Life-Cycle Assessment in Hydrangea Cultivation in Colombia and Their Cleaner Production Strategies

Abstract

In the subregion of La Paz Province in eastern Antioquia, Colombia, hydrangea floriculture has boosted economic and social development, generating high value in the territory; however, there are still environmental gaps to be resolved to make it a sustainable activity. This study analyzed some environmental aspects of cultivation based on life-cycle assessment under ISO 14040/14044 standards. The functional unit defined was 1 kg of hydrangea stems grown on a small farm of 0.45 ha, and the limits selected were gate-to-gate. The environmental impacts were evaluated using the CML methodology, Umberto LCA + 10.0.03 software, and the Ecoinvent 3.8 database. The most significant contributors to these impacts were ozone depletion, terrestrial ecotoxicity, and photochemical oxidant formation, which come from the application and pretreatment of chemical fertilizers and pesticides, plant residue generation, and fossil resource materials, such as polymers and fuels. In addition, two cleaner production initiatives were considered: composting plant residues for fertilizer (the use of 100% and 50% composting) and integrated pest management with biological control and natural agents to reduce pesticide use (30% and 50% of chemical pesticides). And the integration of both actions, with 50% composting and 30% substitution of chemical pesticides, was considered. The environmental impacts were reduced by 19.63% and 9.97%, respectively, for composting, 6.62% and 11.03%, respectively, for biological control, and 16.59% for the integration of actions. The two alternatives allowed for improving the crop, contributing to the minimization of environmental impacts, optimizing the use of inputs and fertilizers, and contributing to the sustainable development of floriculture.

1. Introduction

Agriculture in Colombia is one of the most important sectors in terms of income generation and rural development. It contributes to other countries through the export of products such as coffee, palm oil, cocoa, and flowers, among others. Floriculture, in particular, has reached international markets, so in the country, it has been producing high-quality flowers, and this has positioned it as the second-largest exporter worldwide [1].

Colombia’s flower production sector has a comparative and competitive advantage that makes it a significant player in the global flower market. The country’s geographical location, topography of the producing regions, its climate, and luminosity are all key factors in production. Floriculture in Colombia generates around 140,000 jobs, both directly (69%) and indirectly (31%), located primarily in Cundinamarca and Antioquia, as well as other central and western regions of the country, in 77 municipalities [2].

The industry is also present in several municipalities in eastern Antioquia, Colombia, where the local population is strongly committed to its development [3]. La Paz Province (the focus of this study) is a prime example of a region where commercial flower production has been a longstanding tradition. Floriculture in this region significantly contributes to the national flower exports to several countries, including the United States, Russia, and Japan, providing employment to approximately 34,000 people and making it a livelihood for the inhabitants of the territory [1].

However, the production and marketing of flowers have been found to cause environmental problems, resulting in negative impacts and externalities. Therefore, studies have been conducted worldwide to evaluate the environmental impacts of floriculture using life-cycle approaches with different functional units. These studies focused on chrysanthemum, with 1 kg of flower stems for export [4]; cyclamen and geranium, with 1 marketable plant in a 14 cm pot [5]; and roses, with a number of rose stems produced per square meter of soil per year (100 stems/m² × year) [6], bouquets of roses consisting of 20 stems [7] and 100 stems [8], and one package with 25 bouquets of 20 stems each [9].

Previous studies have examined the annual yield of carnation in the Peloponissos region of Greece, which was found to be 1.5 million carnations per hectare [10]. Additionally, research has been conducted on Australian wax flowers, with a yield of 20,000 bunches, each containing 10 stems weighing 50 g [11]. Furthermore, nursery plants have also been studied, with a production area of one hectare and one hundred plants available for sale [12]. The research found that the main environmental impacts of floriculture were climate change, acidification, and abiotic depletion due to the use of agrochemicals, such as fertilizers and pesticides, polymer-based materials, and fossil fuels, as well as previous production and transportation processes [7,9,13,14].

Only one study has been conducted on hydrangeas (Hydrangea macrophylla as the botanical name and hydrangea as the common name) by Aguirre et al. (2017), where the functional unit was 22 kg of flowers, corresponding to 60 units packed in a box [3]. The study highlighted the most significant environmental impacts, with climate change being the most important category in the transport phase. Eutrophication and acidification were the most relevant in the cultivation phase due to the use of materials such as fertilizers, pesticides, and plastics [3].

The selected crop for this study represents a common production model in the region, where small family farms predominate and most activities are supervised by the family. This type of cultivation includes the necessary processes to ensure the growth and preparation of hydrangeas. Hydrangeas are then transported and delivered to a distributor for export.

