Corn is planted and the 2015 growing season is underway. As with any season, Mother Nature is already throwing many farmers a few curve balls. Large rainfall events can be a blessing, but they can cause nitrogen deficiencies in the soil, robbing corn of yield potential.
“Farmers in many regions have seen heavy rain events the last few weeks, and large rain events are becoming more common,” said Jim Schwartz, regional agronomy manager, 360 Yield Center. “Farmers today are experiencing more four-inch rainfall events during the growing season than ever before. In fact, in the upper Midwest there has been a 50 percent increase in heavy rainfall events in the last half century.”
What’s the big deal about rain?
As every farmer and agronomists knows, heavy rainfall events can negatively affect nitrogen levels in the soil through either denitrification or leaching. Nitrate will move with soil water. As a result, rain can cause leaching, and depending on soil type, structure, sub-horizons, soil moisture capacity and other factors, one inch of moisture can move six to 12 inches of movement into the soil profile, or more.
That movement could be even more dramatic with the recent rainfall events happening in some areas. Anhydrous is placed at least six inches deep in the soil. The converted nitrate, already half a foot underground with a three-inch to four-inch rainfall, begins to move further and further into the soil profile.
“Heavy rains move nitrates lower and lower. And, root systems at this point in the season are shallow and undeveloped,” said Schwartz. “So, it can be assumed that much of the fall-applied N is out of reach of the early-season roots and will likely continue to move with additional moisture.”
Another impact of heavy rainfall is the conversion of nitrate into a gaseous form that is lost in the atmosphere—denitrification. This type of N loss is common in heavy or poorly drained soil types because heavy rainfall causes waterlogged soils to have a lack free oxygen. Organisms that break down residue require oxygen to survive. And, without oxygen in the soil, soil microbes rob oxygen from the nitrate molecules and convert it into a nitrogen gas, which is lost to the atmosphere.
Make sure corn has the N it needs
Schwartz offers tips to better manage N throughout the season and ensure corn has the N it needs to finish the season strong and reach maximum yield potential. He is promoting two products from 360 Yield Center.
- Soil testing throughout the season can help farmers get a handle on how much N is left. 360 Soilscan is an in-field soil nitrate testing system that can test how much N is in a field in real-time. To find out how much and where N is requires taking a 12-inch core and splitting it at the six-inch depth and testing it with 360 Soilscan. That provides information on how much N is in a field and throughout the profile.
- Continually monitor rainfall, especially heavy rainfall events. If they continue, be on alert and address N deficiency issues before they have a negative impact on the corn. You don’t want corn to have a bad day.
- Don’t wait until a nitrogen deficiency is visible in the corn plant. By then, lost yield potential is likely. If you realize there are low nitrogen levels early enough, supplementing a field with in-season N to help rectify the issue. And the 360 Yield Center is promoting a unique 360 Y-Drop to allow for more flexibility in timing of late-season N applications. The company claims N can be applied whenever crops need it most, whether that’s at V6 or all the way up to tassel.
- A field doesn’t have to be treated uniformly the same. It is obvious that not every acre is the same. Rainfall impacts different yield management zones differently. For example, 3.5 inches of rain on a hill is different than 3.5 inches of rain in a valley. Nitrogen levels will likely vary across a field, especially after large rainfall events. The 360 Soilscan allows testing N levels throughout fields to make smart N application decisions for variable rate prescriptions.
More information is available at www.360yieldcenter.com/Nitrogen.