1. Introduction
Avocado is a tropical fruit from Central America that indigenous populations have consumed for at least 10,000 years [
1]. The word avocado has its etymology in the Aztec language word ahuacatl, meaning testicle, is related to this fruit's particular shape [
2]. In recent decades, the international demand for this fruit has increased, and it is considered a superfood and, therefore, widely recommended for a healthy lifestyle [
3]. The ongoing international demand has caused an increase in the planted surface of this fruit in regions with adequate conditions for its development. In many cases, the expansion of the planted area was linked to deforestation and land use change processes in different countries, mainly in Latin America [
4].
Mexico is the leading country in producing, consuming, and exporting this fruit, with nearly 30% of the global production and about 45% of the global export volume [
5]. A flourishing avocado agroindustry in Michoacan state (central west Mexico) generates nearly 2400 million US dollars in annual income, and the United States market is nowadays the largest market and importer of this fruit. Due to its proximity, Mexico is its main provider, and eight out of ten avocados consumed in the US come from Mexico. However, the expansion of this fruit crop had generated social, environmental, and political backfire situations [
5,
6]. On February 12th, 2024, a group of US senators issued a request letter to the current US federal administration to work with Mexican authorities in order to regulate the avocado industry and prevent avocados from illegal deforestation from being marketed in the US [
7]. The senator's request letter cited the NGO Climate Rights International report “Mexico: Avocados for Export Fueling Deforestation and Abuse” [
8] and the New York Times article “Americans Love Avocados. It’s Killing Mexico’s Forests” [
9], which points out that agroindustrial avocado production in Mexico is linked to the loss of forests and the depletion of water resources. Furthermore, on February 26th, 2024 the US ambassador to Mexico (Ken Salazar) visited Michoacan state and declared that Mexican avocados grown illegally shouldn’t be exported to U.S [
10]
Recent research indicates that the agroindustrial production of avocados in the past decades was related to the increase in violence linked to organized crime cartels that infiltrated the avocado business due to its high profitability. This situation has led to this fruit being currently named the “blood diamonds of Mexico”, and recent estimates indicate that nearly 5% of avocado agroindustry in Mexico, mainly in Michoacan and Jalisco states, are controlled by organized crime cartels and used, among other things for money laundry [
3,
11,
12]. Further, recent studies in the main avocado-producing region in the world report forest loss, several impacts on biodiversity, soil degradation, water pollution, as well as illegal water appropriation [
6,
13,
14,
15].
Illegal water appropriation has led to social discontent and protests, and during the 2024 dry season (april 2024), local farmers, indigenous peasants, and environmentalists dismantled several illegally established water containment ponds that served as water reservoirs for avocado plantations in rural locations in Villa Madero and Zirahuen, in Michoacan, arguing water shortage in rural communities and large impact on the environment [
16].
On a global scale, agriculture production is considered the leading water consumption sector [
17]. Estimates indicate that nearly 70% of world freshwater use is directly linked to agricultural activities [
18]. Several studies also indicate that the ongoing global water scarcity and access crisis can be a systemic risk, fueled by climate change and weather pattern modification [
19,
20]. However, by 2024, the water crisis had reached a critical point in the avocado-producing region in Mexico.
The ongoing situation makes it necessary to evaluate the sustainability of water use in the agricultural sector and agroindustrial avocado production from an academic and sound technical perspective. To do so, several methods have been proposed, like ISO 14046, which considers the Life Cycle Analysis method to quantify environmental impacts from the beginning of the process flow to the end [
21,
22]. Another method is described by Deurer et al. [
23], which considers the evaluation of water based on the net water balance, considering the inputs and outputs of water [
22]; However, water footprint is among the most widely used and accepted indicators [
24].
The Water Footprint is an environmental impact indicator introduced in 2002 by Hoekstra [
24]. The WF is defined as the volume of freshwater used to produce a product [
24,
25]. This indicator comprises three components: green, blue, and gray water footprints; the green WF corresponds to the rainfall absorbed by the soil in the unsaturated zone and consumed by vegetation in order to generate biomass [
26]. The blue WF is the volume of fresh water extracted from a surface or underground source to produce goods. In the case of agricultural products, it includes irrigation water, whatever the source [
27]. The gray WF is the freshwater required to assimilate the pollutant load given the natural base concentrations and environmental quality standards [
24,
26,
28,
29].