In this case study, life-cycle assessment (LCA) was used to evaluate hydrangea cultivation practices in Antioquia, which was developed within the framework of the project “Environmental, Economic and Social Life Cycle Assessment for Hydrangea Agro-Industrial Enterprises as a Strategy for the Sustainable Development of La Paz Province in Eastern Antioquia”.

Consequently, the main challenges faced by floriculture in Colombia to consolidate itself as a sustainable activity were systematically and scientifically identified. This activity generally requires intensive production and demands the use of agrochemicals on a permanent basis.

Therefore, this study aimed to evaluate environmental impact indicators using the CML methodology, enabling farmers and scholars to understand the potential environmental damage at first sight without any requirement for analysis. This study focuses on the cultivation of hydrangeas, an area that has been poorly studied from an environmental perspective. The results will provide insight into the implementation of sustainable actions for agricultural activity through two cleaner production strategies: the composting of vegetable waste can produce fertilizer and integrated pest management (IPM) can reduce the use of pesticides through biological control and natural agents.

2. Materials and Methods

2.1. Hydrangea Production

The cultivation of hydrangeas involves soil preparation, planting, and infrastructure preparation. To prepare the soil, the ground is leveled and the top layer homogenized before sowing the plants using a tractor. The soil is fertilized with synthetic or organic fertilizers to provide nutrients, and agricultural lime is added to neutralize the soil. In order to achieve optimal growing conditions, the cultivation area is covered with a saran mesh to provide a cool environment and protect the hydrangeas from direct sunlight. The structure is supported by bamboo poles and steel cables. In addition, a tutoring mesh is required to provide stability to the flowers during their growth, which is supported by wooden posts. The cultivation stage involves several processes, including plant formation, irrigation, spraying, tutoring, and thinning. It is worth noting that three soil fertilizations are performed during the growth cycle of hydrangeas, typically using synthetic fertilizers, such as NPK with varying proportions of nitrogen, phosphorus, and potassium. Chemical pesticides are often used intensively to meet strict phytosanitary management requirements for exported flowers. Pesticides are applied using a gasoline-powered machine. Additionally, physical traps are used to control some pests, such as thrips. During the cultivation stage, any stems that do not meet export quality standards, such as those that are thin, twisted, or have phytosanitary issues, or stems without well-formed apices, are discarded.

At this stage, the stems that have flowered and meet the quality requirements for export are cut. This occurs approximately thirty-two weeks after harvest, after the soil has been prepared. The complete hydrangea flower reaches a height of 1.30 to 1.50 m, but only the last 60 to 70 cm of the stem is used for export. Therefore, at this stage, the stem is manually cut to the required length. After cutting, the flowers are inspected to ensure that there are no pathogens or diseases. Any poor-quality bracts (also known as petals, which surround each flower) and leaves on the lower part of the stem are removed by hand. The stem is then hydrated with water and a hydrating product called Florissima using a small plastic bag and rubber band. A plastic cap is placed on each stem to protect the flower. The hydrangeas are then packed in cartonplast boxes, depending on the type of flower, to be transported to the commercial company.

2.2. Goal and Scope Definition

Environmental impact analysis of the hydrangea production process was conducted under a life-cycle approach following the guidelines of the ISO 14040:2007 and 14044:2006 standards for the development of life-cycle assessment (LCA) for products [15,16].

2.2.1. Goal

The aim of this study was to analyze certain environmental aspects and impacts of the hydrangea production process on a small farm in La Paz Province of Antioquia, Colombia, in order to identify the critical aspects of the process and implement cleaner production initiatives to reduce the impacts.

2.2.2. Functional Unit

The functional unit was defined as one kilogram (1 kg) of hydrangea stems, equivalent to approximately 12 stems, grown in a 36-week production cycle on a small farm of 0.45 ha in La Paz Province, Antioquia, Colombia, packed and transported for export.

2.2.3. System Boundaries

The gate-to-gate system was evaluated (Farming to transport), including the flower cultivation and transportation stages up to delivery to the trader (responsible for overseeing the export of the flowers). This scope considers the activities over which the grower has operational control. Within the system boundaries, the material and energy flows of the activities prior to crop establishment, the cultivation stage, harvesting, post-harvest, transport to the trader, and some end-of-cycle processes, including the removal of waste stems, washing and disinfection, and composting and mulching of plant wastes (Figure 1). In this study, it is important to keep in mind that, in terms of distribution, hydrangeas are perishable goods. Therefore, short transport is essential for product quality and durability. Moreover, this activity is assumed by the producers.

