Effects of Alternative Fertilization and Irrigation Practices on the Energy Use and Carbon Footprint of Canning Peach Orchards

Abstract

Throughout peach orchards in Greece, plant protection, fertilization and irrigation are often conducted empirically, negatively affecting energy use efficiency and greenhouse gas emissions (GHG emissions). The aim of this study was to apply alternative fertilization and irrigation practices in canning peach orchards to improve nutrient and irrigation water management and to assess yield, energy input–output and the carbon footprint of the alternative cultivation practices for three important clingstone cultivars of different ripening periods. Energy use analysis revealed that the cultivation practice with the highest energy use was almost always irrigation, followed by fertilization, plant protection, weed control and pruning. Electricity, fuels, fertilizers and machinery presented the highest energy requirements. Alternative fertilization, in combination with deficit irrigation (DI), was more energy efficient compared to farmers’ practices in all cultivars based on energy use efficiency, energy productivity and specific energy. Irrigation was the cultivation practice with the highest impact on GHG emissions due to electricity and, secondly, to fuel consumption. Alternative fertilization and DI decreased the intensity (kg CO₂eq kg⁻¹) of the emitted GHG compared to farmers’ practices. In conclusion, alternative fertilization and irrigation practices improved energy use efficiency and decreased the carbon footprint of the canning peach orchards by improving yield and decreasing fertilizer and irrigation water input.

1. Introduction

Peach processing is an important sector for the local economy in the cultivation and processing areas, but also for the national economy of Greece. The cultivation of canning peaches in Greece spreads mainly to the area of northern Greece and, to a lesser extent, to central Greece. In the EU, Greece takes up the third position in total production of peaches and nectarines. Important Greek processing industries absorb the total production and the final products (cans, glass jars, aseptic fruit, puree or juice), and almost entirely (98%) are exported mainly to the EU (80%) [1].

In recent years, peach processing industries have been emphasizing the quality and nutritive value of the raw product, which must be safe for humans (mainly free of pesticide residues) and environmentally friendly. Processing industries try to collaborate with farmers to intervene in the cultivation management of the raw product in order to cover the consumer and market requirements and standards. Consumers often hear or use terms such as ‘sustainable’, ‘green’ and ‘reduced carbon footprint’, and expect more sustainable products and services in terms of economics, natural resource depletion and global warming potential (GWP), in addition to healthy and safe products [2]. Thus, the peach processing industries move towards more environmentally friendly products and certification of these products.

On the other hand, the antagonism leads to an intensification of cultivation to reach a higher yield, to decrease production costs and, finally, to provide a higher income to the farmer. Integrated crop management has been implemented for almost 20 years now; unfortunately, it has not been implemented ‘fully’. Usually its application is based on complete plant protection, and it is characterized by incomplete management of other practices such as irrigation and fertilization. Thus a more holistic intervention is required to deal with crop management with the participation of main cultivation practices in addition to chemical plant protection. Apart from the above, we face a climatic change which may hit the tree crops at multiple levels and cause serious stress to plants, which is expected to have a negative impact on crop productivity, mainly because of extreme temperatures, lower precipitation and reduced water availability [3]. For this reason it is crucial to target actions for a more environmentally friendly and sustainable peach cultivation that will improve the antagonism of peaches. Thus the rational management of fertilization, irrigation and crop protection remains of major significance.

Life Cycle Assessment (LCA) is often used to quantify the environmental impact of a product or a service, and can help to optimize energy consumption and minimise environmental burdens during production [4]. A carbon footprint (expressed as the GWP in net kilograms CO₂ or equivalent for other greenhouse gases such as methane (CH₄) and nitrous oxide (N₂O) released or sequestered per functional unit of the product or practice] is usually the most common component of LCA systems [2]. GHG emissions are also directly linked with energy use in agriculture [5].

Energy management is a fundamental issue in terms of efficient, sustainable and economic use of energy [6]. Energy input–output analysis of a system is applied to measure its energy efficiency, as it is one of the main requirements of sustainable agriculture [7,8]. Energy use analysis can indicate ways to decrease energy input and increase energy efficiency without negatively affecting crop production economics [9], while simultaneously it could increase productivity [5]. Thus, energy analysis is frequently used in combination with other environmental or economic indicators to obtain the best management strategies [10].

Several researchers have analysed the energy use [6,7,8,9,11,12] and the GHG emissions [13,14,15,16,17,18] for different crops, agricultural production systems and cultivation practices in order to evaluate the energy use efficiency, the environmental effects and their relationship to sustainability. Enhancing energy efficiency not only helps to increase the productivity and profitability ratio, but also results in minimised GHG emissions and environmental impact [19].

