Northern Arizona University

Energy and Water on Arizona Farms and Ranches

Northern Arizona University ERDENE Program

This web document has been excerpted from the full study.

Executive Summary

This study was conducted to assess water and energy use in Arizona ranching and farming. Three objectives were identified for the project: (1) to identify the magnitude of the opportunity for improving water and energy efficiency and implementing renewable energy in ranching and farming in Arizona; (2) to perform three case studies with ranchers and farmers in Arizona, to identify and analyze the technical, practical and economic feasibility of employing specific water efficiency and energy efficiency measures, as well as utilizing renewable energy resources (primarily solar and wind); and, (3) to define the components of a "toolkit" that ranchers and farmers could use to identify economically feasible water efficiency, energy efficiency, and renewable energy improvements to their operations.

Ranching

Ranching was defined for this study as the raising of livestock. Much of the energy and water that goes into ranching is actually accounted for in the farming section of this study. This energy concentration is in the raising of feed for livestock, such as hay and grains. Ranching, under the definition of this study, is a relatively low energy and water consumer. This study was unable to account for all the energy and water consumed in Arizona ranching since Arizona ranchers purchased $281,141,000 of feed for livestock from outside the state.

Table 1 displays livestock market value and their typical water consumption. While the quantities are significant they are small compared to those of farming (Table 2). Therefore, the focus of this study was upon agriculture.

Table 1 - Market Value and Water of Arizona Ranching

	Number of Head	Market Value - Dollars	Water - Total Gallons	Water - Total Acre Feet
Cattle and Calves	860,000	$722,400,000	14,604,000	44.82
Hogs	127,000	$9,144,000	1,190,000	3.65
Sheep and Lambs	114,000	$13,794,000	1,132,000	3.47
Goats	30,000	$1,950,000	120,000	0.37
Totals	1,131,000	$747,288,000	17,046,000	52.31

Farming

Farming was defined for this study as raising crops including but not limited to produce, cotton, grains flowers and hay. Arizona farming represents the vast majority of energy and water consumed between farming and ranching. Table 2 is a projection of values derived from this study of four Arizona crops (lettuce, wheat, alfalfa and cotton). These four crops were then grouped into their appropriate categories (for example, head lettuce into produce, wheat into grain). After grouping, all crops in their category were assumed to have the same consumable energy and water requirements as the four crops studied in order to acquire an approximation of energy and water consumption in Arizona agriculture. The categories "orchards" and "flowers," having no crops evaluated in this study, had values assigned based upon reasonable engineering assumptions.

Table 2 - Energy and Water in Arizona Farming. Key: P - produce; G - grains; A - alfalfa/hay; C - cotton; O - orchards; F - flowers; T - totals.

	Acres	High Range Btu	Low Range Btu	Water - Acre Feet	Cash Receipts - Dollars
P	136,000	4.47E+12	3.36E+12	464,667	$1,014,627,000
G	246,000	2.56E+12	1.73E+12	799,500	$57,100,000
A	275,000	1.12E+13	1.11E+13	2,169,444	$208,269,000
C	241,000	9.21E+12	7.98E+12	1,225,083	$194,309,000
O	31,950	9.77E+11	8.41E+11	266,250	$55,650,000
F	296	9.05E+09	7.79E+09	1,453	$32,527,000
T	930,246	2.84E+13	2.50E+13	4,926,397	$1,562,482,000

Total Annual Energy		Total Annual Water
High Range	Low Range
2.84E+13 BTU	2.50E+13 BTU	4,926,397 Acre Feet
28,426,050 MMBtu	25,018,790 MMBtu	1,605,273 MMGallons
28.43 TBtu (Tera)	25.02 TGallons (Tera)	1.61 TGallons (Tera)

The energy reflects consumables used in the preparation of fields through harvest. It does not include energy consumed in making fixed goods such as farming equipment nor does it include energy consumed in transporting or processing the crop after harvest. The table does include energy used in consumables such as preparation of the seed, human labor in the field, pumping of water, fuel used in working of the fields through harvest as well as fertilizers and chemicals (herbicides, pesticides, fungicides, defoliants). The volume of water reflects typically consumption in irrigation of the crop.

The unit of energy used in the table is British Thermal Unit (Btu). This is a common energy unit used by American engineers. The "High" and "Low" ranges of energy reflect the discrepancy between experts in the amount of energy required to produce consumables like fertilizer or herbicides.