Water footprint studies in the agricultural sector have increased rapidly, and the method has allowed the quantification of the global average water consumption of various fruits, cereals, vegetables, and derivatives. The most relevant study in this is that of Mekonnen and Hoekstra [
30], where they estimated the water requirement of more than 126 crops, including corn 1222 m³/ton, wheat 1827 m³/ton, orange 560 m³/ton, and avocado 1981 m³/ton.
The present contribution focuses on analyzing the water footprint and evaluating the sustainability of water use in agroindustrial avocado production in one avocado-producing municipality in the State of Michoacán in western central Mexico, Ziracuaretiro.
To carry out the sustainability of water use analysis, we incorporated the Russo et al. perspective [
31], in which the sustainability of water use is the satisfaction of current water demands for all users without harming future supply while contributing to the objectives of society and the maintenance of the environment [
31]. In such a way, the sustainability of irrigation water (SUIW) use in a particular region is determined by the relationship between the agricultural blue WF of a crop and the availability of water in that region.
Consequently, water sustainability and WF allow quantitative evaluations of the water resource in terms of current resources and potential demands that may affect availability over time [
31].
To carry out this analysis, we considered weather variables, soil characteristics, crop characteristics, crop yield, production, and availability of water aggregated at a municipal level. We therefore assumed that the entire municipality studied has the same characteristics. These considerations have already been used in other studies, such as De Miguel et al. [
32] and Gómez-Tagle et al. [
15]. It is essential to clarify that the WF results of this study represent an approximation of water consumption [
33]; in this situation, the challenge is to expand the WF studies to the orchard or single plantation scale and contrast the results with those generated at the municipal scale. Even though we recognize limitations due to the level of data aggregation, the study represents an opportunity to guide water policy-making in a region with the largest contribution to the avocado agroindustry and international markets.
5. Conclusions
In the municipality of Ziracuaretiro, part of the Michoacan Avocado Belt in central Mexico, estimated water footprint for avocado cultivation in rainfed conditions was 839.03 m
3/ton and 2355.80 m
3/ton for irrigation, with a mean of 1597.41 m
3/ton, which means that in this site consumption is 1.5 times greater than the global green and blue WF (1132 m
3/ton) and twice greater than in the main avocado region of Michoacan. The greater water footprint of this municipality can be explained by the fact that the climatic conditions of Ziracuaretiro are generally warmer, the orchards are located at a lower altitude (1226 m.a.s.l. and 2273 m.a.s.l.), and about 55% of the plantations are located between 1226 and 1446 m.a.s.l. These lower altitudes are related to higher air temperatures, as well as less annual precipitation compared to higher altitudes (Uruapan; between 1138 - 2654 m.a.s.l. Gómez-Tagle et al., [
15]. On the other hand, the start and duration of the production cycle are other factors that influence increased water consumption. In this study, the beginning of the production cycle was considered in September. This means that the growth and filling of the fruit occurs during the time of the year with less rainfall. In addition, with the analysis of the water footprint, it was estimated that in Ziracuaretiro, an average of 124.29% of the total volume of water granted for agricultural use is required, a situation that puts the sustainability of the use of irrigation water in this municipality at risk. And it is that appropriation without the legal rights of use, which put at risk the acquisition of water for other users and agricultural crops.
Finally, future work is needed to estimate the water consumption of this crop in the producing region of Michoacan, considering that it is the leading avocado-producing state; added to the above, subsequent studies should focus on the effects of climate change on avocado water consumption and its productivity. Concerning climate change, there is a risk of an increase in water demand, and the supply of water for other uses can be at risk. Last but not least, work on schemes that seek to reduce the amount of irrigation water used in this agro-industrial crop as part of the adaptation measures to climate change is urgently needed.