2.2.4. Temporal Boundaries

The analysis began after the process of removing the remaining stems from the previous crop harvest and ended with the removal of any remaining stems from the crop under study. Therefore, the growth cycle of the crop (thirty-two weeks) and another period (four weeks) for the elimination of any remaining stems from the previous crop and the preparation of the crop under study for flowering were considered, making a total of thirty-six weeks.

2.3. Life-Cycle Inventory Analysis

Following the established system boundaries, a life-cycle inventory (LCI) was conducted by collecting primary information through crop visits and grower interviews. The data collected corresponded to the years 2021 and 2022. In cases where additional information was necessary, technical data sheets for specific agrochemicals, such as pesticides and fertilizers, were reviewed to determine their active ingredients and product composition. Significant efforts were devoted to verifying information by visiting growers, conducting interviews with owners and employees, and utilizing the technical data sheets of the inputs. An agronomist from the municipality’s mayor’s office provided additional support. The goal was to ensure a reliable and exhaustive data collection process, resulting in highly accurate data.

Regarding the material outputs of the system, the agrochemical containers and plant waste generated at different stages of the process were considered: stem selection, reception, packaging, and disposal of the remaining stems. In addition, the direct emissions into the air, water, and soil caused by the use of inputs, such as fertilizers, pesticides, etc., and fuel combustion in the agricultural machinery were also determined. Therefore, the following methodologies were used: the IPCC Guidelines for National Greenhouse Gas Inventories [17,18], EMEP methodology and air pollutant emission inventory of the European Environment Agency [19], SALCA methodology developed by Nemecek et al., (2019) [20], emission factors reported by the Colombian Mining and Energy Planning Unit [21], and some emission factors contained in the Ecoinvent 3.8 database.

2.4. Life-Cycle Impact Assessment and Interpretation

Life-cycle impact assessment (LCIA) involves converting life-cycle inventory data into numerical indicators to assess impact. In this case, the CML methodology developed in 2002 by Guinée et al. (2002) [22] and updated in 2016 [23] was used. This methodology assesses 11 midpoint impact categories: acidification, climate change, freshwater aquatic ecotoxicity, marine aquatic ecotoxicity, terrestrial ecotoxicity, abiotic depletion potential: fossil fuels, eutrophication, human toxicity, abiotic depletion potential: metals, ozone depletion, and photochemical oxidant formation.

The Umberto LCA + 10.0.03 software was used as the LCA tool, which made it possible to model each stage of the process system, as well as compare the material and energy consumption data with the Ecoinvent 3.8 process inventories, establish connections between the process data and the characterization factors (impact indicators) of the CML methodology, and analyze the results of this study in detail.

2.5. Sensitivity Analysis

The selection of different methods to determine an impact leads to inherent uncertainty in a system. This is due to possible variations caused by different raw materials and process inclusions for the same impact category, and by the treatment of input parameters [24]. These models were simulated in Umberto LCA software to evaluate the sensitivity in the environmental impacts of the process. Also, the sensitivity was evaluated in the software using five different impact methods, including: CML 2016, CML 2001; Recipe Midpoints (I); Recipe Midpoints (E); and EDIP (Environmental Development of Industrial Products)

2.6. Life Cycle Interpretation and Analysis of Cleaner Production Initiatives

In order to analyze the data, both LCI and LCIA results were analyzed together to identify the most relevant aspects of environmental impact emissions. Based on the results, some cleaner production initiatives (CPIs) that could be implemented to reduce the environmental impact of the process were analyzed. The initiatives analyzed were prioritized through a multi-criteria evaluation, assessing their contribution to the environmental sustainability aspect. For each criterion, indicators were defined to measure them, both qualitatively and quantitatively. Regarding the qualitative criteria, a numerical homologation was established; therefore, the criteria established were:

• Reduced consumption of raw materials;
• Reduced emissions to the environment (water, soil, and air);
• Reduced impact on ecosystems and human health;
• Producer’s installed capacity to implement the initiative;
• Easier implementation of alternative;
• Required time horizon for implementation;
• Resources and raw materials availability in the region;
• Contribution to the achievement of the SDG.

The criteria indicators were normalized using measures of central tendency. For each indicator, the mean (Equation (1)) and the standard deviation (Equation (2)) were calculated; subsequently, the Z-statistic was applied to normalize them (Equation (3)). The result was the relative distance of each alternative from the mean for a given indicator.

$$\overline{x_j}=\frac{\sum x_{j,i}}{n}$$

(1)

$$S_j=\sqrt{\frac{\sum {\left(x_{j,i}-\overline{x_j}\right)}^2}{n}}$$

(2)

$$Z_{j,i}=\frac{x_{j,i}-\overline{x_j}}{S_j}$$

(3)

where $\overline{x_j}$ is the arithmetic mean of the j-th indicator; x_j,i is the i-th data of the j-th indicator; S_j is the standard deviation of the j-th indicator; n is the number of alternatives; and Z_j,i is the normalized value of x_j,i.