Until now, the quantification of energy use and GHG emissions of different ripening periods for canning peach orchards and the effects of the alternative use of fertilization and irrigation on the energy input–output and GHG emissions are limited. The main objectives of this study were: (1) to evaluate the energy use and carbon footprint of the current cultivation scheme followed by the farmers for three important processing cultivars: the early ripening ‘Catherina’, the mid-season ‘Andross’ and the late-season ‘Everts’, in order to understand the environmental impact of the specific agricultural production system and to identify ways that growers can improve overall the efficiency of the cultivation, (2) to suggest an alternative cultivation method by improving fertilization and irrigation management according to the needs for nutrients and water at specific stages of peach cultivation, and (3) to compare energy use and carbon footprint of the two cultivation methods. The functional unit was defined per kg of peaches at farm gate.

2. Materials and Methods

The research was conducted in three commercial canning peach orchards of three cultivars: the early ripening ‘Catherina’, the mid-season ‘Andross’ and the late-season ‘Everts’ grafted on GF677 during 2020. The orchards were located at Pella, in northern Greece. ‘Catherina’ and ‘Everts’ trees were trained to open vase, while ‘Andross’ trees were trained to a fruiting wall system, and all were cultivated according to local horticultural practices. The size of the studied orchards was 1.20, 0.45 and 0.90 ha; tree spacing was 5 m × 5 m, 2.5 m × 4.5 m and 3.8 m × 5 m; and the age was 5, 7 and 4 years for ‘Catherina’, ‘Andross’ and ‘Everts’, respectively. Soil analysis was conducted for each farm and is presented in the

Table 1. Soil analysis of ‘Catherina’, ‘Andross’ and ‘Everts’ farms.

Farm	‘Catherina’	‘Andross’	‘Everts’
Soil type	Silty loam	Sandy loam	Clay loam
Sand (%)	19.2	61.9	31.5
Silt (%)	57.3	27.0	39.0
Clay (%)	23.5	11.1	29.5
pH	7.84	7.92	7.58
Electrical Conductivity (mmhos/cm)	0.27	0.24	0.24
CaCO3 (%)	6.82	5.72	0.44
Organic Matter (%)	1.20	1.62	1.58
P (mg kg−1)	3	64	13
K (mg kg−1)	237	219	172
Ca (mg kg−1)	4005	3411	2523
Mg (mg kg−1)	587	721	787
Zn (mg kg−1)	0.78	2.52	1.82
Fe (mg kg−1)	8.02	7.66	9.72
Mn (mg kg−1)	7.88	3.86	12.5

.

Detailed data for the horticultural practices of the farmers were collected through personal interviews. The system boundaries for energy analysis and the carbon footprint of canning peach production were defined as shown in Figure 1.

To investigate the effect of an alternative fertilization and irrigation protocol on energy input–output and GHG emissions of canning peach production, experimental applications were carried out at each orchard with the two following treatments:

• Farmers’ traditional practices
• Alterative cultivation protocol comprising deficit irrigation (75% of ETc) and fertilization schemes combining balanced applications of surface granular fertilizers, foliar fertilizers and fertigation.

At the ‘Catherina’ orchard, deficit irrigation was applied in the postharvest stage, while in the ‘Andross’ and ‘Everts’ orchards it was applied at pit hardening. Except for irrigation and fertilization, the other agricultural practices (weed management, crop protection, etc.) were common among the two treatments. Details are presented in Table S1 in the Supplementary Materials.

Each treatment consisted of 10 tree replications. At fruit commercial harvests, yield per tree was recorded and expressed per hectare. The pit hardening period was evaluated by recording fruit growth (diameter measurement) from fruit set until fruit harvest. The pit hardening period for ‘Andross’ was found to be from early June to early July, and for ‘Everts’ from late May to early July.

The energy use for peach production is associated with the machinery used for farm operations, transportation to the field and processing point, water for irrigation, agricultural inputs (fertilizers, pesticides, etc.), supplementary tools (ladders, bins, etc.) and human labour. All necessary detailed data were logged during personal interviews with each farmer (Table S1).

The energy inputs involve direct and indirect energy sources [20]. Direct energy inputs come from human labour and fossil fuel (diesel or gasoline) consumption (accounting also for the lubricants) during field operations or transportation. Human energy was counted as the energy content of the consumed food, equivalent to 2.2 MJ h⁻¹ [21], and was estimated by recording the working hours per ha. Fuel consumption was measured by top filling and refiling the tank of the tractor or light truck after a specific area or distance covered within a certain period of time. The data were used to calculate fossil fuel consumption (L h⁻¹) (

Table 2. Estimation of direct energy inputs based on fuel consumption reported by the farmers.

Item	Fuel Type	Fuel Consumption(L h−1)	Direct Energy Use (MJ h−1)
Vehicles
Farm tractor (75–95 hp)	Diesel	Depending on the specific tasks
Farm car (half loaded)	Gasoline	4.08	172.7
Truck (half loaded)	Diesel	4.2	200.7
Machinery
Mower	Diesel	10.83	517.5
Pruning shredder	Diesel	13.15	628.3
Handheld weed mower	Gasoline	1.62	68.6
Fertilizer spreader	Diesel	6.81	325.4
Orchard sprayer	Diesel	11.39	544.2
Pruning shears (2 workers) with air compressor	Gasoline	3.35	160.1
Irrigation
Centrifugal pump with electric motor	Electricity		92–231 1

¹ MJ h⁻¹ ha⁻¹.

