm{H}4}={\mathrm{E}\mathrm{M}\mathrm{I}\mathrm{S}\mathrm{S}\mathrm{I}\mathrm{O}\mathrm{N}}_{\mathrm{e}\mathrm{c}\mathrm{o}\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t}\mathrm{e}\mathrm{m}\_\mathrm{C}\mathrm{H}4}\times {\mathrm{G}\mathrm{W}\mathrm{P}100}_{\mathrm{C}\mathrm{H}4}$$

(4)

$${\mathrm{F}\mathrm{L}\mathrm{U}\mathrm{X}}_{\mathrm{e}\mathrm{c}\mathrm{o}\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t}\mathrm{e}\mathrm{m}\_\mathrm{N}2\mathrm{O}}={\mathrm{E}\mathrm{M}\mathrm{I}\mathrm{S}\mathrm{S}\mathrm{I}\mathrm{O}\mathrm{N}}_{\mathrm{e}\mathrm{c}\mathrm{o}\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t}\mathrm{e}\mathrm{m}\_\mathrm{N}2\mathrm{O}}\times {\mathrm{G}\mathrm{W}\mathrm{P}100}_{\mathrm{N}2\mathrm{O}}$$

(5)

GWP100_CO2, GWP100_CH4, and GWP100_N2O are coefficients for the greenhouse gases, representing their corresponding global warming potentials (GWPs) over 100 years, as defined by the Intergovernmental Panel on Climate Change (IPCC). According to IPCC AR6 WGI, the GWP100s for CO₂, fossil-origin CH₄, non-fossil-origin CH₄, and N₂O are 1, 29.8, 27.2, and 273 kg CO₂ eq per kg of the corresponding greenhouse gas [5].

LCA studies utilize surveys and interviews to collect data on the quantities of inputs and energy utilized in the cultivation process. In this context, the carbon flux associated with an individual operation is calculated as the sum of the fluxes from its cultivation inputs and energy. Therefore, the total carbon flux for all cultivation operations (FLUX_{cultivation_operations}) is expressed as:

$${\mathrm{F}\mathrm{L}\mathrm{U}\mathrm{X}}_{\mathrm{c}\mathrm{u}\mathrm{l}\mathrm{t}\mathrm{i}\mathrm{v}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}\_\mathrm{o}\mathrm{p}\mathrm{e}\mathrm{r}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}\mathrm{s}}={\mathrm{F}\mathrm{L}\mathrm{U}\mathrm{X}}_{\mathrm{c}\mathrm{u}\mathrm{l}\mathrm{t}\mathrm{i}\mathrm{v}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}\_\mathrm{i}\mathrm{n}\mathrm{p}\mathrm{u}\mathrm{t}\mathrm{s}}+{\mathrm{F}\mathrm{L}\mathrm{U}\mathrm{X}}_{\mathrm{c}\mathrm{u}\mathrm{l}\mathrm{t}\mathrm{i}\mathrm{v}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}\_\mathrm{e}\mathrm{n}\mathrm{e}\mathrm{r}\mathrm{g}\mathrm{y}}$$

(6)

FLUX_production is then estimated by integrating the findings from both study types:

$${\mathrm{F}\mathrm{L}\mathrm{U}\mathrm{X}}_{\mathrm{c}\mathrm{u}\mathrm{l}\mathrm{t}\mathrm{i}\mathrm{v}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}}={\mathrm{F}\mathrm{L}\mathrm{U}\mathrm{X}}_{\mathrm{e}\mathrm{c}\mathrm{o}\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t}\mathrm{e}\mathrm{m}}+{\mathrm{F}\mathrm{L}\mathrm{U}\mathrm{X}}_{\mathrm{c}\mathrm{u}\mathrm{l}\mathrm{t}\mathrm{i}\mathrm{v}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}\_\mathrm{o}\mathrm{p}\mathrm{e}\mathrm{r}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}\mathrm{s}}-{\mathrm{F}\mathrm{L}\mathrm{U}\mathrm{X}}_{\mathrm{c}\mathrm{u}\mathrm{l}\mathrm{t}\mathrm{i}\mathrm{v}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}\_\mathrm{i}\mathrm{n}\mathrm{p}\mathrm{u}\mathrm{t}\mathrm{s}}$$

(7)

The storage stage is more straightforward, as carbon emissions arise from three primary sources: storage inputs, energy consumption, and tuber respiration. The integrated carbon flux of the first two sources is studied in LCA studies (FLUX_{storage_operations}). The carbon flux associated with tuber respiration (FLUX_{storage_tuber_respiration}) is estimated based on research on potato tuber respiration rates during storage, assuming a storage duration of 180 days. Considering both emission sources, the total carbon flux for the storage stage (FLUX_storage) is calculated as:

$${\mathrm{F}\mathrm{L}\mathrm{U}\mathrm{X}}_{\mathrm{s}\mathrm{t}\mathrm{o}\mathrm{r}\mathrm{a}\mathrm{g}\mathrm{e}}={\mathrm{F}\mathrm{L}\mathrm{U}\mathrm{X}}_{\mathrm{s}\mathrm{t}\mathrm{o}\mathrm{r}\mathrm{a}\mathrm{g}\mathrm{e}\_\mathrm{o}\mathrm{p}\mathrm{e}\mathrm{r}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}\mathrm{s}}+{\mathrm{F}\mathrm{L}\mathrm{U}\mathrm{X}}_{\mathrm{s}\mathrm{t}\mathrm{o}\mathrm{r}\mathrm{a}\mathrm{g}\mathrm{e}\_\mathrm{t}\mathrm{u}\mathrm{b}\mathrm{e}\mathrm{r}\_\mathrm{r}\mathrm{e}\mathrm{s}\mathrm{p}\mathrm{i}\mathrm{r}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}}$$

(8)

This study employs the metric unit system, using kilograms (kg) and metric tonnes (t) for weight and hectares (ha) for area. For example, carbon flux is expressed using two units: “kg CO₂ eq ha⁻¹ season⁻¹” and “kg CO₂ eq t⁻¹ season⁻¹.” As previously explained, “CO₂ eq” refers to carbon dioxide equivalents. The term “ha⁻¹” indicates that the carbon flux is measured per hectare of potato cultivation field. At the same time, “t⁻¹” represents emissions per metric tonne of harvested potatoes, and “season⁻¹” denotes carbon flux associated with a potato production cycle. The potato yield is needed to convert between per-tonne carbon fluxes and per-hectare ones. If studies lack this data, estimated potato yields from additional sources are used. Additionally, to convert data in the American unit system to the metric unit system, the following conversions are used: one short hundredweight (cwt) is equivalent to 0.045359 tonnes, and 1 acre equals 0.404685642 hectares [6]. To convert data from moles to kilograms, the following standard atomic weights of elements are adopted: 1.01 g/mol for hydrogen (H), 12.01 g/mol for carbon (C), 14.01 g/mol for nitrogen (N), 16.00 g/mol for oxygen (O), 30.97 g/mol for phosphorus (P), and 39.10 g/mol for potassium (K) [7].

