Little information is available that evaluates long-term use of a range of tillage systems and different cropping sequences on poorly drained soils. This study relates corn (Zea mays L.) growth and yield to several reduced tillage systems used with continuous cropping and a corn-soybean (Glycine max L.) rotation. Experiments were conducted on Chalmers silty clay loam (fine-silty, mixed, mesic Typic Haplaquoll) with 40 g kg-• organic matter for 12 yr, and Clermont silt loam (fine-silty, mixed, mesic Typic Ochraqualf) with 10 g kg-• organic matter for 7 yr. Both soils are nearly level and poorly drained. Tillage systems compared included moldboard plowing, chisel plowing, ridge planting, and no-till planting. Shallow disking (10 em) was also included at the Clermont site. On the high organic matter Chalmers soil, continuous no-till corn was 25 em shorter at 8 wk, 2% wetter at harvest, and 9.2% lower in yield compared to plowing. Data for chisel and ridge systems were intermediate between plowing and no-till. No-till yields were consistently lower than those for plowing after the first 4 yr. When following soybean, no-till corn was 7 em shorter at 8 wk, 1% wetter at harvest, and 2.6% lower in yield than corn under moldboard plowing. Corn growth and yield from chisel and ridge treatments were equal to those with plowing when in rotation. On the low organic matter soil in continuous notill corn, plant growth and yields were reduced for the first 3 yr, but were equal or better, compared to plowed corn, for the final4 yr. In rotation, no-till corn was equal to plowed corn the first 3 yr and significantly better in 3 of the last 4 yr. Yields with intermediate tillage were similar to plowed yields for continuous and rotational cropping. The relative advantage for no-till planting with time on the low organic matter soil is attributed to improved soil physical properties.

In the U.S. Corn Belt, tillage without plowing was used on more than 50% of corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] acreage in 1994, while no‐till planting was used on about 30% of the acreage. Few research studies have evaluated these reduced tillage systems for 20 yr or more. This study includes plow, chisel, ridge, and no‐till systems in continuous corn, corn after soybean, soybean after corn, and continuous soybean rotations. The experiment was conducted on Chalmers (fine‐silty, mixed, mesic Typic Haplaquolls) silty clay loam soil in north‐central Indiana for 20 yr. Objectives were to determine the effect of tillage and rotation on stands, growth, maturity, and yield of corn and soybean and to determine trends that develop with time for these variables. Major stand reductions occurred only in no‐till continuous corn, 8% less than plowing. Compared with plowing, chisel and ridge tillage systems reduced growth and yield and increased harvest moisture by less than 3% in continuous corn. No‐till reduced 4‐wk height of continuous corn by 17%, yield by 14%, and increased harvest moisture by 2.1 percentage points compared with plowing. For corn following soybean, only no‐till corn showed a yield reduction, 2.8%, compared with plowing. Twenty‐year mean soybean yield reductions averaged 4 to 7% in both rotation and monoculture for chisel, ridge, and no‐till systems compared with plowing. Relative yields for no‐till continuous corn tended to be less than other tillage‐rotation systems over time, while no‐till soybean yields tended to improve with time, especially during the last 5 yr of the study. Both corn and soybean yields were better in rotation than in continuous cropping for all tillage systems. Of the tillage systems‐rotation combinations in this study, only no‐till continuous corn is likely to suffer major yield loss on a long‐term basis on dark prairie soils of the Central and Northern Corn Belt. Research Question The use of reduced (no‐plow) tillage systems has increased rapidly in the Midwest during the past 10 yr. Both residue on the soil surface and soil physical and chemical properties are altered with time when farmers change tillage system. These changes may affect crop growth and yield potential. There is a need to determine both long‐term average yields and long‐term trends with the reduced tillage system. Literature Summary Research throughout the Midwest has shown that well drained soil, light surface residue, more southern latitude, and delayed planting lead to greater success with reduced tillage. Most Midwestern tillage system studies were conducted for 10 yr or less. The study reported here includes a range in tillage systems, both continuous and rotational cropping, and has completed 20 yr. Objectives were: (i) to determine the effect of tillage and crop rotation on stands, growth, maturity, and yield of corn and soybean on silty clay loam soil, and (ii) to determine trends that develop in the above variables with time. Study Description The research was conducted in west‐centra...