). The energy equivalent for diesel accounted for 47.78 MJ L⁻¹ (including the caloric value and the energy for mining, refining and transporting the fuel) and for gasoline, 42.32 MJ L⁻¹ [22]. Subsequently, energy use (MJ h⁻¹) was estimated and was finally converted to energy use per ha from all inputs used (Table S1). Lubricant energy was estimated as 4% of fossil fuel energy [22]. Energy for irrigation was estimated by calculating the absorbed power and the electricity consumption as described by [20]. The number of irrigation events, water applied per irrigation event, pumping depth, network pressure, pump rated power and pump discharge rate were all essential information retrieved by the farmers (Table S1). Table 2 presents the direct energy used in irrigation in MJ h⁻¹ ha⁻¹.

Indirect energy inputs come from machinery and infrastructure use and from agricultural inputs. Machinery and infrastructure energy include the energy embodied in materials and the sequestered energy during the manufacturing process. The most widely used value for estimating this type of energy is 86.77 MJ kg⁻¹ [23]. The indirect energy of machinery also includes the energy consumed for repairs and maintenance (estimated as 0.49 times the energy for manufacturing) and energy for trading and the delivery of equipment to the owner (accounted as 8.8 MJ kg⁻¹) [22,24]. The rate of indirect energy use depends on machinery or equipment life span hours (

Table 3. Estimation of indirect energy inputs (MJ h⁻¹) based on farmer interviews, machinery manuals, and information from the literature.

Item	Mass 1 (kg)	Estimated Life (h)	Source	Indirect Energy Use (MJ h−1)
Vehicles
Farm tractor (75–95 hp)	3350–4240	16,000	[25]	18.1–22.3
Farm car	1200	7500	Current estimations	13.9
Truck	2000	7500	Current estimations	23.1
Machinery
Mower	280–350	2000	[25]	12.1–15.2
Pruning shredder	850	1500	[14]	49.2
Handheld weed mower	10	1500	[14]	0.58
Fertilizer spreader	150–220	1200	[25]	10.8–14.5
Orchard sprayer	750–950	2000	[25]	32.5–41.2
Aero-scissors (2 workers) with air compressor	150–180	1500	[14]	8.7–10.4
Irrigation
Centrifugal pump with electric motor	70–150	2160	[20] adapted	15.4–18.5

¹ From farmer interviews and from manufacturer manuals.

) and real field performance (ha h⁻¹) as reported from the farmers (Table S1). For the truck, the estimated life in hours was calculated at 7500 h by considering a travel lifetime of 300,000 km divided by a mean travel speed of 40 km h⁻¹. All inputs were initially estimated per hour of use and were consequently converted to MJ per ha. Another important source of indirect energy inputs is agricultural input (fertilizers, pesticides, etc.). The energy for their production is consumed outside the farm’s gates, but enters the farm embodied in the products. The inputs were estimated from the applied doses per ha and the corresponding energy content from the literature (

Table 4. Energy content of agricultural commodities.

Item	Energy Content (MJ kg−1)	Source
Nitrogen	74.2	[26,27]
Phosphate	13.7	[26,27]
Potassium	9.7	[26,27]
Sulphur	5	[28]
Calcium	8.82	[29]
Herbicides	238	[30]
Fungicides	99	[30]
Insecticides	363	[30]
Mineral oil	43.2	[31]
Lime sulphur	1.3	[32]
Bordeaux mixture	2.35	[33] adapted
Polyethylene pipes	0.092 1	[24,25]

¹ MJ hm⁻¹.

).

The energy outputs were estimated by the energy content of the peach fruit, equal to 3.37 MJ kg⁻¹ [34], and the corresponding yields for each treatment and farm. They were also expressed in MJ ha⁻¹. Net energy (energy outputs minus total energy inputs), energy efficiency (output/input ratio), specific energy (energy used per kg of product) and energy productivity (kg of product per unit energy used) were estimated.

The assessment of GHGs included emissions due to the use of fossil fuels and electricity; emissions due to the production, transportation, storage and transfer of agricultural inputs [35]; and emissions due to the fossil fuel consumption for manufacturing all components of machinery [28]. GHG emissions were managed as CO₂ equivalents (CO₂eq), which was calculated by multiplying the input application rate (fuel, fertilizers, pesticides and electricity used for irrigation) by each corresponding CO₂eq emission factor (

Table 5. Greenhouse gas (GHG) emissions coefficients of each input.

