As an aerial applicator I get a lot of questions on applying products on corn and soybeans and applying nitrogen has been a popular one. So it is an honor to be asked to provide this guest editorial to the Illinois Soybean Advisor.
There is an ongoing challenge to build yield, protein and quality in our soybean production practices. In most of my company’s existence many of our activities have been in crop protection. While there are obvious pest challenges that need to be addressed each year, they tend to be more defensive in nature. Over the last five years we have worked to extend the crops’ potential. Today’s soybean genetics have great yield potential and we have worked to unleash that potential in a real, but practical manner.
Our basic concept is to provide stable, relevant, readily available nutrition to the soybean plant at a time that does not compete with its ongoing growth process. We found nitrogen is still needed after peak nodule growth and at a time when the plant is determining how many flowers to develop into pods, approximately the R2 to R3 stage. Nitrogen and sunlight, along with ample rain, are the biggest drivers of the photosynthesis process in soybeans, and many times producers believe that the nodules provide all that is needed.
Soybeans require about 5 lbs. of nitrogen per bushel. In fact, soybeans do source nitrogen from the nodule process and nitrogen available from the soil. If we rely solely on what is available, we limit yield to roughly 70 bushels per acre. Greater potential yield is obtainable. We do offer the stable, readily available form of nitrogen, ammonium nitrate, for the core product of the soybean program. The other products suggested to be blended together include potassium nitrate and ammonium sulfate, both of which are also stable, active and relevant to increasing yield potential.
We have seen that adding a prescription based upon the active available nitrogen has stimulated the soybean plants to retain more pods and significantly increase yield. In our 2014 trials with the program applied at R2/R3, we found a 10- to 15-bushel yield response on top of a 70-bushel base yield.
And it’s not just about nitrogen. Potassium is also integral to the plant’s ability to process nitrogen and sulfur is a basic requirement for protein production. This concept is a real, targeted fertility approach that goes well beyond many foliar-based enhancements. It does appear that about 40 pounds of nitrogen is needed to raise the soil levels enough to really cause the plants to respond in a meaningful manner, and our actual lead recommendation is 40 pounds of nitrogen, 10 pounds of potassium and 2 pounds of sulfate per acre by combining the three products
The successful quest for increasing soybean yield, protein and quality depends on many things. Pursuing this quest by applying relevant real fertilizer does appear to be worthy of commercial trials this year.