Strip Tillage and Fertilizer Placement
Mar 11Strip Tillage and Fertilizer Placement
Fertilizer placement in a strip tillage system has become a hot topic recently. The first question that arises is generally that of fall versus spring placement of P and K. At one time I believed that fertilizer placement in the fall strip could revolutionize corn planting systems. The appeal was to put all your P and K down in the fall to simplify spring operations, improve the placement compared to broadcast applications, and leave the planter free of any fertilizer in order to improve planting timeliness.
Unfortunately, when we tested this idea on lower testing soils and compared it to spring applied P and K through the planter, it didn’t do so well. In these trials, it was quite clear that without spring applied P and K, corn yields suffered. Why did this occur? There are several possible responses:
- proximity to the seed is significantly better with a spring planter band,
- the fall applications did not result in a concentrated zone that could stimulate early season root growth, and
- the inability to place an N supply in connection with the fall placed P and K that may improve nutrient uptake.
In these trials, the fall placement was down the back of a shank style strip tillage unit to a depth of 6 inches; so there is a possibility that if the fall P and K had been mixed into the zone and placed more shallowly, that some of these shortcomings could be overcome. Remember also that if your soil tests for P and K are higher (above 25 PPM for P and above 120 PPM for K), this disparity between spring versus fall applications may be significantly less, or perhaps absent. In these trials the spring time applications were zero for P and K when it had been placed in the fall strip tillage system.
This question keeps coming up in strip tillage discussions. If I am running a strip tillage/fertilizer placement system, can I eliminate all fertilizer on the planter? In my opinion, to reduce costs and improve planter efficiencies, this should certainly be the goal, but it remains an unanswered question and one that we need to continue to explore. Experience would suggest that for complete fertilizer elimination on the planter (both liquid and dry), then you need to consider a few questions:
- Fall versus Spring. As mentioned already, I believe the spring option is more likely to provide an environment where fertilizer can be eliminated from the planter, but fall strip tillage operators may prove me wrong.
- Soil Test Levels. When soil test levels are medium or lower, then spring applications will be more advantageous. Thresholds are in the range of 15 PPM for P and 90 PPM for K; below those values, spring applications will be favoured. Note: On these lower testing soils, you may not be able to apply all of your P and K requirements in the spring zones.
- Nutrient Placement. P and K should be mixed into a zone that is close enough to the seed so that it can be intercepted by early emerging corn roots.
- Nitrogen. If there is zero fertilizer on the planter, early corn growth will need an N supply whether this is broadcast or included in the strip tillage zone.
How much N, P and K can be applied through a strip tillage system in the spring and still be safe for the subsequent corn seedlings? The OMAFRA safe rates for 2x2 planter bands give us a good place to start this discussion.
- In a 2x2 band, if urea is the N source, then the maximum N and K combined is 70 lbs/acre. For example if a 19-19-19 blend was used and urea was the dominant N source in the blend, then the maximum application rate of the blend would be 184 lbs/acre of product. This would deliver 35 lbs of N and 35 lbs of K20, and you would have arrived at the maximum safe rate for a 2x2 band. Note that on sandy soils in dry years, this may cause some seedling damage. If the fertilizer is to be evenly distributed in a zone close to the seed, two things are happening: you are eliminating a concentrated band which is good, but you will also have some fertilizer closer to the seed than the 2x2 placement. Experience has shown that if you do a reasonable job of mixing the soil and fertilizer in a zone that is 8 inches wide and 4 inches deep, then the safe rate probably moves up from 70 to 90 lbs of N and K combined, but this is a best estimate as it is nearly impossible to predict how different strip tillage tools will incorporate the fertilizer into the zone.
- If urea is not the key source of N, then maximum safe rates in a 2x2 or strip tillage zone go up. In situations where N sidedressing will be delayed to the end of June, then a minimum of 60 lbs should be applied at planting to carry the crop without N deficiency. In this case, a product like ESN will need to be added to the blend to reduce the chances of fertilizer burn or broadcast N applied in addition to the strip tillage approach.
Recently an OMAFRA/IFAO project has looked at strip tillage options and fertilizer placement. In 6 field-scale trials, fertilizer placement was compared in a traditional 2x2 planter placement versus the same amount of fertilizer incorporated into a strip tillage zone using a Dawn Pluribus Unit (see Table 1 for results). The conclusion so far is that the two systems seem pretty comparable. That is, dry fertilizer banded through the planter produced yields equivalent, on average, to a spring zone tillage system with the same fertilizer.
Table 1. Yields and response to P and K fertilizer applied through strip-tiller or planter. Source (Ben Rosser, OMAFRA – Crop Advances 2015). Fertilizer delivered in both systems was 160 lbs per acre of 19-19-19 or 30 lbs/ac actual of each N, P and K
2014 Bornholm 158 149 -9 NS 2015 Bornholm 153 159 +6 NS 2015 Elora 178 180 +2 NS 2015 Belwood 174 173 -1 NS 2015 Woodstock 224 223 -1 NS 2015 Paris 123 113 -10 NS
This is positive news for strip tillers, but it does leave at least one question unanswered. What about the impact of liquid fertilizer delivered in-furrow on the planter? Can a strip tillage fertilizer placement system eliminate the yield boost gained from in-furrow placement? This is a great question to tackle in 2016 and for those with strip tillage systems, a fairly simple test to run. Maizex looks forward to working with industry partners to get some additional insight on this topic.
A grower in Wellington County wants to move to spring strip tillage and apply dry fertilizer at the same time ahead of corn planting. He has soil tests for P that range from 10 to 14 PPM, and soil tests for K that runs from 95-115 PPM. He plans on sidedressing nitrogen by June 15. What’s a reasonable approach for 2016?
A good strategy would be to apply dry fertilizer in the zone to supply 30 lbs of N, 60 lbs of P (P2O5) and 30 lbs of K (K2O). This will keep him safe in terms of fertilizer injury providing the strip tiller does a reasonable job of mixing the fertilizer in the row zone. Enough N is supplied to supply the crops’ demands until sidedressing. P supply certainly meets the soil test requirements for the current corn crop. Additional K will need to be broadcast somewhere in the rotation to keep soil tests from slipping.
Since this grower still has dry and liquid fertilizer on his planter, the suggestion is that there is no need to run the dry fertilizer, but he will run some tests to see if there is any advantage to applying the liquid in-furrow fertilizer in this new system.
Maizex Seeds Agronomy Lead
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