Soybeans have among the highest nitrogen (N) demands of agronomic crops due to a high concentration of protein in the seed. Symbiotic fixation supplies about half of the plant’s N needs, and the remainder comes from the soil and/or fertilizer.
Despite their high demand for N, soybeans have historically received little or no N fertilizer. However, some studies have indicated that fixed N alone may not be sufficient to supply the N required to produce maximum yields. In fact, adequate N2-fixing capacity of soybeans declines rapidly after the R5 stage, which coincides with the peak soybean N demand for protein synthesis in seeds.
To better understand the potential for increased soybean productivity by using additional N, DuPont Pioneer conducted research trials to determine soybean yield response to late-season N applications.
An iron deficiency can also hinder soybean productivity. Soybean iron deficiency chlorosis (IDC) is a nutrient deficiency disorder with symptoms that include chlorosis (yellowing) of the soybean foliage and stunting of the plant. This condition is yield-limiting in many soybean fields in the northern and western Corn Belt as well as parts of the southern U.S. Because soybean varieties vary widely in tolerance to IDC, variety selection is the first and most important step in managing this problem.
DuPont Pioneer conducted a study to determine if an in-furrow application of an iron chelate treatment at planting would help to mitigate IDC symptoms at 11 locations with a history of IDC in Nebraska and Kansas. Results showed that several soybean varieties with a range of IDC tolerance scores had a positive yield response to the iron chelate treatment (Figure 3). Visual differences, such as greener and more robust plants, were noted as well.
In another study, DuPont Pioneer and Auburn University investigated the use of a wheat cover crop to manage IDC on high pH soils in the Black Belt Region of Alabama.
Results from this 2012 study showed that using a cover crop increased yield of several soybean varieties that had a range of IDC tolerance scores. In fact, a cover crop increased the yield of the most IDC sensitive variety by 45 bu/acre. Other varieties showed yield increases ranging from 20 to 31 bu/acre in response to a cover crop (Figure 4).
Always follow grain marketing, stewardship practices and pesticide label directions. Varieties with the Glyphosate Tolerant trait (including those designated by the letter “R” in the product number) contain genes that confer tolerance to glyphosate herbicides. Glyphosate herbicides will kill crops that are not tolerant to glyphosate.
|Varieties with the DuPont™ STS® gene (STS) are tolerant to certain SU (sulfonylurea) herbicides. This technology allows post-emergent applications of DuPont™ Synchrony® XP and DuPont™ Classic® herbicides without crop injury or stress (see herbicide product labels). NOTE: A soybean variety with a herbicide tolerant trait does not confer tolerance to all herbicides. Spraying herbicides not labeled for a specific soybean variety will result in severe plant injury or plant death. Always read and follow herbicide label directions and precautions for use. DuPont™, STS®, Synchrony® XP and Classic® are trademarks or registered trademarks of DuPont or its affiliates.|