Facing the possibility of extended droughts has always been a problem for farmers, especially those crop farmers who rely on consistent rainfall to produce a good crop. According to the American Meteorological Society, drought is defined as “a period of abnormally dry weather sufficiently long enough to cause a serious hydrological imbalance”
Over the last few decades, droughts have become more frequent and more severe as a result of the effects of climate change, at least in some regions of the world. According to a study published in Nature Communications in May 2021, anthropogenic forcing due to climate change has increased the drought frequency, maximum drought duration, and maximum drought intensity experienced in large parts of the Americas, Africa, and Asia.
Within the United States, the Southwest U.S. is not seeing a strong trend in annual precipitation over the full period of record (1895–2023), but rising temperatures and evaporation have led to more rapidly depleted soil moisture, runoff and streamflow in an already arid region. As a result, episodic droughts feature higher temperatures than past droughts and are more impactful on the hydrology of the region, which is already stressed by human use, as described in my previous blogs on the Colorado River system and groundwater depletion.
In recent years, the federal crop insurance program has paid out a larger amount of indemnities from crop losses due to drought than just a few decades ago, both in absolute dollars and as a share of total indemnities. Insurance indemnities paid as a result of drought-induced crop losses averaged $2.65 billion between 2017 and 2021, more than nine times higher than over a comparable period in the early 1990’s, according to data collected by USDA’s Risk Management Agency. Drought-related indemnities accounted for 22.6 percent of all indemnities in the earlier period, while the share increased more than 37 percent to 31 percent for the more recent period.
In the face of increased drought pressures, farmers have a number of options on how to respond. Crop farmers have the opportunity to switch away from their current crop choices to plant more drought resistant crops, such as moving away from corn, which needs 20 to 25 inches of rain annually to produce good yields, to grow a crop like grain sorghum (also known as milo) instead, which needs only 15 inches of rain per year to thrive. Both are coarse grains which are often used to feed livestock, although processed corn has other uses such as ethanol and industrial starch for which sorghum is not often used.
Adoption of conserving agricultural practices such as cover cropping and no-till cultivation can help to improve the soil’s ability to retain water, and can help reduce yield losses in drought situations, especially after the new practice has been in place for several years. Higher soil carbon content makes the soil more resilient to all kinds of shocks, including both droughts and heavy rains.
Farmers raising rain-fed crops also have the option to install irrigation equipment to either replace or supplement the water they receive from the sky, although such equipment is costly to install and operate. A 2019 analysis by the University of Missouri found that it cost $230 per acre annually to install and operate a center pivot irrigation system on a 160-acre field, over and above the normal costs such as seed and fertilizer purchases associated with raising corn or soybeans on that field under rain-fed conditions.
Overall, total irrigated cropland in the United States increased by about one-quarter between 1987 and 2017, according to data collected under USDA’s Census of Agriculture every five years. There has been a marked increase in irrigated cropland acres in the eastern half of the United States over the last several decades, increasing from accounting for only seven percent of irrigated U.S. acres in 1957 to 29 percent as of the 2017 Census of Agriculture. However, as climate change continues, this solution will become increasingly problematic in some regions, as water flow in major surface water systems (such as the Colorado River basin) and groundwater availability both are expected to decline.
Newer technologies, such as seed varieties bred (or genetically engineered) for drought tolerance can also be brought into the mix. As a result of the Drought Tolerant Maize for Africa (DTMA) project undertaken during the first decade of this century by CIMMYT and IATA, both centers of the CGIAR system, millions of African farmers now have access to seed to grow drought-tolerant maize (corn), helping them improve their yields by as much as 30 percent. Much of this work was funded by the Bill and Melinda Gates Foundation. Even though this initial DTMA research was conducted using conventional breeding practices, the drought-tolerant trait they created has now been incorporated into corn seed available to U.S. farmers using both conventional breeding and genetic engineering techniques. By 2016, 22 percent of acres planted to corn in the United States had drought-tolerant protection.
The success of the DTMA project has spurred similar research regarding drought tolerance in other major cash crops around the world, including coffee plants in Uganda, soybeans and wheat in Argentina, rice grown in India, the Philippines, and Nepal, and canola in Canada. The drought resistant soybean and wheat varieties in Argentina and the drought resistant rice varieties, developed by scientists in the International Rice Research Institute (IRRI), have all been released to farmers in the named countries for production, while the others have not yet reached that stage.
Within the United States, the Foundation for Food and Agriculture Research (FFAR) has funded a number of such projects, including looking at drought tolerance in potatoes at the University of Maine and in rice at the University of California at Berkeley. The Foundation received an additional $37 million in the recent extension of the 2018 farm bill to continue its work overall, but more investment in research into helping farmers adapt to drought conditions under climate change is needed.
