When applying moderate amounts of P&K fertilizer (60 lb/ac of both P2O5 and K2O) at ~4″ depth with a shank-style strip tiller across 15 trials on medium to light soil textures and low to moderate soil fertility:
- Yields of spring strip till and P&K were significantly higher (+4 bu/ac) than where P&K was broadcast and incorporated with full width tillage.
- Yields of spring strip till and P&K were significantly higher (+5 bu/ac) than fall strip till and P&K.
- Moving some P&K from fall strip till to starter fertilizer on the planter the following spring resulted in a significant yield response (+3 bu/ac) compared to where P&K was only applied through the fall strip, and produced yields similar to spring strip till and P&K.
- Strip till was competitive yielding with full width tillage when comparing similar nutrient placement and timing, for example:
- Spring strip till and P&K produced yields similar to full width tillage when some P&K was placed as starter fertilizer on the planter, but was significantly higher yielding then when all P&K fertilizer was broadcast (+4 bu/ac).
- Fall strip till with all P&K applied in the fall strip was significantly lower yielding than full width tillage where some P&K was placed as starter fertilizer on the planter (-4 bu/ac), but moving some of the P&K from the fall strip to starter fertilizer on the planter removed most of this yield lag.
- Yield responses for improving P&K placement (strip or planter banding) and timing (spring) tend to increase as soil test P&K declines. Responses to improving placement and timing may be minimal on high fertility soil.
Strip till is gaining in popularity as a reduced-tillage option that also offers conventional tillage benefits for corn production. For example, unlike other reduced tillage options, strip till provides the opportunity to:
- work soil in the planting zone while leaving the remainder of the field unworked
- efficiently incorporate larger amounts of fertilizer into the planting zone, especially important for phosphorous (P)
This project was initiated to answer some of the more common questions around strip till and fertility placement and timing, particularly:
- How does yield of broadcast and incorporate P&K in a full-width tillage system compare to strip till with strip-placed P&K?
- If a grower is on soil they are comfortable strip tilling in either the spring or the fall, from a yield perspective, is there a preferred time to do so?
- If a grower fall applies P&K in the strip, is there yield response for moving a portion of this fertilizer to the planter as starter in the spring?
- How does yield performance of strip till compare to full width tillage?
A total of 15 trials were conducted at 6 locations in Ontario from 2019 to 2021 (Fig. 1). Trials ranged from sandy loam to clay loam soils with either cereals or soybeans as previous crops (Appendix 1). To investigate yield responses to fertility management, fields testing low to moderate for P&K were favoured. Frequent rain delayed planting until the last week of May to mid-June in 2019, while planting in 2020 and 2021 generally occurred in mid May. Planting generally occurred the day after spring strip tillage.
Treatments used to investigate questions 1 through 4 above include:
- Full width tillage, no P or K fertilizer (fertility response control)
- Full width tillage, spring broadcast P&K
- Full width tillage, 50% of P&K spring broadcast, 50% of P&K spring planter banded
- Fall strip till, shank placed P&K
- Fall strip till, 50% of P&K shank placed, 50% of P&K spring planter banded
- Spring strip till, shank placed P&K
Strip tilling was completed with a 6 row (30” row width) Kuhn Krause Gladiator shank-style strip tiller operating 6” deep (Fig. 2). Full width tillage was completed with 2-3 spring passes of a finishing disk/harrow or cultivator leaving soil bare in most cases. Some locations also received a fall chisel plow or disk. Strip till fertilizer was applied by banding tube behind the strip tiller shank at 4” depth (Fig. 3) while planter starter fertilizer was applied by 2”’x2” band. Past Ontario research demonstrates that deep banding strip till fertilizer (e.g. 6”) tends to not provide starter fertilizer response, so 4” depth was selected with aims of balancing crop safety with fertilizer response. Broadcast treatments were surface broadcast between spring tillage passes. To investigate yield response to P&K placement and timing, 60 lb-P2O5/ac and 60 lb-K2O/ac (mono-ammonium phosphate and muriate of potash blend) were applied for all treatments, (roughly 1 corn crop removal, high enough to elicit yield responses, not too high to saturate responses or cause significant crop safety issues). All treatments received 30 lb-N/ac as urea applied in 2”x2” band on the planter, with the balance of N applied as UAN sidedress at most trials.