After defining the criteria and how to measure them, a simple standardization method was used assign weights to each criterion, which made it possible to determine the relative importance of each criterion. As a result, two CPIs were prioritized and their implementation was modeled using Umberto software to analyze the change in environmental impact caused by the process.

3. Results and Discussion

3.1. Life-Cycle Inventory

The data collected included primary and secondary data and each stage included the use of greenhouse plastic, water, fertilizers, pesticides, energy, and packaging material, among others. The farms provided information on the consumption of inputs required at each stage of the process. Emissions were quantified based on emission factors and estimates from different studies and guidelines [25,26,27,28,29,30,31,32,33,34]. Tables S1 and S2 show detailed inventory data for process inputs and outputs, respectively. They are specified in more detail below in Section 3.2.

3.2. Life Cycle Impact Assessment

Table 1. Life-cycle impact assessment results.

Impact Category	Unit	Result
Acidification	kg SO2 eq	0.012
Climate change	kg CO2 eq	0.961
Freshwater aquatic ecotoxicity	kg 1,4-DB eq	1.207
Marine aquatic ecotoxicity	kg 1,4-DB eq	803.897
Terrestrial ecotoxicity	kg 1,4-DB eq	0.572
Abiotic depletion potential: fossil fuels	MJ	10.668
Eutrophication	kg PO42− eq	0.008
Human toxicity	kg 1,4-DB eq	3.036
Abiotic depletion potential: Metals	kg Sb eq	1.172 × 10−5
Ozone depletion	kg CFC-11 eq	7.755 × 10−8
Photochemical oxidant formation	kg C2H2 eq	2.382 × 10−4

and Figure 2 show the results obtained from the LCA of the hydrangea production process, identifying the contribution of every stage on the impact categories.

The results indicate that the cultivation phase has the greatest impact in most categories, including: acidification (56%), climate change (65%), marine aquatic ecotoxicity (50%), abiotic depletion potential: fossil fuels (51%), eutrophication (57%), abiotic depletion potential: metals (70%), ozone depletion (85%), and photochemical oxidant formation (72%). In all other categories, the end-of-cycle phase was the largest contributor. This study found that freshwater aquatic ecotoxicity, terrestrial ecotoxicity, and human toxicity were 70%, 73%, and 47%, respectively. It is worth noting that the pre-harvest and post-harvest stages significantly contributed to several impact categories, while the harvest and transport stages had the lowest contributions to all categories.

These results are consistent with those of other LCA studies conducted on flower crops with the same system boundaries. In the LCA studies on hydrangeas [3], chrysanthemums [4], and roses [7,8], the cultivation stage was found to have the greatest environmental impact. The use of inputs, such as fertilizers, pesticides, plastics, and their respective upstream production and transport processes, was identified as a major contributor to the impact of the cultivation phase.

Fertilization with NPK Triple 15 has been identified as one of the most critical processes in generating environmental impacts. During the application process, nitrogen compounds, such as ammonium (NH₄⁺), nitrates (NO₃⁻), dissolved organic nitrogen, nitrogen particles, and phosphates (PO₄³⁻), are generated. These compounds are not absorbed by plants and can reach surface waters through runoff and leaching, leading to contamination and eutrophication in lakes, streams, and rivers [35,36].

Additionally, the use of nitrogen fertilizers enhances nitrogen availability in the soil, leading to the production of compounds such as nitrous oxide (N₂O), ammonia (NH₃), and nitrogen oxides (NO_X) through nitrification and denitrification reactions. These compounds are then released into the atmosphere, with N₂O being a greenhouse gas that has a global warming potential 273 times greater than that of CO₂ [37]. In addition, NH₃ vaporizes and returns to the soil as acid rain, leading to acidification and the eutrophication of ecosystems. Furthermore, NO_X serves as a precursor to tropospheric ozone, which degrades air quality [35,38,39,40].

The production and transportation of synthetic fertilizer (NPK triple 15) upstream increases the amount of nitrous oxide (N₂O) within the nitrogen cycle, one of the main greenhouse gases. The use of minerals as raw materials, such as dolomite and naturally occurring phosphate and potassium salts found in rocks, contributes to abiotic mineral depletion [41]. Furthermore, these upstream processes require high energy and fossil fuel consumption, which primarily contribute to the impacts of climate change and the abiotic depletion of fossil resources.