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Recent adoption of tillage systems that allow maintaining rows in the same place each year, such as no‐till and ridge planting, has renewed interest in strip‐intercropping tall and short crops to more efficiently use sunlight in grain crop production. This study compared eight‐row strips of corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] with unstripped eight‐row checks. Corn strips were evaluated with and without extra population and N for outside rows. The trials were conducted from 1986 through 1990 on highly productive prairie soils near Lafayette, IN. Yields were checked by row within eight‐row strips. Stripping increased yield of outside corn rows by an average of 25.8% and decreased yield of outside soybean rows by 26.6%, but had much less effect on yield of second rows in strips. The yield of the center six soybean rows was reduced slightly by stripping. Corn strips with extra population and N yielded 20.0 bu/acre more than nonstripped corn with regular management. Stripped soybean averaged 5.9 bu/acre less than unstripped soybean. Net profit was not increased by strip‐intercropping under conditions of this study. Additional management variables that may improve stripping profitability must be evaluated.

No‐till acreage has expanded rapidly in the past 5 yr in the U.S. Corn Belt. Yield potential often improves with no‐till planting on well drained and low organic matter (OM) soils, but no‐till yields are sometimes at a disadvantage on dark, poorly drained soils. Restricted plant rooting due to increased soil density is sometimes reported with no‐till planting. Deep tillage with a Paraplow (Tye Co., PO Box 218, Lockney, TX 79241), leaving most surface residue undisturbed, was evaluated on three soils in Indiana for continuous corn (Zea mays L.). Annual paraplowing and biennial paraplowing were used with no‐till and moldboard plow systems. On dark, poorly drained silty clay loam, annual paraplowing improved stand, growth, and yield, compared with traditional no‐till planting. On a silt loam soil with 2% OM, response to paraplowing for no‐till was variable and on a 1% OM soil, paraplowing did not improve no‐till yield. Carryover effect from biennial paraplowing for no‐till planting was not consistent, even on silty clay loam. paraplowing did not improve plowed yields on any of the three soils. Paratilling was also used on four rows of each 12‐row plot in the 15th year of a long‐term tillage study on silty clay loam soil. Plow, chisel, ridge, and no‐till systems were used in continuous corn, corn after soybean [Glycine max (L.) Merr.], soybean after corn, and continuous soybean. In no‐till continuous corn, there was a positive response to paratilling, but yield for no‐till plus paratilling was significantly lower than plowed yield. With conditions similar to conditions in these studies, deep soil loosening is likely to improve no‐till continuous corn yield on dark poorly drained soil, but is not likely to improve yield on well drained or low OM soils where traditional no‐till is well adapted. Research Question No‐till acreage has expanded rapidly in the past 5 yr, as farmers look for ways to improve profitability, control soil erosion, and stay in compliance with USDA Food Security Acts. On well drained and low organic matter (OM) soils, no‐till yields have often been equal to or greater than yields with full‐width tillage. However, on dark, poorly drained soils in the northern half of the Corn Belt, no‐till yields are sometimes at a disadvantage, especially in heavy residue. Both farmers and researchers have speculated that periodic deep soil loosening may improve no‐till yield potential. The objective of the studies reported here was to determine the effect of paraplowing on crop stands, growth, maturity, and yield in newly established no‐till continuous corn and in long‐term no‐till corn and soybean. Literature Summary Many researchers have found that soil bulk density is greater in no‐till fields than where full width tillage was used, especially for the first half of the growing season. The Paraplow (or Paratill) provides an opportunity to loosen soil to a depth of 14 to 16 in. with little disturbance to surface residue. In Iowa, paraplowing in the fall improved bulk density, water infiltration, plant emergence,...