Commodities: Fieldcrops: Peanuts: 2007 Peanut Update
Using Climate and Weather Information for Managing Peanuts
Joel O. Paz and Gerrit Hoogenboom
The 2006 growing season was a very difficult year for peanut production, in large part because of the prolonged dry conditions in Georgia. Extended periods of no rain resulted in a highly stressed peanut crop in many Georgia counties. The weather conditions and events that occurred last year do not necessarily indicate that we will experience similar conditions in 2007. We have to consider the regional climate conditions and projections and look at historical weather data to see how the peanut 2007 growing season will shape up.
The climate in Georgia is strongly affected by a phenomenon called El Niño-Southern Oscillation (ENSO). When the sea surface temperature in the eastern equatorial Pacific Ocean is higher than normal, the phenomenon is referred to as El Niño. When the temperature is lower than normal, the climatic event is referred to as La Niña. When the temperature is normal, the event is referred to as Neutral. El Niño years tend to be cool and La Niña years tend to be warm between October and April. In terms of rainfall amounts, El Niño years tend to be wet and La Niña years tend to be dry during these months. The ENSO signal in the region is strongest in the fall and winter months and some evidence exists that La Niña summers tend to be slightly wetter than normal.
AgClimate (www.agclimate.org) is an interactive web site developed by the Southeast Climate Consortium (SECC) that allows users to assess management options with respect to their probable outcomes under forecasted climate conditions. One of the web-based applications or tools on the AgClimate website allows a user to evaluate the climate forecast based on the ENSO phase, and to examine average and deviation from normal, and detailed rainfall and temperature predictions for all counties in Georgia. As an example, Figure 1 shows the average total rainfall for every month under El Niño condition in Mitchell county, Georgia. To use this web-based tool, use your computer browser and go to www.agclimate.org. On the left navigation bar, click on ‘Agclimate Tools’ >> select ‘Climate’ >> click ‘Climate Risk Tool’. You can select an ENSO phase (El Niño, La Niña, and Neutral), and examine how the different climate variables (rainfall, temperature) are affected by ENSO.
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Figure 1. The climate risk tool found on the AgClimate web site.
In addition to web-based tools, AgClimate provides seasonal climate forecasts developed by climatologists. These forecasts give the growers an idea what to expect for the next three months in terms of climate conditions in Georgia. The forecast for the winter of 2007 in South Georgia calls for cooler temperatures and above-normal rainfall amounts. This assessment was based on El Niño conditions in the equatorial Pacific Ocean, which actually developed in the fall of 2006. The impact of the rapid development of El Niño was the relative inactivity of the (2006) hurricane season, which partly explains why South Georgia did not get enough rainfall (Figure 2). A summary of the water balance for the entire peanut growing season is shown in Table 1.
Figure 2. Total rainfall from July 1- September 1 observed at different weather stations of the Georgia Automated Environment Monitoring Network (AEMN).
El Niño normally reaches peak intensity and coverage in the winter months. El Niño is known to bring more frequent storms, excessive rainfall, and cooler temperatures to much of South Georgia. It is believed that the increase in rain and cloudiness associated with El Niño causes average temperatures to be cooler than normal during the winter months. The possibility of cooler temperatures and wet conditions extending into early spring may affect planting date decisions.
Although conditions may vary during the growing season, we will continue to provide current climate-based information to help growers manage their peanut farm operations. Check www.agclimate.org for updates on short and long-term climate outlooks.
Growers can use current weather information to decide on what to do in terms of farm management operations including planting, pesticide application, irrigation, and harvesting. The Georgia Automated Environmental Monitoring Network (AEMN) provides a valuable resource for peanut growers looking for reliable and up-to-date weather information in their area. The network which added three weather stations last year now has a total of 71 stations across the state. Each station monitors air temperature, relative humidity, rainfall, solar radiation, wind speed, wind direction, soil temperature at 2, 4, and 8 inch depths, atmospheric pressure, and soil moisture every 1 second. Data are summarized at 15 minute intervals and disseminated through its web site at http://www.georgiaweather.net. Current weather data and weather-based tools are available for each location (Figure 3).
Figure 3. A web page showing available data and simple calculators for each location in the network.
Here is a sample web page that shows the 31-day summary of weather variables including rainfall and evapo-transpiration (ET) in Attapulgus, Georgia (Decatur County).
Table 1. Water balance for the peanut growing season (May 1-September 30, 2006) using data from several AEMN weather stations located in peanut-producing areas. 
* Data from Tennille is from May 6-September 30, 2006.