The use of mulching plant waste on crop soil is a process that can have significant environmental impacts. During cultivation, most of the plant waste is deposited on the soil to promote decomposition and provide nutrients. While this can benefit the physicochemical properties of the soil, uncontrolled use can lead to negative effects, such as excess moisture and increased pests and diseases. Plant wastes are often not degraded before the next cycle starts, which could affect plant growth. Similar to fertilizers, the nitrogen contained in plant wastes increases the nitrogen content of the soil, resulting in to emissions of NH₄⁺ and NO₃^- that could reach surface and groundwater, as well as emissions of N₂O, NO_X, and NH₃ into the atmosphere.

Plant protection management with chemical pesticides is another important process that can have negative long-term effects on the environment and human health [42]. This is because they are not limited to target pests and can also harm non-target organisms. Of all the resources and inputs used in horticulture, pesticides are considered to pose the greatest direct threat to humans and the environment [43,44]. This is mainly due to the potential impact of the active ingredients, which are derived from mineral sources, particularly metals, such as manganese, zinc, aluminum, and lithium, thus contributing to abiotic depletion. Some pesticides contain halogenated substances, such as chlorine, fluorine, or bromine, which can deplete the ozone layer. Additionally, when pesticides are applied to crop soils, heavy metals and toxic active ingredients could reach water sources through run-off and leaching, causing in long-term harm to aquatic organisms.

Other processes that contribute to environmental impacts include the use of polymeric materials, such as polypropylene from hydrators used in flower hydration, polyethylene from saran and trellis netting used in infrastructure, and bamboo poles. These pre-processing materials contribute to climate change due to the use of energy and fossil fuels in the production processes, as well as to abiotic resource depletion and ecotoxicity.

Other impact categories, such as marine and freshwater aquatic ecotoxicity, human toxicity, and terrestrial ecotoxicity, serve as indicators to measure the impact of toxic substances on the environment and human health [22]. At the end of the cycle, flower farms use water and land, and produce waste, contributing significantly to freshwater aquatic ecotoxicity, human toxicity, and terrestrial ecotoxicity. It is important to study these indicators, as human behavior has exceeded the land’s ability to regenerate [7]. Marine aquatic ecotoxicity is a concern regarding cultivation practices that include fertilization, pest, and fungus control. The chemicals used in these practices can spread through the air, be absorbed into the water, and penetrate the soil, potentially harming human health and the natural ecosystem.

3.3. Sensitivity Testing of Method Choices via Scenario Analysis

For analyzing the environmental impact variation resulting from different prioritized initiatives, a sensitivity analysis was performed on the process flow variation and simulated for a second time using Umberto LCA. The results were compared with the impacts obtained in the original process.

Sensitivity tests of different impact assessment methods were conducted for the climate change, acidification, and ozone depletion impact categories. In fact, acidification was the category that showed the greatest variation between methods, with increases from 9.9% for EDIP to 49.3% for Recipe Midpoints (E). This is due to the equal perspective, which is the most cautious, as it considers the longest time frame as well as all impact pathways with available data. The climate change and ozone depletion categories did not show variations higher than 5% compared with the CML 2016 analysis method. The impact categories are presented in Figure 3.

3.4. Cleaner Production Initiatives for Hydrangea Cultivation

The reduction of environmental impacts could be achieved through the application of CPI. Based on an international literature review, environmental management strategies and CPI focusing on good agricultural practices, technical solutions for efficient use of resources and waste management have been identified in the agricultural sector [43,44]. Some of the most important initiatives include the use of biological controls to replace pesticides, the use of organic fertilizers instead of synthetic fertilizers, the best use of natural resources and the valorization of agricultural wastes [43,45,46,47]. For Hydrangeas, it was determined and analyzed eighteen CPIs that could be applied to the crops (

Table 2. Cleaner production initiatives for Hydrangea floriculture.

Environmental Aspect	Cleaner Production Initiative	Priority
Soil use	Mulching of vegetal waste in a controlled manner and reducing waste size	5
	Establishment of agroforestry systems in crops and alongside water sources	7
Infrastructure materials use	Replacement of crop infrastructure materials (wooden poles) with recycled materials.	9
Fertilization	Formulating fertilization from soil analysis or good nutrient management (GNM)	3
	Use of organic fertilizers such as manure, compost, biochar, vegetal waste, sludge, etc.	17
	Use of controlled-release fertilizers	10
Phytosanitary management	Integrated pest management (IPM) with biological control using natural agents to reduce pesticide application	2
	Use of controlled-release pesticides	13
Water consumption	Rainwater harvesting through construction of reservoirs and canals	6
	Post-harvest water reuse	8
	Recirculation of crop water through a closed system with biological treatment	12
Wastewater generation	Biological wastewater treatment with wetland or phytoremediation systems	16
Solid waste generation	Composting of vegetal waste for fertilizer	1
	Vermicomposting of vegetal wastes	4
	Anaerobic digestion of vegetal waste for biogas production	15
	Obtaining biochar through thermochemical processes, such as pyrolysis and gasification, for soil remediation, activated carbon, or energy recovery	11
	Obtaining products such as pallets, boards, or materials with thermal properties from hydrangea stems	14
	Production of liquid fuels and other chemicals by biorefinery processes	18

).

