University of Illinois Extension
The Illinois Steward
Although early and dramatic effects of climate change are appearing first in the polar regions, Illinois will experience effects as well. And agriculture will face some daunting challenges, as will other human and natural systems. The increases in temperature that are forecast will change patterns of precipitation as well as temperature. For Illinois, the prediction is that our summer climate will gradually become similar to the current climate of southeast Texas—hotter, wetter in spring and fall, and drier in the summer. This has enormous implications for our crop and animal food-production systems.
Crops such as corn and soybeans, which require planting in spring, harvest in fall, and pollination can be especially sensitive to changes in precipitation and temperature.
Wet springs mean more risk in planting annual crops like corn and soybeans because windows of opportunity—when soils are dry enough to support equipment and provide a good seedbed—are shorter and less frequent. For farmers with smaller equipment or more extensive collections of fields, this offers large challenges for effective planting. Then after planting, it is more likely that flooding in the fields will drown out younger plants.
The same is the case for harvest. Continual wet weather makes access to fields more difficult. It also leads to slower in-field drying, which means the harvested crop will require drying using natural gas at the grain elevators. Higher planting densities may slow in-field drying because air circulation is decreased, although new hybrids generally have upright leaves that may make this less of a problem. The additional use of fossil fuel for drying obviously exacerbates the problems with greenhouse gases. If a farmer must wait until the ground is frozen in winter to harvest corn, the frozen cornstalks and cobs are hard and wear out equipment dramatically faster than during typical harvests.
Consequently, there may be a move toward purchasing larger equipment and installing more field-drainage systems to remove water faster. However, rates of drainage are ultimately limited by the ability of surface-water systems to convey water away from the field; and if large areas are flooded, time required for draining is extended.
In many ways, the perennial systems, once established, may be more resilient to erratic weather than the annual cropping systems. Appropriately adapted species may be planted in wetter or drier areas of the field and still provide a good mix of forage for grazing animals. Leguminous, nitrogen-fixing plants in the pasture or hayfield will produce their own nitrogen, some of which will also be available to grasses and non-legumes in the field. These forms of nitrogen are less likely to leach out of the soils with excessive rains and are more likely to be efficiently taken up by plants. In addition, because live plants are on the site year-round, and roots are active, any available nitrogen is more likely to be taken up by the plants in early spring and late fall, compared with annual crops, which may have only 2 to 3 months of significant uptake during their fastest growing periods.
Of course, wetter pastures mean such lands are more sensitive to impacts of hooves on soil disturbance, leading to greater compaction. Intensive rotational grazing minimizes the impact of animal hooves on soil (less walking) and would be more appropriate for these systems (see “Growing the New Grasslands” in the Summer 2000 issue of The Illinois Steward for information about these methods of intensive rotational grazing). Some grazing-animal breeds may have larger hooves compared with their weight and consequently less loading and impact on fields.
The harvest of dry, cured hay may become more difficult in spring and fall if weather is wetter. This could lead to putting up more haylage and baleage, both of which allow storage of hay that can be collected and stored 1 to 2 days after cutting to dry to 40 to 60% water content (fully cured hay takes 3 to 5 days, depending on humidity, temperature, and wind conditions). As in the case of silage, mild fermentation occurs in the bale and preserves the forage from mold or rot. The bales are bagged in plastic, which must be maintained intact to avoid entry of oxygen.
Increasingly wet springs and falls, and drier summers, may encourage a new range of pests on Illinois crops. Disease problems that already occur, such as mildews and rusts, may become more widespread and difficult to manage. Root rots may become more severe and depth of rooting more shallow as soils stay continuously wet in the spring. A shallower root system means the plant is less able to manage extended summer droughts because the root system is too close to the surface and can’t access deep soil moisture.
Insects that overwinter in the soil will be less likely to be killed by extended cold soil temperatures, and the depth of freezing will also be decreased. Greater survival of these larvae means greater populations emerging in the spring and hence more difficulty in control.
In addition, southern insects that couldn’t survive or reach economically threatening populations may move northward, where they become major pests. More pest pressure means changes in management, changes in crops, increased crop losses, or more pesticide application for insects, diseases, and weeds.
Milder winters will mean less cold stress on animals. However, many ruminants in Illinois can withstand the typical winter conditions with relatively little shelter except from the wind if they are on a high-fiber diet. Animals in confinement are less sensitive to cold weather because of the building’s protection and the body heat released from the animals.
Animals that are packed closely together during part or all of their adult lifespans may suffer more from heat than from cold. Therefore, chicken and turkey production under typically intense confinement will become more challenging because additional cooling will be required during a portion of the year: Production may simply not be economically possible during a portion of the year if costs of energy for cooling increase.
Ruminants like beef or dairy cows eat less and typically produce less meat and milk during hot periods, although some breeds are more effective than others at maintaining production. These decreases occur under current conditions. As average and peak temperatures increase, there is ever greater likelihood of problems.
Warmer temperatures will allow farmers and gardeners to successfully plant and harvest warmer-season fruits and vegetables. For example, the USDA has changed its recommended growing zones considerably over the past few years to acknowledge increased survival and production in both ornamental and food crops (http://www.usna.usda.gov/Hardzone/ushzmap.html).
The National Arbor Day Foundation completed an extensive updating of U.S. Hardiness Zones in 2006. The revised hardiness zones generally anticipate continued warmer temperatures over most of the country. Since the same data were used that USDA analyzes to produce its hardiness zone maps, it is likely that USDA will reach similar conclusions when it next updates its maps.
Because quality and appearance are important to consumers, most fruits and vegetables are sensitive to weather conditions that affect these attributes. Thus produce may be more at risk than other agricultural crops. High winds can knock fruit off trees or scar the fruit. Perennial fruits are also more at risk: They can’t be rotated off one field and onto another every year because it takes
3 to 7 years for tree crops to reach full production and initial costs of planting are high.
Irrigation will become more essential where short-term droughts may occur. Water supplied from surface or shallow groundwater for irrigation may become more unreliable as summertime drought intensities and frequencies increase. In some areas, groundwater overdrafting may occur, although wetter seasons in groundwater recharge areas could make this less of a problem.
Wesley Jarrell is a professor in the Department of Natural Resources and Environmental Sciences and the Environmental Change Institute at the University of Illinois at Urbana–Champaign. Photos by Robert J. Reber unless otherwise noted.