Blue and Green Water Footprint of Agro-Industrial Avocado Production in Central Mexico
, Diana J. Fuerte-Velázquez 3, Alma G. Barajas-Alcalá 1, Fernando Quiroz-Rivera 1,4, Pablo E. Alarcón-Chaires 5,† and Hilda Guerrero-García-Rojas 6
Round 1
Reviewer 1 Report
1)In Introduction there are some sentences repeated. Introduction can be improoved and become a little smaller. The authors should write about the importance of avocado fruit for Mexico and for the world.
2)In 2.2 the authors should explain why soil properties are important for crop water requirement.
3)In 2.2.1 it is important to inform what method was used to ETo calculating.
4)In 2.2.3 it is our opinion that it is no clear how effective precipitation was calculated for rainfed crop.
5)In page 9, t.test used the years as repettitions ?
6)What are the most used irrigation method in the study area ? Surface irrigation method? Was the irrigation efficience very low ?
7)Table 7 should not contain dry cereals as mayze and wheat.
8)Conclusions have to much numbers. It can be improoved wrinting more finding concepts.
Author Response
Reviewer comment:
- In Introduction there are some sentences repeated. Introduction can be improoved and become a little smaller. The authors should write about the importance of avocado fruit for Mexico and for the world.
Answer: We agree with the reviewer's comment, therefore the last paragraph of the introduction section was changed from:
“In this contribution, we analyzed information of an iconic and representative municipality within the Avocado Belt of Michoacan, Uruapan. This municipality produces nearly 6.5 % of Mexico's annual, 2.4 million tons. We followed the water footprint approach of Hoekstra et al. [7] and estimated direct green and blue water consumption by means of crop water requirement using the CROPWAT v 8.0 software [30], we used daily weather records acquired between 2010 and 2018 from the automated weather stations network of APEAM (Mexico’s Avocado Producer Packing and Exporting Organization) [16], and also soil characteristics information derived from direct field observations and previously acquired and analyzed soil samples. We considered crop characteristics information from previous in situ measurements at selected avocado plantations throughout the target municipality. Finally, we addressed the blue water agricultural water stress index for our study case by comparing the blue WF and the available water for agricultural use through water rights concessions.”
Most of the information provided herewith is given later in the next section (2. Material and methods) and therefore repeated, the paragraph was changed to:
“In this contribution, we analyzed information of an iconic and representative municipality within the Avocado Belt of Michoacan, Uruapan. This municipality produces nearly 6.5 % of Mexico's annual, 2.4 million tons. Evaluate the water green and blue footprints and address the water stress index, comparing the blue WF and the available water for agricultural use through water rights concessions.”
Reviewer comment
- In 2.2 the authors should explain why soil properties are important for crop water requirement.
Answer: We agree with the reviewer's comment.
The availability of both green water (rainfall) and blue water (irrigation) for the crop, depends on soil properties. The most relevant is available soil water which depends on soil depth, soil texture, organic matter content, and bulk density. These soil properties are important for crop water requirements because they determine the water storage water inside the soil (Blum et al., 2018).
It is also important to mention that the CROPWAT model considers infiltration, moisture depletion, and available soil moisture (Smith et al., 1992).
References
Blum, W.E.H., Schad, P. & Nortcliff, S. (2018). Essentials of Soil Science. Soil formation, functions, use and classification (World Reference Base, WRB). Stuttgart: Borntraeger Science Plublishers. ISBN: 978-344-30-1090-4.
Smith, M. CROPWAT: a computer program for irrigation planning management (No. 46). Food and Agriculture Organization of the United Nations (FAO), 1992. Available online: https://books.google.it/books?id=p9tB2ht47NAC&pg=PP1&source=kp_read_button&redir_esc=y#v=onepage&q&f=false
We modified the manuscript text from:
“2.2. Calculating blue and green water footprint indicators
The water footprint methodology is based on the crop water requirement (CWR), in it, the amount of water used in the production of a certain crop will depend on climatic parameters, specifically potential evapotranspiration (ETo), as well as crop and soil characteristics [7]. Although this methodology was developed to evaluate the commercial flows of water in the agricultural sector, it has been adapted to other sectors such as the trade of livestock products and other types of products [38].”
To
“ 2.2. Calculating blue and green water footprint indicators
The water footprint methodology is based on the crop water requirement (CWR), in it, the amount of water used in the production of a certain crop will depend on climatic parameters, specifically potential evapotranspiration (ETo), as well as crop and soil characteristics [7]. Availability of water for the crop is dependent on specific soil characteristics, mainly available soil water which is controlled by soil depth, soil texture, organic matter content, and bulk density which determine water storage and availability in the soil (Blum et al., 2018).
Although this methodology was developed to evaluate the commercial flows of water in the agricultural sector, it has been adapted to other sectors such as the trade of livestock products and other types of products [38].”
Reviewer comment
3) In 2.2.1 it is important to inform what method was used to ETo calculating.
Answer: We agree and consider the reviewer's comments highly relevant. Therefore the manuscript was modified from:
“2.2.1. Crop Water Requirement
The term crop water requirement (CWR, mm) refers to the volume of water needed by a crop to grow and produce a specific product. CWR depends on the evaporation power of the atmosphere, expressed by the reference crop evapotranspiration (ETo, mm) and on crop water use characteristics, which are strongly related to crop health and phenology, and can be summarized in the crop coefficient (Kc, dimensionless) [39].
The CWR is calculated by multiplying ETo by Kc under standard conditions, this is, with no water limitations for crop growth, CWR is equal to actual crop evapotranspiration (ETc, mm):”
To:
“2.2.1. Crop Water Requirement
The term crop water requirement (CWR, mm) refers to the volume of water needed by a crop to grow and produce a specific product. CWR depends on the evaporation power of the atmosphere, expressed by the reference evapotranspiration (ETo, mm) and on crop water use characteristics, which are strongly related to crop health and phenology, and can be summarized in the crop coefficient (Kc, dimensionless) [39]. ETo was estimated using the CROPWAT model and considering the standard Penmann-Monteith equation described by Allen et al. [40].
