Life Cycle Assessment of Laser-Induced Maize Production: Adoption of Sustainable Agriculture Practices

Abstract

Conventional farming practices can provide higher agricultural yields through the extensive use of fertilizers, pesticides, and other inputs. These practices have been associated with severe environmental effects, such as eutrophication, acidification, etc. Laser technology, among many other techniques, could be a viable option for environmental reduction if incorporated into agricultural production systems. However, the environmental performance of using lasers in agriculture practices needs to be investigated in order to provide sustainable management of the agriculture sector. Therefore, in this study, the life cycle assessment (LCA) of laser-induced maize production in bio-stimulated seeds was compared to conventional farming practices using the software SimaPro ver. 9.0. The study emphasized human toxicity, freshwater ecotoxicity, and marine ecotoxicity due to their significant contributions. The results demonstrated that laser technology was an environmentally friendly system for treating maize seeds before sowing. The study further identified the mineral fertilization process as the most critical threat to the environment. Based on normalization, maize production process-related toxicity accounts for the highest environmental impacts of 8.2 and 7.3 kg 1,4-DCB/ton of grain produced by conventional practices and laser maize production, respectively, on the general environmental profile. At the endpoint level, the irradiated maize seeds performed better than their non-irradiated counterpart impacting human health at 5.46 × 10⁻³ DALY, ecosystems at 1.86 × 10⁻⁵ species⋅year, and resources at 60.74 USD 2013. Soil management was also identified as the conventional maize production process with the most significant environmental impacts. The greatest observed impacts were on marine ecotoxicity (19.23 kg 1,4-DCB) and freshwater ecotoxicity (12.94 kg 1,4-DCB) per ton of grain produced. The evaluation of potential human toxicity concluded that zinc contributed more than 90% in ReCiPe 2016 Midpoint (H) and benzene contributed approximately 22% in CML 2000. The study concluded that improved environmental performance was obtained for laser-induced maize production compared to conventional farming practices. The LCA can provide information to policymakers and government agencies about shifting to more sustainable agricultural practices in arid regions, such as Iraq, prone to drought linked to water availability and soil salinity.

1. Introduction

There are numerous impacts of chemical fertilizer application on the environment [1]. They include the leaching of nutrients, soil acidification, salinity, and greenhouse gas emissions, as well as the accumulation of chemical residues [2,3]. However, there is a need to ensure the appropriate use of fertilizers during crop production in order to limit the environmental impacts of conventional farming practices [4]. Nitrogen-fixing bacteria can be found in the roots of most grain legumes, such as soybeans (Glycine max) and wheat (Triticum aestivum). Hence, fewer amounts of nitrogen (N) fertilizers are required to produce such crops [5]. However, certain cash crops, such as maize, require large amounts of N based on their energy, which differs by genotype.

Studies have found that advanced cultivars that achieve optimum growth in nutrient-rich conditions but are exposed to chemical treatments and irrigation processes may not achieve an optimum yield with changes in environmental conditions [6,7] and may also adapt to changes in environmental factors. In this respect, the challenge is to find a technology that can enhance crops with optimum productivity and fewer environmental impacts.

Laser technology, among many other techniques, could be a viable option if incorporated into agricultural production systems [8]. Laser radiation has found applications in all spheres of engineering because of its essential characteristics, such as coherence, monochromatic, polarization, and power density [9]. However, these attributes also made it applicable in the biology and agriculture sectors. Upon exposure to laser radiation, specific changes occur in the physiological state of plants and seeds; depending on the type of laser radiation used, such changes can either encourage or inhibit the development of the seed or plant, as well as its intensity and wavelength [10]. The bioeffects of low laser power in pre-planted seeds, seedlings, or plants were confirmed by numerous studies using the seeds of various crops [3,9,11,12]. These studies harmonically agreed on the positive effect that laser irradiation has on seed germination (such as corn and wheat), which is crucial in implementing a technology that is, first and foremost, efficient. Hasan [10] found that exposing maize seeds to blue laser light prior to sowing as a form of pre-treatment greatly increased the seedlings’ emergence rate and seed emergence uniformity. Additionally, the radicle fresh weight, plumule length, fresh and dry weight, germination % rate, and seed vigor were all positively affected by laser irradiation [11]. The study AlSalhi [9] showed that low-powered argon and He-Ne lasers improved the growth and germination of wheat seeds while affecting their physiological and biochemical properties.

