and No-Tillage under Various Crop Rotations. Tillage x Rotation Interactions: Strip-Tillage compared to Conventional- and No-Tillage under Various Crop Rotations. Justin Hopf and Joe Lauer Department of Agronomy, University of Wisconsin-Madison INTRODUCTION Tillage systems vary from farm to farm, based on soil type, climate, topography, cropping system, equipment, labor availability, and philosophy on management. A tillage system can be one of the most expensive and labor-intensive practices done on the farm, thus it is important that producers make this operation as profitable as possible. Current markets have driven producers towards less crop rotation (more continuous corn with higher residue) leading to more conventional tillage. The objective of this research is to better understand the interaction between tillage operations and crop rotations. Some basic questions include: How does rotation and environment, climate and soil type affect successful adoption of a tillage system? Is Strip-tillage a practical compromise between conventional- (moldboard or chisel plow) and no-tillage? Should tillage systems be adjusted depending on the previous crop within the rotation? Table 1. Corn Grain Yield (bu/Acre) Response to Chisel Plow-, Strip-, and No-Tillage Treatments in Wisconsin during 2007.   Strip-Tillage Berm No Berm Previous Chisel Deep Shallow No Location Crop Plow Knife Tillage LSD(0.05) Technology Development Trial Arlington ARS Corn 216 206 209 203 NS Soybean 222 224 230 231 223 On Farm Verification Trials Sheboygan County 172 170 165 166 171 140 149 148 161 145 Dane County 239 235 240 236 16 255 250 254 242 249 Table 2. Corn Grower Return ($/Acre) Response to Chisel Plow-, Strip-, and No-Tillage Treatments in Wisconsin during 2007.   Strip-Tillage Berm No Berm Previous Chisel Deep Shallow No Location Crop Plow Knife Tillage LSD(0.05) Technology Development Trial Arlington ARS Corn 628 602 612 620 597 595 NS Soybean 656 680 678 700 699 684 On Farm Verification Trials Sheboygan County 482 492 481 483 497 406 437 450 490 452 449 Dane County 629 686 671 690 675 596 49 750 745 757 724 747 MATERIALS and METHODS Field research measuring Tillage x Rotation interactions was conducted during the 2007 growing season at the University of Wisconsin Agricultural Research Station near Arlington, WI (Plano silt loam). The experimental design was a randomized complete block in a split-split plot arrangement with four replications. Main plots were rotation treatment (continuous corn or corn-soybean rotations). Split-plots were tillage treatment, and split-split plots were fertilizer application timings. In addition, two on-farm sites in Dane County (Plano silt loam) and in Sheboygan County (Kewaunee silt clay loam) were established to verify findings of the Tillage x Rotation experiment. The experimental design of the on-farm trials was a randomized complete block in a split-plot arrangement with three replications. Main plots were tillage treatment. Split plots were fertilizer application timing. Fertilizer treatment was either fall or spring application. Hybrids were selected for performance, adaptation and presence of the Roundup Ready trait. Weeds were controlled using glyphosate. Data were analyzed using PROC MIXED (SAS Institute, Cary, NC). Six tillage systems were established including: Conventional tillage (CT), chisel plow in the fall fallowed by one pass with a field cultivator in the spring before planting. No-tillage (NT), the soil is left undisturbed other than planting. Strip-tillage (ST), was preformed in the fall using different knife and fertilizer configurations. Deep knife (9 in.) with full berm. Deep knife (9 in.) with no berm. Shallow knife (6 in.) with full berm. Shallow knife (6 in.) with no berm. Grower Return = (Yield * corn price [$3.39 per bushel]) – costs Where costs include: handling = $0.02 per bushel, hauling = $0.04 per bushel, trucking = $0.11 per bushel, storage = $0.02 per bushel ((yield*0.25*4)+ (yield*0.25*8)), drying = $0.02 per point per bushel, extra N = $12 ($0.30 per lb of N - 40lbs) for continuous corn, equipment = $22.30 for Conventional tillage - chisel plow + field cultivator – tractor and implement overhead, fuel, lube, labor, or Strip-tillage = $8.30 for tractor and implement overhead, fuel, lube, labor (Schnitkey, 2006). RESULTS and DISCUSSION No significant two- or three-way interactions were found in these experiments. Corn rotated with soybean increased grain yield 10 bushel per acre (5%) and increased grower return 9% or $51 per acre (Figures 1 and 2). Overall, no differences were detected between tillage systems and fertilizer application timings. Within environments, differences among tillage systems were detected once in continuous corn (Dane County) where all strip-tillage treatments had greater yield than no-tillage (Table 1). All Strip-tillage treatments had greater grower return than no-tillage (Table 2). Strip-tillage with berm treatments had greater grower return than chisel plow tillage (Table 2). Grain moisture, plant density, plant lodging, plant growth & development, and weed density were not significant for any factors. Previous research in Wisconsin indicates that yields of no-tillage are less than conventional tillage (Al-Darby, 1986). The 2007 growing season was very hot and dry with periods of droughty conditions. Systems with less aggressive tillage are usually better able to conserve soil moisture during these conditions (Ribera et al., 2004), which may explain lack of differences between tillage treatments. Another possible explanation for lack of differences among tillage systems might be the effectiveness of glyphosate weed control systems. With effective herbicide use, reliance on tillage to control weed populations becomes less critical, allowing reduced tillage systems to conserve water and be profitable. SUMMARY Tillage system was not affected by rotation. Weather and the weed control system negated the expected tillage x rotation interactions. Strip-tillage is a viable compromise between conventional- (moldboard or chisel plow) and no-tillage. Overall, there were no differences among tillage treatments. However, in more challenging environments a one-pass strip-tillage system may manage risk better than a no-tillage system. The decision to select a tillage system should be based upon the economics of the system, since no agronomic differences or interactions were observed. REFERENCES Al-Darby, A.M., and B. Lowery. 1986. Evaluation of corn growth and productivity with three conservation tillage systems. Agron. J. 78:901-907. Ribera, L.A., F. M. Hons, and J.W. Richardson. 2004. An Economic Comparison between Conventional and No-Tillage Farming Systems in Burleson County, Texas. Agron. J. 96:415-424. SAS Institute. 1999. The SAS system for Windows. Release 9.1. SAS Inst., Cary, NC. Schnitkey, G., and D. Lattz. 2006. Machinery Cost Estimates: Field Operations and Machinery Cost Estimates. Department of Agricultural and Consumer Economics, University of Illinois.