Great Plains wheat producers face climate change challenges
by Jay Sjerven
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WASHINGTON — Climate change projected across the Great Plains in the next few decades will test the resilience and ingenuity of wheat producers and the agriculture community in general, according to the Third National Climate Assessment issued May 6. The assessment, which considered all other regions of the United States as well, was conducted under the auspices of the U.S. Global Change Research Program as required by the Global Change Research Act of 1990.
At a time when drought across the Southwest commanded the attention of wheat markets, the report suggested the southern Plains may see more extensive dry spells, less precipitation and higher temperatures in the years ahead. Climate change offered a more mixed bag for the northern Plains.
The report indicated projected changes in precipitation and temperature have both positive and negative consequences to agricultural productivity across the northern Plains. Projected increases in winter and spring precipitation in the northern Plains will benefit agricultural productivity by increasing water availability through soil moisture reserves during the early growing season, but this may be offset by fields too wet to plant.
Rising temperatures will lengthen the growing season, possibly allowing a second annual crop in some places and some years, the report said.
At the same time, warmer winters may allow pests and invasive weeds to survive the winters and become more pervasive. Also, winter crops such as hard red winter wheat grown in South Dakota, Montana and increasingly in North Dakota may leave dormancy earlier and be susceptible to spring freezes.
The report noted rainfall events already have become more intense across the northern Plains in recent years, increasing erosion and nutrient runoff. Climate change projections indicate the frequency and severity of these heavy rainfall events will increase. Still, the northern Plains will remain vulnerable to periodic drought because much of the projected increase in precipitation is expected to occur in the cooler months while increasing temperatures will result in additional evapotranspiration.
The report indicated in the central and southern Plains, projected declines in precipitation in the south and greater evaporation everywhere due to higher temperatures will increase irrigation demand and exacerbate current stresses on agricultural productivity.
Increased water withdrawals from the Ogallala Aquifer and High Plains Aquifer were expected to accelerate the ongoing depletion in the southern parts of the aquifers and limit the ability to irrigate. The report cautioned that holding other aspects of production constant, the climate impacts of shifting from irrigated to dryland agriculture would reduce crop yields by about a factor of two.
“Under these climate-induced changes, adaptation of agricultural practices will be needed, however, there may be constraints on social-ecological adaptive capacity to make these adjustments,” the report stated.
The projected increase in high temperature extremes and heat waves will negatively affect livestock and concentrated animal feeding operations across the southern Plains, the report continued. Shortened dormancy periods for winter wheat will diminish an important source of feed for the livestock industry. Climate change may thus result in a northward shift of crop and livestock production in the region. In areas projected to be hotter and drier in the future, maintaining agriculture on marginal lands may become too costly, the report indicated.
The report noted during the droughts of 2011 and 2012, southern Plains ranchers liquidated large herds due to lack of food and water. Many cattle were sold to slaughterhouses while others were relocated to other pastures through sale or lease.
“As herds are being rebuilt, there is an opportunity to improve genetic stock, as those least adapted to the drought conditions were the first to be sold or relocated,” the report said.