There is no such thing as a Nitrogen Credit for soybeans.
If you aren’t taking into account organic matter mineralization and free nitrogen release when you are planning on nitrogen applications, you are likely overspending on N.
Roughly between V9 and V14 in your corn, it will use about 25% of its total nitrogen needs for the season.
If you don’t have a high level of soil potassium, your nitrogen applications could make your crop lodge.
In soil testing after the drought year of 2021 in our region, we’re finding 200 pounds of nitrogen left over in many fields.
Of those 5 statements, which truth is the most shocking to you?
When nitrogen was cheap, it didn’t impact your bottom line all that much if you misapplied or overapplied it. Now that nitrogen costs $1 per actual pound of N, it’s time to dial in your nitrogen rate a little closer in 2022.
In terms of the nitrogen credit for soybeans, that has always been a made-up number, a guess just so people didn’t “have to” soil test. The problem is that after soybeans, sometimes we find 10 pounds of nitrogen left. Sometimes, we find 150 pounds of nitrogen left. Without soil testing, you don’t know.
If you want to continue guessing, that’s fine, but here’s a real-world example from our farm this fall. In a 350-acre field of ours, we found 136 pounds of nitrogen still available AFTER soybeans. Had we gone with the standard “nitrogen credit from soybeans”, we would have assumed approximately 30 or 40 pounds were in that field. Thanks to soil testing, we identified an extra 100 pounds!!! That saved us $100 an acre times 350 acres = $35,000!!! That paid for all the soil testing for our whole 3400-acre farm just with that one result.
In terms of mineralization, we usually figure that 20 to 30 pounds of nitrogen will come available for every 1% of organic matter. Several of our fields are now up to 5%, meaning we get 100 to 150 pounds of free nitrogen each and every year. Since the last two years have been hotter than normal, we’ve gotten even more free N than we were expecting. If you are buying nitrogen and not taking organic matter mineralization into account, you are likely purchasing too much N.
The period in a corn plant’s life when it needs the most nitrogen in the shortest amount of time is roughly from waist-high corn to silking. In that time span, the crop will use about half its N, highlighted especially by the time period between about V9 and V14. In other words, you have to make sure you have lots of nitrogen available to the crop at that point.
In 2022, we saw an incredible amount of lodging in corn and wheat. The main reason why was because soils were dry early on. When the soil is dry, less potassium gets into the plant. The only way to overcome this in dry weather is to have more available K in your soil. That’s why we talk all the time about having enough pounds of K for your crop and keeping your base saturation levels between 4% and 8%. If you have low levels of K, be sure to cut your planting population.
In several of our fields and others throughout our region, we’ve found 200+ pounds of nitrogen in the top two feet. Of all the years to have lots of carryover nitrogen, this is the year due to high prices and dry soils. If you haven’t tested your soil, we highly encourage you to do so before you spend too much on nitrogen or nitrogen replacement products. For example, many farmers are asking us about biological options from Corteva, Pivot Bio, or even the N-Hydro product we carry. While these can all add nitrogen biologically or through amino acids for your crop, here’s what we want you to consider.
Let’s say you cut your nitrogen application rate because you are using a nitrogen replacement product. At harvest next fall, you may have good yields, but did your product actually work – or did you just have lots of nitrogen carryover or mineralization?
Here are our 3 big pieces of advice when it comes to fine-tuning your nitrogen applications this year.
Soil test…and then soil test again. In the fall, as part of complete soil analysis, check your nitrogen levels. Just before side dress time in-season, run a $5 nitrate sample 2 feet deep. With test results in hand, you can apply just what your crop needs.
Vary your rate of nitrogen through your field either upfront or at sidedress time. If you have highly fertile, traditionally high-yielding areas, you probably need more nitrogen there. If you have some areas in your fields that never yield well, cut back in those regions.
While it’s great to shoot for high yield, if you are pushing most everything hard, including high populations and high nitrogen rates, make sure you have adequate potassium and other nutrients. When fertility gets out of balance, your crop is more likely to lodge, catch disease, and have a host of other issues.