Input	Unit	GHG Coefficient (kg CO2eq/unit)	Reference
Nitrogen	kg	1.2	[35]
Phosphate (P2O5)	kg	0.2	[35]
Potassium (K2O)	kg	0.15	[35]
Calcium	kg	0.16	[35]
Sulphur	kg	0.3	[28]
Herbicides	kg	9.1	[35]
Insecticides	kg	5.1	[35]
Fungicides	kg	3.9	[35]
Bordeaux mixture	kg	1.2	[28]
Lime sulphur	kg	0.04	[28]
Diesel	MJ	0.0741	[36]
Gasoline	MJ	0.0693	[28]
Machinery/tools	MJ	0.08	[28]
Electricity	MJ	0.0581	[28]
Water	m3	0.6	[37]

).

3. Results and Discussion

3.1. Analysis of Input–Output Energy Use

Energy use analysis revealed that irrigation was the cultivation practice with the highest energy use for all farms and both cultivation systems except for the farm with ‘Everts’ peaches, where irrigation was the second most energy demanding practice after fertilization (

Table 6. Energy input use per cultivation practice for alternative management practices compared to farmers’ practices, for ‘Catherina’ peach production.

‘Catherina’
	Farmers’ Practices		Alternative Management Practices
Practice	Energy Input (MJ ha−1)	% of Total Energy Input	Energy Input (MJ ha−1)	% of Total Energy Input
Pruning	1566.2	2.7	1561.3	3.1
Fruit thinning	888.1	1.5	888.1	1.7
Irrigation	30,890.4	52.5	27,806.4	54.5
Fertilization	10,284.9	17.5	5598.9	11.0
Weed control	4554.8	7.7	4547.2	8.9
Plant protection	10,274.2	17.5	10,215.1	20.1
Harvesting	361.6	0.6	361.6	0.7
Total energy input	58,820.2		50,978.7

,

Table 7. Energy input use per cultivation practice for alternative management practices compared to farmers’ practices, for ‘Andross’ peach production.

‘Andross’
	Farmers’ Practices		Alternative Management Practices
Practice	Energy Input (MJ ha−1)	% of Total Energy Input	Energy Input (MJ ha−1)	% of Total Energy Input
Pruning	4615.3	5.2	4615.3	6.1
Fruit thinning	537.9	0.6	537.9	0.7
Irrigation	40,138.7	45.0	36,161.9	47.9
Fertilization	18,840.5	21.1	9099.9	12.1
Weed control	12,032.7	13.5	12,032.7	16.0
Plant protection	12,354.3	13.9	12,369.5	16.4
Harvesting	609.0	0.7	609.0	0.8
Total energy input	89,128.4		75,426.2

and

Table 8. Energy input use per cultivation practice for alternative management practices compared to farmers’ practices, for ‘Everts’ peach production.

‘Everts’
	Farmers’ Practices		Alternative Management Practices
Practice	Energy Input (MJ ha−1)	% of Total Energy Input	Energy Input (MJ ha−1)	% of Total Energy Input
Pruning	7371.9	10.9	7371.9	14.7
Fruit thinning	263.8	0.4	263.8	0.5
Irrigation	17,354.5	25.8	15,594.1	31.1
Fertilization	22,932.6	34.0	7402.5	14.8
Weed control	12,021.4	17.8	12,021.4	24.0
Plant protection	6684.2	9.9	6699.4	13.4
Harvesting	726.1	1.1	726.1	1.5
Total energy input	67,354.5		50,079.2

). Following irrigation, the most energy demanding cultivation practices were fertilization, plant protection, weed control and pruning, while fruit thinning and harvest were the cultivation practices with the least energy consumption for all farms and both cultivation systems. Regarding production coefficients, electricity, fuels, fertilizers and machinery presented the highest energy requirements, while human labour, irrigation water, pesticides, herbicides, and tools provided low contributions in total energy input for all cultivars and cultivation systems (

Table 9. Energy input use per production coefficient and energy output for alternative management practices compared to farmers’ practices, for ‘Catherina’ peach production.

‘Catherina’
	Farmers’ Practices		Alternative Management Practices
Inputs	Energy Input (MJ ha−1)	% of Total Energy Input	Energy Input (MJ ha−1)	% of Total Energy Input
Fertilizers
N	9349.2		3554.2
P	247.4		113.1	10.0
K	676.3	17.5	1009.6
Other fertilizers			422.9
Fungicides	870.3	1.5	870.3	1.7
Insecticides	1503.4	2.6	1503.4	2.9
Herbicides	0	0	0	0
Irrigation water	2009.7	3.4	1808.7	3.5
Tools	80.1	0.1	80.1	0.2
Human labour	1560.7	2.6	1562.3	3.1
Electricity	27,720.0	47.1	24,948.0	48.9
Fuels	12,590.6	21.4	13,028.5	25.5
Machinery	2212.5	3.8	2149.1	4.2
Total energy input	58,820.2		51,050.3
Outputs
Yield (t ha−1)	41.65		43.50
Total energy output (MJ ha−1)	140,360.5		146,595.0
Energy indices
Net energy (MJ)	81,540.3		95,544.7
Energy efficiency (MJ MJ−1)	2.39		2.87
Energy productivity (kg MJ−1)	0.71		0.85
Specific energy (MJ kg−1)	1.41		1.17

,

Table 10. Energy input use per production coefficient and energy output for alternative management practices compared to farmers’ practices, for ‘Andross’ peach production.

