Louisiana State University Ag Center Research and Extension personnel recently characterized sources of variability within cotton fields consisting of delta alluvial soil and loess soils on the Macon Ridge by using tools such as the Veris cart for measuring apparent electrical conductivity (ECa), real time kinematic geographical position systems (RTK GPS), and normalized vegetative index (NDVI).
During the past five years, the research and extension teams have worked under grant support from multiple agencies including NASA, Regions 6 EPA of Dallas, and Cotton Incorporated. These sponsorships, geo-spatial tools and their complimentary GIS programs were primarily used to evaluate the potential to use site specific aerial and ground treatments for pest management. However, interactions with nematodes, soil pH and nutrient deficiencies and site-specific application of .fumigation treatments were also evaluated. Movement patterns of plant bugs and cucumber beetles were evaluated to a limited degree.
Most recently the groups have applied their GIS/GPS knowledge to enhance nematode sampling for sweet potato production. There is limited research of this type for Louisiana producers. However, interim studies suggest use of GIS/GPS techniques has the potential to help sweet potato producers fine tune lime and fertilize treatments and also provide relief from costly blanket applications of nematicide treatments; both major expenses incurred in sweet potato production. A limiting factor for further work is the lack of yield monitoring equipment that can aid in on-farm evaluations.
For sweet potato producers, zone management strategies similar to the methods used in the delta since 2001 were modified for use as sample plans. The Veris cart provides a method of separating fields into low — high silt and clay content, because Veris ECa has a very high positive correlation to clay content. Because of the narrow range of electrical conductivity measured in the loess soil regions of the Macon Ridge, three ECa zones are typically used when sample plans and site-specific treatment programs for nematodes are needed.
When root-knot nematodes were the principal nematode pest, site-specific application of fumigation treatments based on the amount of clay content within zones is possible. However, the major nematode pest in most sweet potato fields is reniform sp. Because reniform sp. tolerates a broader range of soil clay content as compared to root-knot nematode, one acre grids were also used in developing sample plans and site-specific application plans.
The grids serve to organize placement of the GPS sample points and organize the soil sampling procedure into a combination of scientific and subjective techniques. Sample plans were developed in ArcGis 9.1. Surface interpolation was accomplished using Inverse Distance Weighting, contour feature classes within zones were labeled, and GPS points were manually placed in order to represent the dominate feature/soil type within a respective grid. When possible, equal numbers of soil samples are collected from each Veris’ ECa zone. For the fine loess soils these methods are adequate for analyzing nematode pest densities and soil fertility as well.
The LSU AgCenter Precision Agriculture teams that conducted the above studies were awarded the Tipton team research award in recognition for excellence in research in 2007. Since then the group has launched new research initiatives including studies with Veris NIR sensors and GreenSeeker sensors. The LSU AgCenter’s Cooperative Extension Service has reacted to the increased need for Precision Agriculture education by providing increased GIS/GPS training and responsibility to a select group of County Agents in each of the major agriculture producing regions.
Farmers in Louisiana, especially in the delta parishes have invested in GIS/GPS technology as well. John Deere, Ag Leader and Trimble all have a significant presence in their respective areas of service to precision agriculture. It is rare to find a harvest machine without a yield monitor and most of the tractors used in row crops are equipped with auto-steering devices. Many of the farmers recognize the advantages of using Veris ECa data to complement USDA soil survey data.
One of the newest efforts to increase the use of Precision Agriculture technology is the construction of a RTK network for the delta parishes. The network serves six stores owned by Goldman Equipment and ranges from MerRouge, LA through St. Joseph, LA. The network is reported to have increased RTK reception for selected areas up to 18 miles and has improved reception around the many tall trees that can easily knock out the RTK signal.
All in all Louisiana seems to be looking forward to the future of agriculture and that includes using Precision Agriculture methods.