By Jennifer Stewart, Purdue University
As the wet spring continues to delay planting in Indiana, grain farmers are faced with tough decisions about their intended tillage operations.
As of May 1, just 2 percent of Indiana's corn crop and 13 percent of the national acreage had been planted. Once the ground is dry enough for farmers to work in the fields, some tillage operations may need to be sacrificed, said Purdue Extension agronomist Tony Vyn.
"The major question this season is, 'How should my intended tillage program change in response to the current realities of saturated soils within fields, the weather forecast and the calendar?'" he said. "Overall, the most essential aspects of tillage management for corn planting in Indiana and surrounding states over the next few weeks will be to exercise caution, control weeds and enhance seedbed quality where possible."
Important to choice of tillage systems is limiting soil damage and root-restricting soil layers during tillage or corn planting.
"It is essential to leave the soil condition with the maximum opportunity for unimpeded corn root development," Vyn said. "Potential corn yields can be compromised more by poor soil structure following poor tillage choices from now on than they have been by lost planting days thus far."
Poor tillage choices can include wrong tool selection, operation timing, tillage depth and frequency.
While corn farmers cannot control the rain on their fields, Vyn said they do have control over tillage and planting systems. Those choices now represent the principal soil management decisions required to get corn plants off to a healthy, though delayed, start.
Vyn gave recommendations farmers should consider when they decide how to handle 2011 tillage operations:
- Tillage operations in specific fields depend on the amounts needed for satisfactory weed control. As air temperatures warm, weed growth continues on fields that did not receive recent residual herbicide applications. Generally, herbicide sprayers should precede tillage and planting operations in fields that are not going to receive intensive, full-width tillage this spring.
- Surface roughness left after fall tillage operations in 2010 constrain tillage options in May. Effectively, soil conditions need to be fit down to, and at least an inch below, the intended tillage depth, before secondary tillage is advised. Farmers will need to be more patient in delaying secondary tillage operations if they have fields with rough soil surfaces.
- Stale seedbed planting often reduces seedbed compaction damage and enables earlier planting. In situations where the soil surface is smooth enough to permit planting corn seed at uniform depths and where timely weed control can be achieved, stale seedbed planting should be considered. Prime candidate fields for stale seedbed planting might be those fields where secondary tillage, but not planting, was completed in the first half of April this year.
- A single, shallow and well-timed tillage operation is preferred if pre-plant tillage is deemed necessary. As long as the first tillage operation following weeks of rain delays is done at a soil moisture condition when tillage can make a suitable seedbed, and when emerged weeds can be killed, no further secondary tillage operations should be required.
- No-till corn planting remains a viable option. The probability of successful yields with no-till does not decline with later planting dates; if anything, the relative yield potential of no-till corn increases versus corn yields likely to be achieved after more intensive tillage operations.
- Vertical tillage systems may speed surface soil drying. Typically, shallow and high-speed vertical tillage operations may help to speed up the rate of surface soil drying when there is non-uniform residue cover or rain-matted residue cover.
- Spring strip-tillage operations should be shallow. If farmers can wait until soil conditions are fit down to a 4- or 5-inch depth and have the equipment options to do shallow strip-till in spring, there can be corn yield advantages associated with doing so.
- Precise automatic guidance tools provide new opportunities to limit soil compaction in the actual corn rows. Use of the real-time kinetic, or RTK, steering systems enable corn farmers to precisely control where the wheel tracks will occur before planting.
Vyn's complete list of recommendations can be found in the April 29 issue of Purdue Extension's Pest and Crop Newsletter.