The Evolution of Sustainable Rice Production along the Lower Mississippi River (USA) with the Increasing Spector of Climate Change

Abstract

It is incumbent to assess the status of U.S. rice production and its agronomic practices and then predict if the status is sustainable with climate change. Climate change expectations include a strong likelihood of higher temperatures and some uncertainty in precipitation. Technological solutions appear to be revolving around (i) rice breeding to improve cultivar heat tolerance, especially for high nighttime temperatures, and (ii) altering irrigation regimes to conserve groundwater. Of concern are the potential of protracted droughts in the Sacramento Valley of California, salinization along the gulf coast and aquifer depletion across portions of the mid-South. The objectives of this manuscript include: (i) evaluate existing US Mid-South rice irrigation strategies, (ii) assess the yield potential and seed quality of emerging water-conserving irrigation regimes, (iii) assess the influence of rice irrigation regimes on aquifer overdraft, and (iv) assess the influence of increased temperatures on rice growth and development. Alternate wetting and drying irrigation and furrow irrigation are attractive irrigation regimes to reduce aquifer depletion. Yield trials show mixed results, with yield differences associated with soil type, timing and frequency of irrigations, nitrogen fertilization, and variety selection. Producer acceptance of furrow irrigation is rapidly developing, even in rice producing regions that have not experienced aquifer overdraft.

1. Introduction

Four regions in the United States support rice (Oryza sativa L) production: (i) Arkansas Grand Prairie, (ii) the Mississippi Delta along the lower Mississippi River, (iii) the eastern Texas and southwest Louisiana Gulf Coast, and (iv) the Sacramento Valley in California. Each of these regions specializes in rice production using unique production methods and specific rice types. Rice types are referred to by the ratio of grain length to grain width as long grain, medium grain, and short grain rice. California produces primarily medium grain rice and constitutes approximately 20% of the US rice harvest. The lower Mississippi River valley and the Gulf Coast producing areas primarily produce long-grain rice, with some new interest in medium grain rice. Short grain rice is a minor entity.

The Mid-South rice producing region is located along the Mississippi River in Missouri, Arkansas, Mississippi, and Louisiana. The state of Arkansas typically grows most of the U.S. long-grain crop; however, increasing quantities of medium-grain rice are currently cultured. All U.S. rice is produced in irrigated fields that are experiencing increasing instances of spikelet sterility because of high nighttime temperatures, delayed planting because of changing rainfall patterns, aquifer depletion, and surface water scarcity, all of which results in altered plant physiology, nutrient uptake, and net photosynthesis.

In this manuscript, the mid-South region along the Mississippi River will be emphasized. The objectives of this manuscript include: (i) evaluate existing US Mid-South rice irrigation strategies (delayed flood), (ii) assess the yield potential and seed quality of emerging water-conserving irrigation regimes compared to traditional rice production systems, (iii) assess the ability of alternate wetting and drying irrigation and furrow irrigation on limiting aquifer overdraft, and (iv) assess the influence of increased temperatures on rice growth and development.

2. Rice production in the Mid-South USA

Most of the rice production in Mississippi, Arkansas and Missouri is in the lower Mississippi River embayment and presents itself as a fluvial landscape. Texas and Louisiana’s rice production is mainly located on the coastal plain and smaller coastal floodplains. The east-central Arkansas Grand Prairie Region is also a major rice producing region. From a global perspective, rice production in the U.S. is not a dominant crop; however, rice production does contribute to the global export capacity. U.S. rice production centers around 1.1 million ha with an average recent annual yield near 8300 kg ha⁻¹ (Table 1). Prior to milling, annual Mid-South rice production is approximately 7251 million kg. Rice production fluctuates over time, a feature attributed to market considerations (Table 2).

State	Production (million cwt)	Yield (kg ha^−1)	Value (million $)
Arkansas	80.3	8305	1373
Louisiana	27.5	7398	473
California	22.3	9819	752
Texas	12.1	7297	207
Missouri	11.8	8900	192
Mississippi	6.2	8261	105

Table 1.

Leading rice producing U.S. States in 2022.

Source: Data from https://www.nass.usda.gov (USDA National Agricultural Statistics Service) [1]; CWT is centum weight or 100 lb. or 50.8 kg.