The CWR is calculated by multiplying ETo by Kc under standard conditions, this is, with no water limitations for crop growth, CWR is equal to actual crop evapotranspiration (ETc, mm):”
Providing the corresponding reference of work:
[40] Allen, R. G; Pereira, L. S; Raes, D., Smith, M. Crop evapotranspiration-Guidelines for computing crop water requirements. FAO Irrigation and drainage paper 56. Food and Agriculture Organization of the United Nations, Rome, Italy., 1998, D05109.
Reviewer comment
4) In 2.2.3 it is our opinion that it is no clear how effective precipitation was calculated for rainfed crop.
Answer: We agree with the reviewer's comment and included a short description of how effective precipitation was calculated according to the CROPWAT model.
The USDA, SCS method, is one of the most widely applied and reliable methods. Dastane (1978) mentioned:
“The U.S. Department of Agriculture's Soil Conservation Service has developed a procedure for estimating effective rainfall by processing long-term climatic and soil moisture data. A comprehensive analysis was made by perusing 50 years of precipitation records at 22 experimental stations representing different climatic and soil conditions. The soil moisture balance was worked out for each day try adding effective rainfall or irrigation to the previous day's balance and subtracting consumptive use. To avoid a high degree of complexity, neither the soil intake rate nor rainfall intensities are considered in this method.”
Dastane, N.G. Effective rainfall in irrigated agriculture. FAO Irrigation and drainage paper 25. Food and Agriculture Organization of the United Nations, Rome, Italy., 1978. Available online at: https://www.fao.org/3/x5560e/x5560e00.htm#Contents
We considered important to include the comment and reference regarding effective rain estimation. Therefore and following the comment of the reviewer, the manuscript text was changed from:
“Ewaid et al. [41] mention that ETg can be either the effective rain (Effrain) or the ETc. In the case that Effrain > CWR, then the ETg = ETc, this assumes that the crop never utilizes more water than is required for ideal growth. On the other hand, if Effrain < ETc, then ETg = Effrain.”
to:
“Ewaid et al. [41] mention that ETg can be either the effective rain (Effrain) or the ETc. In the case that Effrain > CWR, then the ETg = ETc, this assumes that the crop never utilizes more water than is required for ideal growth. On the other hand, if Effrain < ETc, then ETg = Effrain. In this case, Effrain was estimated considering the USDA, SCS method described by Dastane [42] and included within the CROPWAT model [30].”
Besides, the reference section of the manuscript includes now the Dastane (1978) reference:
[42] Dastane, N.G. Effective rainfall in irrigated agriculture. FAO Irrigation and drainage paper 25. Food and Agriculture Organization of the United Nations, Rome, Italy., 1978. Available online at: https://www.fao.org/3/x5560e/x5560e00.htm#Contents
Reviewer comment
5) In page 9, t.test used the years as repettitions?
Answer: Yes, we considered years as repetitions for the t.test applied. However, after an extensive review of the case. The t.test is not applicable in this particular case since there is a violation of the sample independency assumption since crop yield in a year may be correlated with yield in the previous year. The most appropriate statistical test would be a repeated measures ANOVA (Kraska, 2010), besides a Mann-Kendall trend test for crop yield (Hipel & McLeod, 1994). Therefore the manuscript was modified from:
“Regarding crop yield, irrigated plantations had a higher mean yield of 10.26 tons ha⁻¹ year⁻¹ while rainfed plantations had 9.88 tons ha⁻¹ year⁻¹ (t.test = -3.002, df = 9.9378, p-value = 0.01339). Nevertheless, crop yield was steady in the rainfed condition but depicted a rather slight trend to increase in the irrigated condition (Table 3).”
to:
“Regarding crop yield, irrigated plantations had a higher mean yield of 10.26 tons ha⁻¹ year⁻¹ while rainfed plantations had 9.88 tons ha⁻¹ year⁻¹. The one-way repeated measures ANOVA aimed to evaluate the effect of production modality on crop annual yield and showed a significant effect of production modality (F(1, 9) = 8.116, p < 0.05). Further, crop yield was steady in the rainfed condition but depicted a slight increasing trend in the irrigated condition (Table 3). However, the Mann-Kendall trend test [x]* indicated the non-existence of trends in neither of the production modalities.”
References
Hipel, K. W., McLeod, A. I. (1994). Time series modeling of water resources and environmental systems. Elsevier.
Kraska, M. (2010). Repeated Measures Design. In Salkind, N. J. (Ed.).. Encyclopedia of research design (Vol. 1). SAGE Publications.
*[x] correspond to a not yet defined sequential identification number for the citation and reference within the manuscript.
Reviewer comment
6) What are the most used irrigation method in the study area ? Surface irrigation method? Was the irrigation efficience very low?
Answer: We agree with the reviewer's comment.
The most used irrigation method in the study area is sprinkling irrigation, the second one is drip irrigation, we did not find literature regarding irrigation efficiency in the study area. Besides in this project, we did not evaluate the efficiency of irrigation.
We modified the manuscript text from:
“2.3.3. Avocado production, planted surface, and yield data
The data of avocado crop planted surface (ha), production (ton year⁻¹), and yield data (ton ha⁻¹ year⁻¹) of the 2012 to 2017 production cycles, were obtained from Mexico's Agrifood and Fisheries Information Service (SIAP for its name in Spanish) [15].”
to:
“2.3.3. Avocado production, planted surface, and yield data
The data of avocado crop planted surface (ha), production (ton year⁻¹), and yield data (ton ha⁻¹ year⁻¹) of the 2012 to 2017 production cycles, were obtained from Mexico's Agrifood and Fisheries Information Service (SIAP for its name in Spanish) [15]. The SIAP database distinguishes between rainfed and irrigation avocado plantations. The most common irrigation system in the study area is sprinkling irrigation followed by drip irrigation [38].”
Reviewer comment
7) Table 7 should not contain dry cereals as mayze and wheat.