3. Results

This section presents the results of greenhouse emissions and sequestration with various phases of potato production. The results are organized by phase, including soil preparation, seed preparation, planting, growing, harvest, and storage. Each phase contains carbon flux data derived from multiple studies, showing the variability in emissions due to factors such as farming practices, environmental conditions, and potato varieties.

3.1. Soil Preparation

The initial phase of potato production, soil preparation, is critical as it sets the foundation for subsequent emissions. This term encompasses all farming practices used to prepare the seedbed and manage the soil, including tillage methods such as plowing and harrowing. In some studies, emissions from hoeing during the growing phase are also included in this category.

Table 1. Carbon flux of soil preparation.

Count	FLUXsoil_preparation (kg CO2 eq ha−1 season−1)	FLUXsoil_preparation (kg CO2 eq t−1 season−1)	Practice	Publication Year	Location	Source
1	14.477	0.670	Scenario 4; plowing by hired machinery	2021	Kenya	[8]
2	19.028	1.069	Scenario 3; plowing by hired machinery	2021	Kenya	[8]
3	161.410	7.653	80% power tiller, 20% tractor; hoeing at 10–20 days after emergency and second topdressing	2024	Bangladesh	[9]
4	220.273	12.004	Organic potato; 1 plowing, 1 harrowing by rotary cultivator	2022	India	[10]
5	221.548	9.061	Conventional potato; 1 plowing, 1 harrowing by rotary cultivator	2023	India	[11]
6	221.548	12.073	Organic potato; 1 plowing, 1 harrowing by rotary cultivator	2023	India	[11]
7	555.000	37.000	Organic potato; 1 harrowing by rotary harrow, 1 plowing, 1 cultivating, 5 rounds of hoeing	2013	Czech Republic	[12]
8	560.000	70.000	Plot “A1 resettlement”	2018	Zimbabwe	[13]
9	816.000	48.000	Plot “Communal area”	2018	Zimbabwe	[13]
10	1092.000	39.000	Plot “large-scale commercial”; 2 applications of ridging, 1 harrowing, 1 roller harrowing, 1 planting furrow opening	2018	Zimbabwe	[13]
11	1127.000	49.000	Plot “A2 resettlement”; 2 applications of ridging, 1 harrowing, 1 roller harrowing, 1 planting furrow opening	2018	Zimbabwe	[13]
12	1166.000	53.000	Conventional potato; 1 harrowing by rotary harrow, 1 plowing, 1 cultivating, 5 rounds of hoeing	2013	Czech Republic	[12]

shows the results of the carbon flux of soil preparation. The carbon flux of this phase varies widely among studies, ranging from 14.477 to 1166.000 kg CO₂ eq ha⁻¹ season⁻¹ or 0.670 to 70.000 kg CO₂ eq t⁻¹ season⁻¹. This variation can be attributed to several factors. Different soil preparation practices, such as conventional tillage versus reduced tillage, can lead to significant differences in carbon emissions. Additionally, variations in soil characteristics, including texture, organic matter content, moisture levels, drainage, and pH, can influence how soil management practices affect carbon flux. Geographic location also plays a role, as different conditions and agricultural practices in various regions can result in differing emissions profiles. For soil preparation with one plowing and harrowing, the carbon flux is about 221.123 kg CO₂ eq ha⁻¹ season⁻¹ (derived from observations 6–8 in Table 1). For soil preparation involving more operations (one plowing, harrowing, and cultivating), carbon flux can range from 555.000 to 1166.000 kg CO₂ eq ha⁻¹ season⁻¹.

3.2. Seed Preparation

Following soil preparation, seed preparation is another important phase that can influence greenhouse gas emissions.

Table 2. Carbon flux of seed preparation.

Count	FLUXseed_preparation (kg CO2 eq ha−1 season−1)	FLUXseed_preparation (kg CO2 eq t−1 season−1)	Practice	Publication Year	Location	Source
1	114.080	5.409	3% boric acid	2024	Bangladesh	[9]
2	149.600	3.400	Starch potato; 2 chemical mixture treatments	2011	Netherlands	[3]
3	227.500	6.500	Organic potato; no chemical mixture treatment	2011	Netherlands	[3]
4	253.500	3.900	Table potato; 1 chemical mixture treatment	2011	Netherlands	[3]
5	528.000	24.000	Conventional potato	2013	Czech Republic	[12]
6	555.000	14.800	Seed potato; 2 chemical mixture treatments	2011	Netherlands	[3]
7	555.000	37.000	Organic potato	2013	Czech Republic	[12]

lists the carbon flux results for seed preparation, which ranges from 114.080 to 55.000 kg CO₂ eq ha⁻¹ season⁻¹ or 5.409 to 37.000 kg CO₂ eq t⁻¹ season⁻¹. Although seed preparation, such as fungicide and insecticide treatment, plays a role in potato production, fewer studies address its carbon flux. This limited research partly explains the relatively small range of variation in carbon flux for seed preparation compared to other practices. The observed variations can be attributed to the types of treatments used, as different fungicides and insecticides may have varying carbon footprints based on their chemical composition and application methods. Additionally, the origin and quality of the seeds can influence the need for treatments and, consequently, the associated emissions. With the identified data, this farming practice has a mean flux of 340.383 kg CO₂ eq ha⁻¹ season⁻¹ or 13.573 kg CO₂ eq t⁻¹ season⁻¹.

3.3. Planting

The planting phase is essential for establishing the crop and contributes to overall emissions.

Table 3. Carbon flux of planting.

Count	FLUXplanting (kg CO2 eq ha−1 season−1)	FLUXplanting (kg CO2 eq t−1 season−1)	Practice	Publication Year	Location	Source
1	28.954	1.340	Scenario 4, mechanized (hired)	2021	Kenya	[8]
2	33.600	1.593	Seed rate: 1.5 t ha−1	2024	Bangladesh	[9]
3	423.427	23.075	Organic potato; seed rate: 2.5 t/ha	2022	India	[10]
4	427.105	17.469	Conventional potato; seed rate: 2.5 t ha−1	2023	India	[11]
5	427.105	23.275	Organic potato; seed rate: 2.5 t ha−1	2023	India	[11]

presents the carbon flux results for planting, which range from 28.954 to 427.105 kg CO₂ eq ha⁻¹ season⁻¹ or 1.340 to 23.275 kg CO₂ eq t⁻¹ season⁻¹. Planting season, duration, seed size, spacing, and other factors can influence seed rate and, consequently, the corresponding flux [11]. The seed rate and density can explain the wide range of variation. Higher seed rates can lead to increased emissions due to greater resource use. Different planting techniques, such as manual versus mechanized planting, can also result in varying emissions profiles.

3.4. Growing

Following planting, the growing phase is the most time-consuming stage of potato cultivation. This phase encompasses various activities, including fertilization, irrigation, and crop protection, contributing significantly to greenhouse gas emissions. However, despite the substantial emissions associated with these farming operations, the ecosystem can offset these greenhouse gases. The wide range of emissions during this phase can be attributed to the diversity of practices employed. The variety of fertilization, irrigation, and pest management techniques can lead to significant differences in emissions. Additionally, differences in these practices affect plants and soil health, affecting the ecosystem’s capacity to offset these emissions.