Safe Fertilizer Rates with Strip Till
Safe strip till fertilizer rates is a common question. Little data exists on safe strip till fertilizer rates in Ontario and likely depends on how fertilizer is applied in the strip (banding vs mixing, banding depth). As a relative comparison, maximum rates for 2”x2” planter bands with urea-based fertilizer blends are no more than 36 lb/ac of N and 71 lb/ac of all salt fertilizers together (N+K+S) (Brown, 2017).
Fertilizer rates and placement in this project are riskier than these guidelines. Strip till bands in this project are closer to the seed (2” below) than 2”x2” planter starter bands (2.75” diagonal offset) and rates are higher (90 lb/ac of N+K+S) than safe guidelines (71 lb/ac of N+K+S). While fertilizer burn has not been observed at these trials, the rates and placements applied with these treatments should not be considered an endorsement for safe fertilizer practices.
In order to detect differences in yield response between P&K application timing and placement, these trials are generally reflecting worse-case scenarios – moderate amounts of fertilizer being applied on low to moderate fertility soils. Results should be interpreted in this context.
Were trials responsive to P and K applications?
When evaluating fertilizer placement and timing, it’s important to know if trials were responsive to P&K in the first place. Comparing yields of full width tillage treatments where P&K were spring broadcast (treatment 2) to where P&K were not broadcast (treatment 1) gives an indication of responsiveness. On average, there was a 14 bu/ac yield response to broadcasting 60 lb/ac of both P2O5 and K2O in the full width tillage system, with significantly positive yield responses occurring across 7 locations (Fig. 4). As suggested by the low to moderate soil tests, most of these trials were responsive to P and K fertilizer.
How does yield of spring strip till with strip-placed P&K compare to broadcast and incorporate P&K in a full-width tillage system?
Is there greater yield response for placing fertilizer in the strip close to the corn plant with strip till compared to broadcasting fertilizer under full width tillage? On average, there was a 4 bu/ac yield advantage for spring applying P&K with strip till compared to spring broadcast and incorporation of P&K under full width tillage. While there was a significant responses at 3 trials (Fig. 5), there were also many trials with minimal yield response.
Where large yield responses exist, we don’t know how much of each different factor contributed to the yield response – the difference in spring tillage (strip till versus full width tillage) or differences in fertilizer placement (strip band vs broadcast), although research clearly shows greater fertilizer yield responses for planter banding over broadcasting on low fertility soils (Brown, 2017). It is possible fertilizer placement plays a key role, as moving a portion of full width tillage P&K to planter starter placement removed yield lag. Responses were strongest in 2019. While a year effect may be possible, 2019 was also associated with trials having among the lowest soil fertility levels (Appendix 1). Strip till fertilizer placement may offer the most yield benefit on very low fertility soils. The few locations with higher soil fertility levels (19PDF, 21VAN) did not have strong responses to strip placed P&K.
While this demonstrates significantly better yields for strip fertility under this scenario, there are still some practical questions – would this response be diminished if greater rates of fertilizer are applied broadcast, given safe spring broadcast fertilizer rates would be significantly higher than safe spring strip till fertilizer rates?
If soil conditions allow a grower to strip till in either the spring or the fall, from strictly a yield perspective, is there a preferred time to do so?
Another common question, if a grower is on soil they are comfortable strip tilling and applying P&K in either fall or spring, is there a preferred time to do so from strictly a yield perspective? (ignoring logistical, erosion risk differences). On average there was a 5 bu/ac yield response to strip till and P&K placement in the spring compared to the fall, though responses were again variable with some trials having strong responses and others very little (Fig. 6).
With the treatments imposed, we can’t directly say how much of each different factor (fertility timing, tillage timing) contributed to the yield response, though as discussed in the next section, moving a portion of fall P&K fertilizer to planter starter placement the following spring appeared to reduce much of this lag. This suggests fertility timing may play a role.
There are again some practical questions – would this strong of response still be observed on higher fertility soils, or under a scenario where we can more safely apply higher rates of fertilizer in the fall that we can’t in the spring? Also, yield may not be the only factor when deciding between fall or spring strip till (fertilizer and labour logistics, safe fertilizer rates, soil condition, erosion risks). Last, these trials were fairly conducive for spring strip till – yield advantages may not apply to heavier textured or poorly drained soils where spring strip till may be more challenging.