Answer: We agree with the reviewer's comment. We have removed the information regarding Maize, Oats, and Wheat from table 7, as recommended.
Reviewer comment
8) Conclusions have to much numbers. It can be improoved wrinting more finding concepts.
Answer: We agreed partially with the reviewer's comment and modified the corresponding manuscript text in order to provide fewer numbers and more concepts.
The text was modified from:
“The results of this study indicate that the mean WF of agro-industrial production of avocado in Uruapan municipality, between 2012 and 2017 was estimated at 152.0 Mill.m³ year⁻¹. The overall mean WF considering rainfed and irrigation plantations were 744.3 m³ ton⁻¹, below the reported world average water footprint of 1,086 m³ ton⁻¹ for this fruit crop [Mekonnen & Hoekstra, 2011]. Irrigated agro-industrial avocado production comprising green and blue water footprints were 790.6 m³ ton⁻¹, and 280.8 m³ ton⁻¹ respectively, with an overall mean of 1,071.4 m³ ton⁻¹, similar to the reported global mean footprint, while mean yield was 10.26 ton ha⁻¹ year⁻¹. The WF of rainfed avocado production was 417.1 m³ ton⁻¹, with a mean yield of 9.88-ton ha⁻¹ year⁻¹. Green water has a lower opportunity cost than blue water, however, the relationship between yield in rainfed and irrigated plantations indicates that a marginal increase is achieved under irrigated production with a WF about 2.5 times higher than rainfed production.
Unusual spring rainfall in 2015 decreased the blue water demand for the crop in that year. Interannual variability of weather conditions, mainly precipitation, results in variable WF for the studied crop. Irrigation efficiency and water resource management improvements are needed in order to achieve increments in crop yield under irrigated conditions and at the same time reduce the pressure on the stressed water resources in the area.
Major conflicts for water rights and water resources access triggered by water withdrawals overdue by agroindustrial avocado production are foreseen in a short period within the study area, and these conflicts may increase in years with dry conditions.”
to:
“The results of this study indicate that the mean WF of agro-industrial production of avocado in Uruapan municipality, between 2012 and 2017 was estimated at 152.0 Mill.m³ year⁻¹. The overall mean WF considering rainfed and irrigation plantations was, below the reported world average water footprint for this fruit crop [27]. At the same time, green water has a lower opportunity cost than blue water, however, the relationship between yield in rainfed and irrigated plantations indicates that a marginal increase (~ 3%) is achieved under irrigated production with a WF about 2.5 times higher in irrigated than rainfed production.
Interannual variability of weather conditions, mainly precipitation, results in variable WF for the studied crop. For example, in 2015, unusual spring rainfall decreased the blue water demand for the crop that year. Weather and climate fluctuations affect therefore the production of the crop as well as the water demand of it at the production unit scale (plantation), but the steady increase in avocado planted surface indicates an overall increase in water use even if weather conditions are favorable like those during 2015 production cycle.
Our findings evidence that in certain years agroindustrial avocado production in the studied area uses the whole volume of water available to agriculture, according to government REDPA databases. And, indeed, we found that during 2017 water appropriation by avocado production reached up to 120 % of the water volumes concesionned to agriculture in the municipality. This implies that other water uses were depleted of water. We, therefore, foresee that social conflicts between different water users will be triggered by excessive water withdrawals by agroindustrial avocado production within a short period in the study area, and these conflicts may increase in years with dry conditions.
Further, considering the UN Sustainable Development Goal 6 regarding blue water management efficiency and the mitigation of water scarcity, the evidence presented in this communication indicates that the actual agroindustrial avocado production model in the studied municipality does not align well with the UN goal 6. We can state then that the mainstream agroindustrial production model in the study area may generate water scarcity rather than mitigate it, especially during dry years.”
Where we use a more descriptive and data-free narrative that emphasizes the fostering of social conflicts related to water use in the actual and mainstream avocado production model in the area.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Please check the acronyms, units of measure and punctuation. See the comments in detail
Comments for author File: Comments.pdf
Author Response
Comment 1
Please pay attention to acronyms: ETc is mentioned in the abstract without specifying its meaning. The same happens for IR on page 8 (the acronym is explained only in the caption of Table 2). In addition, sometimes subscripts are used, sometimes not (eg ETc or ETc ).
Answer: We agree with the reviewer comment. The thext in the abstract was modified from:
“Abstract: Mexico is the world-leading avocado producer and the municipality of Uruapan in the Avocado Belt region in Central Mexico produces 153,000 tons a year, nearly 6.4 % of Mexico's total volume. We performed a green and blue water footprint (WF) analysis for the years from 2012 to 2017 in this municipality, and compared the estimated WF volumes with water concessions for agriculture. A mean annual rainfall of 1,757.0 mm was estimated in the study period, with a mean effective rainfall of 877.2 mm, and a mean ETc of 933.1 mm, with 312.5 mm of mean irrigation requirement. The mean WFtotal was 744.3 m³ ton⁻¹, below the global mean WF for this crop (1,086 m³ ton⁻¹).”
to:
“Abstract: Mexico is the world-leading avocado producer and the municipality of Uruapan in the Avocado Belt region in Central Mexico produces 153,000 tons a year, nearly 6.4 % of Mexico's total volume. We performed a green and blue water footprint (WF) analysis for the years from 2012 to 2017 in this municipality, and compared the estimated WF volumes with water concessions for agriculture. A mean annual rainfall of 1,757.0 mm was estimated in the study period, with a mean effective rainfall of 877.2 mm, and a mean crop evapotranspiration of 933.1 mm, with 312.5 mm of mean irrigation requirement.”
Comment 2
Please pay attention to the units of measurement. Millions of cubic meters are not indicated as Mill. m 3 but, at most, with Mm 3 (Cubic Megameters). Moreover, sometimes the authors use “ m3 year−1”, sometimes “m3/year”. Please correct everywhere in the text.
Answer: The Mill m³ notation was removed from the manuscript and replaced with the correct Mm³ notation suggested by the reviwer.
