Pictured Above: SPRING APPLIED. Many agree that it’s still best to split fertilizer applications across several stages of the growth cycle. If farmers apply nitrogen (N) with their strip-till bar and planter, there is an opportunity to split it up even further. If you run a 2-by-2 application through a frame mounted fertilizer opener, it doesn’t mean you shouldn’t also be running an in-furrow product.
A strip-tiller’s fertilization strategy is influenced by a combination of factors — when they build strips, soil variances and health, climate and equipment setup.
Building a bankable nutrient management strategy is the cornerstone of a strip-till system and Strip-Till Farmer editors assembled insights and advice from strip-tillers, agronomists and researchers offering proven methods for creating a balanced, efficient fertility program.
1 As one of the leading researchers on fertility placement, Purdue University agronomy professor Tony Vyn understands as well as anyone the comparative benefits of banded fertilizer applications in different tillage systems. Banding nutrients may enable strip-tillers to gain application efficiencies, he says, but growers shouldn’t make decisions in a vacuum.
“Don’t assume that you will have an overall reduction in long-term phosphorus (P) and potash requirements in strip-till,” Vyn says. “You will probably be able to apply less P and potash with strip-till than by broadcasting it. But you still have to meet the nutrient requirements for crops, and P and potassium (K) removed by the grain needs to be replaced.”
2 Working with fertilizer providers or a local agronomist is a good way to determine proper fertilizer depth. Many strip-tillers are trying to place their anhydrous, P and K about 6-7 inches deep, depending on soil types. Depending on the fertilizer type, the depth will change, because liquid will typically be placed shallower. Strip freshener machines can typically place fertilizer in the 2-4-inch range.
3 Deweese, Neb., strip-tiller Brian Herbek says micronutrients have been one of his limiting factors, according to tissue tests and soil samples. Working with his agronomist, he assembled a micronutrient “concoction” of mostly boron, molybdenum, manganese, copper and zinc to dribble out of custom-fabricated and installed liquid tanks of his strip-till rig.
“The number one thing we were deficient on was boron,” he says. “It’s a huge element, we’ve got to watch what we’re doing with it. Agronomists say that most farmers throughout the country are deficient in it, especially on fields with higher corn yields. When you’re getting to that 250-300 bushel mark, you need to focus on it.”
4 Many agree that it’s still best to split fertilizer applications across several stages of the growth cycle. If farmers apply nitrogen (N) with their strip-till bar and planter, there is an opportunity to split it up even further. If you run a 2-by-2 application through a frame mounted fertilizer opener, it doesn’t mean you shouldn’t also be running an in-furrow product.
Farmers seeming to have the most success with a fertilizer opener also have an in-furrow solution. It helps get the seed growing immediately and feeding it until it can grow out to that denser band.
5 Billing Farms, an Enderlin, N.D., strip-till operation of 1,600 corn acres, recently implemented the “2-by-2-by-2” N application method several seasons ago, which consists of placing UAN 28% fertilizer while seeding 2 inches away from the seed on each side of the furrow at a 2-inch depth, while also implementing starter fertilizer in-furrow at 3 gallons per acre.
The setup for 2-by-2-by-2 involves a fertilizer disc or coulter attached to the planting unit so that the more powerful form of N can be applied at a safe, yet accessible, distance from the seed, says strip-tiller Paul Billing. The third in-furrow input of 6-24-6 elemental zinc gives the emerging plant a boost until it can access the UAN 28%.
“We have a large amount of our 28% N alongside the row. Underneath the strip, we have our P, K and some ammonium sulfate applied back in the fall,” Billing says. “It’s the full gamut of fertilizer encompassing the corn seed, placing it wherever it needs to go.”
6 There are differing takes on the value of fall-applied anhydrous, but there’s little argument about it being the most affordable source of N. If applied correctly, it can help minimize nutrient losses during winter because of the chemical composition of the fertilizer. For fall strip-tillers who are dual-applying dry fertilizer for P and K and anhydrous for N, anhydrous should be placed 6-8 inches deep, most likely with a shank or a mole knife that has a 1½-inch foot on it. Because when you stir those soil molecules up, you’re freeing additional water molecules for that anhydrous ammonia to attach to, which is exactly what it seeks out.
7 It’s important to know your cap on the cation exchange capacity of soils. When loading soils up with N in the fall beyond their capacity to hold nutrients, strip-tillers could just be setting themselves up for fall leaching. That’s where a split-application or ESN product is valuable, so farmers can boost their N utilization level. It’s not a matter of putting on more dollars of N, but putting on smarter N.
8 One way to increase N efficiency is to just apply less of it while getting roughly the same results. In some of his most productive fields, Herbek says his N use ratio is down to about 0.7 pounds of N per bushel. While adopting soil health-conscious policies across the farm may have set the stage for this success, Herbek says dialing back application rates is worth a try.
“People are always saying it, but it’s probably true that most of us farmers are overapplying N,” he says. “It’s important, but it’s not as important as we think it is. What we did in 2019 was take some of our N budget and spent that on our micronutrients.”
