Investigating Strip Till P & K Placement and Timing

As strip till gains in popularity for corn production, some questions revolve around phosphorous (P) and potassium (K) fertility management. A 3-year Grain Farmers of Ontario (GFO) strip till fertility project was initiated in 2019 to answer some of the more common questions, particularly:

  1. How does yield of broadcast and incorporate P&K under full-width tillage compare to strip till with strip-placed P&K?
  2. If a grower has soil they are comfortable strip tilling in either spring or fall, from a yield perspective, is there a preferred time to do so?
  3. 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?
  4. How do yields of strip till compare to full width tillage?

Trials were conducted following cereals or soybeans at 5 locations in 2019 (Drumbo, Bornholm (2), Elora, Winchester). Low fertility fields were favoured to investigate fertility management responses.

Strip tilling was completed with a Kuhn Krause Gladiator shank-style strip tiller operating 6" deep and banding fertilizer behind the shank at 4" depth (Figure 1). Planter starter fertilizer was applied by 2"'x 2" band. All treatments received 60 lb-P2O5/ac and 60 lb-K2O/ac.

Figure 1. Strip till fertilizer band 4" below soil surface.

Figure 1. Strip till fertilizer band 4" below soil surface.

Were trials responsive to P and K applications?

When evaluating fertilizer placement and timing, it's important to know if trials were actually responsive to P&K. On average, there was an 18 bu/ac yield response to broadcasting 60 lb/ac of both P&K in the full width tillage system. Significant responses occurred across most locations. As suggested by low soil tests, trials were responsive to P and K.

How does yield of 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 10 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, with positive yield responses at most trials.

While there was a clear yield difference between systems, unfortunately we don't know how much of each different factor contributed to the response - the difference in spring tillage (strip versus full width) or differences in fertilizer placement (strip band vs broadcast). Past research clearly supports greater fertilizer yield responses for planter banding over broadcasting on low fertility soils (Brown, 2017).

If ground allows 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?

On average there was a 7.5 bu/ac yield response to strip till and P&K placement in spring compared to fall, though responses were variable across trials. As before, we don't know how much of each factor (fertility timing, tillage timing) contributed to the yield response.

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 next spring? Overall, there was no significant yield difference for splitting 60 lb/ac P&K applications between fall and spring (50% of P&K in fall strip, 50% as planter starter) relative to applying all P&K in fall strips. There was one location (ERS19) where there was a significant yield response (10% level), but no significant difference at other trials.

How does yield performance of strip tillage compare to full width tillage?

Because of differences in fertility placement for these treatments, we don't have true comparisons that would isolate only tillage effects. Yields of both systems were very comparable, demonstrating strip till could accomplish yields very similar to full width tillage (data not shown). The only exception to this was the spring strip P&K treatment which on average was higher yielding than the full width tillage treatments, likely influenced by the high rates of fertilizer applied close to the seed on low fertility soils.

This is the first of three growing seasons for this project. Reports will be updated as trials are completed in 2020 and 2021. A full year one report is available here at FieldCropNews.com.

References

Brown, C (editor). 2017. Agronomy Guide for Field Crops Publication 811. Queen's Printer for Ontario.


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