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Fluid Journal : Fluid Journal 2005-2007
14 Fluid Journal SPRING 2007 DR. MARTIN KUECKE In the USA and Canada, injection of liquid fertilizers has been used dating back more than 30 years and injection equipment is well developed. Four advantages generally recognized via the injection of fluids are: 1) achieving efficient use of nutrients from plant emergence to maturity, 2) preventing or reducing any harmful effects on the environment, 3) avoiding fertilizer-induced salt injury to plants, and 4) providing a convenient and economical operation for farmers and /or custom fertilizer applicators. While research in the USA and Canada focuses mainly on higher fertilization efficiency by minimizing nutrient losses, the basic idea of the cropping studies carried out at our experimental farm at the Federal Agricultural Research Centre in Braunschweig, Germany, is to use a system called "controlled uptake long-term ammonium nutrition" or CULTAN. This can be achieved by placing N solution containing either ammonium or N forms that are transferred to ammonium (urea). The soil at the injection spot or in the fertilizer band, termed a "depot," is saturated with the fertilizer solution and the ammonium concentration is toxic for plant roots and soil micro- organisms. Due to this toxicity, the ammonium is slowly nitrified to nitrate and remains fairly stable in the hotspots due to the absorption of the ammonium ions by the soil. Part of the crops' roots creates a dense network of fine roots in the diffusion zone around the ammonium hotspots, and the crops can take up N from this diffusion zone as ammonium before it is nitrified. Most growth experiments show highest biomass production and yield formation in systems where Fluids Prosper In German Agriculture Impressive experimental results are reported for potatoes, vegetables, cereals, and maize. SUMMARY The major fluid fertilizers used in Germany for injection are urea ammonium nitrate solution (UAN), urea ammonium solution, and ammonium sulfate solution. Good experimental results have been reported for potatoes and vegetables, as well as for cereals and maize. Sugar beet yields and quality after fluid injection are usually comparable to those after conventional surface application. Experimental datum for grassland is still lacking. Only a few contractors offer fertilizer injection services in Germany, but the interest of farmers, the scientific community, and the public is increasing as the environmental advantages become apparent.
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