The notation ambiguity was eliminated and m³/year was replaced by m³ year⁻¹ throughout the text.
Comment 3
The second sentence of paragraph 2.1 is too long by English language standards. Please insert periods to separate completed sentences.
Answer: We agree with the comment and modified the corresponding text from:
“The municipality covers 101,477.33 ha (1,014.77 km²) [31], and avocado plantations covered 15,101 hectares in 2017 [15], and according to the avocado plantation delimitation of Morales-Manilla and Cuevas [32] can be found between 1138 m.a.s.l. and 2654 m.a.s.l. with a mean altitude of plantations is 1620 m.a.s.l. and standard deviation of 242.4, with a mode altitude of 1580 m.a.s.l.”
to:
“The municipality covers 101,477.33 ha (1,014.77 km²) [31]. Avocado plantations covered 15,101 hectares in 2017 [15], and avocado plantations can be found between 1138 m.a.s.l. and 2654 m.a.s.l. [32]. Mean altitude of plantations is 1620 m.a.s.l. and standard deviation of 242.4, with a mode altitude of 1580 m.a.s.l.”
Comment 4
Before equation (1) in paragraph 2.2.1, please adjust the punctuation by inserting a period after "crop
growth".
Answer: We performed the period addition as indicated in the comment.
The text was changed from:
“The CWR is calculated by multiplying ETo by Kc under standard conditions, this is, with no water limitations for crop growth, CWR is equal to actual crop evapotranspiration (ETc, mm):”
to:
“The CWR is calculated by multiplying ETo by Kc under standard conditions, this is, with no water limitations for crop growth. CWR is equal to actual crop evapotranspiration (ETc, mm):”
Comment 5
After equation (1) in paragraph 2.2.1, a concept already written a few lines before is repeated: "The Kc is the crop coefficient (dimensionless)". I think you can at least delete "dimensionless".
Answer: We performed the modificacion suggested by the comment
The text changed from:
“where ETo is the reference crop evapotranspiration and represents the evapotranspiration from a standard vegetated surface of 0.12 m tall grass with surface resistance of 70 s m⁻¹ and an albedo of 0.23 [39]. The Kc is the crop coefficient (dimensionless) and represents the conditions where no limitations are placed on crop growth or evapotranspiration due to water shortage, crop density, disease, weed, insect, or salinity-derived stress [39].”
to:
“where ETo is the reference crop evapotranspiration and represents the evapotranspiration from a standard vegetated surface of 0.12 m tall grass with surface resistance of 70 s m⁻¹ and an albedo of 0.23 [39]. The Kc represents the conditions where no limitations are placed on crop growth or evapotranspiration due to water shortage, crop density, disease, weed, insect, or salinity-derived stress [39].”
Comment 6
In paragraph 3.5, please delete the comma after (417.1 m3 ton−1) in the sentence “ It is worth noting that the total water footprint of rainfed plantations (417.1 m3 ton−1), was lower than the green water foot-print of the irrigated plantations (709.6 m3 ton−1) (Table 5)”.
Answer: The comment was considered and the text changed from:
“It is worth noting that the total water footprint of rainfed plantations (417.1 m³ ton⁻¹), was lower than the green water footprint of the irrigated plantations (709.6 m³ ton⁻¹) (Table 5).”
to:
“It is worth noting that the total water footprint of rainfed plantations (417.1 m³ ton⁻¹) was lower than the green water footprint of the irrigated plantations (709.6 m³ ton⁻¹) (Table 5).”
Comment 7
Please correct the sentence “The blue water footprint reached its lowest in 2015” with “The blue water footprint reached its lowest level in 2015”.
Answer: The comment was considered and the text changed from:
“The blue water footprint reached its lowest in 2015, a year with outstanding high precipitation for the study area (Figure 2B, and tables 2 and 4), which diminished the requirement for irrigation water and resulted in a low blue water footprint.”
to:
“The blue water footprint reached its lowest level in 2015, a year with outstanding high precipitation for the study area (Figure 2B, and tables 2 and 4), which diminished the requirement for irrigation water and resulted in a low blue water footprint.”
Comment 8
The first 6 lines of paragraph 4.3 show numerous errors in grammar, spelling and punctuation.
Answer: The comment was considered and the text was modified. Highlighted sections indicate modifications.
“4.3. Blue water footprint, water availability, and scarcity
Our analysis indicate that for the years 2013, 2016 and 2017, avocado production concentrated all the concessioned water resources for agricultural production (Table 6). Further, considering the 2017 as example year due to the highest water footprint estimated (Table 6) and taking in account Mexico’s agroindustrial official production data [15]. In 2017 there were 886 hectares of 15 different crops other than avocado under the irrigation modality in the studied municipaity. These produced 25,120 tons of agricultural products including; sugar cane (17,480 tons in 190 hectares), blackberry (2,322 tons in 135 hectares), guava (1,552 tons in 160 hectares), and nopales (fresh edible cactus blades; 1,200 tons in 40 hectares) among others. How were all these crop produced if avocado crop used 120 % of all concessioned water for agriculture?
Well, we consider that the figures reported in this communication (Table 5 and Table 6) are indicative of the existence of a non registered apropriation of water for agriculture use, that may affect water access to other existing uses, such as aquaculture, industrial, livestock, and urban use. Although which uses and how much water are these uses water-depleted is unclear at the moment, and out of reach of the present communication. It is clear that this situation may lead to severe conflicts between different water users in the municipality and may generate social discomfort and protests.”
to:
“4.3. Blue water footprint, water availability, and scarcity
Our analysis indicates that for the years 2013, 2016, and 2017, avocado production concentrated all the concessioned water resources for agricultural production (Table 6). Further, considering 2017 as an example year due to the highest water footprint estimated (Table 6) and taking into account Mexico’s agroindustrial official production data [15]. In 2017 there were 886 hectares of 15 different crops other than avocado under the irrigation modality in the studied municipality. These produced 25,120 tons of agricultural products including; sugar cane (17,480 tons in 190 hectares), blackberry (2,322 tons in 135 hectares), guava (1,552 tons in 160 hectares), and nopales (fresh edible cactus blades; 1,200 tons in 40 hectares) among others. How were all these crops produced if the avocado crop used 120 % of all concessioned water for agriculture?