This study has determined that the annual consumable energy associated with the production of head lettuce is between 1,315 and 986 Btu/lbm (1,667 and 1,250 Btu/head) with water consumption in irrigation (based on the current flood irrigation method) of 56 gallons/head. The water consumption is based on the typical watering practices for the Yuma Valley. Unfortunately, the water required in the production of the inputs (fertilizer, fuel, etc.) could not be found so it was not considered. With lettuce, the single largest annual energy consumer per acre or head is the cost to produce lettuce seed. This is closely followed by the energy cost to produce fertilizer (nitrogen and phosphorus) then the production of herbicides, pesticides and other chemicals such as fungicides.

Fuel associated with the planting, growing and harvesting of the crops is also a significant energy consumer. Water in the Yuma Valley arrives by gravity from the Lower Colorado River thus minimal energy costs are associated with the flood irrigation of the crops. However, if the treaty with Mexico associated with excess salinity of the water in the Lower Colorado River is enforced, the cost of operating the Yuma desalinization unit would significantly increase the cost of irrigation water. The salinity of the Colorado River is elevated due to runoff from irrigation.

Wheat is typically rotated with head lettuce as the hot season crop. Wheat has an annual consumable energy level of between 1,850 and 1,255 Btu/lbm and a water consumption of 189 gallons/lbm.

Alfalfa is typically a three-year crop that is usually rotated out for two years with cotton (total five year cycle). Alfalfa requires between 2,553 and 2,529 Btu/lbm of annual inputs while requiring a typical water consumption of 161 gallons/lbm. Since water in the Phoenix area is pumped there from the Colorado River or is pumped up from subterranean aquifers, the energy associated with the moving of water far outweighs the energies of the other annual consumables. The cost of moving water represents 59% of the average annual energy consumed in the raising of alfalfa.

Cotton requires between 31,097 and 27,011 Btu/lbm of annual consumables and 1,350 gallons of irrigation water per pound of cotton produced. The energy associated with the pumping of irrigation water for cotton represents 59 to 68% of the total annual consumable energy.

In addition to identifying the actual amount of energy and water associated with the production of the primary crops raised in Arizona, the research team has identified numerous areas where significant energy and water savings may occur as well as how those savings may be achieved. Several of these are mentioned below.

STUDIES OF WATER AND ENERGY REDUCTION

The authors have taken the liberty to recommend some areas where additional research or integration of existing systems would help reduce the energy and water consumption of Arizona agriculture.

Ranching

• Study using thinned lumber for residential or commercial fuels. Chipped or palletized wood would provide high heating value fuels that could replace electricity or natural gas for heating while enhancing forest health in a CO2 neutral and renewable form.
• Study extending grazing of cattle to completion in lieu of sending the cattle to a feedlot for finishing. This will save large amounts of water and energy normally used in raising of the feed as well as energy associated with transportation of the cattle and feed to the feedlot. Also reduced are the amounts of antibiotics used to maintain the health of the cattle.
• Evaluate the more frequent placement of wells to increase the production of beef by minimizing the distance they have to travel while optimizing their water consumption. This would facilitate more even grazing. Solar powered wells with minimum evaporative water troughs could be utilized
• Evaluate the planting of drought tolerant trees to provide shade and windbreaks for livestock. Trees may be planted near watering locations so that water waste is absorbed through roots. In lieu of trees, sun shelters could be constructed.

