Precision Agriculture Research
This research is headed by Dr. Ahmad Khalilian and team.
Recently, sucking bugs have become a major problem in current genetically engineered cotton varieties. From 1995 to 2001, insecticide application for stink bug control increased from 0 to 4 million applications at a cost of $27 million. In 2000, crop losses from these pests exceeded $50 million. A major constraint to managing the stink bug is the difficulty associated with obtaining information necessary to make treatment decisions. Development of technologically-derived instrumentation for detecting stink bugs would facilitate treatment decisions and site-specific application of insecticides. The performance of an electronic nose for detecting stink bugs and their damage in cotton production was evaluated under greenhouse/laboratory conditions. The system could accurately identify stink bug damaged bolls approximately 95 percent of the time. Volatile chemicals produce by stink bugs has been identified to be trans-2-decenal, and trans-2-octenal. The E-nose showed similar responses to these chemical as compared to those obtained from sting bugs. Under laboratory conditions, the E-nose identified presence of stink bugs 100 percent of the time. There was a strong correlation between the number of sting bugs in a sample and the E-nose sensors response. Development of technologically-derived instrumentation for detecting stink bugs would facilitate treatment decisions and site-specific application of insecticides.
Sensor-Based Variable-Rate Nitrogen Application
Approximately 9 million tons of nitrogen is routinely applied in cotton, corn, and wheat fields annually in the USA for crop management. The nitrate form of nitrogen moves freely into surface and ground water, and is a major source of water contamination. “Sensor-based variable-rate nitrogen application” (SVNA) is an innovative technology that will minimize the effect of production practices on the environment while optimizing farm profit. This technology matches field variability of nitrogen utilization with an appropriate variable-rate fertilizer application, differentially applying nitrogen to match the needs of crop within a field. SVNA technology can lead to substantial reductions in nitrogen use and its adverse impact on ground and surface water quality while increasing yields by applying fertilizer only where needed at optimum rates. Clemson University has developed SVNA systems for Coastal Plain soils conditions that are ready for use by growers. Our work has shown that compared to uniform rate applications the SVNA system has the potential to reduce N usage by 30 to 70% in cotton, corn and wheat productions. Even a 10% reduction in nitrogen usage will save growers over $200 million.
Soil variation results in the development of cotton plants with a tremendous amount of growth variability associated with them. Blanket applications of plant growth regulators based on a constant rate often results in the application of chemical to areas of a field that may not require treatment and as a result, may decrease yields. Likewise, insufficient application may also decrease yields in excessively leafy areas. A variable-rate application delivery system for PGR and HA was developed and retrofitted to an existing spraying equipment. An algorithm was developed for site-specific application of plant growth regulators (PGR) and harvest aids (HA) based plant Normalized Difference Vegetation Index (NDVI) measured utilizing airborne multi-spectral imagery and a sprayer-mounted GreenSeeker mapping system. The variable-rate applications required 40% less PGR and 33% less HA compared to uniform-rate applications. The soil electrical conductivity (EC) and NDVI data can be used effectively for making PGR and HA application recommendations to address spatial variability of cotton growth in the field.
The U.S. cotton industry lost an estimated $300 million to nematodes in 2006. Clemson University has developed a site-specific nematicide placement (SNP) system that is ready for commercial deployment and use by growers. This technology matches field variability of nematode distribution with an appropriate variable-rate nematicide application, differentially applying chemical to match the needs of individual management zones within a field. GPS-based equipment was developed for delivering variable rates of granular (Temik 15G) and fumigant (Telone II) nematicides to appropriate management zones. Our work has shown a 78% reduction in Telone II and 34% reduction in Temik use with the variable-rate nematicide application compared to uniform application rate. South Carolina farmers annually apply about 800,000 kg Temik to cotton fields. Even a 20% reduction in nematicide use will save over $1 million to our cotton growers. Funded by EPA (Region 4) and NRCS, we have equipped six growers with SNP technology in geographically diverse areas of South Carolina.
Space-Based Moisture Sensors
Tests were conducted to determine soil moisture content and sensing depth utilizing NASA's (Langley Research Center, Hampton, VA) GPS-based sensor technology, and to determine surface ponding depth (depth of runoff) for both pervious soils (field) and impervious cover (asphalt). A 30-ft boom (tower) with a platform for installing the zenith RHCP and the nadir LHCP antennas was constructed and was equipped with a three-point-hitch attachment system for mounting on a tractor. Our results showed that the space-based technology has a great potential for determining hydrologic properties of watersheds (such as soil moisture contents) in the pursuit of eliminating the source of pollution. There were strong correlations between the GPS reflectivity measurements and soil moisture contents.
Technology for Variable-Depth Tillage in Coastal Plain Soils
Nationwide farmers are losing over $1 billion in crop revenues every year due to soil compaction. Reduction of losses due to soil compaction by one percent nationally could result in an additional $100 million in crop revenue. The objective of this work is to develop the technologies, principles, and concepts of site-specific management of soil compaction in coastal plain soils. This project has developed an instrumented shank for measuring soil compaction at multiple depths over the entire top 18 in of the soil profile while moving through the soil. In addition, GPS-based equipment for controlling the tillage depth to match soil physical parameters has been developed. With this system, tillage depth can be changed from zero to 18 in "on the go." Results of this work will provide a realistic estimate of the viability of site-specific farming for enhancing current soil compaction management practices for increased profit. Variable depth tillage reduced the energy requirements by 56% and fuel consumptions by 34%. More than 80% of row crops in South Carolina are produced in fields with soil compaction problems. All of these acres have potential to be more profitably managed using site-specific tillage than with conventional uniform-depth tillage operations.
Variable Rate Application of Herbicides
The results of this project will reduce the threat of environmental contamination from soil-applied herbicides and reduce the threat of crop injury. It will provide clear evidence that inexpensive geo-referenced soil maps can be produced from which soil-applied herbicides can be properly matched to changes in soil texture. In addition, this research will significantly reduce soil-applied herbicide usage by establishing biological effective rates that provide early-season residual control, rather than the standard preferential use of rates that provide season-long weed control. As a result of this project, an inexpensive, site-specific, variable-rate system has been developed that can be retrofitted to grower's current planting and/or application equipment.
Variable- rate overhead irrigation system
Crops in the Southern United States are generally produced in fields which are known to have a high degree of variability in soil type and other major factors which affect crop production. Therefore, conventional uniform-rate overhead irrigation systems tend to over-apply or under-apply water to the crop. VRI is an innovative technology that enables an overhead irrigation system to match field variability with an appropriately variable irrigation application, differentially applying irrigation water to match the needs of individual management zones within a field. It can lead to substantial water conservation while increasing crop yields. A variable-rate irrigation (VRI) system was developed at Clemson which can acquire information from various sensors for site-specific application of water. This system is able to monitor and apply water based on the actual soil moisture content, pan evaporation data, or the U.S. Climate Reference Network (CRN) data. Information from the moisture sensors, evaporation pan and CRN is acquired using wireless technology. A map-based computer program controls the amount of water applied in each section based on irrigation requirements. A GPS receiver is used to determine the position of the lateral irrigation system in the field. Variable-rate speed control system allows the lateral irrigation system to move quickly over wet spots and slow down over dry spots. The irrigation pump was retro-fitted with a variable speed drive in order to maintain constant line pressure. It was found that energy savings of up to 52% can be achieved with the variable rate irrigation system. Supported by NRCS, we have installed six variable-rate irrigation systems on farmers' center pivots in Orangeburg, Darlington, and Calhoun, Barnwell, Bamberg, and Hampton counties.