A SIX HOUR TONGUE ON THE CORN PLANTER
by Greg Stewart, OMAF Corn Specialist

Our most recent attempts to look at efficiencies in tillage and planting operations have included an examination of a spring strip tillage system. Essentially we run the same Yetter unit that we have been using for fall strip tillage except that the mole knife is replaced with a straight anhydrous knife and this is shallowed up to about 3.5 inches deep. In addition, the disc-hillers on the back of the unit are replaced with wavy coulters (angled slightly inwards at the back) see Figure 1.

Figure1. Strip tillage unit performing pre-plant strip tillage and N application.	Figure2. Seedbed after strip tillage and before planting.

The approach is to run the strip tiller ahead of planting and allow the soil some time to dry and warm before planting. It is sort of like running a coulter cart on your no-till planter but with a six-hour tongue (delay) on the planter. Preliminary observations would indicate that this system does provide opportunities to combine some tillage, some timing and some nitrogen application to make a planting system that may be attractive to some growers. The sense is that we can generally do the strip tillage slightly ahead of when you would feel comfortable no-till planting and then when you plant 6-12 hours later the seed bed is considerably more friable and seed to soil contact is improved. Yields have also improved somewhat compared to no-till (see Table 1). A 4 percent yield improvement in these trials represents about 6 bu/ac. It is important to point out that spring strip tillage that is left to dry out for an extended period of time (i.e. several days) can actually result in poorer seedbeds and lowered yields than no-till. Timing is important especially in warm dry conditions at the time of strip tillage. One note of explanation in regards to the Comley site in 2003 is that we delayed planting on this heavy soil into June and then finally planted when the soil was not quite dry enough. As you can see by the yield comparisons the strip tillage provided a massive improvement to corn growth compared to the no-till. I have not included this value in the average, as it was a bit of an extreme situation.
So those corn producers who have eliminated all fall tillage on soybean ground and simply do an excellent job of field cultivating ahead of the planter are saying, "Big deal!" This is essentially the approach you are already taking. First off, I commend you for eliminating fall tillage on bean ground. Research in Ontario has shown that there is very rarely any economic return for any form of fall tillage in a corn after beans scenario. Secondly, in order to not make spring strip tillage merely a spring cultivator which has lost some of its teeth we have used the strip tillage toolbar to strategically place nitrogen in the row zone while we are doing the strip tillage operation. Most growers realize that in reduced tillage systems, when most of the N is going to be sidedressed in June that it is essential to put a significant amount of nitrogen down at planting. In our 2003 trials, we placed about 10 Ibs of N per acre in the row behind the knife and then surface banded another 20-30 Ibs. of N per acre over the top the strip tilled zone. Yields were improved relative to zero planting N treatments (data not included in Table 1).
One of the key advantages to fall strip tillage was better planting timelines on the strips that were drier in the spring. We lose this advantage when leaving strip tillage until the spring. This probably implies that a spring strip tillage/N zone system is best suited for low residue fields that have reasonable drainage. The system does disturb significantly less of the field than in a full width tillage system, which may contribute to better traffic bearing in the soil and less weed seed incorporation. We also use the same unit to sidedress nitrogen after moving some units around. We will continue to examine the system in 2004. If some aspect of the system interests you and you would like to discuss it or perhaps set up a field trial, give me a call.