3.4.1. Irrigation

Table 4. Carbon flux of irrigation.

Count	FLUXirrigation (kg CO2 eq ha−1 season−1)	FLUXirrigation (kg CO2 eq t−1 season−1)	Practice	Publication Year	Location	Source
1	0.000	0.000	Seed potato; no irrigation	2011	Netherlands	[3]
2	17.600	0.400	Starch potato; 120 m3/ha; rain gun	2011	Netherlands	[3]
3	70.000	2.000	Organic potato; 400 m3/ha; rain gun	2011	Netherlands	[3]
4	71.500	1.100	Table potato; 400 m3/ha; rain gun	2011	Netherlands	[3]
5	160.147	6.550	Conventional potato; 889.2 m3 freshwater ha−1; grid electricity, low voltage	2023	India	[11]
6	213.530	11.637	Organic potato; 1185.6 m3 freshwater ha−1; grid electricity, low voltage	2023	India	[11]
7	254.635	13.877	Organic potato; freshwater: 1150.6 m3 ha−1; low-voltage grid electricity	2022	India	[10]
8	999.920	47.412	3 rounds of irrigation	2024	Bangladesh	[9]
9	1173.000	51.000	Plot “A2 resettlement”; 100% area irrigated; rain gun; grid electricity use, no diesel use; 4650 m3/ha water applied; 30 m pumping depth	2018	Zimbabwe	[13]
10	2044.000	73.000	Plot “Large-scale”; 100% area irrigated; rain gun; grid electricity use, no diesel use; 5500 m3/ha water applied; 43 m pumping depth	2018	Zimbabwe	[13]

lists the results of the carbon flux of the farming practice of irrigation. The results show a range of 0.000–2044.000 expressed in kg CO₂ eq ha⁻¹ season⁻¹ or 0.000–73.000 expressed in kg CO₂ eq t⁻¹ season⁻¹. Two factors contribute to these variations. First, the water supply need, affected by cropping season, potato usage, climate conditions, and other factors, directly affects the emissions. Second, the energy system of the irrigation system directly impacts carbon flux. For example, a gravity-fed irrigation system is regarded as having no greenhouse gas emissions [13]. Based on the detailed observations, the carbon flux associated with irrigation can be 17.600 kg CO₂ eq ha⁻¹ season⁻¹, with irrigation water usage of 120 m³/ha using a rain gun. Alternatively, this value can increase to 2044.000 kg CO₂ equivalent per hectare per season when 100% of the area is irrigated by a rain gun, with 5500 m³/ha of water applied and a pumping depth of 43 m.

3.4.2. Fertilization

Table 5. Carbon flux of fertilization.

Count	FLUXfertilization (kg CO2 eq ha−1 season−1)	FLUXfertilization (kg CO2 eq t−1 season−1)	Practice	Publication Year	Location	Source
1	210.000	14.000	Organic potato; fertilizer (kg/ha): N-organic: 20,000; 1 fertilizer spreading by broadcaster	2013	Czech Republic	[12]
2	211.400	11.520	Organic potato; fertilizer (kg/ha): solid cattle manure: 21,000	2022	India	[10]
3	281.505	15.341	Organic potato; fertilizer (kg/ha): solid cattle manure: 21,187.5, 1 liquid manure application	2023	India	[11]
4	774.082	93.263	Reference scenario; fertilizer (kg/ha): diammonium phosphate: 150	2021	Kenya	[8]
5	814.000	37.000	Conventional potato; fertilizer (kg/ha): N-organic: 20,000, N-mineral: 90, P-mineral: 35, K-mineral: 120; 3 rounds of spreading by broadcaster	2013	Czech Republic	[12]
6	920.500	26.300	Organic potato; 2 rounds of manure spreading; organic inputs (t/ha): sheep manure: 7.5, compost: 5, pig slurry: 16	2011	Netherlands	[3]
7	1058.688	43.300	Conventional potato; fertilizer (kg/ha): P fertilizer: 300, K fertilizer: 185, N fertilizer: 125; fertilizer application: 2–3 splits, two-thirds of N and all P and K at planting	2023	India	[11]
8	1203.521	67.614	Scenario 3; fertilizer (kg/ha): diammonium phosphate: 500	2021	Kenya	[8]
9	1204.700	74.826	Scenario 2; fertilizer (kg/ha): diammonium phosphate: 500	2021	Kenya	[8]
10	1230.545	56.970	Scenario 4; fertilizer (kg/ha): NPK (16:8:22): 500	2021	Kenya	[8]
11	1826.350	86.598	Fertilizer (kg/ha): urea: 263, TSP: 135, MoP: 250	2024	Bangladesh	[9]
12	1936.000	44.000	Starch potato; mean applications: fertilizer: 2, manure: 2.5, slurry: 1; fertilizer (kg/ha): N-mineral: 75, K2O-mineral: 50; organic inputs (t/ha): pig slurry: 26, green manure: 20	2011	Netherlands	[3]
13	2167.500	57.800	Seed potato; mean applications: fertilizer: 2, manure: 0.2; fertilizer (kg/ha): N-mineral: 127.5, P2O5-mineral: 100, K2O-mineral: 265; organic inputs (t/ha): pig slurry: 3	2011	Netherlands	[3]
14	3230.500	49.700	Table potato; mean applications: fertilizer: 3, manure: 0.5; fertilizer (kg/ha): N-mineral: 190, P2O5-mineral: 52, K2O-mineral: 115; organic inputs (t/ha): poultry manure: 3	2011	Netherlands	[3]

lists observations of the carbon flux of fertilization, which were extracted from LCA and model studies. The results show a wide range of variations, 210.000–3230.500 expressed in kg CO₂ eq ha⁻¹ season⁻¹ or 11.520–93.263 expressed in kg CO₂ eq t⁻¹ season⁻¹. Fertilizer composition, dose, and application methods can explain the study variations. Similar to mineral fertilizers, a higher fertilizer dose promotes N₂O emission, especially when the soil temperature is below 19.6 °C and soil volumetric water content is under 15% [9,14]. However, distributing fertilizer according to the N uptake of the potato plants might reduce N₂O emission due to improved N-taking efficiency [15]. The carbon flux of fertilization can be approximately 210.000 kg CO₂ eq ha⁻¹ season⁻¹ when only 20,000 kg/ha N-organic is applied. If only synthesized fertilizers are used—125 kg/ha N-mineral, 65 kg/ha P-mineral (300 kg/ha P₂O₅), and 77 kg/ha K-mineral (185 kg/ha K₂O)—the carbon flux can be as high as 1058.688 kg CO₂ eq ha⁻¹ season⁻¹.

3.4.3. Crop Protection

Table 6. Carbon flux of crop protection.