Well, we consider that the figures reported in this communication (Table 5 and Table 6) are indicative of the existence of a nonregistered appropriation of water for agricultural use, that may affect water access to other existing uses, such as aquaculture, industrial, livestock, and urban use. Although which uses and how much water loose these uses is unclear at the moment, and out of reach of the present communication. It is clear that this situation may lead to severe conflicts between different water users in the municipality and may generate social discomfort and protests.”
Comment 9
The first 2 lines of paragraph 4.4 lack a main clause.
Answer: The comment was considered and the text was modified from:
“4.4. Concluding remarks
Even though there are two different production modalities registered within the Mexican government's official databases [15]; rainfed and irrigation plantations. It is of our knowledge that irrigation also takes place in a considerable proportion of rainfed plantations. According to the SIAP databases, a plantation is registered as irrigated when piping and water conduction infrastructure are present. Unless this infrastructure exists, the plantation is registered as rainfed. However, key informants such as farmers, plantation, and production managers, often mention the use of the support or auxiliary irrigation in rainfed plantations, this consists in pouring water directly into the root zone of the trees. This is necessary, especially during the dry and hot season in the spring months (March to May). Support irrigation may take place without piping systems using tractors and mobile water tanks where each tree may receive up to 400 L of water per week. This practice usually takes place between February and the beginning of the rainy season (June). According to the informants, if water deficit is present during flowering, fruit set or fruit development and support irrigation are not provided, a considerable number of flowers and fruit could be aborted and fruit size will be smaller than under well-irrigated conditions, this is consistent with the early findings of Richards et al [62, 63] and Lahav et al [64], as well as later research [46, 65]. So, access to water by avocado trees during flowering, fruit set, and fruit development are critical to ensure fruit production and fruit yield [46, 64]. This is relevant for the water footprint estimation in this contribution. We do not include water poured as support or auxiliary irrigation in rainfed plantations, as part of the water footprint analysis, because even though it is a common crop management practice, not all the rainfed plantations are managed in this way. Besides estimation of blue water supplied as support irrigation, would need additional further fieldwork and is out of the reach of this contribution and may be part of further research initiatives. We, therefore, consider that our water footprint estimates for rainfed plantations may be conservative and perhaps somehow underestimated, although further assumptions could be made in this matter we consider our approach a sound, reliable and reproducible exercise performed with the available data.
Regarding the appropriation of concessioned water for agricultural use by agroindustrial avocado production, the information presented herewith exposes the existence of conflicts in water access and water use by different users. The overdrafting in water appropriation may lead to social distress and socio-environmental conflicts due to water scarcity and water unavailability for certain users and productive activities. Earlier research had shown that water rights assignment and unlawful appropriation of water resources related to the dominant existing agroindustrial avocado production model, generates social conflicts [19,20]. In this perspective social protests triggered by the inaccessibility of water resources, associated with the appropriation of water for crops of high economic value, such as avocados and berries, have recently begun to burst in other municipalities within the Avocado Belt of Michoacan [66,67] but have not been registered yet in the studied municipality.”
to:
“According to the Mexican government's official databases [15], two production modalities are registered; rainfed and irrigation plantations. A plantation is registered as irrigated when piping and water conduction infrastructure are present. Unless this infrastructure exists, the plantation is registered as rainfed. However, key informants such as farmers, plantation, and production managers, often mention the use of support or auxiliary irrigation in rainfed plantations, this consists in pouring water directly into the root zone of the trees. This is necessary, especially during the dry and hot season in the spring months (March to May). Support irrigation may take place without piping systems using tractors and mobile water tanks where each tree may receive up to 400 L of water per week. This practice usually takes place between February and the beginning of the rainy season (June). According to the informants, if water deficit is present during flowering, fruit set or fruit development and support irrigation are not provided, a considerable number of flowers and fruit could be aborted and fruit size will be smaller than under well-irrigated conditions, this is consistent with the early findings of Richards et al [62, 63] and Lahav et al [64], as well as later research [46, 65]. So, access to water by avocado trees during flowering, fruit set, and fruit development are critical to ensure fruit production and fruit yield [46, 64]. This is relevant for the water footprint estimation in this contribution. We do not include water poured as support or auxiliary irrigation in rainfed plantations, as part of the water footprint analysis, because even though it is a common crop management practice, not all rainfed plantations are managed in this way. Besides estimation of blue water supplied as support irrigation, would need additional further fieldwork and is out of the reach of this contribution and may be part of further research initiatives. We, therefore, consider that our water footprint estimates for rainfed plantations may be conservative and perhaps somehow underestimated, although further assumptions could be made in this matter we consider our approach a sound, reliable and reproducible exercise performed with the available data.
Regarding the appropriation of concessioned water for agricultural use by agroindustrial avocado production, the information presented herewith exposes the existence of conflicts in water access and water use by different users. The excessive appropriation of water may lead to social distress and socio-environmental conflicts due to water scarcity and water unavailability for certain users and productive activities. Earlier research had shown that water rights assignment and unlawful appropriation of water resources related to the dominant existing agroindustrial avocado production model, generate social conflicts [19,20]. In this perspective social protests triggered by the inaccessibility of water resources, associated with the appropriation of water for crops of high economic value, such as avocados and berries, have recently begun to burst in other municipalities within the Avocado Belt of Michoacan [66,67] but have not been registered yet in the studied municipality.”
The subsection 4.4 Concluding remars was removed from the manuscript.
