Water In The There are no easy answers to protecting our surface and underground .

Dr. Raun Lohry and Dennis Zabel

The Fluid Journal • Official Journal of the Fluid Fertilizer Foundation • Summer 2014 • Vol. 22, No. 3, Issue #85 ▼ DOWNLOAD Summary: Complex problems cannot be solved simplistically. Balancing the social, ecological, economic, and agricultural interests in water will be clearly complex. Protecting our surface and underground water sources will require a holistic approach. Solutions will be regionally based but implemented and applied appropriately on a farm scale.

ater is an essentially fixed entity in levels on Devils Lake rose 31.68 feet. with the most common gravity systems Wthe world. No more will be created. Surface areas of the lake increased from being furrow . Subsurface drip Water has, over time and civilizations, 44,230 acres to 211,300 acres. That irrigation systems were used on only a been worshiped, managed, and wasted. is an additional 261 square miles of small portion of the land. It has been responsible for the rise and land covered with water. The volume of 1942 agreement fall of kingdoms and empires. It has water has grown by 7 times in that time Progress has its consequences. It been fought over and generously given period. North Dakota State University would’ve been impossible for anyone as a source of life. As Benjamin Franklin expects the water body to inundate an to predict the impacts of the increase once said, “When the well’s dry, we additional 10,000 acres in 2014 with in irrigation. In 1942, the states of know the worth of water.” In this article millions of dollars lost in economic , , and joined we will take a fleeting glimpse into water activity. Roads, highways, and railroads together to form an agreement called and irrigation issues in the Great Plains. have been raised to avoid being the Republican River Compact. This permanently inundated. Hundreds of Like other regions of the world, was necessary before the Crops of buildings have been lost to flooding the Great Plains has to balance Engineers would agree to build Harlan or have been moved. Hundreds of water for farming and water for its County Reservoir on the Republican residents have abandoned their homes citizens. Farming feeds people and River to reduce downstream flooding. and farms through “buyouts” where a it economically supports those who A disastrous flood in May/June of 1935 state agency buys the land. Some have provide food for the world’s growing killed an estimated 113 people and called it the “slow moving monster.” population. Irrigation increases yields, perhaps as many as 41,000 head of allows a myriad of crops to be grown, Ogallala formation livestock. and mitigates weather uncertainties The largest of these systems, This multi-state agreement was in crop production. Irrigation water the Ogallala formation, is shown in ratified by Congress and approved is derived from surface water and Figure 1, with a concentration of water by the Supreme Court. In it, the deep wells. Wells extract water from appearing underneath Nebraska. The authors determined that Colorado subsurface but sometimes steady increase in Nebraska irrigation was responsible for about 11 percent surface water and aquifers are led to that state being number one in of the beneficial consumptive use intimately connected. Two examples of the nation for irrigated cropland. The of the Republican River drainage the complexities of these relationships 2007 Census of reported system. Nebraska was allocated about are the interactions that come out of that Nebraska had more than 8.5 million 40 percent and Kansas 41 percent. extracting water for irrigation from acres under irrigation. Nebraska had Despite best intentions of the states the , and the legal, more irrigated farmland acres than any to adhere to the compact, progress is economic, and political conflicts from other state, accounting for about one in taking its toll. Colorado now pipes water the Republican River system. every 6 acres of US irrigated farmland. from deep wells into the Republican Overflow The 2012 Census of Agriculture reported River system and has been forced Deficits of water are not the only that Nebraska had about 8.2 million to drain the reservoir in Bonny Lake problem in the Great Plains. In northern acres under irrigation and California had State Park, a locally popular recreation and across North Dakota, about 7.8 million acres. Between 1988 area, to make up for over-allocated lakes are increasing in surface area and and 2007 corn accounted for 70 percent consumption Nebraska is also diverting depth due to increased precipitation of the irrigated acres in Nebraska; water from deep wells into Republican and runoff over the past several soybeans accounted for 19 percent River feeder streams and yet is still the decades. Devils Lake in northeast (Figure 2). A 2003 survey suggested brunt of Kansas lawsuits claiming up to North Dakota is a good example of that 72 percent of the irrigated acres $72 million in damage. Prosecuting the where too much water is a massive were center pivot systems and 28 defending lawsuits is expensive for all problem. Between 1993 and 2011, percent were gravity irrigation systems, involved.

