March 27, 2012
Unseasonably warm weather might have farmers tilling their fields earlier than normal, but a Purdue Extension agronomist cautioned them against tilling more than necessary.
While thereís nothing wrong with early tillage, Tony Vyn said producers need to think ahead and not increase the total number of passes theyíre making across their fields.
"From the soil, fuel and time conservation points of view, early tillage operations need to be considered as candidates for the final tillage operations farmers complete," he said. "Itís important not to till now and then do it again later before planting. That means that when farmers are ready to plant, they should consider using a stale seedbed approach."
Vyn also said that with long time gaps between tillage and planting, it is important to avoid the risks of excessive seedbed moisture loss if dry conditions prevail.
"Cloddy seedbed preparation several weeks before planting should not even be considered acceptable, and certainly not on high clay soils," he said.
After a winter with very few freeze and thaw cycles, Vyn said soils are not as well structured as they normally might be, but soil drainage has been reasonably good.
The warm weather also means the moisture contrast between the near-surface and the sub-surface soils is less - which could mean less planting delays for producers considering no-till. Good drainage and warm weather combine to more quickly dry soil under surface residue, such as corn stalks.
"This spring weather is not only speeding up tillage, but itís making it more likely that no-till operations can occur in a more timely manner," Vyn said. "There will be less delay associated with planting into higher residue. However, chemical weed control needs to be timely in a spring with such early weed pressure to maintain the no-till option."
Other tillage systems farmers can consider, beyond conventional and no-till, include vertical and strip tillage.
Vertical tillage is a method of shallow soil penetration and some disturbance of the crop residue. It helps soils dry faster, so farmers can plant earlier. Strip tillage, on the other hand, disturbs only the residue in the berms where seeds will be planted. The remainder of the crop residue is left alone.
Both vertical and strip tillage help maintain soil structure.
In addition to early tillage operations, Vyn also said that the warm, dry weather has given farmers an opportunity to apply anhydrous ammonia earlier.
"By applying anhydrous ammonia now, there is a clear time separation between application and planting," Vyn said. "That means less likelihood of zones of high ammonium concentrations potentially interfering with early seedling corn growth.
"However, itís a trade-off, because with early applications, mineral nitrogen has to stay in the soil longer for it to be available to plants."
He recommended using nitrification inhibitors with such early nitrogen fertilizer applications with such warm soil temperatures because they slow down the rate at which the ammonium converts to nitrate-nitrogen. This prevents nitrate leaching and reduces nitrous oxide emissions. It also helps to make sure more nitrogen is available when the crop needs it.