Type	2022	2021	2000	2019	2018
Long grain	128.2	144.5	170.8	125.6	163.6
Short grain	30.0	44.3	53.9	57.1	57.3

Table 2.

U.S. rice production over time for long/medium grain (million cwt).

Source: Data from https://www.nass.usda.gov (USDA National Agricultural Statistics Service) [1].

The temperature and rainfall observations are for Memphis, TN., given that this city is relatively equidistant from the northern and southern reaches of the Mid-South rice belt. The mean maximum temperature occurs in mid-July and averages 28°C (82°F) (Figure 1). The mean annual temperature is 17.5°C (63°F). The mean maximum precipitation occurs in April and averages 15 cm (6 inches). The driest month is September with 7.5 cm (3 inches). The mean annual total rainfall is near 140 cm (55 inches) (Figure 2). Considerable variation may occur, frequently attributed to tropical cyclones [2].

Figure 1.

The average, minimum and maximum temperature by month at Memphis TN. Source: Data from National Weather Service [2] at https://www.weather.gov/media/meg/August2017ClimateSummary.pdf.

Figure 2.

The mean rainfall amounts by month at Memphis TN. Source: Data from National Weather Service [2] at https://www.weather.gov/media/meg/August2017ClimateSummary.pdf.

3. Typical rice growing practices in the Mid-South USA

Abundant radiant energy (17–28 MJ m⁻² for July clear skies), land-graded soils that limit water percolation, plentiful groundwater for irrigation permit profitable rice production. Mid-South rice production is characterized as drill-seeded and delayed flood with ponding initiated at the 4th or 5th leaf stage. During dry periods, fields are “flushed” with a temporary and shallow flood to promote seed germination and herbicide activation.

Two common nitrogen fertilization programs include: (i) a two-way or three-way split with approximately 65–75% of the total nitrogen applied at flood, with the remainder applied in one or two airplane applications starting at internode elongation, or (ii) all nitrogen applied preflood. Recently furrow irrigated rice producers have been experimenting with additional nitrogen applications prior to internode elongation [3]. Urea (46-0-0) and ammonium sulfate (21-0-0) 24% S are commonly used nitrogen fertilizers. Rice-soybean (Glycine max (L.) Merr.) and continuous rice are common rotations. In Louisiana and Texas, producers frequently employ a ratoon rice crop, given their longer growing season. Field draining and soil drying provides for mechanical harvest. On-farm rice storage is a common practice.

Recently, rice producers have adopted furrow irrigation on graded-land [3]. In furrow irrigated rice, groundwater is conveyed in flexible plastic tubing and applied as side inlet water. Producer advantages of furrow irrigation include: (i) water conservation, (ii) reduced levee construction, (iii) lower production costs, and (iv) smaller arsenic concentration in rice. Current producer disadvantages of furrow irrigation include: (i) greater emphasis on weed management, (ii) nitrogen losses attributed to nitrification-denitrification, (iii) lack of crop insurance, (iv) less predictable yield potential, (v) need for disease resistance in plant materials, and (vi) producer education [4].

4. Defining greenhouse gases, global warming potential and carbon dioxide equivalent

Greenhouse gases are trace atmospheric gases that absorb outgoing long wavelength electromagnetic radiation, thus increasing the atmospheric temperature. Water vapor is a greenhouse gas; however, water vapor is treated separately from other greenhouse gases. Global warming potential is an estimate of the energy absorbed from a unit mass of a specific gas compared to carbon dioxide’s energy absorption. Generally, the amount of energy absorbed is estimated for a 100-year time frame. Global warming potential values for methane vary from 25 to 36, with an atmosphere residence of 10 years [5, 6, 7]. Nitrous oxide has global warming potential values ranging from 265 to 298, with an atmosphere residence time of more than 100 years. Carbon dioxide accounts for approximately 75% of the global greenhouse gas emissions, an attribute primarily associated with fossil fuel combustion, deforestation, and biomass decomposition. Carbon dioxide concentrations during the Industrial Revolution were approximately 280 ppm, current CO₂ concentrations are greater than 395 ppm CO₂ [7].