7 The Fluid Journal Summer 2014 Figure 1. Ogallala aquifer system.

Summer 2014 The Fluid Journal 8 Much has changed on the land since the 1942 agreement. Spring water once flowed into the Republican River, keeping a steady flow throughout much of the year. Since 1942, deep wells and irrigation development in Colorado and Nebraska lowered water tables, which dried up many of the springs in the feeder streams. Soil and practices were applied to the land beginning in the late 1940s and continue through to the present time. Terraces and farm ponds kept soil and water on the farm, thus reducing runoff into the river. More recently, crop residual management, minimum tillage, and no-till farming methods have reduced runoff even further. “Reuse pits” were installed to collect runoff water from gravity irrigated fields with the water being recycled to use for irrigation again and again without leaving the farm. Inefficient gravity irrigation gave way to more efficient center pivot irrigation systems. Through the decades, the goal of soil and water conservationists who assist the growers was and is to reduce erosion by keeping Figure 2. Corn accounts for 70% of irrigated corn acres. rainwater and irrigation runoff to near zero, thus much less water reaches shutdown of half of the irrigated acres in more probable, thousands of years of the river. On well-managed farms, the Republican River basin would cost rain required to restore aquifer levels water leaves the property only through billions long-term in economic activity even if no additional irrigation was evapotranspiration. to the state. The number and value of allowed. The Great Plains area is not Zero-sum game irrigation-related transactions for seed alone in ground water depletion. The fertilizer, herbicides, feed, machinery, USGS map (Figure 3) indicates known In the end, the Republican River insurance, and the sale of forage depletion areas. controversy has resulted in a zero- quickly mount. Not only agriculture The villain sum game. Water consumed upstream is affected. There are also industrial, The villain of this drama is the farmer’s cannot be used downstream and the recreational, and municipal components friend--the center-pivot irrigation system. benefit to the upstream user is to the that have a strong reliance on water. detriment of those downstream. For The pivot makes irrigating crops easy many years, Nebraska argued that The High Plains Aquifer is a in comparison to other systems and was not included in the waterlogged jumble of sand, clay, and requires much less labor. The center- Republican River Compact. Kansas filed gravel that begins beneath pivot irrigating system is, perhaps, the suit in 1998 and the case wound its way and South Dakota and stretches to the most efficient way to create an oasis. to the Supreme Court. Panhandle. The Northern portions Center-pivot irrigation efficiency was That case was settled in 2002 when the of the aquifer hold enough water for improved by the addition of dropped three states agreed to use a computer perhaps hundreds of years of irrigated nozzles, which reduce water lost to model using an algorithm including agriculture. Most of the water lies evaporation and drift. Paradoxically, it precipitation, stream flow, and assumed under the Nebraska , a mass was often found that farmers ended up values for recharge from precipitation of stable sand dunes covering a third applying more groundwater to fields. and subsurface leakage in and out of of the state, an area not suitable for Rather than reducing consumption, the Republican River area. The model farming. As one travels south, pumping some farmers use the efficiency also included water used by irrigators water is increasingly elusive. Kansas “savings” to expand irrigation into poor and others. Years of legal wrangling wells that used to pump 1,600 gallons soils or grow higher value crops such followed with Kansas notifying the other to the surface every minute now may as corn, alfalfa, and soybeans, which states in late 2007 of an alleged failure yield only 300 gallons or be completely consume more water. dry. High Plains Texas irrigators find to comply with the settlement. Kansas Texas researchers set out to they have to drill deeper and deeper to proposed a remedy to groundwater and determine how much water loss occurs extract water from the declining aquifer. stream flow depletions and asked for a in the air above the canopy, within From 1940 to 1980, the was shutdown of all wells within 2.5 miles of the plant canopy, and from the soil lowered by more than 100 feet in parts the Republican River and its tributaries surface. They compared different of Texas, , the and a suspension of irrigation on lands sprinkler devices and heights of panhandle, and Kansas. Follow-up added since 2000. The 2009 nonbinding sprinkler devices with respect to the studies show that the water table has arbitration meeting resulted in a no crop canopy. Table 1 shows the water dropped an additional 40 feet or more. resolution conclusion among the three loss during irrigation and the application states. Replenishing the aquifer will require efficiency for 1) six-degree low angle The economics of water are more than just a few seasons of rainy impact sprinklers located on the staggering. David Cookson, Nebraska’s weather, as is often the case in surface sprinkler pipe, 2) spray heads located chief deputy attorney general, said the waters. Rather, it could be hundreds or, five feet above the ground, and 3) a Low

