Temperature, Residue, and Yields From Different Tillage Systems

Bill Simmons

Associate Prof., Dept. of Natural Resources
and Environmental Sciences

Office: N-317 Turner Hall (UIUC)
Phone: (217) 333-9649
E-mail: fsimmons@illinois.edu


The best tillage system for your field or farm will vary depending on soil type and, on an annual basis, by spring weather conditions. Since weather cannot be predicted ahead of spring planting, one needs to select a system that will provide a consistently good seedbed across a range of climatic conditions while still maintaining adequate erosion control. A reduction in tillage trips will increase residue cover on the soil surface, and thus reduce erosion potential. Unfortunately, this increase in residue cover may result in cooler, wetter soils that may result in delayed emergence and slower early-season growth. Many farmers are adopting conservation tillage systems not only to reduce erosion potential but also to reduce labor and equipment costs. The system you select must have a balance between input cost and consistency of yield over time.

Crop residue management (CRM) is an excellent technique to minimize erosion. The term CRM refers to a philosophy of year-round management of residue that will maintain the level of cover needed for adequate control of erosion. Conservation tillage, which is defined as a system that provides at least 30 percent cover after planting, will help meet the goals of crop residue management. Several tillage systems are classified as conservation tillage. These include no-till, strip-till, and mulch-till. Adequate erosion control may require more than 30 percent residue cover after planting. In those cases, additional conservation techniques or structures may be needed to attain the necessary erosion reduction.

No-Till and Strip-Till

With no-till, the soil is left undisturbed year round, except for the soil disturbance in a narrow band created by a row cleaner, coulter, seed furrow opener, or other device attached to the planter or drill. No-till planters are usually equipped with row cleaners to clear row areas of residue. No-till planters and drills must be able to cut residue and penetrate undisturbed soil. Strictly speaking, a no-till system does not allow operations that disturb the soil other than the planting or drilling operation. Some producers apply anhydrous ammonia, thus disturbing some of the soil.

A modification of the basic no-till system is strip tillage, where the near-row zone is tilled, typically in the fall, and often in conjunction with fall anhydrous ammonia application. This system incorporates some of the theoretical advantages of tillage (soil drying and warming) with those of no-till (residue cover for erosion control).


Mulch-till includes any conservation tillage system, other than no-till, strip-till, and ridge-till, that maintains a minimum 30 percent crop residue cover after planting. Tillage might be performed with a subsoiler or chisel plow; tillage before planting might include one or more passes with a disk harrow, field cultivator, or combination tool. Crop cultivation may be used to aid in weed control; however, tillage tools must be equipped, adjusted, and operated to ensure that adequate residue cover remains for erosion control, and the number of operations must also be limited. This system is commonly used in Illinois.

SOILS Statewide Tillage Study

A statewide study was commissioned in 1999 by the Illinois Department of Agriculture to study corn production under no-till, strip-till, and mulch-till tillage systems in field size demonstrations. Twelve sites were selected, and a variety of parameters, including soil temperature, residue cover, emerged plant population, and final grain yield, were measured. The data from 11 of the sites combined showed identical yields for no-till and strip-till. Also shown are average yields from nine of the sites, excluding two low-yielding and variable sites from southern Illinois. This data shows a slight increase in yield with tillage, but this difference is not significant, meaning that we don't have much confidence that type of tillage affected yield at all. Strip-till benefits over no-till would be more likely in a spring that was cooler and wetter than 2000. This study will continue in 2001.

Greater in-row and inter-row residue levels were found in no-till (N) treatments with strip-till (S) being intermediate to no-till and mulch-till, here indicated as C, chisel plowed. Temperatures recorded in-row were cooler with less tillage. The average daily cycle of soil temperature for two sites is shown in Figures 4 and 5. At a central Illinois site, the temperatures were similar for strip-till and mulch-till during the warmest part of the day, while later in the day, temperatures under strip-till were similar to that under no-till. At a site near the Quad Cities, diurnal fluctuations in temperature were more sensitive to tillage.

University of Illinois Study

A two-year study at three locations in Illinois-Urbana, Monmouth, and DeKalb-was designed to investigate the interaction of tillage and N application timing. Across all tillage systems, spring-applied N gave the greatest yield. Strip-till and chisel-plow systems gave a nearly identical yield for different N application timing.


Tillage systems may affect crop residue distribution, soil density, and, subsequently, water and temperature relationships in the germination zone. Differences in soil properties do not always translate into significant grain yield advantages for one particular tillage system over another. Weather conditions in the early part of the growing season help determine the likelihood of crop response to tillage systems.

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