I’ve had conversations in years past with farms who were pretty skeptical when it came to reducing their fertilizer applications. At the time, fertilizer was maybe $200 per ton; even if an extra 50 pounds of nitrogen per acre wasn’t necessary, it added up to $12-15 and that was considered cheap insurance for making sure you had enough feed for your cows. For the upcoming season, fertilizer materials are going for somewhere between $900-1100 per ton, and that extra nitrogen is going to be close to $75 per acre – whatever peace of mind it may bring, you can’t consider it cheap.
No one is suggesting that you simply cut out fertilizer use altogether. Any money you’d save on the fertilizer bill would cost you in feed purchases, weed control, or animal performance. Crops need their nutrients, and you need to make sure you’re providing them. But you also don’t need to stick with the same fertilizer program you’ve used for the last several years, even if it’s served you pretty well. It is possible to reduce fertilizer purchases -dramatically, even - without sacrificing crop performance with the following practices:
Test your Soil
Yeah, this is really basic, and you’ve heard us preach this plenty of times already, but it bears repeating: testing is the only way to assess your soil’s fertility and your crops’ needs. Spending just a few dollars per acre has the potential to save you many times that in fertilizer purchases. Basing nutrient applications on anything else is just guessing, and it will likely yield unsatisfactory results from either wasting money or poor crop performance – and maybe both. If the report indicates that levels of a given nutrient are high, then there’s no need to apply any more of it; additional fertilizer is a totally unnecessary. Even if plants take up nutrients in excess of what they need, it doesn’t translate into additional yields. If the soil test report indicates that pH is low, then any nutrients that are in the soil are not fully available to your crop, and you’re better off spending your money on lime to neutralize acidity.
Take the time to take representative samples, and be as accurate as you can with specifying yield goals or the proportion of legume in a stand. And this should go without saying, but follow the recommendations. This may call for doing things differently from the way you’re used to: using a different starter blend (or maybe even doing away with a starter altogether), or sidedressing your nitrogen instead of broadcasting it prior to planting. That might make some uneasy, but consider that these are not wild, newfangled ideas; they’re practices that have been well established by research and used by producers (quite possibly including your neighbors) for years.
Test your Crops
The soil samples you send in spring, or the previous fall, form the basis for your planning, but you have opportunities to check things mid-season and adjust those plans if necessary. It’s better to provide nitrogen to corn as a sidedress than as a preplant broadcast, but it may be that your fields already have enough nitrogen to meet the needs of a corn crop without any additional fertilizer. There’s a lot of nitrogen in plant residues or manure that isn’t immediately available; it tends to become available once the soil warms up in late spring and early summer, which happens to be when developing corn plants have their greatest nitrogen demand. Using a Pre-Sidedress Nitrate Test, chlorophyll meter, or the Adapt-N program estimates the current nitrogen supply in the soil, letting you know if sidedressing is necessary. We, or your crop dealer’s field representative, would be happy to work with you on this.
Make the Most of Manure and Crop Rotations
While soil test results are valuable, they work best when you couple it with an inventory of nutrient sources on the farm and allocate them where they’ll provide the most benefit. If manure spreading decisions are governed by convenience, where the most accessible fields get the most, then you’re going to end up with some fields that are overfertilized and others that are underfertilized – each of them costing you in terms of wasted nutrients or lower production.
There’s no denying that it takes extra time to bring manure to further fields, but it’s still going to be cost effective. You can satisfy the nitrogen requirement for silage corn yielding 25 tons per acre with 20 tons of dairy manure or pay more than $200 to provide it with urea. You can meet the potassium needs of an alfalfa-grass stand yielding 4-5 tons with about 6,000 gallons of slurry or spend $90 per acre with purchased potash . Routine manure analysis will make for the best application rates but using book values will get you started.
And don’t forget about the nitrogen credit you get when you rotate out of sod. There’s plenty of research demonstrating that first-year corn planted after a perennial forage does not respond to additional fertilizer (other than 20 pounds of N in a starter band), because it has all the nitrogen it needs from that sod breaking down .
These are not just cost-saving measures; they’re good practices that address crop needs (and environmental quality) that make sense whether fertilizer is in the $1000 range, or in the unlikely event it ever goes back down to $200.