Count	FLUXcrop_protection (kg CO2 eq ha−1 season−1)	FLUXcrop_protection (kg CO2 eq t−1 season−1)	Practice	Publication Year	Location	Source
1	0.000	0.000	Organic potato; no spraying	2011	Netherlands	[3]
2	17.542	0.956	Organic potato; chemicals: water: 250 L/ha, buttermilk: 7.5 kg/ha	2023	India	[11]
3	29.035	1.188	Conventional potato; chemical: water: 30 L/ha, mancozeb: 3.5 kg/ha	2023	India	[11]
4	41.749	2.275	Organic potato; chemicals: water: 250 L/ha, buttermilk: 7.5 kg/ha	2022	India	[10]
5	59.886	7.215	Reference scenario; 3 sprays of Ridomil/Mancozeb	2021	Kenya	[8]
6	66.000	3.000	Conventional potato; chemicals (kg/ha): herbicides: 1.5, fungicides: 8, insecticides: 0.2	2013	Czech Republic	[12]
7	81.748	5.077	Scenario 2; 4 sprays of Ridomil/Mancozeb	2021	Kenya	[8]
8	152.009	7.037	Scenario 4; 8 weeks of mixed sprays	2021	Kenya	[8]
9	174.660	8.282	5 sprays (1250 g spray−1)	2024	Bangladesh	[9]
10	218.822	12.293	Scenario 3; 11 sprays at different stages	2021	Kenya	[8]
11	328.000	41.000	Plot “A1 resettlement”; 9–14 biocide applications (average: 11)	2018	Zimbabwe	[13]
12	331.500	5.100	Table potato; 14 sprayings	2011	Netherlands	[3]
13	431.200	9.800	Starch potato; 17 sprayings	2011	Netherlands	[3]
14	607.500	16.200	Seed potato; 9.5 sprayings	2011	Netherlands	[3]
15	612.000	36.000	Plot “Communal area”; 11–28 biocide applications (average: 18)	2018	Zimbabwe	[13]
16	713.000	31.000	Plot “A2 resettlement”; 14–41 biocide applications (average: 22)	2018	Zimbabwe	[13]
17	728.000	26.000	Plot “Large-scale commercial”; 10–33 biocide applications (average: 25)	2018	Zimbabwe	[13]

presents the results of the carbon flux of the farming practice of crop protection, including weeding and disease control practices, such as biocide applications. Similar to other farming practices, the carbon flux of crop protection varies in different observations, with a range of 0.000–728.00 expressed in kg CO₂ eq ha⁻¹ season⁻¹ or 0.000–41.000 expressed in kg CO₂ eq t⁻¹ season⁻¹. Other factors also impact the emissions from crop protection, including potato usage.

3.4.4. Transportation

Transportation of farming inputs is a critical activity that occurs throughout the various stages leading up to storage, and the emissions associated with it cannot be overlooked.

Table 7. Carbon flux of on-farm transportation.

Count	FLUXtransportation (kg CO2 eq ha−1 season−1)	FLUXtransportation (kg CO2 eq t−1 season−1)	Practice	Publication Year	Location	Source
1	4.000	0.500	Plot “A1 resettlement”	2018	Zimbabwe	[13]
2	8.500	0.500	Plot “Communal area”	2018	Zimbabwe	[13]
3	11.200	0.400	Plot “Large-scale commercial”	2018	Zimbabwe	[13]
4	11.500	0.500	Plot “A2 resettlement”	2018	Zimbabwe	[13]

presents the carbon flux results for transportation. The findings indicate that transportation acts as a carbon source, with a carbon flux range of 4.000 to 11.500 kg CO₂ eq ha⁻¹ season⁻¹ or 0.400 to 0.500 kg CO₂ eq t⁻¹ season⁻¹. Several factors contribute to the observed variations in carbon flux during transportation. Firstly, emissions increase as transportation distance increases. Secondly, the type of transportation method used—whether manual, tractor-drawn, or truck-based—can significantly influence emissions, with mechanized transport vehicles generally resulting in higher emissions due to fuel consumption. Thirdly, the load capacity of the transport vehicles affects related emissions. Additionally, the terrain and road conditions can impact fuel efficiency; rough or unpaved roads may lead to increased fuel consumption and higher emissions.

3.4.5. Greenhouse Gas Sequestration

The carbon flux of CO₂, CH₄, and N₂O from various studies are presented in

Table 8. Net CO₂ emission of the ecosystem of soil, potato plants, and farming inputs.

Count	FLUXecosystem_CO2 (kg CO2 eq ha−1 season−1)	FLUXecosystem_CO2 (kg CO2 eq t−1 season−1)	Practice	Publication Year	Location	Source
1	−13,433.860	−537.354	Irrigated	2021	Colombia	[16]
2	−11,431.607	−457.264	Full-irrigation	2024	Colombia	[17]
3	−11,359.784	−1514.638	Seed potato in 2006	2017	Belgium	[18]
4	−8794.671	−1136.262	Seed potato in 2014	2017	Belgium	[18]
5	−7695.337	−971.633	Seed potato in 2010	2017	Belgium	[18]
6	−5276.803	−152.509	With flux footprint correction	2023	Canada	[4]
7	−633.949	−28.816	Deficit-irrigation	2024	Colombia	[17]
8	11.360	0.431	Seed potato	2008	Belgium	[19]
9	4602.000	70.790	Average in 2005	2008	US	[20]
10	5668.898	286.308	Rainfed	2021	Colombia	[16]
11	5754.000	82.801	Average in 2006	2008	US	[20]
12	6860.210	346.475	Rainfed	2024	Colombia	[17]

Note: A negative value of FLUX_{ecosystem_CO2} represents the ecosystem absorbing CO₂ from the atmosphere, while a positive value denotes that the ecosystem emits CO₂ into the atmosphere.

,

Table 9. Net CH₄ emission of the ecosystem of potato plants, soil, and farming inputs.

Count	FLUXecosystem_CH4 (kg CO2 eq ha−1 season−1)	FLUXecosystem_CH4 (kg CO2 eq t−1 season−1)	Practice	Publication Year	Location	Source
1	−12.624	−0.314	Seed potato in 1998	2002	Germany	[21]
2	−11.748	−0.297	Seed potato in 1997	2002	Germany	[21]
3	−6.854	−0.099	Average of conventional and reduced till treatments in 2005	2008	US	[20]
4	−4.768	−0.073	Average of conventional and reduced till treatments in 2006	2008	US	[20]
5	167.209	4.833	Goldrush Russet, with flux footprint correction	2023	Canada	[4]

Note: A negative value of FLUX_{ecosystem_CH4} represents the ecosystem absorbing CH₄ from the atmosphere, while a positive value denotes that the ecosystem emits CH₄ into the atmosphere.

, and

Table 10. Net N₂O emission of the ecosystem of potato plants, soil, and farming inputs.

Count	FLUXecosystem_N2O (kg CO2 eq ha−1 season−1)	FLUXecosystem_N2O (kg CO2 eq t−1 season−1)	Practice	Publication Year	Location	Source
1	248.430	3.821	Average of conventional and reduced till treatments in 2006	2008	US	[20]
2	253.890	3.654	Average of conventional and reduced till treatments in 2005	2008	US	[20]
3	1389.599	35.141	Seed potato in 1997	2002	Germany	[21]
4	1732.710	43.137	Seed potato in 1998	2002	Germany	[21]
5	4374.664	126.435	With flux footprint correction	2023	Canada	[4]

Note: A positive value of FLUX_{ecosystem_N2O} denotes that the ecosystem emits N₂O into the atmosphere.

