While planting season is well underway in the southern half of the U.S., a cold and wet spring has many farmers in more northern states playing a waiting game. In the USDA’s Crop Progress report released Monday, April 25, 7% of the nation’s corn crop and 3% of the soybeans were in the ground. These numbers indicate a slower start to planting, as the five-year average for planting progress at this same time point is 15% for corn and 5% for soybeans.
Now that the calendar page has turned to May, more farmers may be itching to get into the fields. Trends from the past few decades show that more early planting is taking place, but Michigan State University (MSU) Extension’s Manni Singh recommends that farmers pay closer attention to field conditions rather than the calendar date.
When determining the time to plant, Singh said the number one factor to consider is soil moisture. “That is very critical,” the cropping systems agronomist noted during a MSU Field Crops Virtual Breakfast webinar. “You do not want to be working the ground when it is wet.”
Planting into wet ground can have both short-term and long-term consequences. For the current growing season, it can cause non-ideal seed placement and poor seed to soil contact, which affects the plant’s ability to take up nutrients. There is also the potential loss of yield.
Down the road, this field activity can cause compaction. Singh shared that the risk of compaction is greater when the soil moisture is closer to the field’s maximum capacity. Soil texture also plays a role.
To see if a field is at the right moisture for planting, Singh said to grab a handful of soil at planting depth, about 1 to 2 inches deep. If a ball forms, the soil is too wet. If it crumbles, that means planting can proceed.
Singh said the second equally important factor is soil temperature. He recommended waiting for soil temperatures to be 45°F to 50°F and rising, along with a favorable forecast, before planting. New seed genetics provide more options and lower temperature thresholds for planting, but he said to still proceed with caution.
A risk to seeds planted into cold soil is called imbibitional chilling injury. Singh said this happens when a seed takes its first “sip” of water and it’s too cold, which can cause disruption in cell growth and development. This may lead to slow emergence and uneven plant stands. Other dangers of early planting are freeze damage to emerged plants and insurance coverage limitations.
He said that planting time does impact yield, especially in states such as Michigan that have a shorter growing season. However, the yield decline from delayed planting is not consistent. In Michigan, research indicates that optimal soybean planting begins at the end of April, but Singh noted that soybeans seeded in mid to late May can still result in high yield when planted in the right soil conditions.
If planting early, Singh said to target feeds that have good drainage. There may be some management factors, such as seeding rate and row spacing, that can also help improve yield if planting time is delayed. The overall goal is to minimize risks and maximize the potential rewards by planting when the fields are ready.
“Plant in good conditions, because planting in marginal soil conditions can limit yield now and have longer term implications,” Singh reminded.