Comment 10
At the beginning of pag. 15, please correct the sentence “ Besides estimation of blue water supplied as support irrigation, would need additional further fieldwork and is out of the reach of this contribution and may be part of further research initiatives. We, therefore, consider that our water footprint estimates for rainfed plantations may be conservative and perhaps somehow underestimated, although further assumptions could be made in this matter we consider our approach a sound”
with
“Besides, estimation of blue water supplied as support irrigation would need additional further fieldwork and is out of the reach of this contribution and may be part of further research initiatives. We, therefore, consider that our water footprint estimates for rainfed plantations may be conservative and perhaps somehow underestimated. Although further assumptions could be made in this matter, we consider our approach a sound...”.
Answer: The comment was taken into account and the text was modified from:
“Besides estimation of blue water supplied as support irrigation, would need additional further fieldwork and is out of the reach of this contribution and may be part of further research initiatives. We, therefore, consider that our water footprint estimates for rainfed plantations may be conservative and perhaps somehow underestimated, although further assumptions could be made in this matter we consider our approach a sound, reliable and reproducible exercise performed with the available data.”
to:
“Besides, estimation of blue water supplied as support irrigation would need additional further fieldwork and is out of the reach of this contribution and may be part of further research initiatives. We, therefore, consider that our water footprint estimates for rainfed plantations may be conservative and perhaps somehow underestimated. Although further assumptions could be made in this matter, we consider our approach a sound...”
Comment 11
In the Conclusions, please correct the sentence “Green water has a lower opportunity cost than blue water, however, the relation between yield in rainfed and irrigated plantations indicates that a marginal increase is achieved under irrigated production”.
Answer: The comment was considered along with comments of the other reviewers for the same section, therefore the whole paragraph was rewritten and manuscript text was modified from:
“The results of this study indicate that the mean WF of agro-industrial production of avocado in Uruapan municipality, between 2012 and 2017 was estimated at 152.0 Mill.m³ year⁻¹. The overall mean WF considering rainfed and irrigation plantations was 744.3 m³ ton⁻¹, below the reported world average water footprint of 1,086 m³ ton⁻¹ for this fruit crop [Mekonnen & Hoekstra, 2011]. Irrigated agro-industrial avocado production comprising green and blue water footprints were 790.6 m³ ton⁻¹, and 280.8 m³ ton⁻¹ respectively, with an overall mean of 1,071.4 m³ ton⁻¹, similar to the reported global mean footprint, while mean yield was 10.26 ton ha⁻¹ year⁻¹. The WF of rainfed avocado production was 417.1 m³ ton⁻¹, with a mean yield of 9.88-ton ha⁻¹ year⁻¹. Green water has a lower opportunity cost than blue water, however, the relation between yield in rainfed and irrigated plantations indicate that a marginal increase is achieved under irrigated production with a WF about 2.5 times higher than rainfed production.”
to:
“The results of this study indicate that the mean WF of agro-industrial production of avocado in Uruapan municipality, between 2012 and 2017 was estimated at 152.0 Mm³ year⁻¹. The overall mean WF considering rainfed and irrigation plantations were, below the reported world average water footprint for this fruit crop [27]. At the same time, green water has a lower opportunity cost than blue water. However, the relationship between yield in rainfed and irrigated plantations indicates that a marginal increase (~ 3%) is achieved under irrigated production with a WF about 2.5 times higher in irrigated than rainfed production.”
Author Response File: Author Response.pdf
Reviewer 3 Report
1. The last paragraph under chapter one is basically supposed to be part of the materials and methods under chapter 2.
2. There is need to clearly show that the green water footprint measures the part of the evaporated rainwater that has been appropriated by human beings and is therefore not available for nature.
3. Further, its good to emphasizes that the water footprint expresses the cost of a crop in terms of its total water use.
4. Need to explain, why there was no attempt by the authors to further classify the water footprint into more specific components. For instance, blue water footprint could further be distinguished between surface water, renewable groundwater and fossil groundwater.
5. Other than the method used to calculate the water footprints/water footprint accounting, are there other methods? If so, the authors should present a critique of the other methods and clearly justify the selection of the method used.
6. Information under Concluding remarks especially on the procedure used is not captured under materials and methods.
7. Include discussions on sustainability based on water footprint calculated and balanced with irrigation.
Author Response
Comment 1
The last paragraph under chapter one is basically supposed to be part of the materials and methods under chapter 2.
Answer: We agree with the comment. The last paragraph in the introduction section of the manuscript was aimed to prepare the reader and give a “heads up” of what can be expected in the reading of the paper giving the most relevant information, we agree with the reviewer and consider that most of the information provided herwith is given later in the next section (2. Material and methods). Therefore the text was modified from:
“In this contribution, we analyzed information of an iconic and representative municipality within the Avocado Belt of Michoacan, Uruapan. This municipality produces nearly 6.5 % of Mexico's annual, 2.4 million tons. We followed the water footprint approach of Hoekstra et al. [7] and estimated direct green and blue water consumption by means of crop water requirement using the CROPWAT v 8.0 software [30], we used daily weather records acquired between 2010 and 2018 from the automated weather stations network of APEAM (Mexico’s Avocado Producer Packing and Exporting Organization) [16], and also soil characteristics information derived from direct field observations and previously acquired and analyzed soil samples. We considered crop characteristics information from previous in situ measurements at selected avocado plantations throughout the target municipality. Finally, we addressed the blue water agricultural water stress index for our study case by comparing the blue WF and the available water for agricultural use through water rights concessions.”
to:
“In this contribution, we analyzed information of an iconic and representative municipality within the Avocado Belt of Michoacan, Uruapan. This municipality produces nearly 6.5 % of Mexico's annual, 2.4 million tons. Evaluate the water green and blue footprints and addressed the water stress index, comparing the blue WF and the available water for agricultural use through water rights concessions.”
Comment 2
There is need to clearly show that the green water footprint measures the part of the evaporated rainwater that has been appropriated by human beings and is therefore not available for nature.