, respectively, expressed in CO₂ equivalent. Generally, while the results indicate a wide range of values for all greenhouse gases, N₂O is consistently considered to be emitted and not absorbed by the ecosystem. In contrast, studies suggest that the ecosystem can absorb CO₂ and CH₄ from the atmosphere. Upon data review, the gross sequestration potential of the ecosystem primarily depends on potato plants and soil, with carbon dioxide CO₂ being utilized by the plants and CH₄ associated with the soil. Soil compaction has a significant negative effect on the fluxes of N₂O and CH₄ [15]. The growing phase is when the most sequestration occurs, as photosynthesis occurs in this period.

Table 11. Carbon flux of diesel consumption during the cultivation stage.

Count	FLUXcultivation_energy (kg CO2 eq ha−1 season−1)	FLUXcultivation_energy (kg CO2 eq t−1 season−1)	Practice	Publication year	Location	Source
1	207.000	9.000	Plot “A2 resettlement”	2018	Zimbabwe	[13]
2	211.446	11.523	Organic potato	2022	India	[10]
3	219.738	11.975	Conventional potato	2023	India	[11]
4	219.738	11.975	Organic potato	2023	India	[11]
5	224.000	8.000	Plot “Large-scale commercial”	2018	Zimbabwe	[13]
6	303.901	11.958	Large farms (>5 ha)	2012	Iran	[22]
7	317.178	14.287	Medium farms (1–5 ha)	2012	Iran	[22]
8	357.076	19.334	Small farms (<1 ha)	2012	Iran	[22]
9	360.149	9.949	Efficient farms	2020	Poland	[23]
10	402.715	15.312	Inefficient farms	2020	Poland	[23]
11	406.916	10.917	Average of 26 provinces	2024	China	[24]
12	621.900	19.434	Conventional early potato	2021	Italy	[25]
13	635.720	25.429	Organic early potato	2021	Italy	[25]

lists the results of the carbon flux of diesel consumption during the cultivation stage, showing a range of 207.000–635.720 kg CO₂ eq ha⁻¹ season⁻¹ or 9.000–25.429 kg CO₂ eq t⁻¹ season⁻¹. This category encompasses all diesel used throughout the entire cultivation stage, including, but not limited to, applications for planting, fertilization, and harvesting.

3.5. Harvest

The harvest phase concludes the potato cultivation. The average carbon flux (FLUX_harvest) for harvest is 69.530 kg CO₂ ha⁻¹ season⁻¹ or 3.420 kg CO₂ eq t⁻¹ season⁻¹, as shown in

Table 12. Carbon flux of harvest.

Count	FLUXharvest (kg CO2 eq ha−1 season−1)	FLUXharvest (kg CO2 eq t−1 season−1)	Practice	Publication Year	Location	Source
1	14.477	0.670	Scenario 4; mechanized (hired)	2021	Kenya	[8]
2	30.240	1.434	Manually, about 60 man-days ha−1	2024	Bangladesh	[9]
3	95.063	5.181	Organic potato	2022	India	[10]
4	96.722	5.271	Organic potato; 1 haulm cutting	2023	India	[11]
5	111.146	4.546	Conventional potato; 1 haulm cutting	2023	India	[11]

. The carbon flux for harvest is relatively small, ranging from 14.477 to 111.146 kg CO₂ eq ha⁻¹ season⁻¹ or 0.670 to 5.271 kg CO₂ eq t⁻¹ season⁻¹. However, it remains a positive value, indicating that harvesting is a carbon source. The use of machinery directly affects the carbon flux during this phase, and the type and efficiency of the machinery used can explain emission variations. Different harvesting methods can also contribute to the observed differences in carbon flux.

3.6. Storage

3.6.1. Storage Operations

Finally, the storage phase also affects carbon emissions.

Table 13. Carbon flux of potato storage operations.

Count	FLUXstorage_operations (kg CO2 eq ha−1 season−1)	FLUXstorage_operations (kg CO2 eq t−1 season−1)	Practice	Publication Year	Location	Source
1	96.800	2.200	Starch potato; 33% stored for 4 months	2011	Netherlands	[3]
2	607.500	16.200	Seed potato; 70% stored for 8 months	2011	Netherlands	[3]
3	669.500	10.300	Table potato; 100% stored for 6 months	2011	Netherlands	[3]
4	780.500	22.300	Organic potato; 100% stored for 6 months	2011	Netherlands	[3]

presents the carbon flux results for potato storage operations, which indicates that this phase is a carbon source, with a carbon flux range of 96.800 to 780.500 kg CO₂ eq ha⁻¹ season⁻¹ or 2.200 to 22.300 kg CO₂ eq t⁻¹ season⁻¹. Storage is the least researched among the practices examined in the identified studies. Although all four observations originate from the same study, the variation in carbon flux during storage can be seen in the results. The variations in carbon flux can be attributed to several factors. First, different potato varieties and cultivation methods exhibit distinct respiration rates. Second, the duration of storage also impacts emissions; longer storage periods can result in higher flux. Furthermore, the type of storage facility and its energy efficiency can also influence emissions.

3.6.2. Storage Tuber Respiration

In addition to the emissions from the storage operations, stored tubers also emit greenhouse gases through respiration, which consumes O₂ and releases CO₂, water, and heat. FLUX_{storage_tuber_respiration} based on monthly or weekly respiration rate estimation from two studies is summarized in

Table 14. Carbon flux of the tuber respiration during storage (kg CO₂ ha⁻¹ season⁻¹).

Cultivar	Number of Observations	Mean	Range	Standard Deviation	Standard Error of the Mean	Source
Dakota Russet	21	197.902	[152.065, 310.288]	34.433	7.514	[29]
Russet Burbank	21	236.266	[148.894, 356.335]	50.304	10.977	[29]
Ivory Russet	21	245.680	[190.392, 405.001]	47.127	10.283	[29]
Rainier Russet	21	268.570	[206.062, 419.891]	48.521	10.588	[29]
Monona	106	409.857	[63.687, 988.276]	175.723	17.068	[28]
Snowden	107	453.971	[154.005, 1056.513]	243.189	23.510	[28]

, assuming a storage duration of 180 days and different mean yields for different studies [26,27]. The results show that FLUX_{storage_tuber_respiration} varies in a wide range, from 63.687 to 1056.513 kg CO₂ ha⁻¹ season⁻¹, due to factors such as cultivar, growing season, chemical treatment, and storage environment [28,29].

3.7. Scenarios

Table 15. Summary of carbon flux statistics for the potato cultivation and storage stages per hectare of potato farming field (kg CO₂ eq ha⁻¹ season⁻¹).

