While the rains we have received in Central to Northern Illinois have pushed planting dates later into April than we may have originally anticipated, planting will be running full speed once we dry up, especially in soybeans. With that in mind, I wanted to talk about a topic that generally is overlooked in soybeans and that is planting depth. When we think about a year of lower commodity prices than we would like, we realize that we need to optimize the factors that do not actually cost us anything such as planting depth and date.  

Though this may be a topic we do not talk about much, the Beck’s Practical Farm Research Network has a few different data sets to reference. First, looking at planting depth alone, we know when planting soybeans we generally think of moisture first and temperature second. The multi-location data set below should be no surprise that when planting soybeans timely, we see very similar results from one to two-inch planting depths with an inch and half being the best on average.  

D. Beckman, Beck’s Hybrids

But, what happens if we begin to push planting dates later in the growing season? As we see below, the later we move, the more critical maintaining proper depth is and how critical it is to not push depths over two inches. 

D. Beckman, Beck’s Hybrids

I am sure many are going to beg the questions of “why does this matter?” This question makes sense as we have pushed planting dates earlier, we have proved that soybeans can withstand early season hits such as uneven emergence. When we think planting depth, we almost need to think opposite of corn. When beans are planted over two inches deep, it can take much longer for them to emerge. This length of emergence, coupled with cooler and wetter conditions from earlier planting, allows plenty of time for soil borne seedling diseases to infest and impact our soybean seedlings.   

When we look at both data sets, it is easy to conclude that soybean planting depth is more of a range than a science. So, what do we need to do if our planter or drill makes us pick between too shallow or too deep? Really that is going to be a field-by-field decision based on conditions. Overall if the field is cold and wet, we may want to look at keeping that seed within an inch to an inch and a half on the soil surface.  If we are early in the year, we may be able to push that seed a little deeper in the ground if conditions are optimal, but as we move later in the year, we really see a huge disadvantage to burying that seed and losing days that soybean should be capturing light to emergence.