‘Andross’
	Farmers’ Practices		Alternative Management Practices
Inputs	Energy Input (MJ ha−1)	% of Total Energy Input	Energy Input (MJ ha−1)	% of Total Energy Input
Fertilizers
N	14,927.4		4429.9
P	518.4	18.7	191.5	8.4
K	1160.1		1263.2
Other fertilizers	7.4		438.1
Fungicides	754.8	0.8	754.8	1.0
Insecticides	1958.1	2.2	1958.1	2.6
Herbicides	535.2	0.6	535.2	0.7
Irrigation water	2116.8	2.4	1905.1	2.5
Tools	90.1	0.1	90.1	0.1
Human labour	1625.4	1.8	1627.5	2.2
Electricity	30,744.0	34.5	27,669.6	36.7
Fuels	24,334.5	27.3	24,842.5	32.9
Machinery	10,356.3	11.6	9721.0	12.9
Total energy input	89,128.4		75,426.2
Outputs
Yield (t ha−1)	48.0		51.5
Total energy output (MJ ha−1)	161,760.0		173,550.0
Energy indices
Net energy (MJ)	72,631.6		98,123.8
Energy efficiency (MJ MJ−1)	1.81		2.30
Energy productivity (kg MJ−1)	0.54		0.68
Specific energy (MJ kg−1)	1.86		1.46

and

Table 11. Energy input use per production coefficient and energy output for alternative management practices compared to farmers’ practices, for ‘Everts’ peach production.

‘Everts’
	Farmers’ Practices		Alternative Management Practices
Inputs	Energy Input (MJ ha−1)	% of Total Energy Input	Energy Input (MJ ha−1)	% of Total Energy Input
Fertilizers
N	21,748.0		5194.0
P	32.4	34.0	191.5	14.3
K	57.2		1263.2
Other fertilizers	1060.0		504.7
Fungicides	660.7	1.0	660.7	1.3
Insecticides	1632.0	2.4	1632.0	3.3
Herbicides	1713.6	2.5	1713.6	3.4
Irrigation water	963.9	1.4	867.5	1.7
Tools	78.1	0.1	78.1	0.2
Human labour	1021.4	1.5	1022.2	2.0
Electricity	13,248.0	19.7	11,880.0	23.8
Fuels	18,685.8	27.8	18,891.9	37.7
Machinery	6453.4	9.6	6179.9	12.3
Total energy input	67,354.5		50,079.2
Outputs
Yield (t ha−1)	35.0		37.80
Total energy output (MJ ha−1)	117,950.0		127,386.0
Energy indices
Net energy (MJ)	50,595.5		77,306.8
Energy efficiency (MJ MJ−1)	1.75		2.54
Energy productivity (kg MJ−1)	0.52		0.75
Specific energy (MJ kg−1)	1.92		1.32

). In other peach orchards in Greece, the most important production coefficients were machinery and tools followed by irrigation, fuels, fertilizers, pesticides and labour [14]. The impact of orchard management activities and products on the use of resources and energy as well as on GHG emission was studied in the peach production sector of Italy, and both fuel consumption and GHG-emissions were found to be the most significant inputs due to the energy use for water pumping and for the maintenance of agricultural equipment [16].

Comparing the three cultivars, the highest energy input was found for the mid-season ‘Andross’, and the lowest for the early ripening ‘Catherina’ (Table 6, Table 7 and Table 8). Concerning irrigation, ‘Andross’ consumed the highest and ‘Everts’ the lowest energy use. The energy use for irrigation depended on irrigation events, water quantity used, pumping depth, irrigation network pressure, pump rated power, pump discharge rate, ripening period of the cultivar and soil texture (Table S1). Because of the earlier ripening period of ‘Catherina’ and limited postharvest irrigation, the farm was irrigated fewer times than the other cultivars. In the case of ‘Andross’, the soil texture of the farm was light, and this justifies the higher frequency of irrigation compared to the late ripening ‘Everts’. In the case of ‘Everts’, irrigation water supply came from the Local Organization for Land Reclamation resulting in lower energy use for irrigation compared to the other cultivars. In addition, the irrigation method used for ‘Everts’ can be characterized as inefficient, because the farmer irrigated sparsely with low irrigation water quantities (on a farm with heavy soil), and this resulted in low electricity use for this farm. The insufficient irrigation volume of ‘Everts’ could also be ascertained from the low yield and vigour of the trees observed in situ. In contrast, the ‘Andross’ yield was high, but the irrigation method and fertilization could still be improved, because in situ observations showed very dense and vigorous shoot growth, causing problems such as increased needs for pruning and plant protection.

