Agronomy Update July 2019
Posted by Dave Dyson, Agronomist on July 18, 2019
MANAGEMENT
By Dave Dyson, Agronomist
The excessive rain this spring and late planting dates, combined with increased participation in crop insurance, are creating a unique situation. On average, the U.S. has around 3 million acres declared prevent planting per season. According to The Andersons Trade Group, this year’s projections are around 8-10 million acres, but nothing final has been communicated yet. To prepare for the 2020 cropping year, we have to make some decisions on what to do with these 8-10 million acres that have been left idle this year.
By leaving a field idle with no crops planted, weeds have free range to grow and set seed if nothing is done to avoid it. Allowing the weeds to set seed will increase the weed seed bank of the field, doing nothing positive for future crop cultivation. Everyone has differing opinions on how to keep the weeds at bay for the rest of the growing season. The first reaction may be to work the idle ground. This is a short term remedy because once the ground is worked, weeds will begin germinating within a week. Additionally, excessive tillage can cause runoff, erosion, and destruction of soil structure which may lead to soil compaction (Figures 1 and 2).
Figure 1: Compacted soil caused by excessive tillage.
Figure 2: Compacted soil causing the corn roots to stay in the upper 2 inches.
The second option to control weed populations is the application of herbicides during the summer season. While this can be an effective method, it can also be expensive. If you choose to apply herbicides, beware of overusing non-selective herbicides such as glyphosate or glufosinate. If weeds are not resistant to either product yet, they might become resistant after multiple applications during the season. Glyphosate-resistant marestail can be a nightmare to kill once it achieves any height over three inches. A dicamba application in July may not be the best idea because drift can cause severe issues to surrounding soybeans (Figure 3). Choosing a residual herbicide may cost more upfront, but may prevent resistance issues in the near future.
Figure 3: Soybean field affected by dicamba drift.
The third option is a combination of the first two methods with a cover crop. If an herbicide application can successfully wipe the field clean of weeds, then start with applying an herbicide. If you have herbicide-resistant weeds, a tillage pass may be required. Once you have a clean field, I recommend planting a cover crop. When a cover crop is established, the field will benefit from canopy closure, shading out troublesome weeds and preventing others from germinating. Cover crops can become a catch crop to absorb and retain nutrients throughout the summer. Once the cover crop dies it will release nutrients back into the soil. Cover crops have additional benefits of feeding soil microbes with root sugars, thereby increasing nutrient cycling for a future cash crop, increasing soil tilth and soil organic matter, and creating pore space for air and water infiltration. They also hold the soil in place and prevent water and wind erosion.
In any of the above three scenarios, an application of UltraMate® LQ or Fulvic LQ™ will help bring life into soils, which will better prepare prevent plant acres for profitability next year. When applying herbicide, adding UltraMate LQ or Fulvic LQ will provide carbon to the soil. This carbon will then feed the soil microbial population. In doing this, the weed residue will decompose quicker, allowing for more efficient nutrient cycling. The application of UltraMate LQ or Fulvic LQ will also benefit cover crop populations by increasing nutrient availability in the soil profile. Providing carbon to the soil is essential for overall soil health, even on prevent plant acres.
Effectively managing prevent plant acres through burndown applications, cover crops, and soil health strategies this year will greatly influence the yield potential of next season’s crop.
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