Under conventional farming practices, higher agricultural yields are achieved through the extensive use of fertilizers, pesticides, and machinery. These practices have been associated with severe environmental effects such as eutrophication [13,14]. The LCA method is used to assess the environmental impacts because of its focus on the entire crop production process, from the source of the raw materials to the consumption of the product and disposal or recovery of the associated waste. LCA quantifies all the resources used in producing a product and the associated emissions or discharges to the environment [15]. This end is achieved by assessing two primary components: resource utilization and the level of pollutant emission or discharge [16,17,18]. A better benchmark for developing emission reduction strategies can be obtained by analyzing the environmental impacts of these cropping systems. The farm materials used and the path of N losses significantly differ depending on the crop management process employed. The reduction of pollutant discharge demand that future efforts be geared toward developing processes and techniques that optimize the use of chemical fertilizers without adverse impacts on crop yield and soil fertility.

Various studies have been conducted to assess the environmental impacts of technologies employed in maize production [19,20,21,22] and to compare the performance against conventional maize production. Overall, it was found that irrigation, machinery, and fertilizer use impacted most of the environmental impacts and energy use of wheat and maize production [19]. Similar findings were observed [20] in which higher agricultural resources input per unit of grain yield produced an increase in the impact of global warming, acidification, and eutrophication, among others, making conventional planting perform the worst environmentally. The incorporation of the economic and social aspects allows consideration at a holistic level to identify trade-offs and ensure a sustainable solution is selected. Thus, a small number of studies attempted to include these aspects [20,22,23,24,25] to draw a conclusion that did not sacrifice cost, and that was socially acceptable in an effort to mitigate adverse environmental impacts.

LCA, as an international standard method, can support analyses of input and output emissions from production systems proportional to the life cycle of crops or processes and is taken into environmental experts for consideration. Furthermore, the environmental aspects and potential throughout the life cycle of a crop or one step of processed raw material to production (consumption, end of biological practices, recycling, and final disposal) can be investigated. Based on the ISO 14040 standard, LCA contains four portions, including the express purpose, determined inputs and outputs of the system, evaluated environmental impacts, and their interpretation [26]. Thus, LCA can be considered a comprehensive tool to evaluate and compare the environmental performance of laser-induced maize production in bio-stimulated seeds with conventional farming practices.

Additionally, no research has been found that surveyed the environmental performance of laser-induced maize production through LCA despite having various studies on the economic and environmental impact of maize production. Using the LCA method, the objectives of this study were to compare different maize production processes using laser technology and conventional techniques to determine the optimum method with the least environmental impact on corn cultivation. SimaPro ver. 9.0, PRé Sustainability, The Netherlands software and the calculation models of CML baseline 2000, University of Leiden, The Netherlands, IMPACT 2002+, Swiss Federal Institute of Technology,—Lausanne (EPFL), Switzerland and ReCiPe 2016, PRé Sustainability, the Netherlands were used for the impact assessment. The final section of this paper discusses the implications and recommendations for policy-making decisions leading to sustainable agricultural practices in Iraq.

2. Materials and Methods

2.1. Goal and Scope of the Study

The study’s objective was to evaluate the LCA-based environmental performance of maize production induced by lasers and compare it to conventional maize production in Baghdad Province, Iraq. The environmental impacts of these two production systems were analyzed using impact assessment tools in ver. 9.0 SimaPro, IMPACT 2002+, CML baseline 2000, and ReCiPe 2016. This gate-to-gate study considered the processes utilized in the fields and excluded processes in the infrastructure, capital goods, and the development of laser devices. The functional unit selected was one ton of maize production, requiring 0.142 ha. All inputs and outputs used in the study reflected one ton of maize production. In this study, the stages of maize production were divided into four parts, (i) laser irradiation of seeds, (ii) field preparation, (iii) cultivation, and (iv) harvesting.

The study’s scope and flow, covering the various stages of maize production and related processes, are shown in Figure 1.

2.2. Life Cycle Inventory and Analysis

The LCA of one ton of maize production was conducted based on the data obtained from the field in Baghdad, Iraq. The inventory of agricultural input per functional unit and the yield of maize production are shown in

Table 1. LCI for the production of one (1) ton of laser-irradiated and non-irradiated maize.

