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Planting Considerations for a Late Spring

Updated September 12, 2019
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Ruth Beck

SDSU Extension Agronomy Field Specialist

Written collaboratively by Ruth Beck and Dwayne Beck.

Farm fields in some areas are unusually wet this year with many low areas under water. These conditions will make planting a challenge for farmers this year.

Crop Rotation

In anticipation of a late spring, many farmers are already shifting some acres from crops like wheat, oats and peas that are typically planted in early April, to other crops that favor later planting dates, such as corn, soybeans and sunflowers. Small grain producers may also consider seeding a cover or forage crops in lieu of the cool-season grain crop. It is possible to grow two forage crops in one season in most areas. This can take advantage of the improved moisture conditions this year. This might be preferable to totally changing crop types which also means changing the rotation. Careful consideration is necessary when crop rotation changes are being made. Changing the rotation can have consequences for several years due to impacts this has on residue levels and weed, disease, and insect spectrum.

Cool-Season Crops

The ideal planting window for spring wheat, oats and peas is thought to be the first three weeks of April or earlier if planting conditions are favorable. Spring wheat, oats and peas are all cool season crops that will germinate at lower soil temperatures (35-40 deg. F) and can survive moderate frost at early stages of growth. Planting these crops as early as possible promotes plant development before the warmer period of the summer. Heat and water stress can negatively impact yield of these crops, especially if this occurs during pollination and grain fill. Yield data from research on spring wheat suggests that wheat loses 1.5% of its yield potential every day after the optimum planting date. However, situations where there is ample moisture at seeding might temper this negative response, especially if cool weather prevails during the early summer.

Selection of early season varieties can also help producers still committed to these early crops due to fall herbicide applications or crop rotation restrictions. Earlier varieties can improve the chance of avoiding mid and late summer heat during sensitive growth stages. If planting spring wheat later than usual, a heavier planting rate is generally recommended to compensate for reduced tiller development.

Corn

Soil temperatures need to be warmer for corn planting. Fifty degrees Fahrenheit is usually what is required for corn to germinate. Typically corn planting begins in late April and can run through May or longer, if conditions are not conducive for planting. Delayed planting reduces the number of growing degree units accumulated during the season. Corn that does not receive the required heat to mature properly will result in a product with low test weight, poor quality and increased drying costs. If planting is delayed producers should consider planting early maturing varieties to avoid these issues. Producers can be proactive by working with seed dealers to select corn varieties with a range of maturities. This will help reduce risk.

Soybeans

Soybeans require warmer soil temperatures (54 deg F) for germination. If drying conditions prevail this spring and soybean planting is timely, selecting a soybean variety with the appropriate maturity rating for the growing area provides the best chance to achieve the highest yield. If planting dates for soybeans are delayed past mid-June, the maturity rating for soybean seed should be reduced by 0.5 from normal. A further reduction in maturity rating may be required if planting date is delayed until early July.

Planting Deadlines

Producers should check with their crop insurance agent for planting date deadlines.

References:

  • Kleinjan, J., When is it Too Late to Plant Wheat?
  • Hall, Robert G., K. Reitsma, D. E. Clay. 2009. Corn Planting Guide. In iGrow Corn: Best Management Practices for Corn Production in South Dakota. South Dakota State University, SDSU Extension, Brookings, SD.
  • Mueller, N., C. G. Carlson, R. Hall. 2013. Selecting Soybean Varieties. In iGrow Soybeans: Best Management Practices for Soybean Production in South Dakota. South Dakota State University, SDSU Extension, Brookings, SD.