9 At 40 days after emergence, agronomist Mike Petersen says that the corn root system usually extends down about 2½ feet. His examination of roots around this time has taught him that a Y-Drop set-up for a sprayer is a more efficient N delivery system than sidedressing.
“With Y-Drops, we put N down right alongside the plant where it feeds the corn quickly so we can time our application better,” says Petersen. “I did a test using a coulter and we put it in the middle of the row on 30-inch centers, 7 inches away from the plant. After checking, we saw that it resulted in 16 bushels per acre less than when it was up against the plant because we had uptake within 4 days, compared to having to wait a week or two before the plant started taking advantage of what we put in with the coulter.”
He notes that when N is applied to the middle of the rows, not only does it take longer to migrate to the corn’s roots, but in a strip-till system, microorganisms in the residue layer will also steal some of the N on its way down.
DROPDOWN MENU. With Y-Drops, we put N down right alongside the plant where it feeds the corn quickly so we can time our application better,” says agronomist Mike Petersen. “I did a test using a coulter and we put it in the middle of the row on 30-inch centers, 7 inches away from the plant. After checking, we saw that it resulted in 16 bushels per acre less than when it was up against the plant because we had uptake within 4 days.”
10 Persia, Iowa, farmer Bill Darrington recommends adding sugar to a fertility mix. Every time he goes across the field, he applies
1 pound of sugar per acre. For $0.75 an acre, it’s a bargain for the increased nutrient uptake and energy source it provides for microorganisms. To further emphasize the point, in a pinch, he bought out the local grocery store’s supply of RC Cola and added that to his mix. “I think it worked great,” he says.
“Think about what’s in soda — carbon dioxide, sugars, phosphoric acid and caffeine,” he says.
11 Petersen says product type and placement can have a heavy impact on N application if it’s not well thought out. “Many times, you’ll have to do a fall application, because we know how our soil conditions can be in the central and eastern part of the Corn Belt,” he says. “Be smart about it. If you are going to use dry fertilizer, use products like ESN — a coated product that is going to last. When you are looking at liquid products, don’t place it too deep, because then you are going to lose it.”
12 Vyn stresses that application recommendations depend on which form of N — anhydrous, UAN or urea — strip-tillers select, as well as placement depth. “In the spring, all of these forms of N could be pre-plant applied in the intended corn-row areas — even as shallow as 5 inches deep — if less than 75 pounds of actual N is applied per acre,” he says. “However, at 100 pounds of actual N per acre applied in the spring, pre-plant and in the row zone, the deeper the fertilizer is placed,
Strip-tilling corn in the spring involves trade-offs. In a much wetter environment, strip-tillers may be losing some opportunity for enhanced root growth in corn due to smearing and clodding, Vyn says. For this reason, he is very nervous about spring strip-till for corn, with in-row placement of high rates of N — especially anhydrous and urea.
“If a strip-tiller is applying 100-200 pounds of UAN on 30-inch spacing, it should be placed 5 inches to the side of where the corn will be planted,” Vyn says. “Placing this rate of UAN 5 inches below where the corn is planted might be OK.”
13 Variable-rate application is a focal point for Billings Farm when it comes to corn, utilizing the practice both for nutrient application accuracy and savings since 2005. Since they regularly rotate corn and soybeans every other year across most of their fields, they’ll zone sample the fields for incoming cereal crops (corn and wheat).
The maps constructed for Billing provide recommendations on P, N and seeding totals for each field in question. By detecting variances in vegetation and average yields, the maps specify parts of the field needing particular nutrient applications to reach sufficient levels, while also indicating regions where savings can be maximized. For several 100-acre fields, it’s not uncommon for Billing to see savings north of $5,000 per field using the recommended variable rates of N compared to standard applications.
“With our N program, we’re down to about 0.7 pounds per bushel, and that’s been very consistent for the past 4 years. Prior to using the maps, we were adding around 1.1 pounds per bushel,” Billing says.
14 Strip-tilling a 70-acre plot in spring, Wanatah, Ind., strip-tiller Jeff Herrold applied a total program of 253 units of N, 73 units of P, 83 units of K and 56 units of sulfur. “It excited me because we didn’t throw a bunch of N out there and it was corn-on-corn,” Herrold says.
In recent years, he has become a firm believer in spacing fertilizer applications out in order to maximize their plant uptake, while also marginally dialing back rates. Data pulled from his field indicates his cation-exchange capacity (CEC) values — measuring the retention of soil particles — are low, making split applications particularly important.
“When we’re timing our N, we’re applying at pre-plant, planting, sidedress and during irrigation,” says Herrold. “We do it 4 different times because our soils can’t handle a lot at one time. This way, we’re also better stewards of what we have because it reduces leaching and prevents murking up our groundwater.” During irrigation, Herrold will fertigate 50 units per acre of K through the center pivot. “I see K as a really important thing, as it is the money-mineral and our plant is a luxury up-taker of K,” he says.
