Posted 29 May 2012. Crop Management.
Timing of Tillage Crucial to Crops
Source: Crop Science Society of America Press Release. www.crops.org
Madison, Wisconsin (May 12, 2012)--Tilling—how much, when, and even where—seems to be the hot topic these days. It started, when the weather turned warm much earlier than usual, and continues due to concern about the number of passes a producer may now end up making across a field.
The unseasonably warm weather sent many farmers into the fields earlier than normal. Now, as the work really gets underway, there’s caution being shared against tilling more than necessary.
American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America Member Tony Vyn is trying to get producers to plan ahead. "From the soil, fuel and time conservation points of view, early tillage operations need to be considered as a candidates for the final tillage operations farmers complete," Vyn says. "It's important not to till early, then do it again before planting. It means when farmers are ready to plant, they should consider using a stale seedbed approach."
Vyn, a Professor at Purdue University in West Lafayette, Indiana, and also Cropping Systems Extension Specialist, believes it is important to avoid the risks of excessive seedbed moisture loss if dry conditions prevail. "Cloddy seedbed preparation before planting should not be considered acceptable, and certainly not on high clay soils," says Vyn.
The weather also means the moisture contrast between the near-surface and sub-surface soil is less-- which could mean fewer planting delays for producers considering no-till. Good drainage and warm weather can combine to quickly dry soil under surface residue, such as corn stalks. "The weather is not only speeding up tillage, but it's making it more likely no-till operations can occur in a more timely manner,” according to Vyn. "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."
There are other tillage systems farmers can consider, beyond conventional and no-till, including vertical and strip tillage. Vertical tillage is a method of shallow soil penetration and some disturbance of the crop residue. It helps soil dry faster, so farmers can plant earlier. Strip tillage, 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.
1. On some soils, crop rotations and regions, farmers may already have an “ideal” soil environment in terms of soil moisture, soil temperature and soil physical structure (i.e. tilth) without doing any spring tillage at all. No-till or spring “stale-seedbed” planting options after fall tillage operations such as strip-tillage and fall disking should be considered.
2. The earlier and deeper farmers do spring tillage, the more likely farmers will encounter variable–depth soil compaction, non-uniform soil moisture content, and poor soil tilth (e.g. hard or large clods) at or near seed depth.
3. Impatience to do spring tillage can result in poor stands and lost yields in a dry spring. Secondary tillage timing just before planting, makes it most likely seedbed moisture contents are uniform at the depth of seed placement.
4. Each additional spring tillage pass increases the risk of soil erosion and adds to the fuel/time/equipment investment costs.
5. Pre-plant, full-width tillage is not the only way to deal with weeds. Weeds can also be controlled by contact and residual herbicides in applications well ahead of planting. In some cases, pre-plant herbicide applications may be cheaper and more effective than pre-plant tillage operations.
6. Decisions about tillage today may affect future yields (e.g. this fall and long-term), soil erosion, and soil quality for future generations.
7. Even when residue cover is similar, soils are most vulnerable to erosion with high intensity rain in the first day or two after spring tillage.