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Fluid Journal : Fluid Journal 1993-1995
3 Fluid Journal Fall 1995 Figure 4. Effect of N placement on corn yield in three tillage systems, Griffith et al. , Purdue University, 1974. Broadcast Inject 140 135 130 125 120 115 100 Yields - bu/A Plow Chisel Tillage System No-till additives such as NBPT may help improve N efficiency. A recent multi- location study in Indiana that compared lower-power-demanding , less- soil- disturbing methods with subsurface methods of applying N in no-till corn is shown in Figure 5. Note all of the alternatives were more effective than surface broadcast. Note also that the most effective method of N placement was deep injection. All plots received 25 Ibs/A as starter and 100 lbs/A of N sidedressed. Timing. As was noted earlier, N placement is especially sensitive to timing. Increased water infiltration and reduced evaporation from increased surface residue can increase N leaching and denitrification and affect crop performance. Coarse-textured soils and irrigation can also increase potential N loss. This is where timing comes in. Research has shown that waiting until after plant emergence to soil test for N need opens the door to better timing of N applications. N is put in the soil at the optimum moment the plant needs it, thus improving N-use efficiency. End result: better yields. Dr. Lohry is agronomist for Nutra-Flo Company in Sioux City, lowa. !
Fluid Journal 1996-1998