Imagine our surprise as we weighed these trials and the treatments with the zinc added did not rise to the top. Once again the treatment of 10-34-0 was the highest yielding. This goes against what the plant was telling us in mid-August and early September. We believe that the zinc and additives present us with a sense that we have the ability to set more pods by presenting more nodes and branches but that the plant can only support a set amount of yield. The additional P is getting us to our set yield potential and the zinc and additives are not providing us with additional yield because of the amount of time needed to process the zinc. Should we push the zinc earlier in the plant and then provide additional P later in the growing season? Certainly we feel that is what we are seeing after two years of this trial. The yield data in Figure 7, shows how yields compared when we weighed the trials. Although we had a buffer along the tree line, we feel that the treatment with Boost was lower than expected due to the competition with the trees for moisture throughout the growing season, especially in August and September. While the addition of zinc and Terramar still provided a positive ROI why should you put on products that are not going to improve yield overall. We feel that the consistency of the 10-34-0 treatment over two years has been really good even with the change of timing. Next year we plan on testing the timing of application, along with rates to help dial in what the best rate should be. Many have asked if we would see results with a Y drop application. This will be addressed with another trial later in this book. We assume, because of the immobility of P that it will be best when applied near the plants roots.
4 gal 10-34-0 + Zn
4 gal 10-34-0 + Zn + Terramar
4 gal 10-34-0 + Zn + Boost
Check
4 gal 10-34-0
Yield 13.0
83.6
88.6
85.9
87.3
84.1
Difference from check
5.0
2.4
3.7
0.6
Product Cost Grain Price
$20.09 $14.48 $72.71
$24.28 $14.48 $34.22
$32.65 $14.48 $54.00
$28.03 $14.48 $8.16
Revenue Change
Net Revenue
$52.62
$9.94
$21.35
-$19.87
ROI
262
41
65
-71
Figure 7. Soybean Side-dress trial yield results.
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