Farming

• Study using alternate rotation crops in lieu of wheat with lettuce. Potential alternate crops include those that could be used for the local production of ethanol fuel. The mash byproduct could be fed locally. Ideally, the crop would be selected to be salt tolerant or even better, to remove salts from the soil.
• On existing sprinkler systems, develop more energy efficient methods of piping water from the pump suction through to the sprinkler heads. This could include a solar powered traveling screen, which would minimize the suction head, eliminate the need for the discharge screen and simplify the pipe configuration thus reducing capital outlay while improving pumping efficiency by minimizing line loss.
• Where electrical pumping is used, program irrigation to occur on non-peak demand schedules and also during times that would maximize the water use efficiency.
• Develop low till, no till planting technologies for lettuce, alfalfa, cotton and their crop rotations utilizing non flood irrigation.
• Improve water application techniques through low energy precision application (LEPA) or drip irrigation to minimize air, canopy, surface and deep-water losses. Develop method to measure then adjust irrigation quantity for specific locations (per plant or plant area). LEPA utilizes lower pressures and volumes that could possibly be propelled by alternate renewable energies.
• Analyze different light spectrums or surface temperatures (moisture content of leaf) to analyze water needs of plants. The light spectrums may also be used to determine the nutrient requirements as well as pesticide and herbicide requirements.
• After the light spectrums analysis technology is developed, water, nutrients, pesticides and or herbicides could be applied with LEPA technology (fertigation or chemigation) on an as needed basis by monitoring plants from the sprinkler. Nutrients, pesticides or herbicides can be injected into the water supply drop lines ahead of the sprinkler heads as the water is applied at required rates. This is different from the existing fertigation and chemigation technology, which injects the fertilizers or chemicals into the main water, feed line. System driven by onboard optics monitoring system, minimizing consumption while optimizing yield.
• Improve planting techniques to minimize mortality of seeds and minimize seed consumption.
• Develop robotic devices to thin and weed fields possibly driven off of solar panels. Optics detect alien plants and extract them using low energy system. Optics also detect undesirable excessive spacing in the field and plants seed to maximize production. This could eliminate the need for herbicides.
• Subsequent to harvest and cooling, lettuce is stored in refrigerated buildings. Significant improvements in energy efficiency could be achieved with simple things such as better barriers at the garage doors, reflective surfaces on the exterior, more insulation and by subdividing the building to minimize area to be cooled.
• Automate harvesting to rapidly extract the lettuce during the core temperature's coolest time of the day. This could be transported in a vehicle that could use evaporative cooling to further drop the temperature. In an energy efficient temperature and humidity-controlled building, the heads could be stripped and packaged while keeping them cool. They would then be cooled and stored for transport.
• Though controversial, even between this study's authors, develop genetically modified (GM) crops that are resistant to fungi and pests, required less water, and are salt tolerant or actually extract salt from the soil.
• Develop a scoreboard for agriculture operators to evaluate their success individually and system wide and be used as a marketing tool showing success.

Conclusion

There is no one silver bullet for reducing energy and water consumption in Arizona farming and ranching. In some instances, for example, reducing water consumption with the implementation of an energy and water efficient sprinkler system, the farmer's energy consumption will actually increase (relative to flood irrigation) as pumps are required to apply the water. If the sprinkler system is integrated with other existing technologies, the farmer's energy costs could be reduced. If energy and water efficient sprinkler systems are available in the Phoenix area, the total energy consumption will be decreased, especially if integrated with other approaches such as fertigation or chemigation. Many of the energy and water issues require an integrated approach for reduction.

If the utilities, which are already struggling to meet increasing power demands with limited water availability, were to promote water and energy efficiencies amongst farmers in Arizona, all would benefit. This "all" extends beyond the utilities and farmers to the general population by minimizing environmental impacts of producing less fertilizer and chemicals as well as emissions from coal fired power plants, the primary source of power for processing the consumables.

This evolution in farming will all start with the academic world working with farmers and businesses to bring these technologies together in a unified, cost effective package. The farmer must then recognize the need to make some initial capital investments in order to reap the long-term benefits of practicing energy and water efficient farming activities.

Biography

Dr. Tom Acker - Associate Professor of Mechanical Engineering, Director of NAU Sustainable Energy Solutions Group, PI on related seed grant.

Dr. Gary Deason - Deputy Director of the Center for Sustainable Environments, Co-PI on related seed grant, over 30 years of related professional experience.

Mr. Mark Glauth - Bachelors of Science Degree in Physical Science, 20 years experience in engineering, surveying, and ranching. Owner and Principle of company R3.

Mr. Ken Shannon - Bachelors and Masters Degree in Mechanical Engineering, registered Professional Engineer, 25 years experience in power engineering and 15 years experience in farming.

Dr. Kurt Nolte - University of Arizona, Area Extension Agent, Agriculture and Natural Resources, Yuma County Office.

 

   

CSE is proud to be in our new home in the Applied Research and Development Building - one of the most efficient buildings in the world!  The ARD building has been granted the US Green Building Council's LEED "Platinum" certification, the highest level attainable.