Input			Process	Output
Process	Amount			Emissions (kg)	Laser	Control
	Laser	Control
Electricity (kWh)	0.002	/	Laser Irradiation	CO2	1.22 × 10−4	/
				CH4	5.54 × 10−9	/
				N2O	1.76 × 10−8	/
Maize seeds (kg)	2.42	2.71	Field Preparation	CO2	1.80 × 101	2.01 × 101
Fuel (L)				N2O	1.19 × 10−5	1.33 × 10−5
Harrowing	1.71	1.91		CH4	1.14 × 10−5	1.27 × 10−5
Plowing	2.49	2.78		NOx	1.46 × 10−2	1.63 × 10−2
Spring spike tooth harrow	2.38	2.66		SO2	2.63 × 10−2	2.94 × 10−2
Irrigation (m3)	19.68	17.58	Cultivation Process	NH3-N	1.30 × 101	1.45 × 101
Fertilizer (kg)				N2O	2.78	3.11
				NOx	1.13 × 10−1	1.26 × 10−1
DAP N:P 46:18	74.24	83.07		CO2	2.18 × 10−1	2.44 × 10−1
Urea	62.25	69.65		PO4	6.71 × 10−3	7.51 × 10−3
Pesticides/Diazinon	0.85	0.95		SO2	1.57 × 10−2	1.76 × 10−2
Fuel (L)				CH4	2.40	2.68
				Cd	1.34 × 10−3	1.50 × 10−3
Sowing	1.85	2.07		Cu	4.12 × 10−3	4.61 × 10−3
Herbicide application	0.14	0.16		Zn	3.50 × 10−2	3.91 × 10−2
Fertilizer application	0.09	0.11		Pb	6.14 × 10−3	6.87 × 10−3
Electricity/irrigation	12.85	14.37		Ni	3.64 × 10−3	4.07 × 10−3
				Cr	1.80 × 10−2	2.02 × 10−2
Harvest machine/fuel	2.71	2.71	Harvesting	CO2	7.40	7.40
				N2O	4.91 × 10−6	4.91 × 10−6
				CH4	4.69 × 10−6	4.69 × 10−6
				NOx	6.02 × 10−3	6.02 × 10−3
				SO2	1.08 × 10−2	1.08 × 10−2
				Maize	1.00	1.00

. The field was cultivated, disked, furrowed, and then plotted before sowing the seeds. The field (520 kg/ha) was fertilized with compost (46:18 N: P₂O₅). Before seeding, 436 kg/ha of the urea was applied to the soil (50% on the 14th day after seeding and 50% during flowering). The Office of Agriculture Research supplied the seed variety selected for the study (cultivar Baghdad 3); the seeds were pre-filtered to an equal size and pre-irradiated using a diode laser (wavelength = 410 nm, irradiation time = 85 s, laser intensity = 4 mW/cm²) before sowing. During the growing phase, the field was irrigated at five-day intervals based on 80 mm of evaporation from a class A pan. During the growing season, weeds were manually removed (while pest control was achieved using diazinon at the rate of 1.5 kg/ha); the pesticide was applied on the 20th and 35th days after sowing. The plants were harvested 110 days after sowing and de-grained. The grain yield was expressed in kg/ha at a 15% moisture ratio.

The emissions and discharges, particularly from nitrogenous fertilizers, such as urea, phosphorus, and pesticides, were calculated using the EcoInvent database. The discharges due to the use of fuels were estimated using the directories of the [27]. Discharges from the application of fertilizers and pesticides were calculated and estimated according to [21]. The pesticide discharges were as follows: soil = 90%, freshwater = 1%, and air = 9%. The following equations were used to calculate the fertilizer-induced discharges of nitrous oxide (N₂O), ammonia (NH₃), nitrate (NO³⁻), carbon dioxide (CO₂), and phosphorus (P):

Nitrous oxide (N₂O) emission:

$${\mathrm{N}}_2\mathrm{O}=\left(\mathrm{Fsn}+\mathrm{Fon}+\mathrm{Fcr}+\mathrm{Fsom}\right)\times \mathrm{EF}1\times \frac{44}{28}$$

(1)

Nitrate (NO₃) emission:

$${\mathrm{NO}}_3=\left(\mathrm{Fsn}+\mathrm{Fon}+\mathrm{Fcr}+\mathrm{Fsom}\right)\times \mathrm{FLEACH}-\left(\mathrm{h}\right)\times \frac{62}{14}$$

(2)

Ammonia (NH₃) emission:

$${\mathrm{NH}}_3=\left(\mathrm{Fsn}+\mathrm{FracGASF}\right)\times \frac{17}{14}$$

(3)

where,

FSN = the quantity of applied chemical fertilizer, N, to the soil (kg N).

FON = the quantity of N in the applied manure to the soil (kg N).

FCR = the amount of N in the crop residues (above-ground and below-ground) (kg N).

FSOM = the amount of N in the mineral soils that are mineralized (kg N).

