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Fluid Journal : Winter 2014
14 The Fluid Journal Winter 2014 Nitrogen is not uniformly utilized in the field in the Southeastern United States due to high variability in soil texture. Application of N at one rate over the entire field is not effective and may decrease environmental quality. Standard procedures for N application on corn, based on soil spatial variability, are not available for the Coastal Plain soils. Determination of the extent to which the crop will respond to additional N as side-dressing can help growers to apply only what is needed. Numerous studies have shown high correlations between vegetation indices and crop yields. Plant normalized difference vegetation index (NDVI), defined as NIR-Red/ NIR+Red, is used for mapping plant growth. The Red and NIR values represent the reflectance in the Red and NIR bands, respectively. Higher positive NDVI values indicate increasing proportion of green vegetation. The Fluid Journal • Official Journal of the Fluid Fertilizer Foundation • Winter 2014 • Vol. 22, No. 1, Issue #83 Dr. Pawel Wiatrak Clemson algorithm successfully used in Southeastern Coastal Plains. Summary: High nitrogen (N) rates are often not fully utilized under dryland corn production systems and may lead to environmental pollution, especially in sandy and less productive soils. Significantly higher corn grain yields were obtained from split applications than from all-at-plant N applications, and higher from 160 lbs/A of N when compared to other treatments. Plant normalized difference vegetation index (NDVI), N content in corn leaves, test and grain weight, and grain N content generally improved with higher N rates. Higher soil nitrate-N concentration was recorded from zones 2 and 3 than from zone 1. The predicted sidedress rate of 90 lbs/A of N, using Clemson algorithm, was 30 lbs/A N less than fixed rate and did not significantly reduce yields compared to fixed N rate. Therefore, Clemson algorithm can be successfully used in improving N use efficiency (NUE) of dryland corn in the Southeastern Coastal Plains. The algorithm for predicting N requirements in corn grown in the Southeast has to take into account the soil spatial-variability due to high variability in soil texture. A commercially available soil electrical conductivity (EC) measurement system (Veris Technologies 3100) can help to identify variations in soil texture across the field and create soil EC zone maps using global position systems (GPS) and geographic information systems (GIS). The main objective of this project was to evaluate application methods, rates, and Clemson N algorithm on corn under different soil electrical conductivity (EC) zones to improve NUE and yields of corn. Methodology Soil/location. The study was conducted on Dothan loamy sand (fine loamy, kaolinitic, thermic Plinthic Kandiudult) in a production field at Clemson University, Edisto Research and Education Center (REC) near Blackville, SC in 2012. Winter wheat cover crop was killed in early spring. The experimental area was divided into four soil texture zones, based on soil electrical (EC) conductivity measurements, which were derived from Veris system measurements (Veris Technologies 3100), global positioning system (GPS), and geographic informational system (GIS). Soil zone 1 (lowest soil EC readings) was very sandy with low water and nutrient-holding capacity and soil zone 4 (highest soil EC reading) was mostly clay with high-water and nutrient-holding capacity in this experiment. Three (1- 3) zones were used for analyses. N rates. Each soil EC zone consisted of two N application N Use Efficiency Improved On Dryland Corn “Significantly higher N concentration was recorded. ” ▼ DOWNLOAD