9 The Fluid Journal Summer 2014 Energy Precision Application (LEPA) evaporation demands being met by the storage must be created to prevent system using bubblers located one water evaporating from plant leaves. any runoff and maintain infiltration foot above the ground. Both the water To realize the full potential of LEPA uniformity. On-farm efficiency is loss and application efficiencies given systems, growers must plant the crop in lower than that reported by research are based on a daytime irrigation of a pattern matching the irrigation track. institutions. USDA/ARS publications one inch applied to mature corn under Drop tubes must be placed at a height suggest that efficiencies of 95 to 98 no-wind conditions. Evaporation from of 12 to 18 inches between every other percent of the sprinkler water being the soil during irrigation is assumed to crop row. Water must be discharged in available for crop use are attainable by be negligible for the low angle impact the bubble mode or through socks to growers. sprinkler and spray head, a result of avoid wetting plant leaves. The surface Drip irrigation Perhaps the most efficient method of Table 1: Sprinkler water losses and application efficiency for 1-inch water application. irrigation is drip irrigation or subsurface Water Loss Component Low-Angle Impact Spray Head Water LEPA Water drip irrigation (SDI). Drip irrigation Sprinkler Water Loss loss Loss delivers water through the use of Air Evaporation and Drift 0.03 in. 0.01 in. 0.00 in. pressurized polyethylene tubing, also known as drip line, and drippers that run Net Canopy Evaporation 0.08 in. 0.03 in. 0.00 in. close to the plants and can be placed Plant Interception 0.04 in. 0.04 in. 0.00 in. either on the soil service or below ground. Generally, only the immediate Evaporation From Soil Negligible Negligible 0.02 in. root zone is wetted and the system Total Water Loss 0.15 in. 0.08 in. 0.02 in. allows precise application of water Application Efficiency 85% 92% 98% soluble fertilizers and other agricultural chemicals. Growers can achieve yield

Figure 3. Map of the United States (excluding Alaska) showing cumulative grounwater depletion, 1900 through 2008, in 40 assessed aquifer systems or subareas. Index numbers are defined in table 1. Colors are hatched in the Dakota aquifer (area 39) where the aquifer overlaps with other aquifers having different values of depletion.