5. Influence of temperature increases on rice growth and development

The specter of increasing temperature associated with climate change may impact rice production [8]. The prevalent modern view is that high temperature-induced spikelet sterility is a serious concern. Many studies have focused on high nighttime temperatures as more critical than high daytime temperatures. In a review, Wichelns [9] predicted that increased minimum and maximum daily temperatures and changes in the timing, intensity, and duration of rainfall will occur and increased temperatures may intensify the likelihood of spikelet sterility. High temperature impacts on pollen viability and spikelet sterility are more prominent in indica cultivars than japonica cultivars [6]. Ali et al. [10] noted that rice plants are particularly sensitive to high temperature stress during microspore and megaspore formation and that increased spikelet sterility will reduce yield. Rice yield losses because of applied heat stress were greatest from panicle exertion to anthesis; however, there were significant genotype and heat stress interaction differences. Thus, rice breeding efforts to provide heat tolerant cultivars is warranted.

6. Influence of irrigation on rice yield and quality

Ye et al. [11] asserted that long-duration varieties better tolerated the impact of climate change. In California. Lui et al. [12] completed a soil fertility study involving nitrogen, phosphorus, potassium, and silicon with contrasting high daytime temperatures. High day time temperatures decreased grain yield and decreased the transference of nitrogen, phosphorus, and potassium to panicles. Under conditions of high day time temperatures, silicon fertilization improved grain yield and the nitrogen, phosphorus, and potassium translocation to panicles.

Climate change may support CO₂ enrichment and yield advancement; however, grain quality may be negatively affected. In Arkansas, Esquerra et al. [13] tested rice varieties at (i) flag leaf collar and (ii) initial elongation of grain on the panicle for two elevated nighttime temperatures. The control temperature was 23°C and a high night-time temperature was 28°C. Spikelet fertility and yield were reduced for some varieties for high nighttime temperatures imposed at flag leaf collar.

Based on a compelling review, Horie [6] reiterated that given an increase in the CO₂ atmosphere content that the literature results include: (i) under optimum nitrogen availability rice biomass increased 24% between 24 and 31°C, (ii) panicle weight reductions at temperatures greater than 29°C were attributed to spikelet sterility, (iii) leaf area index was consistent regardless of temperature and the increased biomass was attributed to enhance photosynthesis, (iv) water use efficiency was improved because of the increase of biomass and photosynthesis, (v) panicle yield increased because of improved tillering, (vi) indica genotypes showed higher yield responses to enhanced atmosphere CO₂ than Japonica genotypes, and (vii) spikelet sterility was attributed to pollination failure.

Arnell et al. [14] investigated global and regional impacts because of increased temperatures arising from increased major heat wave frequencies, hydrological droughts, reduction in crop growth durations, increased river flooding, and others. Xie et al. [15] estimated crop yields and planted acreages along the Lower Mississippi River and inferred that US Mid-South rice yields would slightly decrease; however, planted acreages were estimated to increase because of land expansion to rice at the expense of corn (Zea mays L).

7. Sustainability of ground water resources

In Missouri, as in other rice producing states, groundwater resources substantially augment rainfall for rice and other row crops. The Mississippi River Valley Alluvial Aquifer in Arkansas, Mississippi, and Missouri is the major ground water resource for rice irrigation. In general, the Mississippi River Valley Alluvial Aquifer is typically an unconfined aquifer in Missouri, whereas the aquifer varies from an unconfined to confined aquifer in Arkansas [16]. Aquifer recharge is by rainfall and base flow from the Mississippi River, other rivers and streams, drainage ditches, and surface water bodies. Critical Ground-Water Areas are aquifers where water declines of 0.3 m (1 ft) occur for a minimum of five consecutive years. The Grand Prairie Region of Arkansas, composed primarily of Jefferson, Arkansas, Lonoke, and Prairie Counties, has been certified as a critical ground-water area, which predisposes producers to more detailed extension services to protect water resources. In Louisiana, excessive groundwater withdrawal from the Coastal Lowland Aquifer system is also a concern.

The Mississippi River Valley Alluvial aquifer is largely composed the sands and gravels (valley train), which are overlain by sandy to clayey alluvium. The confining unit, where present, is typically composed of silty and clayey alluvium in floodplains, backswamp, and meanderbelt sediments. In Missouri the confining unit is approximately 6–9 m (20–30 ft), whereas the confining unit in west-central Mississippi may be greater than 30 m (100 ft) and in the Grand Prairie Region of east-central Arkansas is greater than 18 m (60 ft). The Mississippi River Valley Alluvial aquifer is incised by multiple rivers, including the Mississippi River, White River, Cache River, St. Francois, and St. Charles River. Natural aquifer recharge may occur by (i) rainfall, (ii) upward flow from deeper aquifers, and stream aquifer flow (base flow) [16, 17].