A multi-criteria assessment was conducted to identify those cleaner production alternatives that would make the greatest contribution to the environmental dimension of hydrangea floriculture sustainability. Therefore, eight criteria were evaluated by a group of experts who participated in the project “Environmental, Economic and Social Life Cycle Assessment for Hydrangea Agro-Industrial Enterprises as a Strategy for the Sustainable Development of La Paz Province in Eastern Antioquia” (Table S3).

Subsequently, the CPA were rated, with each participant assigning a value to each criterion according to the evaluation scales presented in Table S3. In this way, an average of the scores assigned by the evaluators was obtained (Table S5). The evaluation was carried out taking into consideration the current production conditions of the crop and the results of the LCA so that the critical environmental aspects of the process and the needs to reduce environmental impacts were known.

Based on these results, the simple standardization method (numeral 2.5) was applied to obtain normalized values to compare the results of the different criteria evaluated. The results of the standardized values are presented in Table S6. Finally, the normalized results of each criterion were multiplied by their respective weighting, the values were added, and the indexes were obtained that synthesized the indicators of each of the criteria and their weightings. With the results of the indexes, the LMP alternatives were ordered hierarchically from highest to lowest, obtaining the prioritized alternatives for the contribution to the environmental performance of the hydrangea production process (Table S7).

The following alternatives were prioritized through the evaluation and implementation of a simple standardization method: plant waste composting for fertilizer and integrated pest management (IPM) with biological control using natural agents (Table 2).

New changes were introduced to the process flows and the environmental impacts were simulated a second time in the Umberto LCA software for analyzing the environmental impacts variation with the prioritized initiatives. The results were compared with the impacts obtained in the original process.

3.4.1. Composting of Vegetal Waste for Fertilizer

Plant waste compost could provide the necessary nutrients for the crop, having the potential to partially or fully replace NPK Triple 15 fertilizer. Furthermore, this would reduce the environmental impacts caused by the synthetic fertilizer application and production process, as well as reduce the impacts caused by the current process of mulching plant wastes.

It was possible to obtain a maximum amount of compost from the plant wastes of the crop under study of 1.736 kg per kg of hydrangea, giving an average composting yield of 61.11%, calculated from the yields reported in different sources [48,49]. The nutrient supply (nitrogen, phosphorus, and potassium) that could be achieved with plant waste compost was analyzed and contrasted with synthetic fertilizer (based on its nutritional composition). According to the nitrogen supply, plant waste compost could replace 59.19% of the currently applied fertilizer to provide the same amount of nitrogen. Nevertheless, the phosphorus and potassium composition were lower in the compost, so other fertilizer sources would be needed to supply the same amount.

Therefore, two scenarios were analyzed:

• In the first scenario, it was assumed that all the vegetal waste currently mulching (2.841 kg/kg hydrangeas) was recovered through a composting process to obtain 1.736 kg compost/kg hydrangeas. As the compost was not sufficient to provide the phosphorus and potassium currently provided by NPK Triple 15, monoammonium phosphate (MAP) and potassium nitrate fertilizer application were included. The fertilizer quantities per kilogram of hydrangea were 0.032 kg NPK Triple 15, 0.03 kg MAP, 0.028 kg potassium nitrate, and 1.736 kg compost.
• In the second scenario, it was assumed that 50% of the vegetal waste currently mulching (1.421 kg/kg hydrangea) was recovered through a composting process to obtain 0.868 kg compost/kg hydrangea. This scenario considers that the vegetal waste mulching was also beneficial for the crop soil. Similar to scenario 1, the application of MAP and potassium nitrate was included. The fertilizer quantities per kilogram of hydrangea were: 0.100 kg NPK Triple 15, 0.016 kg MAP, 0.015 kg potassium nitrate, and 0.868 kg compost.

It was quite possible to achieve a reduction in all environmental impact categories due to the application of this CPI, as shown in Figure 4. The reduction in the total environmental load could be 19.63% for composting 100% of the plant wastes (scenario 1) or 9.97% for composting 50% of the plant wastes (scenario 2).