Summer 2014 The Fluid Journal 10 goals of up to 100 percent, water section will have similar seeding and in Hastings, Nebraska, and Wichita, savings of up to 40 to 80 percent, and fertilizer rates. It also simplifies record Kansas, are the result of industrial associated fertilizer, pesticide, and labor keeping for crop insurance and farm solvent disposal. savings over conventional irrigation program benefits. Modern farming practices are systems. It is potentially the most Deficit irrigation demonstrating their ability to improve efficient irrigation system available, but Deficit irrigation is the practice of water quality. Groundwater nitrate that efficiency depends on the irrigation applying less water than a crop needs concentrations are an example. system itself, its proper design, for a full yield potential. Studies have Certain areas in Nebraska, like the installation, and management. Only shown that a reduction in irrigation is Central Platte Valley, have been using if designed, installed, and managed usually less than the reduction in yield. more environmentally friendly farming correctly can SDI be more efficient than The marginal productivity of irrigation techniques such as not applying any other irrigation system. water is lower when water application nitrogen in the fall, using nitrification Drip lines are buried 13 to 18 reaches full irrigation. Applying 75 inhibitors, and applying scientifically inches below the soil surface so the percent of full irrigation may result justified nitrogen rates. Once elevated, soil surface stays dry and practically in 90 percent of the fully irrigated levels of groundwater nitrate are no irrigation water is lost due to yield. One study, based on 28 years markedly lower due to implementation evaporation. Because of the potential of corn production data, showed that of sound research. The evidence for high irrigation efficiency, it may applications of 50 percent of the non- is clear in the Central Platte Valley, be a good alternative for areas where yield limiting irrigation rate reduced because the aquifer is close to the irrigation water is limited. Researchers yield only 13 percent. Yield variability at surface and changes can be observed in Kansas have reported that net lower irrigation levels is usually higher in a geologically short period of time. irrigation needs could be reduced by and in the previous study mentioned Other areas where the vadose zone is 25 percent with SDI, while maintaining year-to- year yield variance increased much larger will take much longer to high corn yields. Increased water use fourfold. Deficit irrigation at lower see change. efficiency reduces pumping cost. Since levels increases economic and weather Summing up no excess irrigation water is applied, uncertainties. Dryland yields, as a Balancing the social, ecological, nutrient leaching, with it potential to fraction of fully irrigated yields (relative economic, and agricultural interests in enter into surface and subsurface yield), are more variable than deficit water is clearly complex. Agreements waters, is minimized. irrigated yields. So, deficit irrigation become unworkable as time goes on. SDI can be automated to apply mitigates some of the economic and Efforts to improve irrigation efficacy fertilizers and other chemicals such as weather uncertainties, but not to the result in higher consumption of acids, chlorine, and even pesticides extent of fully irrigated conditions. groundwater and aquifer depletion. with irrigation water. SDI systems are Under deficit irrigation conditions, Compliance with watershed agreements often managed to apply small amounts corn grown in rotation with another crop results in the expense of transferring of water and other inputs daily or even is often found to yield better than corn water from one source to another several times a day. Spoon feeding following corn. In one study in Western and the draining of recreational water and nutrients could, theoretically, Nebraska, under semiarid conditions, impoundments. Reductions and result in increased yields and decreased corn in a wheat-corn-soybean rotation moratoriums on wellhead development nutrient and water losses. was able to use more stored soil result in fewer calories for food and One of the main disadvantages of SDI water than the continuous corn crop. feed. It seems that simply allowing is its high initial cost. The University Increased use of stored soil water led to market forces to operate does not of Nebraska estimates an average less dependence on irrigation. adequately balance the social, gross cost of between $500 and $800 Water quality economic, and environmental needs per acre. Center pivot systems cost for the sustainable use of water. Even It is not just the quantity of water, about half as much per acre. Kansas our legal system seems inadequate to too little or too much, but the quality estimations suggest that as the fields provide enduring solutions. that is getting much attention. As become smaller SDI becomes more the water table is drawn down, total Complex problems cannot be solved cost-effective. However, even with dissolved solids have been increasing. simplistically. Protecting our surface smaller fields it may be more cost- In areas vulnerable to leaching, nitrates and underground water sources, our effective to just dryland farm and and hazardous chemicals have been environment, and mankind will require not irrigate at all. Much depends on increasing in concentration to levels a holistic approach. Solutions will be the value of the crop grown and the adverse to human health. Increasing regionally based but implemented availability of water. SDI lends itself well nitrate levels have been especially and applied appropriately on a farm to specialty and tree crops under limited serious in areas of Nebraska and scale. Components to the solution water situations. Kansas. Nitrogen fertilizers and animal include increasing irrigation efficiency, SDI systems are being installed in manure applied to farmland susceptible deficit irrigation, crop rotations, using field corners where center pivots cannot to leaching are the main contributors. surface water sources that may be reach. A typical pivot irrigates about Herbicides such as atrazine and more abundant, planting less water- 134 acres out of a 160-acre quarter metolachor are commonly found in both hungry crops and crop combinations, section. After taking out country road surface and ground waters. Carbon withdrawing some land from irrigation, right–of-ways there might be 24 or 25 tetrachloride and ethylene dibromide, and improving crop water use efficiency acres of excellent soil in the corners used to fumigate grain, are found under through advanced plant breeding that aren’t irrigated. Farming the or near grain elevators. Chemicals techniques. corners as dryland creates management associated with military bases and challenges. An SDI system can associated industries such as RDX and Dr. Lohry is President and Dennis complement the center pivot by bringing TNT and the commonly used degreaser the field corners under irrigation. This trichloroethylene are found in some Zabel is Senior Agronomist at Nutra-Flo simplifies management when all acres in areas. Large trichloroethylene plumes Company in North Sioux City, SD. the field are irrigated. The entire quarter

11 The Fluid Journal Summer 2014