There is growing concern that ground water withdrawal rates exceed recharge rates, leading to declining water tables or deeper equipotential surfaces [18]. Currently in Arkansas significant cones of depression exist in the Grand Prairie region and west of Crowley’s Ridge [18]. In Missouri, Arkansas, and Mississippi the Mississippi River Valley Alluvial aquifer water level data strongly indicates that groundwater utilization is exceeding replenishment rates, indicating the water utilization rates are not sustainable. Water level declines are especially apparent in regions where water utilization rates are correspondingly high, especially in the Grand Prairie and Cache River areas. There is some correlation between the intensity of the groundwater drawdowns and their distance from major water streams and rivers, especially the Mississippi, Arkansas, and White Rivers.

The underlying Mississippi Embayment Aquifer has an extensive areal extent, ranging from Missouri to the coastal lowland aquifers. The hydraulic conductivity is substantial, ranging from 61 to 75 m d⁻¹ (200 to 245 ft. d⁻¹) in eastern Arkansas and northeastern Louisiana to more than 75 m (245 ft. d⁻¹) is southeastern Missouri. The underlying Mississippi Embayment Aquifer is partitioned into the Claiborne and Wilcox aquifers and the deeper McNary-Nacatoch aquifer [16, 17].

The United States Geological Survey (USGS) has established a series of observation wells across the USA [https://www.usgs.gov/mission-areas/water-resources/data-tools] (verified April 2023) [19]. Selecting one observation well from Missouri illustrates regional differences in aquifer overdraft potential (Figure 3). Located in Qulin, Missouri, the observation well shows that the water table drawdowns only exist during the irrigation season, after which the water table levels return to their pre-irrigation levels. Rainfall and base flow return consistently refurbishes the aquifer (Figure 4).

Figure 3.

Depth to water table (meters) from United States geological survey well in Qulin, Missouri. Data from USGS. https://waterdata.usgs.gov/monitoring-location/363551090152801/#parameterCode=72019&period=P7D.

Figure 4.

Mean monthly depth to water table (meters) for Qulin, Missouri. Data from USGS. https://waterdata.usgs.gov/monitoring-location/363551090152801/#parameterCode=72019&period=P7D.

Table 3 provides examples of 16 US Geological Survey monitoring wells from Missouri, Arkansas, and Mississippi. In Missouri, every monitoring well indicates recharge every year, whereas Arkansas demonstrates some wells having consistent annual recharges and other wells exhibiting decades-long declines.

Location	Depth (m)	Range (m)	Aquifer recharge estimate
Steele, MO	3.3	1.5–5.3	Recharge every year
East Prairie, MO	2.4	1.2–3.7	Recharge every year
Cardwell, MO	3.0	0.9–4.3	Recharge every year
Sikeston MO	2.1	1.0–2.7	Recharge every year
Naylor, MO	2.1	1.2–4.3	Recharge every year
Caruthersville, MO	5.8	5.7–6.8	Recharge every year
Jackson Co. AR	—	16.8–22.3	Decline for 32 years
Phillips Co, AR	4.3	1.5–6.0	Recharge every year
Drew Co, AR	—	6.2–10.4	Decline for 60+ year
Jonesboro, AR	—	17–9.2	Decline for 55+ year
Crittenden Co, AR	7.6	7.3–8.2	Recharge every year
Mississippi Co, AR	3.7	1.5–4.3	Recharge every year
Arkansas Co, AR	—	29.3–31.1	Slight decline for 63+ year
Cross Co, AR	—	26.8–26.5	Very slight decline for 19 year
Craighead Co, AR	25.9	24.4–26.8	Recharge every year
Sunflower Co, MS	7.9	3.6–9.4	Slight decline for 12+ year

Table 3.

Examples of Groundwater depths and assessment of aquifer recharge.

Source: United States Geologic Survey [19].

