Published on 08/18/99

Heating Up: Severe Drought Expands in Georgia

Another week with little rain and temperatures in the 90s and low 100s has caused severe drought conditions to expand into southwest and central Georgia. Only in south central Georgia did drought conditions improve last week.

Timely rains in the next few weeks will be critical for many in Georgia agriculture. Even among some producers who have been irrigating, concern is growing over the level of water remaining in some irrigation ponds.

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Lack of Topsoil Moisture Critical

The Georgia Agricultural Statistics Service reports that moisture is short to very short in 81 percent of the state's soils. Last year at this time, soil moisture was short to very short in 46 percent of the soils. The average over the past five years is 33 percent.

GASS rated more than 50 percent of soybeans and pastures in poor to very poor condition. A third of the state's cotton is rated poor to very poor.

The lack of topsoil moisture is most critical in southwest Georgia, according to the Aug. 14 Crop Moisture Index values. The CMI is a measure of soil moisture in the root zone of crops.

Crops Damaged

The CMI value for southwest Georgia shows a potential for dryland crops to be ruined because of dryness. Actual crop losses will depend on the growth stage of a crop and its ability to withstand drought conditions. Timely rains will save some crops.

The CMI indicates that dryness may severely cut crop yields in west central and central Georgia.

Soils in northeast and east central Georgia are excessively dry, with crop yield prospects reduced.

Abnormally dry soils are found in northwest and north central Georgia, and crop yield prospects are deteriorating.

The topsoil moisture in south central and southeast Georgia is rated as short.

Through mid-August, all major cities in Georgia were below normal for monthly rainfall. Rainfall totals (and monthly deficits) through Aug. 17 were: Athens, 0.55 inches (-1.61 inches); Atlanta, 0.10 (-2.02); Augusta, 0.49 (-2.06); Columbus, 0.80 (-1.39); Macon, 0.22 (-1.88); and Savannah, 1.61 (-2.59).

4 Regions in Severe Drought

Long-term conditions according to the Palmer Drought Severity Index indicate that northeast, west central, central and southwest Georgia are in severe drought. North central, east central and southeast Georgia are in moderate drought.

Mild drought conditions are found in the northwest and south central regions of the state.

The PSDI is most useful in hydrological aspects of drought.

Stream flows across the state are generally running in the 10th percentile range. Many water systems have begun either partial or total outdoor watering bans.

Above-normal Rainfall Needed

Soil moisture loss from evapotranspiration ranged from 1.25 to 1.5 inches across the state last week. Above-normal rainfall will be needed just to keep up with soil moisture loss through evapotranspiration.

To end the long-term drought, more than half a foot of rain is needed across most of the state. The best hope for long-term drought relief is a tropical weather system.

You can get updates on drought conditions in Georgia and across the Southeast at the University of Georgia drought Web site. Or call your county Extension Service agent.

Get updated weather conditions at the Georgia Automated Environmental Monitoring Web site.

David Emory Stooksbury is associate professor of Biological and Agricultural Engineering at University of Georgia's College of Agricultural and Environmental Sciences.