Answer: According to the comment in section 4.1, where “Crop production” and “Crop water requirements”, an additional paragraph addressing the appropriation of the green water foot print by humans was included. Therefore the manuscript text was modified from:
“Our results and the ratio between water footprint of rainfed and irrigated plantation is nearly 2.6 while yield increases only 3.8 %. This means that irrigated plantations use more than twice the water of the rainfed plantations but the increase in yield is under 5 %. We therefore state that an urgent need for water efficiency strategies and actual crop yield improvement is urgent throughout the study area.”
to:
“Our results and the ratio between water footprint of rainfed and irrigated plantation is nearly 2.6 while yield increases only 3.8 %. This means that irrigated plantations use more than twice the water of the rainfed plantations but the increase in yield is under 5 %. We, therefore, state that an urgent need for water efficiency strategies and actual crop yield improvement is urgent throughout the study area. Besides, the estimation of the green water footprint of the avocado crop in Uruapan showed a lower water consumption in the rainfed plantations than in the irrigated ones. It is important to address that a considerable proportion of the green water flux is stored in the soil and became productive for humans through plant assimilation and fruit biomass production. This water was therefore not available as runoff in the ecosystem. This condition turns green water flux into a scarce resource, since the appropriation and use of green water for a specific purpose may turn it unavailable for other purposes (Schyns et al., 2015). Consequently, the appropriation of green water by avocado cultivation could represent a threat to ecosystems, especially those depending on surface runoff.”
References
Schyns, J. F; Hoekstra, A. Y; Booij, M. J. Review and classification of indicators of green water availability and scarcity. Hydrology and Earth System Sciences 2015, 19(11), 4581–4608. doi:10.5194/hess-19-4581-2015
Comment 3
Further, its good to emphasizes that the water footprint expresses the cost of a crop in terms of its total water use.
Answer: The economic value of agricultural production for each cubic meter of water used, allows the evaluation of the economic efficiency of the water consumed. Nevertheless, in the present comunication we did not evaluate it, since this evaluation requires to account the apparent productivity of the water, understanding that this is the value of production at current prices per unit of water consumed (Salmoral et al., 2012). In this sense, it was not possible to take into account the reviwer's comment. Since such evaluation would be out of reach of the present study. However, it is important to mention that this is a research line worth to continue because the economic and environmental analysis of avocado cultivation needs to include specific economic parameters in order to achieve a more efficient water management that allows the production of avocado but using less water (Rodríguez et al., 2008).
Referencia
Ferrero, N., Martinez, M. T., & Martos, J. (2008). Un analisis de la eficiencia socioeconomico del agua en el regadio andaluz (No. 1102-2016-90793, pp. 183-208).
Salmoral, G., Dumont, A., Aldaya, M. M., Rodríguez-Casado, R., Garrido, A., & Llamas, M. R. (2012). Análisis de la huella hídrica extendida de la cuenca del Guadalquivir. Fundación Marcelino Botín.
Comment 4
Need to explain, why there was no attempt by the authors to further classify the water footprint into more specific components. For instance, blue water footprint could further be distinguished between surface water, renewable groundwater and fossil groundwater.
Answer: The reason why no further attempt to estimate the water footprint in different categories, especially the blue one was made. Was because the CROPWAT model was used to estimate the water requirement, and it considers only two different water sources; rainfall and irrigation. However, in the irrigation, the CROPWAT model does not distinguish between surface or groundwater sources (Smith, 1992). In order to distinguish between different blue water sources, as suggested by the reviwer, a specific fieldwork campaing should be conducted in order to register water sources used by producers according to the classification proposed by the reviwer (between surface water, renewable groundwater and fossil groundwater). A review of the available data of water sources, from the study region does not include renewal rate of the aquifers in order to address if water is renewable groundwater or fossil groundwater (REDPA, 2022).
References
REDPA (Registro Público de Derechos de Agua). Database of the Public Registers of Water Rights, National Water Commision (México), Uruapan Municipality. 2022. Accessed April 30, 2022. Database available at: https://app.conagua.gob.mx/consultarepda.aspx
Smith, M. CROPWAT: a computer program for irrigation planning management (No. 46). Food and Agriculture Organization of the United Nations (FAO), 1992. Available online: https://books.google.it/books?id=p9tB2ht47NAC&pg=PP1&source=kp_read_button&redir_esc=y#v=onepage&q&f=false
Comment 5
Other than the method used to calculate the water footprints/water footprint accounting, are there other methods? If so, the authors should present a critique of the other methods and clearly justify the selection of the method used.
Answer:
According to the comment about the existence of other methods to quantify the water footprint, the answer is that it is not the only tool developed to estimate water consumption in an agricultural crops. In this sense, in the introduction section of the manuscript, we decided to include additional information. Therefore, the manuscript text was modified from:
“In water-stressed regions, identifying and recognizing the spatial and temporal dimensions of water withdrawals and consumption is key to provide effective and sound water resources management guidelines. In this context, the water footprint and water scarcity concepts had proven to be useful tools. The first, introduced by Hoekstra et al. [7] is an integrated sustainability indicator in agriculture and food production [5] which recently has been applied to other types of goods, e.g. clothing [6]. This concept is aimed to contribute toward the adequate, efficient management and use of freshwater resources, and refers to the volume of freshwater required to produce a specific product [7]. Three water footprint categories are established: green, blue, and gray. The green water footprint is defined as the volume of rainwater that does not become run-off and is consumed in the production process. The blue corresponds to the volume of surface or groundwater that is used in the production process, while the gray water footprint is defined as the volume of freshwater required to reduce the pollutants to ambient levels [7-5].”