Environmental impact reduction occurs at the cultivation and end-of-cycle stages, achieving further reductions in the impact categories of terrestrial ecotoxicity (impact reduction of 0.57% due to 1% composting increase), freshwater aquatic ecotoxicity (impact reduction of 0.55% due to a 1% composting increase), and human toxicity (reduction of 0.39% due to a 1% composting increase), as the plant wastes would no longer decompose on the cultivation soil. Instead, the wastes would be taken to a composting process where decomposition occurs under regulated conditions, avoiding excessive accumulation of heavy metals and nutrients, thus reducing the possibility of run-off and leaching into water sources.

Furthermore, eutrophication in surface waters caused by nutrients such as ammonium, nitrates, dissolved nitrogen, phosphates, etc., was reduced by composting instead of mulching, as well as the acidification caused by H⁺ and NO_X ions generated during waste decomposition and the impact on climate change caused by the emissions of N₂O.

Additionally, reducing the use of synthetic fertilizers would reduce the impact on climate change and abiotic depletion of fossil resources and metals, as pre-production processes are energy-intensive and consume large amounts of abiotic resources, such as natural gas and minerals, to obtain nutrients such as phosphorus and potassium. Acidification is also reduced, as explained above; synthetic nitrogen fertilizers disrupt the natural nitrogen cycle, leading to the stagnation of plant yields, soil acidification, nutrient imbalance, and salt accumulation, whereas the use of plant residues generated in the same crop would contribute to nutrient recycling.

The results obtained with the incorporation of compost are similar to those reported by Bonaguro et al., (2021) [5] and Boldrin et al., (2010) [50], who evaluated the use of compost on crops of different species, achieving lower impact values for different categories, including climate change, acidification potential, eutrophication potential, and photochemical ozone formation.

3.4.2. Integrated Pest Management with Biological Control and Natural Agents

The introduction of pest and disease control methods based on biological control and the use of natural agents could reduce the use of synthetic pesticides for the crop and thus reduce the associated environmental impacts. According to Sarkar et al. (2021) [42], it is impossible to have a total absence of pesticides in developing countries, but it is possible to reduce highly hazardous pesticides and make a more selective and targeted use of pesticides classified as harmless. Among the pesticides used for the crop, Abafed and Magister are classified as Category II: moderately hazardous and the pesticides Polythion and Dithane as Category III: low hazard, in accordance with the World Health Organization’s toxicological classification [51]; therefore, they could still be used in a controlled and reduced way.

Microorganisms, plants, and natural extracts with the ability to control the main pests and diseases present in hydrangea crops were identified to evaluate this CPI. An outstanding example of a global biological insecticide is the entomopathogenic fungus Beauveria bassiana. This fungus has been shown not to harm natural enemies or beneficial insects present in the soil [47]. For hydrangeas, this fungus is able to control mites, thrips, whiteflies, and aphids [52,53,54].

Lecanicillium lecanii is another fungus used as an agricultural insecticide for the control of several species, such as powdery mildew, whitefly, aphids, and thrips. In addition, Ampelomyces quisqualis has been shown to control powdery mildew on hydrangeas [55], as well as being resistant to some fungicides [3]. Bacillus thuringiensis, Kurstaki, Isaria fumosorosea, Purpureocillium lilacinum, and Metarhizium anisopliae are other fungi used in biological control products.

Biological control could also use predatory species, such as the mite Phytoseiulus persimilis, which has been successfully used in chrysanthemum, rose, and hydrangea crops for the control of the red mite (species Tetranychus urticae) known as spider mite [56,57], as well as for the mite Neoseiulus californicus of the same Phytoseiidae family [58]. Paez (2021) [56] also indicates that plant extracts, such as garlic and chili, or Neem extracts are highly effective in controlling flower pests, such as thrips and mites. To a lesser extent, the use of emulsions, agricultural soaps, or vegetable oils is also recommended for the control of mites and other pests in crops [59].

In cases of biological control with fungi and predatory species, more in-depth studies on the compatibility of chemically synthesized pesticides with these species should be conducted to ensure the compatibility and selectivity of these products. In other words, controlling pathogens, but allowing beneficial organisms to survive. This study was based on the fact that biological control applied was compatible with the chemical pesticides currently used on the crop.