Stage	Carbon Flux	Number of Observations	Mean	Range	Standard Deviation	Standard Error of the Mean
Cultivation	FLUXecosystem_CO2	12	−2977.462	[−13,433.860, 6860.210]	7580.528	2188.310
	FLUXecosystem_CH4	5	26.243	[−12.624, 167.209]	78.871	35.272
	FLUXecosystem_N2O	5	1599.859	[248.430, 4374.664]	1688.149	754.963
	FLUXcultivation_energy	13	345.191	[207.000, 635.720]	145.516	40.359
	FLUXsoil_preparation	12	514.524	[14.477, 1166.000]	437.568	126.315
	FLUXseed_preparation	7	340.383	[114.080, 555.000]	198.000	74.837
	FLUXplanting	5	268.038	[28.954, 427.105]	216.144	96.662
	FLUXirrigation	10	500.433	[0.000, 2044.000]	682.786	215.916
	FLUXfertilization	14	1219.225	[210.000, 3230.500]	842.083	225.056
	FLUXcrop_protection	17	270.156	[0.000, 728.000]	257.833	62.534
	FLUXtransportation	4	8.800	[4.000, 11.500]	3.473	1.736
	FLUXharvest	5	69.530	[14.477, 111.146]	43.868	19.619
Storage	FLUXstorage_operations	4	538.575	[96.800, 780.500]	303.087	151.543
	FLUXstorage_tuber_respiration	297	376.891	[63.687, 1056.513]	202.384	11.744

and

Table 16. Summary of carbon flux statistics for the potato cultivation and storage stages per tonne of harvested potatoes (kg CO₂ eq t⁻¹ season⁻¹).

Stage	Carbon Flux	Number of Observations	Mean	Range	Standard Deviation	Standard Error of the Mean
Cultivation	FLUXecosystem_CO2	12	−334.306	[−1514.638, 346.475]	597.265	172.416
	FLUXecosystem_CH4	5	0.810	[−0.314, 4.833]	2.252	1.007
	FLUXecosystem_N2O	5	42.438	[3.654, 126.435]	50.261	22.477
	FLUXcultivation_energy	13	13.776	[8.000, 25.429]	4.960	1.376
	FLUXsoil_preparation	12	28.211	[0.670, 70.000]	23.714	6.846
	FLUXseed_preparation	7	13.573	[3.400, 37.000]	12.733	4.813
	FLUXplanting	5	13.350	[1.340, 23.275]	11.096	4.962
	FLUXirrigation	10	20.698	[0.000, 73.000]	26.395	8.347
	FLUXfertilization	14	48.445	[11.520, 93.263]	26.316	7.033
	FLUXcrop_protection	17	12.495	[0.000, 41.000]	13.009	3.155
	FLUXtransportation	4	0.475	[0.400, 0.500]	0.050	0.025
	FLUXharvest	5	3.420	[0.670, 5.271]	2.197	0.982
Storage	FLUXstorage_operations	4	12.750	[2.200, 22.300]	8.571	4.286
	FLUXstorage_tuber_respiration	297	15.064	[2.841, 47.130]	10.083	0.585

summarize the statistics of the carbon fluxes of different farming operations during the cultivation stage. The data shows that all operations emit greenhouse gases. Among the operations involved, on-farm transportation has the lowest carbon flux with the smallest deviation when measured again per hectare. In contrast, fertilization has the most negative impact on greenhouse gas emissions. As shown in Table 15 and Table 16, the standard deviation values for certain practice carbon fluxes indicate substantial variability among the studies. This dispersion likely arises from differences in site-specific conditions (such as climate, soil, and farming practice). Therefore, the mean values should be interpreted as indicative rather than definitive.

Figure 2 demonstrates the carbon fluxes of CO₂, CH₄, and N₂O of the ecosystem during the cultivation period, with confidence intervals at different levels. Observations from studies on CO₂ showed the widest range, including negative and positive values. The contradictory results were due to different farming practices applied to cultivation. For example, the results of a study in Colombia showed that agricultural drought led to limited gross primary cultivation [16]. The gross primary cultivation of the irrigated potato crop was 337.5% higher than its rainfed counterpart, with a difference of 29,451.155 kg CO₂ ha⁻¹ season⁻¹. This difference led to the rainfed potato crop suffering a reduction in yield. In addition, the cumulative net carbon ecosystem exchange results suggested that the irrigated crop is a carbon sink and the rainfed crop is a carbon source.

Figure 3 and Figure 4 illustrate the carbon fluxes associated with various operations during potato production. Variations occur in each phase due to specific operational settings. The carbon flux of storage operations exhibits the most significant variation, followed by fertilization and irrigation. In contrast, transportation shows the most minor carbon flux and variation. Fertilization has the highest carbon flux, and the N₂O emission rate is related to the amount of fertilizer applied. The results of Ruser et al. showed there would be a twofold difference in the N₂O emissions in low and high rates of N fertilization, 6862.218 and 13,724.437 kg CO₂ eq year⁻¹ [15].

This study uses “kg CO₂ eq ha⁻¹ season⁻¹” to provide a more consistent and comprehensive measure for different farming inputs, such as fertilizers and biocides. Three scenarios are addressed, with operational details shown in

Table 17. Three scenarios of potato production and corresponding carbon fluxes.

Carbon Flux	Scenario
	Scenario 1: Worst	Scenario 2: Best	Scenario 3: Average
FLUXeco-CO2	6860.210 kg CO2 eq ha−1 season−1	−13,433.860 kg CO2 eq ha−1 season−1	−2977.462 kg CO2 eq ha−1 season−1
FLUXeco-CH4	167.209 kg CO2 eq ha−1 season−1	−12.624 kg CO2 eq ha−1 season−1	26.243 kg CO2 eq ha−1 season−1
FLUXeco-N2O	4374.664 kg CO2 eq ha−1 season−1	248.430 kg CO2 eq ha−1 season−1	1599.859 kg CO2 eq ha−1 season−1
FLUXsoil_preparation	1166.000 kg CO2 eq ha−1 season−1 (1 plowing, 1 harrowing, 5 rounds of hoeing)	14.477 kg CO2 eq ha−1 season−1	514.524.000 kg CO2 eq ha−1 season−1
FLUXseed_preparation	555.000 kg CO2 eq ha−1 season−1 (2 chemical mixture treatments)	114.080 kg CO2 eq ha−1 season−1 (3% boric acid)	340.383 kg CO2 eq ha−1 season−1
FLUXplanting	427.105 kg CO2 eq ha−1 season−1 (seed rate 2.5 t ha−1)	28.954 kg CO2 eq ha−1 season−1	268.038 kg CO2 eq ha−1 season−1
FLUXirrigation	2044.000 kg CO2 eq ha−1 season−1 (100% area irrigated; rain gun; grid electricity use, no diesel use; 5500 m3/ha water applied; 43 m pumping depth)	0.000 kg CO2 eq ha−1 season−1 (no irrigation)	500.433 kg CO2 eq ha−1 season−1
FLUXfertilization	3230.500 kg CO2 eq ha−1 season−1 (mean applications: fertilizer: 3, manure: 0.5; fertilizer (kg/ha): N-mineral: 190, P2O5-mineral: 52, K2O-mineral: 115; organic inputs (t/ha): poultry manure: 3)	210.000 kg CO2 eq ha−1 season−1 (20,000 kg/ha N-organic)	1219.225 kg CO2 eq ha−1 season−1
FLUXcrop_protection	728.000 kg CO2 eq ha−1 season−1 (25 biocide applications)	0.000 kg CO2 eq ha−1 season−1	270.156 kg CO2 eq ha−1 season−1
FLUXtransportation	11.500 kg CO2 eq ha−1 season−1	4.000 kg CO2 eq ha−1 season−1	8.800 kg CO2 eq ha−1 season−1
FLUXharvest	111.146 kg CO2 eq ha−1 season−1	14.477 kg CO2 eq ha−1 season−1	69.530 kg CO2 eq ha−1 season−1
FLUXcultivation_inputs	7637.531 kg CO2 eq ha−1 season−1	178.988 kg CO2 eq ha−1 season−1	2845.898 kg CO2 eq ha−1 season−1
FLUXstorage_operations	780.500 kg CO2 eq ha−1 season−1	96.800 kg CO2 eq ha−1 season−1	538.575 kg CO2 eq ha−1 season−1
FLUXstorage_tuber_respiration	1056.513 kg CO2 ha−1 season−1	63.687 kg CO2 ha−1 season−1	376.891 kg CO2 ha−1 season−1
FLUXproduction	13,874.816 kg CO2 eq ha−1 season−1	−12,830.567 kg CO2 eq ha−1 season−1	−90.703 kg CO2 eq ha−1 season−1