to:
“In water-stressed regions, identifying and recognizing the spatial and temporal dimensions of water withdrawals and consumption is key to provide effective and sound water resources management guidelines. In this context, the water footprint and water scarcity concepts had proven to be useful tools. In this context, there are other tools that reveal both, water consumption and scarcity. In this sense we can mention the following; the water footprint method, the water footprint according to the ISO: 14046 standard and the agronomic productivity of water (WP). The first, introduced by Hoekstra et al. [7] is an integrated sustainability indicator in agriculture and food production [5] which recently has been applied to other types of goods, e.g. clothing [6]. This concept is aimed to contribute toward the adequate, efficient management and use of freshwater resources, and refers to the volume of freshwater required to produce a specific product [7]. Three water footprint categories are established: green, blue, and gray. The green water footprint is defined as the volume of rainwater that does not become run-off and is consumed in the production process. The blue corresponds to the volume of surface or groundwater that is used in the production process, while the gray water footprint is defined as the volume of freshwater required to reduce the pollutants to ambient levels [7-5]. The second method according to Agualimpia (2017) was approved in 2014, and it is based on the approach of the Life Cycle Analysis of a product, then, it serves as a tool to evaluate the use, transformation, consumption and destination of natural resources, including water. The water footprint standard ISO: 14046 standard identifies the impacts generated in the environment (Ramírez, 2014). Finally, the agronomic productivity of water, defined as the relationship between production and the water used or consumed. Allows the definition of the physiological and agronomic mechanisms that govern the relationships between the input and output of crop water (Rodés , 2013). Although the aforementioned methods are all adequate to measure the water consumption associated with a specific agricultural crop, we decided to use the water footprint approach in the present study, because this sustainability indicator has the advantage of allowing the estimation of the volume of water used in relation to the water resources available at a specific time and place (Le Roux et al., 2017).”
References
Agualimpia, O. N. G., Andina, P. S. (2016). Manual de aplicación de evaluación de huella hídrica acorde a la norma ISO 14046.
Rodés, R. R., Robaina, F. G., Puebla, J. H. (2013). Eficiencia en el uso del agua de riego en el cultivo de la papa (solanum tuberosum L.) en el occidente de Cuba. Revista Ingeniería Agrícola, 3(3), 3-7.
Ramírez, A. A., Carmona, L. G., Romero, S. A. (2014). Análisis de ciclo de vida en el sector agrícola: el caso del municipio de Viotá, Cundinamarca (Colombia). Ambiente y Desarrollo, 18(35), 117-133.
Le Roux, B., van Der Laan, M., Vahrmeijer, T., Bristow, K. L., Annandale, J. G. (2017). Establishing and testing a catchment water footprint framework to inform sustainable irrigation water use for an aquifer under stress. Science of The Total Environment, 599-600, 1119–1129. doi:10.1016/j.scitotenv.2017.04
Comment 6
Information under Concluding remarks especially on the procedure used is not captured under materials and methods.
Answer: We agree partially with the comment
We removed the 4.4 Concluding remarks, section header in order to provide fluency to the text.
A substantial part of the material and methods section was modified in order to provide ke information in forrehand which is used later in the discussion.
The last paragraph material and methods section (2.3.2. Crop and soil parameters) was modified from:
“We also considered fruit development duration of 9.6 months (290 days) and assumed that standard conditions occurred during the whole crop cycle. These included: the crop is under optimum soil water conditions, it is well-fertilized, grown in large fields, disease-free, and achieving full production under the given climatic conditions.”
to:
“We also considered fruit development duration of 9.6 months (290 days) and assumed that standard conditions occurred during the whole crop cycle. These included: the crop is under optimum soil water conditions, it is well-fertilized, grown in large fields, disease-free, and achieving full production under the given climatic conditions.
It is known to us that even in the absence of irrigation infrastructure in the plantations, trees can receive auxiliary irrigation during flowering, fruit set and later fruit development in order to avoid the loss of flowers and fruits due to water stress. However the quantification of such input is out of the reach of the present communication since it implies knowing the exact amount of water poured in each plantation. The spatial scale considered, and the available data sets does not allow this level of analysis.”
Comment 7
Include discussions on sustainability based on water footprint calculated and balanced with irrigation.
Answer: We agree with the comment and modified the discussion according to the reviewer recomendations. Therefore the manuscript text was modified from:
“4.2. Avocado Water Footprint
First, it is important to note that our results on the total water footprint of avocado production were much lower under rainfed conditions (417.1 m³ ton⁻¹) than under irrigation conditions (1,071.4 m³ ton⁻¹) (Tables 5 and 7).”
to:
“The WF as an indicator of sustainability refers to the maintenance of water resources by human activities (Rivera-Hernández, 2017). In this sense, it is essential to understand the way in which natural resources are used in the system and thereby conceive that ecosystems are not only a source of resources for human activity, but also fulfill various ecosystem functions (Foladori, 2001). Due to the increase in water consumption, there is a growing scarcity of water resources in several regions of the world (Hoekstra et al., 2012). Accounting the WF is substantial, besides, increase blue water efficiency and reduce blue water scarcity according to the SDGs is one of the major goals an one of the main international concern.
In this context, our results on the total water footprint of avocado production were much lower under rainfed conditions (417.1 m³ ton⁻¹) than under irrigation conditions (1,071.4 m³ ton⁻¹) (Tables 5 and 7). This situation of increased consumption of blue water occurs in many places worldwide, where irrigation water is used to compensate for soil moisture, causing pressure on the blue water resources. Nevertheless, according to Mekonnen (2020), the great challenge nowadays is to transit towards more sustainable production models in order to reduce negative social, ecological and economic impacts.”
Referencies:
Foladori, G. (2001). Ch.7. La economía ecológica. In Sustentabilidad Desacuerdos sobre el desarrollo sustentable. Guillermo Foladori G. & Pierri, N. Eds. 189-195. México: Miguel Ángel Porrúa. ISBN 970-701-610-8, available online at: http://visitas.reduaz.mx/coleccion_desarrollo_migracion/sustentabilidad/Sustentabilidad10.pdf
Mekonnen, M. M., & Hoekstra, A. Y. (2020). Sustainability of the blue water footprint of crops. Advances in Water Resources, 103679. doi:10.1016/j.advwatres.2020.10
Rivera-Hernández J. E., Blanco-Orozco N. V., Alcántara-Salinas G., Houbron E. P., & Pérez-Sato J. A. (2017). ¿Desarrollo sostenible o sustentable? La controversia de un concepto. Posgrado Y Sociedad Revista Electrónica Del Sistema De Estudios De Posgrado, 15(1), 57-67. https://doi.org/10.22458/rpys.v15i1.1825
Author Response File: Author Response.pdf