Fertilization, especially in the farmers’ practice, was a major energy input because of the application of high quantities of fertilizers. It is crucial to manage tree mineral nutrition to optimize fruit yield and quality [38]. As shown in Table S1, farmers in the study area commonly apply excessive amounts of fertilizers, and also spread the fertilizers around the tree canopy, not only on the irrigation zone. In particular, the manager of the ‘Everts’ farm used mainly, and in very high quantities, nitrogen fertilizers resulting in the highest energy input from fertilization compared to the ‘Andross’ and ‘Catherina’ farms (Table S1, Table 6, Table 7 and Table 8). As irrigation of the ‘Everts’ trees was limited (one sprinkler with low water supply per tree), fertilizer use efficiency was low, given also the low yield. Excessive use of fertilizers results in low use efficiency of fertilizers and possible environmental contamination, but also increased cultivation and energy costs. A correct nutrient supply should take into account expected fruit yield (including fruit quality and storage issues) and environmental concerns (to minimise leaching, soil pollution and volatile emissions) [38]. Fertilizer inputs should be based on periodical soil and leaf analysis, expected yield and tree vegetative growth, and an upper limit to annual fertilizer applications should be set [38].

The energy consumption for plant protection for the three cultivars depended on the frequency of pesticide applications, the kind of pesticide, machinery use and the fuel consumption by the tractor (Table S1). Thus, the ‘Andross’ farm showed the highest energy use for plant protection, while the ‘Everts’ farm had the lowest. Concerning weed management, ‘Catherina’ farm presented the lowest energy use compared to the other cultivars, as weeds on the tree row were mowed with a handheld mower without any herbicide use (Table S1). Energy use for pruning was also the lowest at the ‘Catherina’ farm, because the farmer used only electric scissors instead of aero-scissors that the other farmers used. For all the above cultivation practices, fuel became one of the most important production coefficients for all farms and both cultivation systems (Table 9, Table 10 and Table 11). In all farms, fuel consumption was due mainly to the use of tractor for plant protection, foliar fertilization, weed management, and, to a lower degree, pruning and pruning shredding (Table S1).

Alternative fertilization and irrigation practices significantly reduced energy use compared to farmers’ practices (Table 6, Table 7 and Table 8). Regulated deficit irrigation has been studied in peach orchards in various production regions as a strategy to reduce water use in dry climates [39]. This approach induces a moderate stress to decrease vegetative growth and increase water savings at particular physiological stages without influencing yields [40]. Water stress-tolerant stages for peach have been reported as stage II (pit hardening and the lag phase of fruit growth) and postharvest. In the current study, the application of deficit irrigation during pit hardening for ‘Andross’ and ‘Everts’, or during postharvest for ‘Catherina’, decreased electricity and water consumption by 10% compared to farmers’ practice, without any negative effect on fruit yield (Table 6, Table 7 and Table 8). It was reported that RDI in peaches at pit hardening could be effective for maintaining fruit yield by reducing vegetative growth, but it was also pointed out that trees should have recovered from water stress before stage III. In addition, postharvest deficit irrigation in early-maturing cultivars is a practice to save water during the long postharvest period rather than in the preharvest period, and does not interfere with fruit growth in the same season, given that there will be no negative effect on the subsequent year’s yield [41].

The application of alternative fertilization was targeted to a complete and balanced tree nutrition based on tree needs and in doses during the season. The foliar application of N, P, B and Zn in autumn (Table S1) was conducted for tree preparation for next spring’s shoot and fruit growth. The alternative fertilization resulted in a reduction of the quantity of fertilizers and a significant reduction of energy input by fertilization compared to farmers’ fertilization. Alternative fertilization caused slightly higher fuel consumption because of the extra foliar fertilization in repeated applications until September that increased the use of a tractor and sprayer (Table S1, Table 9, Table 10 and Table 11). Alternative fertilization increased fruit yield, resulting in higher fertilizer use efficiency, compared to farmers’ fertilization practices.

Energy indices, including energy use efficiency, energy productivity and specific energy, revealed that alternative fertilization in combination with deficit irrigation was more energy efficient compared to farmers’ practices in all cultivars (Table 9, Table 10 and Table 11). In addition, alternative fertilization with deficit irrigation slightly increased fruit yield in all farms, thus increasing energy outputs (Table 9, Table 10 and Table 11). Comparing the three farms (and farmers’ vs alternative practices), the ‘Catherina’ farm was found to be the most energy efficient, followed by the ‘Andross’ farm, while the least efficient was the ‘Everts’ farm.