. Scenario 1, the worst scenario, where the minimum sequestration is assumed while the maximum fluxes are used for each emitter, results in a net carbon flux of 13,874.816 kg CO₂ eq ha⁻¹ season⁻¹, acting as a significant carbon source. In contrast, Scenario 2, the best-case scenario, where the maximum sequestration is achieved with the minimum fluxes for each emitter, yields a significant net carbon flux of −12,830.567 kg CO₂ equivalent per hectare per season. This scenario demonstrates the potential for the ecosystem to absorb substantial amounts of greenhouse gases. Lastly, Scenario 3 is the average scenario where the mean fluxes are used for both sequestration and emissions, resulting in a net carbon flux of −90.703 kg CO₂ equivalent per hectare per season. Although the sequestration potential is not as high as Scenario 2, this scenario also reflects the capacity of the system to sequester greenhouse gases. Collectively, these scenarios highlight the varying impacts of agricultural practices on carbon emissions and sequestration, emphasizing the critical role of management strategies in mitigating greenhouse gas emissions in potato production, particularly during the growing phase. It is important to note that the “worst” and “best” scenarios are hypothetical combinations of reported practices from different regions. These scenarios are intended to illustrate the potential range of carbon flux outcomes under favorable or unfavorable management conditions, rather than to represent any specific location or agronomic system.

4. Discussion

4.1. Cross-Study Patterns

While the rate of repeated findings was not quantified, the studies reviewed showed consistent patterns in several areas. For example, emissions from fertilization were identified as the largest source of greenhouse gases in nearly all LCA studies. Similarly, N₂O emissions were consistently reported as a major contributor to total emissions. By contrast, CO₂ fluxes from the ecosystem were more variable, with several field-based studies identifying net carbon sinks in irrigated cropping systems and net sources in rainfed fields.

4.2. Environmental Factors

Soil content has a significant effect on both the cultivation and storage stages, and their properties can affect the soil’s ecological functions and the greenhouse gas emissions of the ecosystem [30,31,32]. Some positive effects of these soil properties, such as soil organic carbon, lead to underground organ growth and nutrient uptake [33]. However, others, such as soil compaction, negatively affect greenhouse gas emissions during cultivation. A study in Germany reveals that up to 52% of the N₂O emissions were caused by tractor-traffic soil compaction [15]. Another study confirms the negative effects of soil compaction and reveals that loose soil can not only decrease N₂O emissions but also increase CH₄ uptake [21]. Both studies found that the potato ecosystem acted as a net sink for CH₄. The CH₄ sink is driven by O₂-dependent methanotrophic bacteria, whose activity declines when soil is compacted and O₂ diffusion is restricted. Thus, practices that maintain loose soil structure can enhance CH₄ oxidation and improve overall greenhouse gas balances in potato cropping systems.

Temperature and humidity also significantly affect the carbon flux of the potato production. On the one hand, CH₄ uptake can benefit from high soil temperature and low soil moisture [15]. On the other hand, high soil temperature promotes autotrophic respiration and microbial activity, resulting in higher greenhouse gas emissions [14,34]. In addition, high air temperatures and increased relative humidity also significantly worsen the emergence of diseases such as late blight and their spread [9,35].

4.3. Farming Inputs

Fertilizers have two opposite effects on the ecosystem in terms of carbon flux. On the one hand, fertilizers can increase net primary cultivation in potato plants [33]. But they are also found to be positively correlated with N₂O emissions [9,14,36]. According to a study in India, compared to the control with an N₂O flux of 291.035 kg CO₂ eq ha⁻¹ season⁻¹, the N₂O emission from the field with the treatment of 270 kg N/ha urea is approximately six times higher, about 1751.504 kg CO₂ eq ha⁻¹ season⁻¹ [37]. On the other hand, another study also finds that lower fertilizer rates can lower N₂O emissions, especially in degraded fields where the potato yield does not benefit much from the increased fertilizer rate [38]. It is worth mentioning that the CH₄ emission is more affected by soil compaction than the fertilizer rate [15].

In addition to fertilizers, the carbon flux of the cultivation stage is also highly correlated with water supply (r > 0.85) [17]. Generally speaking, an irrigated potato crop absorbs more CO₂ while rainfed crops emit more, and the gross primary productivity of the irrigated potato crop is 337.5% higher than that of the rainfed potato crop [16]. With sufficient water supply, the irrigated potato crop has greater sink capacity because it has higher gross primary productivity and evapotranspiration and high intrinsic use efficiency [17]. The gross primary productivity can be more than two times higher than Reco when no water limitations exist [39]. In contrast, when drought appears, potato plants suffer a decrease in gross primary productivity [40]. Additionally, plant organic carbon decreases because of drought, and the soil organic carbon will decrease accordingly. The ecosystem will become a net carbon source as a result [30]. The reason behind this is that water stress reduces the maximum gross photosynthetic rate of the canopy, which may decrease up to 50% in the seasonal net carbon assimilation [41].

Although using machinery enhances potato yield, it results in higher greenhouse gas emissions. For example, less developed potato-producing countries may have greenhouse gas emissions that are three times lower as their farming practices rely less on machinery [9]. Additionally, the efficiency of agricultural equipment tends to decline over time [35].

4.4. Growing Types

Organic and conventional potatoes differ in the greenhouse emissions during the cultivation stage. More farming inputs, such as fertilizers and biocides, introduce more sources of greenhouse gas emissions in the cultivation of conventional potatoes. Although organic potatoes are usually grown on a smaller scale [42], they are more eco-friendly because of their farming practices [11,25].

Potatoes grown in different cropping seasons vary in terms of growing duration and challenges. Regarding growing duration, it may take longer to harvest the winter crop because of sudden rain events after tubers mature [35]. As for growing challenges, the winter crop tends to require more water supply, while the spring crop may need more biocide spraying to treat more active diseases [35]. The differences are mainly due to their climate conditions: the temperature and humidity for the winter cropping season are low, whereas the spring cropping season tends to have high temperatures and humidity.

