Are your high-yielding soybean varieties getting enough S and N?
Over the years, soybeans have been shown a lot more attention and data proves that they are no longer just a rotational crop. Progressive growers are finding a high yield pay-off in soybeans that they have extensively managed. The Crop Life Learning Center wrote a recap article from Dr. Shawn Casteel’s, Extension Soybean Specialist at Purdue University, recent Crop Life webinar.
The webinar stressed the importance of timely planting and proper nutrition for your soybeans. When those things are done at the correct growth phase, there will be a significant difference in modern high-yield varieties. The recap shared an important quote from Casteel,
“Growers are starting to be more intentional with their decisions in regard to soybeans. It no longer should be a crop you just plant and hope for the best. We have good data that shows earlier planting of soybeans is a critical part of yield management. And the newer varieties are taking up more nitrogen (N) and sulfur (S) than the older varieties, which means we have to be more purposeful about nutrient management.”
The sulfur take-up pattern has not always been this way, as you know. Over the years, more sulfur is being removed at harvest. The problem comes down to this: varieties that need more S, have less S in the soil to take up. The Clean Air Act in 1990 has significantly reduced the amount of sulfur emissions by about 13 lbs. Also, the newer corn varieties are using way more N and S at harvest.
When asking yourself, how much sulfur do I apply to my fields? Know that this answer depends on many variables. Sulfur is mobile in the soil and soil tests will not be reliable. This is why it is so important to plant during the “sweet spot.” The article informed us of the sweet spot according to Casteel which is late April to early May in the mid-west. The canopy should close before reproduction starts, which is usually around the fourth of July. Casteel’s research shows that there is a loss of yield potential of at least 0.3 to 0.4 bu/ac daily anytime after mid or even early May.
After testing different sulfate sources, Casteel and his team found that sulfur from ammonium sulfate was twice as efficient in achieving maximum yield grain than S from elemental-S containing products. The optimal amount of S needed is up to the source and the timing for soybeans. If you are applying sulfur within a few weeks of planting, (before or after) 10 to 20 lb S/ac will be more than enough if S is needed. Late spring/summer is when the lower rates could be used and is associated with soluble S sources.
All of this is important to keep in mind regarding your management of soybean fields this year. Becoming more purposeful in management of nutrition going on your fields can give you a big pay off at harvest. Pay close attention to the variety you are using, the time at which you are planting, and the sulfur source you will be using. Feel free to reach out to our team at Novus Ag for helpful ideas regarding soybean management and nutrition product options for your operations this year.
Source: Crop Life Learning Center