Other researchers have found lower total energy for peach production in Iran, i.e., 47,951.52 MJ ha⁻¹ with the highest share of energy consumption due to chemical fertilizers (35.37%) and energy use efficiency, energy productivity, specific energy and net energy calculated as 0.433, 0.228 (kg MJ⁻¹), 4.38 (MJ kg⁻¹) and −27,161.722 (MJ ha⁻¹), respectively [11]. In another area of Iran, total energy consumption for peach production was 37,536.96 MJ ha⁻¹, lower than that found in the current study, where the diesel fuel had the highest contribution on energy consumption (26.32%) and peach production was less energy efficient because energy use efficiency, energy productivity, specific energy and net energy were 0.55, 0.29 kg MJ⁻¹, 3.41 MJ kg⁻¹ and −16,642.03 MJ ha⁻¹, respectively [42]. In Turkey, the total energy requirement for peach production on average was 36,284.51 MJ ha⁻¹, lower than our findings. Total energy input use decreased as orchard size increased, and energy input from fertilizers was the largest energy input, followed by diesel oil and pesticides for all orchard sizes [6]. Research on Sicilian peaches documented that the largest impact on environmental and economic sustainability for peach production was due to irrigation, as large volumes of water and energy were used, and thus GHG emissions could be reduced by improving irrigation practices and agricultural machinery use. Other significant factors were land transformation, fertilizer and pesticide production and use [16]. A comparison of energy efficiency among conventional, integrated and organic farming systems of peach orchards in Greece, and the effect of the farming systems on GHG emissions, proved that organic farming resulted in lower GHG emissions and energy inputs in a more efficient way [14]. In another study, comparative energy use and an economic analysis of peach production using good agricultural practices showed that total energy consumption was 28,416.08 MJ ha⁻¹ when good agricultural practices were applied, compared with 40,036.94 MJ ha⁻¹ for local practices, proving that using good agricultural practices in peach farming is advantageous [12]. In that study, fertilizers and diesel fuel contributed significantly to total energy consumption, especially when good agricultural practices were not applied.

3.2. Analysis of GHG Emissions

The farm with cv. ‘Catherina’ presented the lowest total GHG emissions (kg CO₂eq ha⁻¹), followed by that with cv. ‘Everts’, while the farm with cv. ‘Andross’ presented the highest GHG emissions (

Table 12. GHG emissions per cultivation practice for alternative management practices compared to farmers’ practices, for ‘Catherina’ peach production.

‘Catherina’
	Farmers’ Practices	Alternative Management Practices
Practice	GHG Emissions (kg CO2eq ha−1)	GHG Emissions (kg CO2eq ha−1)
Pruning	86.2	86.2
Fruit thinning	7.2	7.2
Irrigation	1702.3	1532.3
Fertilization	177.8	153.6
Weed control	301.7	301.7
Plant protection	718.7	718.7
Harvesting	7.4	7.4
Total GHG emissions	3001.3	2807.2
Yield (t ha−1)	41.65	43.50
kg CO2eq kg−1	0.0721	0.0645

,

Table 13. GHG emissions per cultivation practice for alternative management practices compared to farmers’ practices, for ‘Andross’ peach production.

‘Andross’
	Farmers’ Practices	Alternative Management Practices
Practice	GHG Emissions (kg CO2eq ha−1)	GHG Emissions (kg CO2eq ha−1)
Pruning	310.8	310.8
Fruit thinning	11.0	11.0
Irrigation	2359.9	2126.0
Fertilization	445.8	345.4
Weed control	874.2	879.9
Plant protection	833.4	833.4
Harvesting	12.8	12.8
Total GHG emissions	4847.8	4519.3
Yield (t ha−1)	48.00	51.50
kg CO2eq kg−1	0.101	0.0878

and

Table 14. GHG emissions per cultivation practice for alternative management practices compared to farmers’ practices, for ‘Everts’ peach production.

‘Everts’
	Farmers’ Practices	Alternative Management Practices
Practice	GHG Emissions (kg CO2eq ha−1)	GHG Emissions (kg CO2eq ha−1)
Pruning	534.7	534.7
Fruit thinning	5.0	5.0
Irrigation	1017.8	917.1
Fertilization	419.3	186.1
Weed control	828.0	828.0
Plant protection	453.5	453.5
Harvesting	11.8	11.8
Total GHG emissions	3270.2	2935.9
Yield (t ha−1)	35.00	37.80
kg CO2eq kg−1	0.0934	0.0777

, Figure 2, Figure 3 and Figure 4). The difference in total GHG emissions per ha among the peach cultivars was not associated with the different maturation period, but with the different cultivation practices applied by the farmers. Yield output was also found to be responsible for the differences in kg CO₂eq emissions per kg of peach fruit among cultivars. Compared with other studies, the results of our study of the GHG emissions at the farms for the three cultivars are close to those derived from a multiyear LCA analysis of a peach orchard in Spain, where CO₂ emissions per kg of peach value were 0.15–0.20 kg CO₂eq kg⁻¹ [43]. Higher GHG emissions from peach orchards in major peach-producing regions of China have been reported [44]. They found that GHG emissions from peach orchards of different regions ranged from 15,668 to 580 kg CO₂eq ha⁻¹, with corresponding carbon footprints from 0.48 kg CO₂eq ha⁻¹ to 0.20 kg CO₂eq ha⁻¹, respectively. Fertilizer inputs, fuel consumption, cultivar and yield output were the reasons for these large GHG differences [44]. In Iran, an LCA analysis of peach production to evaluate cradle-to-gate environmental impact showed that to produce 1 Mg of peaches, 172.16 kg CO₂eq were emitted [45]. Thus, in northern Greece, the carbon footprint of canning peach orchards was relatively low compared with other areas around the world.