In IPM, it is recommended to use biological control in combination with chemical control measures. According to Deguine et al. (2021), the use of green technologies (ecological regulation, biological control, physicochemical deception control, and scientific medication) could reduce pesticide use by 30–50%. Even in a program developed by FAO to implement IPM on crops in Southeast Asia, an average reduction in pesticide use of 70–75% was achieved (with reductions of up to 99% in some districts in Indonesia) [60]. Similarly, in the floriculture life-cycle assessment developed by Aguirre et al. (2017) [3] and Bonaguro et al. (2021) [5], the implementation of biological control replaced 50% and 40% of pesticide use, respectively, and with the implementation of these measures, an improvement of 39% of the total environmental load of the crop was achieved in the case of Aguirre et al., and an overall reduction in impacts, especially in the categories of human toxicity (−25%) and acidification potential (−16.3%) for cyclamen in the case of Bonaguro et al. (2021) [5]. Therefore, based on this information, two scenarios were evaluated:

• Implementation of biological control, replacing 30% of the use of chemical pesticides;
• Implementation of biological control, replacing 50% of the use of chemical pesticides.

For the simulation of this initiative, it was assumed that the environmental impact of the biological and natural control products used would be minimal, as they are organic, biodegradable, and do not cause harm to non-target organisms [52].

By implementing IPM, a reduction in all environmental impact categories could be achieved, as shown in Figure 4. In Scenario 1, a total environmental load reduction of 6.62% could be achieved due to the substitution of 30% of the chemical pesticide used; in Scenario 2, a total environmental load reduction of 11.03% could be achieved due to the substitution of 50% of chemical pesticides.

In this case, the environmental impact reduction would only occur at the cultivation stage. The greatest reduction might occur for the abiotic metal depletion (reduction of 0.39% per 1% of pesticides replaced), ozone depletion (reduction of 0.70% per 1% replaced), and photochemical oxidant formation categories (0.58% per 1%). For abiotic metal depletion, the reduction in the use of pesticides would reduce the minerals used for the production of active ingredients. Consequently, there would be a reduction in the impacts on ozone depletion caused by halogenated substances and the formation of photochemical oxidants by volatile organic compounds in pesticide active ingredients and solvents.

This initiative could also reduce the abiotic depletion of fossil fuels by reducing pre-processing fuel use and pesticide spraying, acidification caused by pre-production substances, marine and freshwater aquatic ecotoxicity due to emissions of toxic compounds in pesticides, and climate change due to pre-production and transport processes.

3.4.3. Plant Waste Composting and IPM with Biological Control and Natural Agents

The implementation of both CPIs was evaluated based on composting 50% of the plant wastes and replacing 30% of the chemical pesticides with biological control initiatives and natural agents. Such a scenario could result in a 16.59% total environmental load reduction of the crop, with reductions in all impact categories, as shown in Figure 4.

It was evidenced from the implementation of both CPI actions together that all impact categories had a reduction of over 12%, showing significant results for freshwater ecotoxicity (29.83% reduction), terrestrial ecotoxicity (28.64% reduction), acidification (25.54%), and ozone layer depletion (24.26%), which was attributed as mentioned to the individual actions (numerals 3.4.1 and 3.4.2). These actions have the following benefits; (i) composting can increase water-holding capacity, soil amendment, pollution prevention, erosion control, pollutant cleanup, heavy metal contaminated soil cleanup [61], and (ii) biological control. Furthermore, it has several advantages because it has no negative effects on agricultural workers, it has a positive impact on biodiversity, and the agricultural products have the highest quality as they are free of chemical residues, concepts closely related to IPM [62].

4. Conclusions

The sustainability of hydrangea floriculture in La Paz Province requires several actions to reduce the environmental impacts throughout the life cycle of the process. Based on the life-cycle analysis methodology, it was found that the most critical aspects affecting environmental performance that should be focused upon include ozone depletion, terrestrial ecotoxicity, and photochemical oxidant formation, which are attributed to the use of synthetic fertilizers and chemical pesticides, as well as their upstream production processes; the plant waste that remains as mulch in the soil of the crop; and the use of materials from fossil resources, such as polymers and fuels.

Also, following a multi-criteria evaluation of eighteen cleaner production initiatives that could be applied to hydrangea cultivation, it was found that the initiatives most likely to contribute to environmental performance were the composting of plant wastes to obtain compost and integrated pest management with biological control and natural agents to reduce pesticide application. As a result of the environmental impact variation assessment when applying these two initiatives, a significant reduction was found in all the environmental impact categories evaluated. Therefore, the integration of different initiatives focusing on several environmental aspects of the process could lead to better results in the environmental impact reduction while facilitating a gradual transition towards the adoption of new practices by growers.

The analysis of the life cycle for the production of hydrangeas in the study area contributes to making it more competitive at an international level, with the environmental impacts identified and reduced, contributing significantly to the environmental dimension of sustainability. In addition, small farmers supply environmentally friendly products. For example, with the support of the ACV, a sustainability label could be introduced for the production of hydrangeas, considering the social and economic components.