Water level declines in the Mississippi River Valley Alluvial Aquifer are attributed largely to withdrawals for rice (Oryza sativa L.) irrigation [20]. For Arkansas the 2020 estimate of groundwater application in agriculture was 25,380,820 m³ d⁻¹ (5583 Mgal d⁻¹) from the Mississippi River Valley Alluvial aquifer and the deeper Sparta aquifer. The withdraw from the Mississippi River Valley Alluvial aquifer was 23,148,690 m³ d⁻¹ (5092 Mgal d⁻¹). The sustainable yield is estimated as 15,338,508 m³ d⁻¹ (3374 Mgal d⁻¹) [17]. For a considerable time-frame, the Big Sunflower River and lower Yazoo River have drained the alluvial aquifer [17]. Massey et al. [21] noted that the US mid-South region contains four million ha irrigated croplands. When averaged across all years and irrigation methods, irrigation rates were 9200 m³ ha⁻¹ for rice, substantially greater than for corn (Zea mays), soybean (Glycine max), and cotton (Gossypium hirsutum).

8. Climate change prospects for the Mid-South USA and technology-based mitigation strategies

It is likely that the US Mid-South region will witness (i) greater likelihood of inland water flooding because of increasing rainstorm intensities, especially in fall and winter, (ii) drought risk, and (iii) greater frequency of daytime temperatures exceeding 35°C (95°F). These forecasts imply that (i) flood-induced delayed spring plantings may be more frequent, (ii) increased irrigation and greater likelihood of aquifer overdraft, (iii) need for high-temperature tolerant cultivars, (iv) amplified insect, disease and weed pressures imply the creation of improved integrated pest management approaches, and (v) augmented producer-oriented education programs promote emerging technology and farmgate acceptance [22].

Reviewing the literature, Walthall et al. [22] noted that wheat (Triticum aestivum), soybeans (Glycine max) and rice are likely to experience 12–15% yield reductions upon transition from atmospheric CO₂ concentrations from 370 ppm to 550 ppm. Walthall et al. also presented evidence suggesting that temperatures increase of 1–2°C are expected. Aggregate affects of climate change include: (i) soil behavior, (ii) soil erosion, (iii) wind and humidity changes, (iv) insect and disease incidents, (v) weed growth characteristics, and (vi) invasive organisms.

One important and potentially transformational climate change mitigation practice focuses on irrigation water efficiency. The introduction of (i) multiple-inlet irrigation, (ii) tailwater recovery, (iii) surge pumps permit uniform depth of soil water infiltration. Recently alternate wetting-drying and furrow irrigation strategies have the potential to reduce field runoff, employ smaller amounts of water and maintain high rice yields [23].

9. Intermittent flood or alternate wetting and drying

Intermittent flood or alternate wetting and drying was initially developed at the International Rice Research Institute (Philippines), where at a minimum of three weeks after the initial flood the flood is permitted to recede to the point where the soil surface is either wet or dry, then reflooding occurs [24]. Flood should be present at panicle initiation, anthesis, and grain fill. The reflood scenarios are influenced by growth stage, irrigation capacity, and risk tolerance. Advantages of alternate wetting and drying include greater capacity for rainfall capture, reduced methane emission, reduced arsenic accumulation, and potential likelihood of groundwater conservation [24].

Atwill et al. [25] compared conventional flood, multiple side inlet with and without alternating wetting and drying. Multiple side inlet with alternating wetting and drying required 39% water applications and rough rice yield was not significantly different across irrigation regimes. Irrigation water use efficiency was 59% greater for alternate wetting and drying. Where groundwater levels were reasonably deep, the net production returns were more positive because of the reduced costs of water pumping. In southeastern China, Yang et al. [26] compared controlled irrigation and traditional flood irrigation. A decrease of 46% irrigation water usage did not influence rice yield but did improve water use efficiency. In Arkansas, Chlapecka et al. [27] compared furrow irrigation and alternate wetting and drying rice systems, demonstrating that (i) the alternate wetting and drying system favored water conservation and (ii) rice yields were comparable, supporting a greater water use efficiency. In Missouri, multiple years of furrow-irrigation of rice shows promise in maintaining yields; however, substantial issues remain in securing a consistent (i) nitrogen fertilization regime, (ii) weed management program, and (iii) irrigation timing protocol [4, 28, 29]. In a greenhouse project, Lunga et al. [30] documented that the above ground biomass was greatest for the flood system.

