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Fluid Journal : Summer 2015
Dr. Longchamps is an Assistant Professor and Dr. Khosla is Professor of Precision Agriculture at Colorado State University in Ft. Collins, Colorado. Dataset. When dividing the dataset in lower and higher yield based on yield average, it was possible to observe a higher optimal plant population for the higher yield dataset than for the lower yield dataset (Figure 3). For the lower yield dataset, the optimal plant population was 37,500 plants per acre with a maximal modeled yield of 159 bu/A. For the higher yield dataset, the optimal plant population was 40,550 plants per acre with a maximal modeled yield of 172 bu/A. The results are consistent with observations of Doerge, et al. (2015) who observed an increase in optimum economic seeding rate with increasing local yield potential. Student’s t-test. As per Student’s t-test, several soil properties were significantly different between the locations of the lower yield level and the locations of the higher level (data not presented). In general, soil properties in the higher yield locations tended to indicate a more fertile soil (e.g., higher organic matter and phosphorus content, higher CEC, etc. in the higher yield locations). However, even though Student’s t-test p-values showed strong significant differences between the two classes, in an agronomic perspective, the 0 10000 20000 30000 40000 50000 60000 050100150200 Plant population (plants/ac) Yield(bu/ac) G G G G G G GG G G G G G GGG GGG G G G G GG G G G GG G G G G GG G G G G G G GG GG G G GG G GG G G G G GG GG G G G GGGG G G G G G G G G G G G GGG G G G G GGG G G GG GGGG G G G G GGGGG G G G GGG G GG G G G G GG GGGGGG GG G G G G G G G G GG G GG G G GG G GG G GG G G G GG GG GG GGGG G GGG G G GGG G G G GGGGGGG GG GG G G G GG G G G G GG GG GG G G G G G G G G G G G G G G G G G G G G G G G GG G G G GGGG G GG GG GG GG GG G GG G G G GG GGG G G G G GG G G G G GGG GG GG GG GG G G GG G GGG G G GG GGG GGG G GGG GG GG GG G G G G G G GGG G G G G G GGG G GG G GGGG G G G GGG GG GG G G G GG G G G G G G G G G G GG GG G G G G G GGG G GGG GG G G G GGG GGG G GG G G GGGG G G G G GG G G G G G G G G G G GG GG G G G G Higher yield Lower yield Figure 3. Relationships between plant population and yield for two yield classes (lower or higher than yield average). Vertical lines indicate optimal plant population for each yield class. The Fluid Journal, flagship publication of the Fluid Fertilizer Foundation (FFF), makes over two decades of archives available on its web site. The magazine investigates and informs its readers on innovative uses of fluid fertilizers under varied cultural, pest control, and water management practices, focusing on evaluating: • the agronomics of fluid fertilizer in the production of maximum economic crop yields • application techniques for fluid fertilizers • the efficiencies and conveniences of fluid fertilizer systems • methods of controlling environmental problems with fluids. Going on Twenty-Two Years of Archives! Since its formation, the FFF has funded over $3 million in fluid fertilizer research and accumulated thousands of pages of research data. The main goal of the Fluid Journal is to transfer this technical information into easy-to-read form to its farmers and dealers. The Fluid Journal also provides links to its articles on Twitter: http://www.twitter.com/fluidjournal For information on how to become a member of the FFF, contact the foundation’s office at 785/776-0273 or the foundation’s website: http://www.fluidfertilizer.com differences are not considered very strong. Nevertheless, a synergetic combination of all these factors may have explained the higher yield obtained in these locations and hence the potential to reach higher yield with higher seed rate. Summing up Variable seed rate stands as a potent way to manage spatial variability in soil properties existing at field scale. This study showed that the relationship between plant population and yield follows a quadratic function where an optimal plant population can be applied to reach maximum yield. A higher level of fertility such as higher phosphorous or high organic matter content can potentially indicate a higher optimal seed rate.