With Skip Hyberg
We are currently observing unprecedented conditions in the Southwestern United States. Over the past few months, temperatures have hit all-time records in dozens of cities and towns. The region is experiencing an extended and intensive drought and Lake Meade, a reservoir of the Colorado River which forms part of the border between Arizona and Nevada, is at its lowest observed level in history. These conditions are consistent with future projections for the Southwest Region. A consensus of climate change models project higher temperatures, reduced precipitation, and longer, more severe droughts. In short, we may be getting a glimpse of the future right now.
What does this mean for agriculture? Well let’s start by looking at a recent statement from the Arizona Department of Water Resources (ADWR). In an April 2021 statement, ADWR indicated that in August the United States Bureau of Reclamation is likely to declare a water shortage for the Colorado River Basin. For Arizona, such a declaration would result in an 18 percent reduction in 2022 water deliveries from the Colorado River. The statement indicates the reduction will be absorbed by customers of the Central Arizona Project and “means less water for agriculture in the central and south-central areas of the state”. Although some of the water reductions will be made up from other sources, the impact on agriculture will be painful. Farmers interviewed by CBS News and the Associated Press stated that with less water they would have to let some land go fallow.
We’re looking at the agricultural sectors of three states in the Southwest—Arizona, Nevada, and New Mexico--which largely fall within the Colorado River basin. According to state-level data reported by USDA’s Economic Research Service, the sectors in all three states are dominated by livestock production, with cattle and calves and dairy production landing among the top three commodities produced in each state. The three states have less than four million acres of cropland combined, while they have 63 million acres classified as either permanent pasture or rangeland. The only significant crop grown in the region other than hay for the livestock is lettuce in Arizona, which was planted on nearly 68,000 acres in 2020. There were 2.6 million acres of irrigated farmland across the three states, as of the 2017 Census of Agriculture.
We’ll take a closer look at crop production in Arizona, where 68 percent of cropland is irrigated. First, it is likely that scarce water will lead to some row crops that require substantial amounts of water to become scarcer in the state. For example, Arizona farmers grew more than 850,000 acres of grain and forage crops in 2017, and except for sorghum, the vast majority of it was on irrigated land. Sorghum acreage could well increase in light of reduced access to irrigation resources in this region, at the expense of corn for grain and silage.
Second, high valued crops such as fruits and vegetables will be more likely to continue to be grown, but it is feasible that we might see some reductions in the area dedicated to these crops as well. For example, production of specialty crops that are both labor intensive and require irrigation in the Southwest climate, such as lettuce and spinach, may see reduced acreage due to constrained access to both inputs.
Third, data from the 2018 Census of Irrigation show that there are opportunities to adopt more efficient irrigation systems. We are likely to see a transition away from inefficient irrigation systems such as gravity systems which accounted for two-thirds of irrigated acres in the three states in 2018, to more efficient systems such as drip and trickle irrigation. Adopting these systems can reduce water use by as much as 40 percent to 70 percent, while also reducing energy expenditures by as much as 50 percent. Such an evolution has already begun in other western states such as California, where nearly half of irrigated acres use low-flow systems such as drip irrigation, but it is likely that greater water scarcity will speed it up.
And let’s not ignore livestock production, which will also be affected. For beef cattle, the higher temperatures and lower precipitation will reduce the optimal stocking densities for rangeland, lowering the number of head that can be maintained. For dairy cattle, of which there are about 562,000 head in all three states, water scarcity may require operators to reduce the number of cows they are milking, since each drinks an estimated 30 gallons of water per day. In short, with decreasing water available, all types of production agriculture will change.
The entire global agricultural sector will be forced to adapt to changing climatic conditions in the future, but the U.S. Southwest is a region where the current situation brought about at least in part by climate change is already a challenge. All of us will see change, especially farmers and ranchers. So what do you do? Prepare. Become informed. Plan. Adapt. USDA provides resources for each of these steps. There is a Climate Hub for your region. Each Climate Hub has a website that provides resources that can help you become informed about ways your operation can adjust to changing conditions. As for planning and adapting, NRCS has Service Centers in nearly 2000 counties. The conservationists at each center can help you assess your operation and design a plan that meets your needs.
Finally, we all need more information that can only come from closer examination of the changes agriculture faces in the next few decades. More research at our Land Grant Universities and USDA is necessary to develop more and better ways for farmers and ranchers to adapt to a changing climate.