The International Rice Research Institute listed potential advantages for alternate wetting and drying [24]. With continuing research, some of the alternate wetting and drying advantages included: (i) potential for cultivars with improved characteristics for aerobic production, (ii) improved ecosystem services, human health, and environmental protection, (iii) improved soil fertility, weed management, and integrated pest management practices, and (iv) reduced soil sodium accumulation because of elevated sodium adsorption ratios.

In India, Shekhar et al. [31] conducted alternate wetting and drying field research involving three levels of soil moisture depletion with sub-treatments involving nitrogen management. Yields for conventional irrigation with alternate wetting and drying imposing only mild stress were statistically equivalent. Alternate wetting and drying imposing severe moisture stress resulted in a 9% rice yield reduction. The nitrogen use efficiency was similar for conventional irrigation and mild stress alternate wetting and drying. Atwill et al. [25] performed field research in Louisiana and Mississippi comparing conventional irrigation and alternate wetting and drying and documented that rice grain yield for six cultivars was statistically equivalent.

Carrijo et al. [32] conducted a meta-analysis to identify soil properties and land management that favored successful alternate wetting and drying and estimate the water conservation potential and differences in rice yield. The conventional flood and mild stress alternate wetting and drying irrigation regimes showed similar rice yields and the mild stress irrigation regimes demonstrated small water usages. Carrijo et al. [33] imposed three alternate wetting and drying irrigation treatments having increasing water severity between full canopy cover and 50% heading. The experimental data suggests that the availability of soil water in the 25–35 cm soil rooting depth was critical for maintaining rice yields.

10. Furrow irrigated rice

In Arkansas, Frizzell et al. [34] compared twelve cultivars in a furrow irrigation trial, where rice yields were evaluated at the side-inlet portion of the field with the bottom portion of the field where tailwater accumulated. Rice yields and headrice yields were greater in the bottom portion of the field, especially for the hybrids. In Arkansas, Henry and Clark [35] evaluated furrow irrigated rice having six different irrigation timings, that is, continuous, 3, 5, 7, 10 and 14 days. The continuous water timing had the highest yield and the poorest water use efficiency, whereas the 14-day irrigation frequency had the lowest yield and the highest water use efficiency. Irrigation having a 40% allowable depletion was considered the threshold for yield penalties.

In a two-year field study in Missouri, Aide and Goldschmidt [4] compared 12 and 17 varieties for their yield and arsenic uptake because of furrow irrigation or delayed flood irrigation. The plots were 450 m long and divided into three sections based on the distance from the side-inlet water application. The tail water accumulation portion of the field and for the delayed flood irrigation exhibited the greatest yields and the highest arsenic levels in straw, rough rice, and milled rice. The plot portion adjacent to the side-inlet irrigation exhibited the lowest yields and the smallest arsenic levels. Similar results were documented for the same experimental design in subsequent years [28, 29].

11. Projections of needed rice research to address climate change and unsustainable water use

With the threat of climate change, the mid-South rice region is anticipating greater temperatures and uncertainty in precipitation. Additionally, the irrigation water application rates is challenging aquifer sustainability. These two issues collectively influence rice production and quality. With nighttime temperatures approaching 29°C (84°F) the likelihood of spikelet sterility becomes an increasing threat to production. Cultivars do show a range of heat stress, thus favorable results of dedicated rice breeding programs are quite possible. Aquifer overdraft is recognized on a regional basis, which reduces the long-term sustainability of rice production. Producer adoption of either furrow irrigated rice or alternate wetting and drying irrigation has substantial potential to reduce aquifer overdraft. Thus, two technological solutions may mitigate the deleterious influence of climate change. Other water conserving solutions include: (i) surface water capture, (ii) tailwater recovery, and (iii) development of constructed wetlands.

12. Conclusion

The specter of climate change is real and the effects on rice production will certainly develop. Conversely, advances in technology may reduce rice yields and impair quality degradation; however, substantial refinement of these technologies must be implemented before there is widespread commercialization. The development of rice plant genetics to improve high temperature tolerant cultivars and the continuing development and producer adoption of water conserving irrigation regimes are critical to mitigating the influence of climate change. Other agronomic concepts are potentially viable; however, they will not be sufficient without improved cultivars and innovative irrigation practices. Furrow irrigation is becoming more accepted and considerable rice acreage is actively using this irrigation regime. Research that supports consistent yields and rice quality will increase producer implementation and subsequently will support aquifer sustainability.

Conflicts of interest

The author declares that there is no conflict of interest.