SAFE & ACCESSIBLE. Application recommendations depend on which form of nitrogen — anhydrous, UAN or urea — strip-tillers select, as well as depth. Spring-applied, pre-plant N could be applied in the intended corn row areas — as shallow as 5 inches deep — if less than 75 pounds of actual N is applied per acre.
15 Strip-tillers using anhydrous ammonia in the spring should place it at least 7 inches deep, Vyn says. However, there are two exceptions to this rule. The first is the anhydrous is placed at least 3 inches away, in an offset manner, before the radical roots reach the anhydrous zone. The second is that there are at least 2 weeks or 1-2 inches of rain between anhydrous application and planting corn.
16 One of Persia, Iowa, farmer Bill Darrington’s guiding principles for managing his operation is to treat it like a human being. The longtime no-tiller and strip-tiller builds his fertilization strategies around the philosophy that like humans, crops need to eat on a regular basis to grow and remain healthy.
“It takes multiple feedings for us to maintain complete nutrition and stay energized,” Darrington says. “It’s the same concept with plants. We know that corn plants determine how many rows will be around an ear at V3 stage, and how long that ear will be at V8. “It’s all about basic prenatal care to promote a healthy and happy growing environment to maximize yield potential.”
17 Shell Rock, Iowa, strip-tiller Jeff Reints and his son, Clay, have long subscribed to the philosophy that fertilizer needs to be placed where plants need it most — in the root zone. One constant for the Reints has been their commitment to banding fertilizer in the strip because it saves time, fuel and fertilizer costs.
To illustrate their comparison of broadcast and banded applications, they pulled corn plants from two different fields and mounted 8 plants on a board, 6 inches apart, to represent a 34,500 planting population. The Reints then weighed, on a gram scale, the exact amount of P, K and sulfur applied for a 200-bushel-per-acre yield goal. For the broadcast application, they applied 160 pounds per acre of diammonium phosphate (18-46-0), 100 pounds per acre of potassium chloride (0-0-60) and 100 pounds per acre of ammonium sulfate (21-0-0-24). The total application (360 pounds) costs $74 per acre.
“We measured it out to 3.75 grams of fertilizer per square foot, which meant that this is what we’d see on the soil with a broadcast application by a floater,” Jeff says.
For strip-till, the Reints reduced application rates by 25%, banding the fertilizer in an 8-inch wide by 5-inch deep strip. They applied 120 pounds of diammonium phosphate, 75 pounds of potassium chloride and 75 pounds of ammonium sulfate.
Not only was banding a cheaper method — $18 less per acre than broadcast application — the fertilizer concentration was higher with 10.5 grams per square foot. Overall, the Reints estimate a fertilizer application savings of more than $20,000 per year with banded application in strip-till vs. broadcast application in conventional tillage practices.
18 Soil testing and sampling can produce variable and even inconclusive results. But they’re still good tools to assess nutrient needs. “We look at recent soil sample results to determine if we need to address a nutrient deficiency,” says Le Roy, N.Y., strip-tiller Donn Branton. “Why spend the money if it is not justified?” he says. In the past, Branton has pulled soil samples using 1-acre grids, by soil types and, more recently, by management zones based on soil types and topography.
19 To maximize N-use efficiency, apply a base N in the fall — maybe 30-50% of your total complement for the year of the N product. Then come back with some starter on the planter, followed by a sidedress injection around V6 stage if you really have a good crop. If you feel like it’s going to increase your N use efficiency, come back in the V10 to V12 stage with some sort of application, with a sprayer and a coulter or another type of application that would to top out your yield.
20 Preventing nutrient loss is one of the issues that Illinois growers grapple with regularly, with the Illinois River draining into the Mississippi. Agronomist John Pike notes that after a good soybean yield, research conducted by University of Illinois researcher Lowell Gentry, funded by the Illinois Nutrient Research & Education Council (NREC), has shown as much or more nitrate loss can occur after corn due to the carbon-to-nitrogen ratio of soybean residue and how it affects nutrient breakdown.
Capturing natural mineralization is another opportunity that growers should be looking for, Pike says. With warmer winters in recent years, soil temperatures stay elevated. That means there is increased biological activity, creating opportunity for increased mineralization of soil N.
“If we’ve got warm, wet winters being more common, the chances of that mineralization, even though it’s slow, is going on and there are no living roots out in that field,” Pike says. “There’s no other way to capture that, so it’s totally subject to loss. Utilizing cover crops in our system really makes the most of it. It helps keep these mineralized nutrients in play, rather than being subjected to loss without the presence of living roots.”
21 Stockton, Iowa, strip-tiller Keith Schlapkohl believes that pesticides and herbicides don’t stop after just killing off the “bad stuff.” Beneficial biology, bugs and plant life are killed, too. “Four ounces of insecticide is all I use for rootworm beetle control, which is way below labeled rates,” Schlapkohl says. “For herbicides, my complete corn program for weed control is 2 quarts of Lexar and .5 pounds of Atrazine. By doing something different with water, I’m able to reduce my herbicide and insecticide rates.”