Q: Strip-till is touted as the answer to nearly every problem in the Corn Belt. Should every producer consider adopting it?
A: No. If your current no-till system works, keep it. But if you’re making changes and want to consider a system that’s efficient and offers solutions to many Corn Belt challenges, take a look at strip-tilling.
If you are successful and pleased with no-till, strip-till offers few improvements. Compared to conventional tillage, it has several major advantages.
Q: Most articles talk about fall strip-tilling. How should spring strip-till be managed?
A: Strip-tilling in the spring is an option, but growers run the risk of not getting strips prepared if the weather turns cold and wet. When this happens, you have to no-till or revert to tillage.
When preparing strips in the spring, focus on fertilizer depth and strip quality. Placing fertilizer too shallow can result in seedling death from fertilizer burn. Use tru-depth shanks or measure actual running depth. Building strips in the spring can result in very cloddy strips and poor seed-to-soil contact.
The advantage with fall strip-till is the clods can overwinter and mellow down. To avoid clods, prepare strips as early in the spring as possible. Place them as close to the old rows as possible to avoid wheel track problems.
Q: Is knifing or deep banding fertilizer necessary?
A: Several growers prepare a strip with the anhydrous bar (nitrogen only) while others use a coulter cart a few weeks to a few days ahead of planting. In the western and northern Corn Belt, there are advantages for deep banding potassium. Since most growers fertilize in the fall, banding fertilizer while preparing the strips offers a very efficient operation.
A replicated corn study at Williams, Iowa, showed a 3.5 bushel per acre advantage for applying fertilizer in the fall strips compared to building strips without fertilizer.
Q: Will knives other than the moleknife work?
A: Over a dozen styles of knives are available for deep fertilizer placement. They differ in quality and the amount of soil which is brought up for forming the strip.
Don’t prepare strips that are nearly level or slightly depressed after stripping. This will result in cold, wet strips that are prone to soil erosion and seedbed washing.
Q: How should I soil sample with strip-till?
A: The odds of placing the strips in the same location every other year (assuming a corn and soybean rotation) are slim. General soil sampling guidelines should be followed.
If the strips can be precisely located, sample 6 inches over from the center of the strip and 6 inches deep.
Q: Will strip-till work for soybeans?
A: Two replicated studies in central Iowa in 1999 showed a yield response of 3 bushels per acre for strip-till soybeans compared to no-till soybeans. One study looked at 30-inch rows and the other at 7.5-inch rows. Both studies were done on high fertility soils and placed only phosphorus and potassium in the strips.
There’s a lot to learn about soybean response to deep banded fertilizer. But if you do the math, a 3 bushel per acre response may not be enough to cover the added costs of preparing the strips if you already no-till. If you’re changing from conventional tillage, this yield response combined with fewer savings field trips offers an exciting opportunity.
Q: What’s the best weed control program for strip-till?
A: It’s similar to no-till. There may be more weeds and earlier weed growth in the strip-till area versus the row middle, but not enough to warrant a separate herbicide application.
The biggest factor is how the field is sprayed. Floater trucks can smash down a large number of rows, defeating the purpose of strips. When hiring custom spraying, make sure a machine with narrow profile wheels is used or do your own spraying.
Q: Can I eliminate starter fertilizer since I’ve already banded fertilizer in the strip?
A: For most of the Corn Belt, the answer is yes. In more northern latitudes (such as central and northern Minnesota) where banded fertilizer is more than 2 inches away from the planted seed, the answer is no.
By removing starter fertilizer from the planter, efficiency is greatly improved. For someone farming 1,000 acres, the time needed for planting could be reduced by 1 or 2 days.
Q: Do corn hybrids perform differently in strip-till?
A: Yes. Selection for tolerance to foliar diseases like grey leaf spot is a must. Strip-till allows earlier planting so selection for early season emergence and vigor is important to take advantage of drier, warmer soils.
Q: What planting populations are recommended?
A: University of Illinois research shows a greater survival rate of corn seedlings in strip-till compared to no-till. Since strips are warmer and drier at planting, the yield potential is optimum. Hybrids rated for medium to high planting populations should be planted at the high rate. Low to medium rated hybrids should be planted at the medium rate.
Don’t plant at higher than recommended rates as this can lead to lodging. Two replicated studies in central Iowa showed optimal planning rates for fall strip-till were 33,000 plants per acre.
Q: From the road, some strip-till fields look like they’ve been chisel plowed. Is there enough residue cover for erosion control?
A: While the strips behave like conventional tillage and have little residue cover, the field will still have significant residue cover. Several research sites in Illinois, Iowa and Minnesota show residue cover for fall strip-till is within 10 percent of that for no-till and significantly higher than for conventional tillage.
The only thing that can reduce the amount of residue are strips that are slightly sunken or depressed which lead to washed-out seed rows from concentrated water flow.
Q: Is strip-till more like ridge-till or no-till?
A: It’s more like ridge-till but with the efficiencies of no-till. While it’s similar to ridge-till since the system is based on small ridges, the strips are not permanent. When you compare the number of field trips per acre, strip till (including banding of fertilizer) is the most efficient system.
Q: What fertilizer rates are recommended for fall strip-till? Can I use only anhydrous ammonia?
A: University of Minnesota research suggests deep banded fertilizer rates should only be half of those recommended for broadcasting fertilizer in conventional tillage. However, this is inconclusive since recent studies have found reduced banded rates may lower yield potential.
Begin strip-tilling using standard recommended rates, apply potassium and phosphorus in the strips and use side-by-side trials to see if reducing rates will work on your soils.
Q: I’m looking into starting a custom strip-till business. What’s a reasonable charge?
A: A recent survey of ag chemical retailers who do strip-till shows rates range from $11 to $13 per acre. I’d charge at the high end since you are preparing a seedbed for next year’s corn crop and managing fertilizer at the same time.
Compared to conventional and no-till systems, strip-till can increase your yield potential by as much as 10 bushels per acre. This can be worth up to $20 per acre.
Q: Should I strip-till with liquid or dry fertilizer?
A: It’s a matter of handling convenience, availability of product and horsepower availability. Dry fertilizer is the most common system where a blend of 18-46-0, 0-0-60 or 9-23-0 is used.
Less horsepower is required for liquids. However, liquid fertilizers are typically more expensive and usually low analysis which makes it difficult to apply high rates. For the northern Corn Belt, avoid using urea as the primary source of nitrogen since several studies have shown reduced yield potential.
Q: How much horsepower is needed for a 12-row strip-till unit?
A: If you apply dry fertilizer and anhydrous (with capacity for up to 9,000 pounds of dry fertilizer), a 12-row unit would need a 250 horsepower tractor for most soil types in the Corn Belt. This would allow you to run 5 to 6 mph and place fertilizer 7 inches deep.
Q: Most recommendations suggest applying nitrogen, phosphorus and potassium in the strip as soon after soybean harvest as possible. Do you recommend applying anhydrous ammonia even if the soils are still warm?
A: While it’s most efficient to apply all three nutrients at once, it’s not sound environmentally or economically to apply anhydrous to warm soils.
Even the addition of N-Serve won’t be effective if soil temperatures are over 60 degrees for an extended period. Consider building strips on a limited number of acres and apply only phosphorus and potassium (sidedress nitrogen in the spring). On the remainder of your acres, wait to apply anhydrous ammonia until soil temperatures are optimal.
(This article with information from Monsanto agronomist Pete HIll originally appeared in the January 2000 issue of No-Till Farmer.)