EF1 = the emission factor for N₂O emissions from N inputs:

$$\left(\frac{{\mathrm{kg}\mathrm{N}}_2\mathrm{O}-\mathrm{N}}{{\mathrm{kg}\mathrm{N}}_{\mathrm{INPUT}}}\right)$$

(4)

FLEACH-(H) = fraction of all added N lost to leaching.

$$\left(\frac{\mathrm{kg}\mathrm{N}}{\mathrm{kg}\mathrm{of}\mathrm{N}\mathrm{additions}}\right)$$

FracGASF = fraction of the fertilizer N that volatilizes as NH₃ and NOx.

$$\left(\frac{\mathrm{kg}\mathrm{N}\mathrm{volatilized}}{\mathrm{kg}\mathrm{N}\mathrm{applied}}\right)$$

Carbon dioxide (CO₂) emissions:

$${\mathrm{CO}}_2=\left(\left({\mathrm{M}}_{\mathrm{limestone}}\times {\mathrm{EF}}_{\mathrm{limestone}}\right)+\left({\mathrm{M}}_{\mathrm{dolomite}}\times {\mathrm{EF}}_{\mathrm{dolomite}}\right)+\left({\mathrm{M}}_{\mathrm{urea}}\times {\mathrm{EF}}_{\mathrm{urea}}\right)\right)\times \frac{44}{12}$$

(5)

where,

M_limestone, M_dolomite, M_urea = amount of calcic limestone (CaCO₃), dolomite (CaMg(CO₃)²) or urea, respectively (kg)

Phosphorus (P) emission = amount of P fertilizer (kg) × 0.053 (emission factor).

2.3. Life Cycle Impact Assessment

A life cycle impact assessment (LCIA) was conducted to determine which processes or materials contributed the most to the environmental impacts. The inventory data were gathered and analyzed using the SimaPro 9.0 software, while the selected background inventory sources were EcoInvent 3.4 and the USLCI databases. The ReCiPe 2016, used to calculate the LCI category indicators, was developed by Huijbregts [28] for the evaluation of 18 impact categories at the midpoint level: stratospheric ozone depletion (ODP), global warming (GWP), ozone formation (human health) (HOFP), ionizing radiation (IRP), ozone formation (terrestrial ecosystems) (EOFP), fine particulate matter formation (PMFP), freshwater eutrophication (FEP), terrestrial acidification (TAP), terrestrial ecotoxicity (TETP), marine eutrophication (MEP), marine ecotoxicity (METP), freshwater ecotoxicity (FETP), human non-carcinogenic toxicity (HTPnc), human carcinogenic toxicity (HTPc), mineral resource scarcity (SOP), land-use change (LUC), water consumption (WCP), and fossil resource scarcity (FFP). The impact categories were divided into three damage assessment categories: (1) damage to human health (HH), (2) damage to resource availability (RA), and (3) damage to ecosystem quality (ED).

Similar categories in the CML baseline 2000, IMPACT 2002+, and ReCiPe Midpoint (H) methods were compared to identify the “hot spots” in each impact category. The results were presented at the midpoint and endpoint levels. The impact assessment results were presented in the following stages: characterization, damage assessment, normalization, and weighting.

During the characterization stage, the LCI results were converted and combined into representative indicators of environmental and human health impacts. The characterization served as a way of making direct intra-category comparisons of the LCI results [29].

In the normalization stage, the impact indicator data were expressed to allow easy comparison among the impact categories. An indicator’s result was normalized by dividing it by a predetermined reference value. By multiplying the normalization factors by the impact or damage category values, the values could be expressed as person equivalents [29].

The weighting stage involved assigning relative values or weights to the calculated impact categories to consider their perceived relevance/importance. Weighting was an essential process because the goals of the study had to be reflected in the impact categories. Weighting was accomplished by multiplying the weighting factors by the normalized values of a weighted milli-person (1/1000 person) equivalent [29]. The LCIA results were interpreted to provide recommendations and suggestions for government agencies and policymakers working toward sustainable agricultural practices.

3. Results and Discussion

3.1. LCA of Maize Production Induced by Laser versus Conventional Maize Production

The environmental impacts of the two maize production systems analyzed in this study are presented in

Table 2. The impact categories at the midpoint and endpoint levels.

Impact Category	Unit	Total
		Non-Irradiated	Irradiated
Midpoint
Global warming	kg CO2 eq	2243.78	2006.82
Stratospheric ozone depletion	kg CFC11 eq	0.034	0.031
Ionizing radiation	kBq Co-60 eq	14.28	12.91
Ozone formation, Human health	kg NOx eq	1.314	1.17
Fine particulate matter formation	kg PM2.5 eq	5.39	4.82
Ozone formation, Terrestrial ecosystems	kg NOx eq	1.42	1.28
Terrestrial acidification	kg SO2 eq	31.66	28.31
Freshwater eutrophication	kg P eq	0.11	0.10
Marine eutrophication	kg N eq	0.03	0.029
Terrestrial ecotoxicity	kg 1,4-DCB	2401.10	2149.70
Freshwater ecotoxicity	kg 1,4-DCB	12.94	11.63
Marine ecotoxicity	kg 1,4-DCB	19.23	17.27
Human carcinogenic toxicity	kg 1,4-DCB	13.25	11.96
Human non-carcinogenic toxicity	kg 1,4-DCB	2069.86	1851.40
Land use	m2 a crop eq	784.08	699.31
Mineral resource scarcity	kg Cu eq	7.05	6.31
Fossil resource scarcity	kg oil eq	179.81	161.51
Water consumption	m3	39.48	39.26
Endpoint
Human health	DALY	6.10 × 10−3	5.46 × 10−3
Ecosystem	PDF species.yr	2.07 × 10−5	1.86 × 10−5
Resources	USD2013	67.64	60.74