Seed potatoes are grown for a shorter period, and this shortened growing duration impacts their carbon flux [19]. Because of the shorter cultivation period, the carbon sequestration of seed potatoes is limited [18,43].

Throughout the whole growing season, the majority of carbon sequestration happens during tuberization [43]. According to a study in 2012, about 75% of carbon sequestration occurs during tuberization [39].

4.5. Limitations

On the one hand, potato production represents only a portion of the overall potato supply chain, with subsequent stages, such as processing, contributing significantly more to the overall greenhouse gas emissions [12]. A 2021 study indicates that these later stages—processing, retailing, and consumption/food service—account for approximately 72% of total emissions [44].

On the other hand, some of the included farming factors were not fully explored, and we could not conduct a regression analysis for the identified factors, which limits our understanding of their influence on carbon flux. Firstly, in potato production, which includes the cultivation and storage stages, the carbon flux is influenced by factors such as fertilizer application rate, water supply, and climate conditions, among others [45]. Differences in these practices and variations in the defined inventory of inputs and outputs contribute to the significant variability in carbon flux results from study to study [12]. However, we could not quantitatively explain this variability or conduct a regression analysis to determine the extent to which these independent variables affect the carbon flux due to the lack of data from controlled experiments. Secondly, although potato planting density may also affect the gross primary productivity of the ecosystem, this data is not available in most of the studies [43].

Lastly, carbon fluxes per tonne of harvested potatoes are explored but relatively developed. Although the carbon flux of potato production can be estimated per hectare of the cultivation field, it can also be discussed per tonne of harvested potatoes. Moreover, this difference can lead to potential conclusions. For example, although organic farming has lower absolute greenhouse gas emissions than traditional farming, its per-tonne production carbon flux may be higher due to its lower production yield.

4.6. Mitigation

Mitigation strategies play a crucial role in reducing greenhouse gas emissions in agriculture, and various approaches can be tailored to potato production, especially for farming operations in the cultivation stage, to maximize its carbon sink potential and reduce emissions.

One effective method is to promote and support organic farming. There is a trend that more conventional potatoes are processed before consumption. In contrast, organic potatoes are often consumed fresh. Therefore, organic farming can reduce or reverse the trend [12].

For sowing, stress-tolerant, high-yield potato varieties can help reduce carbon emissions [9]. Additionally, no-till practices allow the soil to develop improved porosity, leading to better moisture retention and increased organic matter accumulation [46].

Accurate fertilizer application and certain application methods can also reduce greenhouse gas emissions. Prior soil analysis and consulting can inform the farms of a concise fertilizer application rate, which can not only reduce carbon emissions during the growing period but also eliminate emissions from excessive fertilizer cultivation, which is also a major emission source [13,35]. In addition to accurate fertilization, band placement and splitting fertilization can improve the efficiency of nitrogen uptake and reduce N₂O emissions, and organic fertilizers may be a potential approach to improve soil conditions, which helps nutrient uptake [15,33].

The environment can also benefit from irrigation optimization using a field weather station and drip irrigation techniques. A weather station in the growing field can support evidence-based irrigation decisions by providing needed information, including soil temperature, soil moisture, air temperature, precipitation, wind, and sunlight radiation. By doing this, about 16% of water use can be saved for irrigation. Diseases and pest management can also benefit from this. In addition, the irrigation practice can benefit more if this sensor-based technology is used along with a drip irrigation system [35].

Proper equipment maintenance is another important strategy for mitigating emissions. Diesel-fueled equipment is a main greenhouse gas emission contributor and becomes less energy-efficient over time [47]. Therefore, maintenance and catalyst installation are needed [35].

Reduction in diesel fuel use can also contribute to greenhouse gas mitigation by avoiding unnecessary energy waste and using green energy. To reduce energy consumption by farming equipment, sustainable practices should be considered, including reduced tillage and reduction in water, biocides, and fertilizer inputs. These sustainable practices also minimize soil erosion [46]. In additionally, solar power and biomethane can be used in the irrigation system and agricultural equipment to decrease carbon emissions further [35]. Alternatively, farmers can purchase more fuel-efficient equipment.

Integrating crop rotation with sustainable practices can also contribute to greenhouse gas mitigation by optimizing nutrient cycling. Continuous potato cropping decreases soil water potato storage and use efficiency [48]. Crop rotation maintains soil water balance, productivity, structure, and fertility. It can also repress weeds, pests, and plant diseases. As a result, potato yield can significantly increase with the same or fewer inputs, and the greenhouse gas emissions per unit weight decrease accordingly, resulting in a reduction of 34.4–52.4% in N₂O emissions [14,35]. It is worth mentioning that even using cover crops as green manures before potato planting can enhance soil carbon potato storage; it may lead to an increase in greenhouse gas emissions and contribute to global warming [33].

Reducing waste, including that generated during harvest, also decreases carbon emissions [47]. This can be achieved by adopting efficient harvest tools and conducting harvest at optimal soil temperature and moisture levels.

Supportive policies and educational programs are essential for encouraging the adoption of these mitigation strategies among farmers. For example, programs supporting farmers purchasing energy-efficient equipment promote more eco-friendly potato cultivation.

In conclusion, combining these mitigation strategies can significantly reduce agricultural greenhouse gas emissions, paving the way for more sustainable farming practices.

4.7. Future Research

Based on the findings of this review, further research is needed to strengthen the understanding of carbon flux dynamics in potato production systems. Specifically, controlled field experiments should be conducted to quantify the effects of individual management practices (such as fertilizer type and rates) and environmental factors (such as soil type and radiation level) on net greenhouse gas emissions. These efforts would contribute to the development of regionally optimized, low-emission potato farming strategies.

5. Conclusions

This paper estimates the carbon flux of potato production by synthesizing sequestration and emission data from field-scale studies (EC and chambers) and LCA studies. Two calculation methods are employed to estimate the carbon flux of potato production.

The carbon flux of potato production is estimated in three scenarios: Scenario 1, the worst-case scenario, is identified as a carbon source, exhibiting a carbon flux of 13,874.816 kg CO₂ eq ha⁻¹ season⁻¹. In contrast, both Scenario 2 (the best-case scenario) and Scenario 3 (the average scenario) are classified as carbon sinks, with carbon fluxes of −12,830.567 and −90.703 kg CO₂ eq ha⁻¹ season⁻¹, respectively.

All potato production operations contribute to carbon emissions. Among these, fertilization is a primary source, with an average carbon flux of 1219.225 kg CO₂ eq ha⁻¹ season⁻¹ or 48.445 kg CO₂ eq t⁻¹ season⁻¹.

To effectively mitigate greenhouse gas emissions in potato cultivation, it is crucial to optimize key practices—such as adopting no-till or reduced tillage, using precision fertilizer application, implementing sensor-based irrigation systems, maintaining energy-efficient machinery, and rotating crops to preserve soil health. Additionally, controlled experiments are necessary to better understand the quantitative relationships between farming factors and carbon flux.