Irrigation was the cultivation practice with the highest impact on GHG emissions for all the cultivars and both cultivation systems (Table 12, Table 13 and Table 14; Figure 2, Figure 3 and Figure 4), followed by plant protection, weed control and fertilization. It is clear that the cultivation practices (either farmers’ practices or alternative practices) with the highest impact on carbon footprint for the three cultivars are the ones most demanding of fuel consumption and electricity (for irrigation). Electricity and fuel were the production coefficients with the highest contribution to energy inputs, and this is related to the increased GHG emissions of the practices with high consumption of electricity and fuel. The proper sizing of agricultural machinery in a farm is proposed in order to minimise GHG emissions from diesel consumption [46]. Ingrao et al. [16] also found that the most significant sources of environmental impact for Sicilian peach production were electricity and diesel fuel consumption, as well as production and the use of fertilizers and pesticides. Vinyes et al. [43] reported that fertilizers represented the input with the highest GHG contribution in a 15-year LCA analysis of a peach orchard, due mainly to high emissions during industrial production. The main contributor of GHG emissions in major peach-producing regions of China was fertilizer, followed by electricity, pesticides, and diesel [44].

The reduction of total GHG emissions achieved by the alternative fertilization alone was 13.6% for ‘Catherina’, 22.5% for ‘Andross’ and 55.6% for ‘Everts’ (Table 12, Table 13 and Table 14; Figure 2, Figure 3 and Figure 4). In addition, the reduction of GHG emissions by the deficit irrigation practice was around 10% for all cultivars. Alternative fertilization and regulated deficit irrigation decreased the intensity (kg CO₂eq kg⁻¹ of fruit) of the emitted GHG, compared to farmers’ practices by 10.5% for ‘Catherina’, 13.1% for ‘Andross’ and 16.8% for ‘Everts’. Fiore et al. [47] found that fertilization accounted for most GHG emissions from a peach orchard, suggesting that improving nitrogen use efficiency is crucial for the carbon footprint reduction of peaches, together with any available low-carbon intensity processes for fertilizer production. In a review article, it was reported that applying intensive cultivation practices to achieve high yields with efficient nutrient uptake was identified as an effective way to achieve reductions in GHG emissions [48]. Vilarrasa-Nogué et al. [49] found that N₂O and N₂O + N₂ emissions were linked to fertilization and increased with N dose. According to Xiloyannis et al. [50], further reduction of GHG emissions could be achieved by the adoption by the farmers of more sustainable practices such as no-till farming, cover crops, incorporation of organic matter back into fields and reduction of chemical fertilizers [50]. Thus, it is highly important to optimize nutrient and irrigation management, including the proper selection of fertilizer rates and types combined with water-saving irrigation practices, to increase fertilizer and water use efficiency and to maintain a sustainable peach production system [44].

4. Conclusions

Canning peach production is of high importance for the Greek economy and provides the major income for the farmers of northern Greece. In most Greek peach orchards, integrated crop management is insufficiently applied, with empirical fertilization and irrigation (usually applied in excess) increasing energy use and GHG emissions. The aim of this study was to suggest alternative fertilization and irrigation practices for canning peach orchards to improve nutrient use efficiency and save irrigation water, and to assess yield, energy input–output and the carbon footprint of the alternative cultivation practices for three important processing cultivars: the early ripening ‘Catherina’, the mid-season ‘Andross’, and the late-season ‘Everts’. Energy use analysis revealed that the cultivation practice with the highest energy use was almost always irrigation, followed by fertilization, plant protection, weed control and pruning in all the farms and for both cultivation systems. Regarding production coefficients, electricity, fuels, fertilizers and machinery presented the highest energy requirements for all cultivars and cultivation systems. Irrigation was the cultivation practice with the highest impact on GHG emissions for all the cultivars and both cultivation systems due to electricity use. Plant protection, weed control and fertilization also presented significant GHG emissions. Alternative fertilization in combination with deficit irrigation was more energy efficient compared to farmers’ practices for all cultivars. These alternative practices also decreased the intensity (kg CO₂eq kg⁻¹) of the emitted GHG compared to farmers’ practices. Differences in energy use and GHG emissions per ha among the peach cultivars were not associated with the different maturation period but with the different cultivation practices followed by the farmers. Yield output was also found to be responsible for the difference in kg CO₂eq per kg of peach fruit among cultivars. In conclusion, alternative fertilization and irrigation practices improved energy use efficiency and decreased the carbon footprint of the canning peach orchards, in addition to improving yield. Thus, optimization of nutrient supply and irrigation in peach orchards should be applied based on existing scientific knowledge and guidance.