. As the table shows, the conventional method of maize production accounted for 10.5% higher environmental impacts among all the evaluated categories. This means that the pretreatment of maize seeds with a laser before planting is an environmentally friendly approach, even after normalizing the data with world values to accommodate the relative significance of each impact category (Figure 2).

More farm inputs are required for maize production without laser pre-irradiation. These inputs increase the potential environmental impacts related to the extraction, production, and use. Figure 2 shows the higher environmental impacts associated with conventional maize production in all the evaluated impact categories. Soil management contributed significantly to the increased use of inputs and machinery. Data normalization revealed the importance of toxicity in the impact categories. Figure 3 shows that the greatest environmental impacts on marine and freshwater ecotoxicity resulted from the use of nitrogen fertilizers, with 8.2 and 7.3 kg 1,4-DCB/ton of grain produced by conventional practices and laser maize production, respectively. Other contributors were urea, with 7.4 and 6.6 kg 1,4-DCB/ton of grain produced by conventional and laser maize production, respectively. In contrast, the highest score in the freshwater ecotoxicity category was obtained from the nitrogen fertilizer with 5.4 kg 1,4-DCB/ton of grain produced by conventional maize production compared to 4.9 kg 1,4-DCB/ton of grain produced by laser-induced maize production.

Figure 3 also shows the stages and substances contributing most to the human ecotoxicity category of environmental impacts. The use of nitrogen and urea are associated with its application, which produced 207.4 and 169.7 kg 1,4-DCB/ton, respectively, of grain produced under the conventional practices and was the primary factor contributing to this category’s impacts compared with those generated by laser-induced maize production.

In regions with extensive agricultural operations, excessive or improper soil fertilization is a significant issue that contributes to ammonia emissions, soil deterioration, groundwater contamination, surface water eutrophication, and greenhouse gas emissions [30]. Additionally, it has an impact on food quality, the deposition of heavy metals on agricultural fields, and greenhouse gas (GHG) emissions. Nutrient loss from farmlands remains a significant contributor to these forms of pollution and results from urea application to the soil. Almost 15% of the total applied urea can be lost to leaching [31]. The primary cause is the use of chemical nitrogen-based fertilizers; the extent of the impacts depends on the type and applied dose of N-based fertilizers [7,30]. In conventional agriculture, fertilization relies primarily on the use of urea. However, urea is associated with NH₃, SO₂, and NOx emissions during and after application [31]. The excessive use of applied inorganic fertilizers increases the potential for ecotoxicity and related impacts.

The rate of the human toxicity indicators of non-irradiated seeds was more than the irradiated seeds. According to the rate of environmental indicators in Figure 2 and Figure 3, most inputs are related to nitrogen fertilizer consumption, electricity consumption, diesel fuel, and pesticide consumption. Thus, some management approaches should be presented to reduce these indicators.

3.2. Assessment of Midpoint Ecotoxicity Impacts of Laser-Induced Maize Production Using the CML 2000 and ReCiPe 2016 Methods

The assessment of the impacts on freshwater ecotoxicity, marine ecotoxicity, and human toxicity was conducted based on one ton of laser-induced grain maize production. The assessment used the midpoint approach from CML 2000 and ReCiPe (H) and was presented in a relative contribution of the impact categories evaluated (Figure 4). The impact on freshwater ecotoxicity using the CML 2000 method was similar to that of the ReCiPe midpoint (H). The primary contributing factors in the CML 2000 method were nickel, copper, and beryllium. In contrast, the ReCiPe midpoint (H) showed the primary impacts of zinc and copper (Figure 5).

The results of the CML 2000 and ReCiPe midpoint (H) applications differed because each method considered the toxicity indicators and the characterization factors for the limited substances; this was reflected in the results [32]. These findings agreed with the results presented by Pradel and Aissani [33], in which copper and nickel discharges were directly linked to freshwater aquatic ecotoxicity, while mercury and chromium discharge caused terrestrial ecotoxicity. Furthermore, the discharge of waste sludge from wastewater treatment plants directly impacts the environment because the heavy metals in the waste sludge negatively affect the soil and farmlands [34].

