Maximizing economic return is the payoff sought by growers with any precision farming technology. And a new story in Southeast Farm Press talks about how the Precision Farming team at the University of Georgia is using soil texture to target nematodes.
With precision agriculture, we try to refine things in order to achieve the goal of maximizing returns,” says Richard Davis, USDA-ARS plant pathologist in Tifton, Ga. “And when we talk about precision agriculture in nematode management, what we really end up talking about is more effective targeting of nematode applications.”
Many of the things growers do for managing nematodes involve making applications over entire fields rather than specific parts of a field, says Davis.
As part of a large project funded in part by Cotton Inc. and the Georgia Cotton Commission, the Precision Farming Team at the University of Georgia has been evaluating a number of techniques for delineating areas within fields at high risk for nematodes.
The fact that root-knot nematodes prefer sandy areas has encouraged researchers to find ways to rapidly measure soil texture — either directly or indirectly — and one of the most promising techniques is to directly measure soil EC. Soil EC is a function of soil texture and soil moisture. Sandy soils produce low soil EC while heavier soils result in higher values of soil EC.
While different instruments have been developed to measure soil EC, one of the most popular is the Veris 3100. This instrument has six coulter-electrodes (disks) mounted on a toolbar. As the Veris is pulled through the field, one pair of disks transmits an electrical current into the soil while another pair of disks measures the drop in voltage. The separation between the disks determines the depth to which soil EC can be measured. In the most commonly used configuration, soil EC is measured simultaneously from 0 to 1 foot (shallow) and 0 to 3 feet (deep).
In addition to directly measuring soil EC, there are other promising methods for indirectly measuring soil texture. These include using real time kinematic (RTK) GPS to rapidly create detailed topographic maps of fields. Elevation and slope of the terrain frequently dictate where coarse textured soil particles are deposited by erosion.