Tips to Consider When Planting Soybeans Early

Planting soybeans early is not a new idea to most Michigan farmers. The number of frost-free days in Michigan continues to increase. In fact there are now about two weeks more frost-free days than there were 40 years ago, which allows some opportunities to plant crops earlier than the historical average. While the growing season is now extended, the amount of precipitation is also increasing, which creates more days of being rained out of the field. These facts are pressing farmers to utilize all opportunities to get crops planted at the best date possible to optimize yields. Although soil conditions sometimes allow early planting, soil temperatures are not always warm enough for germination or consistent quick emergence.

Studies have shown that emergence timing, consistency and overall good planting and emergence conditions can be less critical to soybeans than corn. Therefore, planting soybeans into a good seedbed that is colder than you would like should not hurt yields. While we have more to learn about the impact of cold soils on planting of soybeans, you can expect a soybean seed and seedling to be more resilient in cold conditions than previously thought.

Well balanced soil fertility and pH are the most effective means of supplying a soybean plant with nutrients that it needs. It is known that plant root growth and nutrient availability are improved by increased soil temperatures. Therefore, a starter fertilizer application to early planted soybeans has a higher chance of producing a favorable crop response than one applied at a more normal planting date.

The energy source of a plant that has germinated but has not emerged is the seed itself. This seed may initiate the germination process but not emerge through the soil surface for several weeks. During this time, the seed/seedling is susceptible to infection from many seedling diseases and insect pests which may cross its path. Therefore, the use of a seed treatment is advised when planting early.

The opportunity for soil crusting can be increased when there are several weeks between planting and emergence. This is dependent on weather conditions as soil crusting can be increased by rainfall followed by fast soil drying. Under cool conditions, this is not very likely but can still occur, as extreme weather events can happen at any time. Fields with crusting potential may not be good candidates for early planting.

Frost and freezing damage to emerged soybeans are less likely than presumed but can occur. Typically, temperatures must reach 29-30 degrees Fahrenheit for damage to occur to emerged beans before the first trifoliate leaves emerge. Seedlings just below the soil surface and those with fully emerged cotyledons are pretty tough, while those seedlings in the crook stage can be more susceptible to cold injury.

Pushing your normal soybean relative maturity has the best chance of adding yield when planted early. Michigan State University research has shown that an increase of 0.5 or more maturity group for early planted fields can result in higher yields. This yield effect is not noticed when a more average planting date is used.

If soil conditions give you an opportunity to plant early this spring, be confident in the resilience of soybeans to handle less than optimum conditions. Choose your fields carefully, avoiding soils with crusting issues and those with a history of crop injury from frost. Choose a longer maturity variety with a base seed treatment for early planted fields. Consider a starter fertilizer application under cool conditions. If the conditions of the growing season don’t provide you with a yield increase from earlier planting dates, you may still benefit from avoiding a weather-delayed planting date which can reduce yield potential.