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Fluid Journal : Fluid Journal 2005-2007
SPRING 2007 Fluid Journal 15 7,900 7,700 7,500 7,300 7,100 6,900 6,700 6,500 Yield lbs/A N - lbs/A 0 112 134 112 134 Surface Injected plants are supplied with half of ammonium and half nitrate. As almost all N fertilizer is usually completely transformed to nitrate by soil microorganisms after surface application and during passage through the soil to the plant root, this situation can hardly be achieved under field conditions with common fertilization strategies based on surface application. Under open field conditions, injection of ammonium and urea solutions opens the possibility to shift N nutrition of the crops toward the physiologically ideal ammonium/nitrate ratio. Agronomical aspects Winter rye. With conventional spraying of UAN + ammonium thiosulfate at 134 lbs/A of N (150 kg N/ha), yield of winter rye on a sandy loam was 7,300 lbs/A (8.2 tonnes/ha) as shown in Figure 1. A single injection of the same amount of UAN resulted in a 6 N - lbs/A Yield bu/A Surface Injected 165 150 135 120 105 90 75 60 0 94 134 179 134 Figure 1. Yield and grain quality of winter rye after surface spraying and injecting UAN plus thiosulfate, Lindau, Germany, 2001. percent yield increase, and even a UAN injection of 112 lbs/A of N (125 kg N/ha) gave a higher yield than 134 lbs/A of N (150 kg N/ha) conventionally applied. As a result of the higher stem stability, lodging in the injection plots was about half of that in the conventionally fertilized plots, and N-use efficiency was doubled after UAN injection in this experiment. Winter wheat. In another experiment on a silt loam soil, injection of UAN to winter wheat was compared with three conventional split surface fertilizations with solid urea (Figure 2). Two amounts of 94 and 134 lbs/A of N (105 and 150 kg N/ha) were chosen when the trial was established, but injection of the lower rate failed due to technical problems. On the other hand, a lack of N was recorded in May in the surrounding field and the farmer decided to apply an additional 45 lbs/A of N (50 kg N/ha). Injection ofUANat134lbs/AofN(150kg N/ha) resulted in a 26 percent yield increase compared to the conventional surface fertilization. This yield was almost the same as that harvested in the surrounding field receiving the additional 45 lbs/ A of N (50 kg N/ha). Grain quality (%N and protein) was slightly better than after conventional fertilization. Such clear yield increases were not recorded in all experiments and locations in the following years, due to technical problems, summer drought, and floods. Winter wheat yields were recorded over six years in a water protection area in southern Germany, where UAN injection was used as an instrument to decrease the nitrate content in the ground water by minimizing nitrate leaching from arable land. After injection fertilization over the six-year span, a yield increase of 9 bu/A (0.6 tonnes/ha) was recorded. Protein content over five Figure 2. Yield and grain quality of winter wheat after surface application of solid urea and injecting UAN, Ohrum, Germany, 2001.
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