Wet Spring Concerns
It is difficult to wait: the calendar is ticking and you have corn to plant. However, with wet soil conditions in many areas, doing tillage and planting before soils are fit can have many negative impacts now through harvest. In addition to increased risk of seedling diseases, compaction from tillage and traffic, sidewall compaction, and restricted root growth are some of the common problems caused by working and planting when soils are too wet.
Compaction from Tillage and Traffic
Wet soils in the spring are very susceptible to compaction. Disking or field cultivating fields before they are fit can lead to a compaction layer just below the depth of tillage. The weight of tractors used in tillage or planting can also cause a compaction layer just a few inches below the soil surface. This type of compaction leads to shallow root systems since they cannot penetrate the compaction layer.
Sidewall Compaction
Sidewall compaction occurs when furrow sidewalls are smeared by the combination of double-disc openers and gauge wheels of the planter. This can cause poor seed to soil contact, which has several negative consequences including reduced germination and poor stands, and uneven emergence. When emergence is uneven, larger plants compete with smaller plants for light, water, and nutrients. The smaller plants are effectively weeds because they have little yield potential, resulting in lower overall yields at harvest.
Symptoms of Compaction
Above ground symptoms often include stunted plants, leaves with premature yellowing or death, or wilted or curled leaves. These symptoms are attributed to the root system not being able to access the moisture and nutrients, even if they are in ample supply. Below ground symptoms are smaller root systems that appear abnormal when they grow around the compaction layer to follow the path of least resistance (Figure 1). Compaction symptoms can be similar to those from other issues such as herbicide carryover, fertilizer deficiency, or insect damage. Look for patterns to help determine the actual cause of the symptoms.
Restriction of Roots
Root growth is reduced not only because of compaction but also because of low soil oxygen availability. Nutrient deficiencies such as potassium and nitrogen may occur due to slow root growth and poor root exploration. Restricted root development can also increase lodging and have a negative impact on yield, especially if the latter half of the growing season is hot and dry.
Yield Impact
During years when adequate water and nutrients are available, compaction usually will not impact grain yield. When the crop is water or nutrient stressed, compaction can reduce
yield by up to 50%. Keep in mind the impact wet planting can have on corn development as you decide when to enter your fields for planting or scouting this spring. For more information regarding planting issues, please contact your local Border States Agronomist.
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