It has been a wet spring in many farming areas. While it dried up (and warmed up) a bit this week – giving growers a small window of opportunity for planting – there is more rain to come this weekend in much of Eastern Canada. And so, many growers are continuing to experience wet or saturated soil conditions. This begs the questions: Do I plant now? Or wait for drier fields? How dry does my soil really need to be? Is there anything I can do to plant sooner but mitigate the risks posed by wet soil?

With wet or saturated soils, planting early is probably unwise, especially while cooler temperatures are still possible – and even planting “on time” this year merits careful weighing of your risks versus waiting for drier field conditions.

Reduced Emergence and Seedling Mortality

Planting corn or soybeans into wet or saturated soils can increase your risk of seedling mortality, poor germination, and reduced emergence. This is especially true in wet clay soils – after you plant your soybean seed, the top layer can dry out and form a hard crust that can damage or even break off the soybean cotyledons or corn seedlings as they try to push their way out of the ground.  If your corn or soybeans do manage to push their way out of the ground, you may still see side effects of soil saturation, such as plant growth restriction and decreased oxygen availability to the plant. Saturated soils can inhibit root growth, leaf area expansion, and the photosynthetic process.

If you do decide to go ahead and plant while the soil is still wet, it can help to adjust your seeding rate and depth – more shallow seed placement to improve chances of emergence, and an increased seeding rate to allow for higher mortality.

Sidewall Compaction

Working a wet field can cause soil compaction, including sidewall compaction along the furrows, especially if the soil then dries out after planting. If the furrows dry out, the roots can have trouble pushing out through the furrow wall. Instead, the roots tend to grow along the furrow wall, resulting in sidewall compaction. Soil specialist DeAnn Presley of Kansas State University Research and Extension said: “With corn, the plants might look fine for a while, but the symptoms of this problem will probably show up after the plants get to be several inches tall. Symptoms will look like drought stress, nutrient deficiency or both.”

Once you have a problem with sidewall compaction, you can’t fix it, so it is best to avoid the issue in the first place by waiting for drier soil before planting. “If [the soil at the desired planting depth] crumbles, it’s ready to plant. If it deforms, it would be best to wait before resuming field operations. Even waiting as little as half a day could make a big difference,” Presley said.

PROSeeds - Plowed Field in spring

Image credit: suteishi / iStock / Getty Images Plus 656760850

Tillage

As we mentioned in our previous blog post, “Is Your Soil Ready for #Plant17?”, not only should you try to avoid planting in soggy conditions, it’s also important to avoid pre-plant tillage when the soil is wet. If you till when the soil is wet, you can end up with compacted soil below the tillage depth, as well as a “cloddy seedbed that reduces seed-to-soil contact.” Planting no-till on wet fields can also result in poor seed-to-soil contact. Corn & Soybean Digest noted that one of the key factors for successful corn planting is excellent seed-to-soil contact, which “is essential for rapid and uniform imbibition of moisture by seeds and uniform emergence.”

After Emergence

After emergence, how will soybeans respond to standing water and saturated soil

0 conditions? If soybean plants are submerged for less than 48 hours, there is a good chance they will survive, especially in cooler water. You can check for damage after the water recedes by splitting the tip of the stem: of the growing point is firm and white or cream coloured, it is healthy; if it is soft and dark, it is injured. Ignacio Ciampitti, Crop Production Specialist at Kansas State University Extension mentions: “In some cases, the silt coating the plant after short-term flooding can cause more injury and plant death than the water itself.”

He also notes that even if only the roots are flooded, there can still be damage: “When soils are saturated for a prolonged period of time, a lack of oxygen in the roots can lead to the accumulation of lactic acid and other products of anaerobic respiration.“ His article on “Soybean Response to Standing Water and Saturated Soils” is a great source of information on the impact of waterlogged soils on soybeans in various stages of growth, and from different durations of saturation.

Diseases that Like Wet Conditions

While unpredictable, there are a number of diseases that like it wet, including phytophthora root rot, fusarium, Pythium, and rhizoctonia. If you are seeding into wet conditions and are concerned about the potential for these diseases to flourish, consider applying a fungicide. This needs to be done pre-emergence, within the first 2-3 weeks after seeding, to be effective, and only protects your crop up until the early leaf stages.

Spreading Out the Risk

Cassandra Tkachuk of Manitoba Pulse and Soybean Growers (MPSG) notes that the window of opportunity for planting soybeans is much longer than originally thought (based on her research into soil temperature and planting date effects on soybeans in Manitoba). As a result, she recommends that growers not plant all their seed at the same time. Spread out the risk by spreading out your planting dates.

 

While early planting can lead to higher yields, the risks of cool, wet soil or even overnight frost may outweigh the potential benefit. Planting a week or two later, into warmer, dryer soil, can still deliver good yield. If you do decide to delay planting to wait for drier conditions, you may want to consider switching from late-maturity to early-maturity soybean varieties and corn hybrids.  While long-season varieties have a higher yield potential, they also typically have a greater yield penalty related to late planting. By contrast, short-season varieties usually yield less than long-season varieties when planted early, but offer a similar yield when planted mid- to late-planting season.

Contact your PROSeeds Regional Sales Manager for advice on soybean varieties and corn hybrids suitable for your soil conditions and target planting date.

 

Feature image credit: igorbondarenko / iStock / Getty Images Plus 685293426

 

Resources:

Planting Soybeans into Wet, Cold Soil? Maybe Wait a Bit! http://www.northstargenetics.com/ca/2017/05/02/planting-soybeans-into-wet-cold-soil-maybe-wait-a-bit/  (May 2017)

Planting Corn or Soybeans Into Wet Soils Can Cause Sidewall Compaction:
http://www.cornandsoybeandigest.com/seed/planting-corn-or-soybeans-wet-soils-can-cause-sidewall-compaction (2011)

Soybean Response to Standing Water and Saturated Soils: https://www.no-tillfarmer.com/articles/5727-soybean-response-to-standing-water-and-saturated-soils (May 2016)

Corn and Soybean Planting when it is Cold and Wet: http://blog-crop-news.extension.umn.edu/2017/05/corn-and-soybean-planting-when-it-is.html (May 2017)

Plant Corn and Soybeans by Soil Temperature and Conditions, Not According to the Calendar:
http://www.aganytime.com/Corn/Pages/Article.aspx?article=106

Planting corn in wet conditions – is it worth it?
http://msue.anr.msu.edu/news/planting_corn_in_wet_conditions_is_it_worth_it (May 2016)