IF YOU WANT HIGHER YIELDS, YOUR CROPS HAVE TO HAVE ENOUGH PLANT FOOD. There are many questions about this topic, and I’ll answer some of the most common ones we receive each year.
Q.
SHOULD I ADD NITROGEN TO MY SOYBEANS THIS SUMMER?
A.
ONLY IF YOU HAVE A REALLY HIGH YIELD GOAL OR IF YOUR SOIL ORGANIC MATTER IS VERY LOW. Since organic matter releases nitrogen for your crop throughout the season, it’s rare when we see a yield gain from added nitrogen in high organic matter soils. However, the higher the yield, the more nitrogen you need. For example, even if you have 5% organic matter, which would be very high, it’s possible that added nitrogen could help if you were going for 100+ bushels. If you have 3% organic matter, which is common, I would not even try added nitrogen unless the yield goal is over 60.
Q.
HOW CAN I INCREASE MY PROTEIN IN WHEAT?
A.
NITROGEN. NITROGEN. NITROGEN. Granted, there are other nutrients like sulfur, phosphorus, and potassium that can help, but having available nitrogen late in the season is key. If you don’t have high organic matter levels, the only thing you can do is apply lots of N. A soil nitrate test costs $5. If your nitrogen levels aren’t sufficient for your yield goal AND high protein, streambar some more N in June. You could also foliar apply a low rate, maybe 3 gallons, of liquid nitrogen along with some water late in the season.
Q.
IS BORON THE SILVER BULLET I’M MISSING IN MY CORN FERTILITY PROGRAM?
A.
DOUBTFUL. HOWEVER, BORON IS VERY IMPORTANT. It’s just that if you don’t have enough N, P, K, S, Zn, Mn, Fe, Ca, Mg, and Cu, adding boron probably won’t give you a huge yield boost. Of course, the only way you will find out is by trying some. We’ve done foliar feeding with boron in every crop, and while that can certainly get some boron in the plant, we’ve had better luck raising our soil boron levels by applying dry boron in the fall. The number one thing we hear about boron is, “It’s toxic!” Yes, I added the exclamation point on purpose because a lot of farmers are super worried about it. Don’t be. We’ve applied what some people would call “ridiculous rates” of boron, and we have yet to hurt our yield. In soils, calcium safens boron, so our standard “safety ratio” we usually talk about is 1000 to 1, calcium to boron.
Q.
SHOULD I FOLIAR FEED MY SOYBEAN CROP?
A.
YES. HOWEVER, I WOULDN’T INVEST MUCH MONEY IN THIS. If you can combine a foliar fertilizer with fungicide or insecticide, you save yourself a trip, and as long as you’re only spending $5 to $10 per acre, you don’t need much yield gain. We’ve seen good results from products like Ferti-Rain from AgroLiquid and AC-97 from CH Bio.
Q.
CAN SULFER HELP MY CROP? EVERYONE SEEMS TO BE TALKING ABOUT SULFER.
A.
YES. HOWEVER, A LITTLE BIT OF SULFER COMES OUT OF YOUR SOIL ORGANIC MATTER, SO THE MORE ORGANIC MATTER YOU’VE GOT AND THE LOWER YOUR YIELD GOAL, THE LESS SULFER YOU NEED. That said, think about your yield goals compared to what your parents raised. Since we now have “clean air”, we don’t get acid rains like we used to, which delivered every field a bunch of free sulfur. Add all this up and it’s easy to see why wheat and soybeans usually benefit from a small dose of sulfur, and corn usually needs quite a few pounds added.
Q.
SHOULD I APPLY NITROGEN BASED ON SATELLITE IMAGERY?
A.
MAYBE. SATELLITE IMAGERY FROM SYSTEMS LIKE VRAFY IS FANTASTIC FOR HELPING YOU IDENTIFY PROBLEM AREAS DURING THE SEASON. The important thing is to go out to those areas and figure out what’s right and wrong. Once your crop gets behind, it never catches up and yields as much as the areas that look great early on. That’s why more and more people are using satellite imagery to make in-season fertility applications. The more green the crop is early on, the higher the yield in most cases, but again, do some field investigations to confirm things before you make applications. Also, pull some soil tests. Both tissue testing and satellite imagery are NOT predictive. They only tell you how things are looking today. They don’t know how much fertility you do or do not have in the soil for the rest of the season.
Q.
I DIDN’T GET ENOUGH PHOSPHORUS ON THIS SPRING. SHOULD I APPLY MORE RIGHT NOW?
A.
ONLY IF YOU INJECT IT. If you lay phosphorus on the soil surface, that phosphorus will likely still be sitting right there this fall. Phosphorus, like zinc and copper, is very immobile in soils. Rain isn’t going to move it down in the ground. Also, leaves don’t absorb phosphorus well, so foliar feeding doesn’t do the trick, either. Your best bet with P is always to apply it early and get it down in the root zone.