The CML and ReCiPe methods exhibited similar impact rankings for marine ecotoxicity, as shown in Figure 4. However, there was a difference between the two methods for nitrogen and urea-induced impacts. The different discharges are shown in Figure 5. Significant variations occurred in the metal components: hydrogen fluoride and beryllium in the CML method and zinc and copper in the ReCiPe method. Based on these results, we concluded that the midpoint (H) successfully established the inter-subcategory differences, namely the freshwater and marine ecotoxicity, with the marine waters exhibiting the most significant impact from fertilizer use. The primary sources of marine ecotoxicity are industrial activities, power plants, fossil fuels, and the application of phosphate fertilizers [35]. These processes are associated with the release of pollutants into the atmosphere. The contaminants are subsequently washed into the soil by rain, polluting the surface and drinking waters.

Note that both methods calculated the effects of toxicity on humans for various materials, especially the metals released into the environment through waste sludge and wastewater. Huijbregts [36] developed the fate factors (FF) to enable the approximation of N’s surface water deposition due to airborne NOx and NH₃ emissions. The role of FF is to indicate the amount of emitted NOx or NH₃ in various European countries that migrate to marine ecosystems. The basis for the calculation was the modified Regional Air Pollution Information and Simulation (RAINS) model, which was initially developed for an integrated evaluation of acidification, photochemical ozone creation, and terrestrial eutrophication in Europe [37]. Nitrate (NO₃) is the primary pathway of N leaching from the soil into aquatic ecosystems. No relationship exists between the soil N-input (from fertilizers) and the nitrate levels of the surface and groundwater. Groundwater nitrate losses through leaching are heavily reliant on agricultural practices and site-specific climate and soil conditions.

There were strong correlations between the two methods for human toxicity at different magnitudes. The most significant effect for this impact category related to the land use life cycle, which showed a decline from being the third most impacting category with the CML 2000 to the sixth most impacted according to the ReCiPe. The difference between the two approaches may be due to the nature of this case. The primary contributing substance differed for the two analysis methods, as shown in Figure 4. Figure 5 shows the contribution analysis for the emissions from other substances; it confirms that the differences in the applied characterization factors prompted such differences in the results. For CML 2000, the highest contributors to emissions were benzene, nickel, and chromium; for the ReCiPe method, zinc was predominant. Figure 5 shows that the only consistency between the methodologies is the wide variations in the primary contributing substances. Such a category was evaluated with each LCIA method using a different approach; this may cause inconsistent results.

Based on the results, the most significant contributor to potential environmental impacts was mineral fertilization; the type of N fertilizers utilized was responsible for potential eutrophication and acidification. The literature suggested that 8% of N in most fertilizers can undergo a loss through volatilization, thereby forming ammonia [38]. This high rate of ammonia emissions contributes primarily to these impact categories. Therefore, when planning to improve fertilizer management processes, the principal target should be replacing liquid nitrogen fertilizers with those low in-field N emissions. This finding contradicts the outcome of a study by [39], in which mineral fertilizers were found to contribute substantially to maize production’s environmental performance.

There are several sources of impacts on human and ecological toxicity from farming activities; these include the emission or discharge of pollutants, pesticides, and heavy metals from chemical fertilizers. Heavy metals and pesticides are the primary contributors because they typically relate to more toxic and longer-lasting substances. The production of phosphate fertilizers is also important because it relates to eutrophication; phosphates contribute to over 30% of the eutrophication indicator. The observed differences in the outcome of this indicator could not be due primarily to the deployed technology. It could also be associated with natural environmental conditions, such as climate, terrain relief, soil quality, and water conditions, and determined potential crop productivity.

3.3. Endpoint Damage Assessment of Laser-Induced Maize Production Using the IMPACT 2002+ and ReCiPe 2016 Methods

The damage assessment to produce one ton of laser-induced grain maize is presented at the endpoint by the two methods, ReCiPe 2016 and IMPACT 2002+ (Figure 6). The damage assessment shows the relative impact contributions in the system. The endpoint method was not just used to compare the midpoint-endpoint methodology; both rely on different logic for determining environmental impacts. The endpoint method conducts the damage assessment in various areas of protection, while the midpoint method considers the cause and effect of released substances [37]. The assessment evaluates the impacts on human health, ecosystem quality, and resources.

Figure 6 shows that production, land use, and fertilizer use posed the most severe threats to human and environmental health in both methods. The plantation-related impacts were caused primarily by fertilizer use as an input of N fertilizers; this dominated most of the impacts. As expected, the IMPACT 2002+ method results indicated a higher impact on human health and ecosystems than the ReCiPe method. Saswattecha [40] reported that the chemical production of synthetic fertilizers is an energy-intensive process that emits high levels of CO₂. N₂O is known to be emitted into the atmosphere primarily from chemical reactions and during the application of chemical fertilizers into the soil. Most of the ammonia in such fertilizers is converted into N₂O by soil denitrification bacteria. Meanwhile, emissions from commercial fertilizer production and application, especially N fertilizers, are unavoidable as fertilizers are essential for plant growth.

