BATON ROUGE, La. -- Louisiana farmers and agricultural researchers now can obtain estimates of daily evapotranspiration, thanks to a new tool available through the LSU AgCenter’s Louisiana Agriclimatic Information System.

LSU AgCenter weather specialist and Extension climatologist Jay Grymes explains that the weather data the system accumulates serve as the basis for calculating “reference crop evapotranspiration,” which defines how much water area fields and crops have lost through evaporation and plant use (transpiration).

“This information is critical in deciding when and if to irrigate and, if so, by how much,” notes David Greenland, an LSU AgCenter climatologist and developer of the new tool.

Greenland adds, “We’ve seen in the recent past that drought can be a slow, insidious phenomenon that can catch producers unaware if they do not keep track of the daily input and output of water to their soils. This newly available information can help growers evaluate regional soil moisture conditions.”

The agriclimatic system has long provided real-time and historical weather information for farmers from its network of weather stations across the state. To see the network, go to the Louisiana Agriclimatic Information System home page, LSU AgCenter Weather/.

Users can select any of the operating weather sites and obtain daily evapotranspiration estimates for any period of dates since September 2001. Daily data then can be downloaded for detailed analysis.

The data can be used to make adjustments for specific crops at specific stages of development.

An example of a specific application of evapotranspiration can be found by clicking on the Agriclimatic Tools link. It was prepared by Greenland and titled, “Use of Evapotranspiration Estimates in Turfgrass Irrigation.”

“Louisiana cotton producers were the first to request the development of the evapotranspiration tool, but we found that the methodology is applicable to a number of different crops,” Greenland says.

“This is the first of what we hope to become a series of value-added, weather-based agriclimatic tools made available through the Louisiana Agriclimatic Information System Web site,” Grymes says, adding, “We encourage current and potential users to provide feedback for this tool, and we are always seeking suggestions from the agricultural and environmental communities concerning the development of new weather-based tools.”