If a grower fall applies P&K in the strip, is there yield response for moving a portion of this fertilizer to starter P&K on the planter in the spring?
For logistics and planter efficiency, it would be ideal to incorporate all fertilizer through the strip tiller and plant without starter fertilizer. But the question arises, if we are applying fertilizer in the strip in the fall, is there a benefit to having some starter fertilizer on the planter the next spring? Overall, there was a significant 3 bu/ac yield response for splitting 60 lb/ac of P2O5 and K2O between fall and spring (50% of P&K in fall strip, 50% as planter starter) relative to applying all P&K in the fall strips with no starter fertilizer at planting (Fig. 7). Responses across locations were highly variable however.
In practice, fall P&K applications with strip till would likely be at much greater amounts than these treatments trying to detect differences in efficiency, perhaps further lessening responses. There may also be similar starter fertilizer questions for spring strip till, but this treatment was not evaluated. In these trials, strip fertilizer placement is theoretically banding very close to the seed (fertilizer outlet 2” below planting depth), though actual fertilizer distribution or placement is not measured. This may not reflect starter fertilizer responses for strip tillers that are banding deeper or mixing fertilizer throughout the strip.
We can only speculate why moving a portion of P&K to the spring provided a yield response. A couple possible factors:
- ammonium is known help improve P uptake, and the ammonium in monoammonium phosphate applied in fall treatments would no longer be present at planting the following spring
- there could possibly be more opportunity for soil tie-up of fertilizer between fall applications and spring planting on very low fertility soils
While the yield response was statistically significant relative to applying all P&K in the fall strip, growers would have to determine if there is enough yield response to cover costs associated with using starter fertilizer (spring logistics or delivery equipment if planter is not already equipped for starter fertilizer).
How does yield performance of strip tillage compare to full width tillage?
Does strip till have the ability to yield competitively with full width tillage? Because of differences in fertility placement for these treatments, we didn’t have true comparisons that would isolate only tillage effects. However, when comparing similar nutrient placements and timings, yield performance of strip tillage and full width tillage were very similar. For example:
- Spring strip till and P&K yielded equal to full width tillage when 1/2 of the P&K was placed as starter fertilizer on the planter, but yielded significantly higher (+4 bu/ac) than full width tillage where all P&K fertilizer was broadcast
- Fall strip till and P&K was similar yielding to full width tillage where P&K were broadcast, but significantly lower yielding than full width tillage where 1/2 of P&K was placed as starter fertilizer on the planter (-4 bu/ac).
- However, moving 1/2 of the P&K from the fall strip to starter fertilizer on the planter removed most of the yield lag associated with fall strip till.
Overall, results demonstrate that strip till is a conservation tillage program that has the ability to yield competitively with full width tillage. On low fertility soils, incorporating fertilizer applications with strip till may provide higher yields than full width tillage relying on broadcast fertilizer applications, and similar yields to where starter fertilizer is used. For fall strip tillage, starter fertilizer may provide some yield benefit. Yield responses for improving P&K placement (strip or planter banding) and timing (spring) tend to increase as soil test P&K declines. Responses to improving placement and timing may be minimal on high fertility soil.
Appendix 1. Strip till trial location information.
Appendix 2. Treatment yields across all trials.
When making treatment comparisons within trials (rows), yield cells containing the same letter are not significantly different at the 10% level.
This three year project is now complete. This is the final report.
The information produced from these projects is not possible without assistance for funding, equipment, trial co-operation and technical field support. Thanks to Grain Farmers of Ontario and Canadian Agricultural Partnership for project funding. Thanks to Stoltz Sales and Service and Kuhn Canada for providing the strip tiller for the duration of the project. Thanks to Premier Equipment and John Deere Canada for providing tractors to make field trials possible. Thanks to the on-farm co-operators, and Scott Banks, Holly Byker and Ben Melenhorst for conducting the Winchester trial. Thanks to Alissa Reid, Andrew Priest and Duncan Willemse for their exceptional hard work and dedication completing field trials in 2019, 2020 and 2021.
Brown, C (editor). 2017. Agronomy Guide for Field Crops Publication 811. Queen’s Printer for Ontario.
Ben Rosser, Corn Specialist, OMAFRA, email@example.com