3.4. Comparison with Previous LCA Studies on Maize Production

The results of this study were compared to previously published LCA studies on maize production. Wang [41] analyzed the double high production system for summer maize production and found that N fertilizer applications were reduced by 2.37%, and applications of P were reduced by 56.54%. According to the authors, reduced fertilizer uses during the winter wheat-summer maize production system significantly reduced acidification, greenhouse gas emissions, and aquatic eutrophication. The range of GWP values from the studies was 346.9 kg of CO₂ eq. per ton of maize production, with fertilizer application accounting for 83%. The contribution to GWP by seed sowing, tillage, harvesting, transport, and pesticide stages was negligible.

The environmental impacts of the entire maize crop production process and the identification of hotspots in the production chain were studied by Fantin [42]. The results of acidification (93%), global warming (54%), marine eutrophication (99%), and terrestrial eutrophication (97%) were associated primarily with the fertilization process that contributes significantly to freshwater eutrophication. Human toxicity effects (cancer 59% and non-cancer effects 52%) and aquatic freshwater ecotoxicity (65%) values were associated primarily with the production, transport, and packaging of superphosphate. The results of [41] are higher than those observed in this study due to the inclusion of some additional factors in the system boundaries. Those factors, including buildings, machinery, and humus mineralization, are typically excluded from the analysis. Moreover, in [41], the impact categories are dominated by field emissions, followed by tractor use, pesticide production, and fertilizer production. Given the availability of numerous impact assessment methods, a detailed comparison of the additional impact categories may not be possible.

Supasri [43] assessed the environmental impacts of GWP using the LIME-2 and ReCiPe methods. The highest contribution to the global warming impact category occurred in the farming process in which fertilizer was used. The GHG emissions estimated in the ReCiPe method were slightly higher than those in the LIME-2 method (approximately 20–30%).

Ghasempour [44] investigated the environmental impacts of maize production and estimated the amounts to be 14.9 kg SO₂ eq for acidification and 0.634 kg C₂H₄ eq for photochemical oxidation. Therefore, producing this crop according to this type of production system means that the rate of inputs consumed and the identified negative impact on the environment during planting are essential for properly managing resources.

Sadeghi [7] assessed the environmental impact of producing four maize genotypes using three rates of N fertilizer application based on the LCA method. The study noted that the production of one ton of grain from the urea-treated hybrid KSC 647 emitted the lowest levels of NH₃ (2.158 kg/ton, N₂O (0.368 kg/ton), NO_X (0.449 kg/ton), CO₂ (64.510 kg/ton), CH₄ (0.090 kg/ton), and SO₂ (0.115 kg/ton) of the four genotypes. Potential environmental damage was reduced by selecting a high-yielding genotype that reduced the rate of emissions per functional unit of maize grain yield.

4. Challenges to Sustainable Agriculture Practices in Iraq

The 21st century needs technological improvements to increase the global production of food to feed a world population projected to grow by two to three billion people by the year 2050 [45]. At the same time, escalating the production of food will intensify the need to reduce environmental damage [6]. Ensuring a sufficient, high-quality food supply with limited environmental effects remains a significant challenge for 21st-century agricultural development [15].

In Iraq, agriculture is the second-largest contributor to the gross domestic product, exceeded only by the oil sector [46]. It is also a significant source of income for the vulnerable; hence, its depletion will reduce the population’s food security [46]. In 2018, global maize production was 1147 million tons [47]. The Arab Agricultural Statistics yearbook (2019) stated that areas in Iraq that cultivated maize covered approximately 128,000 hectares in 2019, with a total production of 439,000 tons. According to the FAO, maize production in Iraq has declined in recent years. The causes of that decline include soil salinity, water deficits, inadequate land maintenance, and poor management. Given the environmental concerns linked to modern crop production practices, it is necessary to establish the standards of environmental performance that will sustain high-quality maize production. Therefore, in response to constant population growth and persistent supply shortages, it is critical to pursue more advanced maize production methods per functional unit.

Iraq is in the northern hemisphere, is a country in Southwest Asia and among the countries of the Middle East on the latitude 33°19′15.60″ N and longitude 43°48′07.20″ E. Of the country’s total land area of 437.072 km², agricultural land accounts for 24% (10.5 million hectares) and provides about 30% of its agricultural produce [48]. Iraq is currently facing food insecurity. The available food supply is not sufficient for the population because of soil desertification, salinity, and military activities. Drought is another significant problem in Iraq, as annual rainfall is low (approximately 150 mm/year). To achieve food security for a growing population, areas devoted to agriculture and food production must be expanded [44]. The country’s ecosystems have been heavily impacted by chemical compounds, such as herbicides, fertilizers, and pesticides for agriculture. The agricultural sector accounts for about 40% of the available land but consumes approximately 70% of the country’s natural resources. This fact makes further progress in development unachievable without sustainable agricultural practices.

In Iraq, agriculture is mostly small-scale and based on a low input–low output system. This has been the case for several years and has made the country more dependent on food imports to meet domestic needs. There is a lack of robust agricultural extension services that can ensure technology transfer to small producers and encourage production. There is also the issue of post-harvest losses due to inadequate storage facilities. Iraq has experienced episodes of environmental and natural resource management problems and is susceptible to climatic change due to scarce water resources.

Iraqi farmers are challenged in the area of farm produce due to various environmental factors, such as drought, salinity, inadequate facilities, pests, and shortages of inputs. Cereal production in Iraq has decreased considerably over the years due to issues with the seed multiplication system. The effect has been lower on seed productivity and quality. In the 1980s and 1990s, the planting of low-quality seeds led to weed and pest infestations and low yields [49]. Most farmers have abandoned their farms due to a lack of quality seeds, reducing agricultural efficiency.

Agricultural production in Iraq is dominated by smallholders who do not realize how economies of scale could reduce their transaction costs. The price of agricultural commodities varies significantly because there are no market mechanisms to regulate prices. Farmers find it difficult for their product prices to compete with those of imported foods. Post-harvest and marketing facilities are non-existent due to low levels of agricultural industrialization. This results in poor marketing infrastructure and the underdevelopment of local markets. There is little quality data on the extent of food losses in Iraq. Estimates are that 15% of cereals and legumes and 33% of other perishable crops are lost due to inadequate post-harvest facilities. Farmers are unlikely to invest in marketing infrastructure until the private sector fully emerges to leverage the available opportunities. Although there are cooperative frameworks for establishing farming associations and agriculture cooperatives, little or no attention has been paid to their development.

Iraq is prone to various natural and environmental problems owing to flawed policies. The lack of effective policies has increased the extent of land degradation, water shortages, desertification, soil infertility, soil salinity, and declining forest cover (only 4%). The salinity level in Iraq’s Shatt al-Arab waterway is exceedingly high due to the confluence of two major rivers (Tigris and Euphrates) in Basra. Because the Euphrates River’s salinity is high and is expected to increase with more irrigation channels in the basin, many people have been forced to abandon their farms. Excessive irrigation and high evapotranspiration rates have necessitated the use of adaptive management practices such as conventional residue management.

Environmental agriculture includes clean agriculture, safe farming, and healthy food production using practices that optimize the use of natural resources without polluting the environment. Those practices include soil protection, biodiversity promotion, water management, climate conservation, and the avoidance of chemical compounds. About 60% of ecosystem functions are prone to deterioration due to unsustainable agriculture.

Therefore, sustainable agricultural practices, such as organic farming and clean technologies (e.g., the use of lasers), must be adapted to local farming in Iraq to ensure that crops respond to the prevailing environment and climate conditions. These practices can be benchmarked using LCA to identify the hotspots for improvement. So far, however, no LCA studies have been conducted on maize production in Iraq. Although laser-induced maize production is less impactful to the environment than conventional practices, several challenges hinder the adoption of the LCA framework: data limitations, data assumptions, the lack of awareness by farmers and local agencies, etc. This study found that laser-induced maize production can reduce global warming, human toxicity, aquatic ecotoxicity, acidification, aquatic eutrophication, and soil ecotoxicity. These findings can help promote new policies that will improve the environmental performance of the available maize production systems.

5. Conclusions

The study results demonstrated that maize production induced by a laser has slightly fewer environmental impacts than conventional practices. The three analysis methods compared in the present study achieved reasonably consistent results for emissions and discharges to the environment. Each of the three analysis methods exhibited some advantages and is considered a valuable tool in assessing the environmental impacts of maize production. Although the methods showed some level of correlation, they do not share the same capabilities. Therefore, the selection of a method must depend on the specific factors considered in the proposed analysis. Those factors may include the type of fertilizer studied, environmental stressors, whether the study focuses specifically on fertilizer-related toxicity, or whether they assess multiple environmental impacts. Using local data is always preferred for identifying actual impacts. In addition, broader system boundaries need to be considered in future studies that assess different stages of maize production.

This study can guide farmers and decision-makers to reduce the environmental impacts of agriculture and achieve sustainable farming practices not only in Iraq but that is also applicable to other arid and semi-arid regions in Middle Eastern countries.