Effect of Tillage and Rotation on Agronomic Performance of Corn and Soybean: Twenty-Year Study on Dark Silty Clay Loam Soil

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 QuestionThe 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 SummaryResearch 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 DescriptionThe research was conducted in west-central Indiana on nearly level Chalmers silty clay loam with 4% organic matter. Tile drainage was at 66 ft intervals. Beginning in 1975, four tillage systems were compared within continuous corn, corn following soybean, soybean following corn, and continuous soybean rotations. Tillage systems included: (i) fall moldboard plowing with two seedbed preparation passes in the spring; (ii) fall chiseling with two seedbed preparation passes in the spring; (iii) ridge planting after the top 1 to 2 in. of soil and residues were scraped from the ridge; and (iv) no-till planting with one fluted coulter ahead of standard planter units. Residues were not moved from the row area for no-till planting. There were three replications of all treatments. Plots were 30 ft (12 rows) wide and 150 ft long. Row width was 30 in. for both corn and soybean. Rows were planted into the previous years' rows for both rotational and continuous cropping. Bulk P and K were broadcast biennially for all plots and N was applied annually as ammonia for all corn. Starter fertilizer was used for all corn. Herbicides only were used for no-till weed control, while a combination of herbicides and cultivation was used for other systems. The center four rows of each plot were machine harvested to determine yield. Applied QuestionsWhat is the long-term yield potential of reduced tillage systems on the dark prairie soils of the Central Corn Belt? Both tillage system and rotation influenced stand, growth and yield of corn and soybean in these studies (Table 1). In continuous corn, tillage system also influenced grain moisture. On dark prairie soils, with planting conditions similar to those in this study, the following conclusions appear to be justified. Both corn and soybean yields are greater in rotation than in continuous cropping for all tillage systems. The positive response to rotation, is greatest for no-till corn. Yields with chiseling and ridging may be reduced slightly (less than 3%) in continuous corn, soybean after corn, and continuous soybean. When corn follows soybean, yields with plow, chisel, and ridge systems are likely to be about the same. No-till (no residue moved from row) continuous corn yield on dark, poorly drained soil is likely to be reduced, compared with yield with other systems, and the yield reduction may be greater with time. Part, but not all, of the yield loss may be due to reduced stand or nonuniform plant emergence. No-till corn yield following soybean may be slightly reduced (less than 3%) compared with other systems, but the difference changes little with time. Stand and emergence are not associated with the yield loss. Corn grain moisture for no-till compared with plow, chisel, and ridge is likely to be increased by 2.5 percentage points following corn and 1.0 point following soybean. No-till soybean yields in rotation and continuous cropping may be reduced slightly for several years, but no-till yields should be more competitive with time. In drought years, no-till crops may not respond to the extra soil moisture available under surface residues if no-till plant rooting is delayed. Table 1Corn and soybean yield response to tillage and rotation, Chalmers silty clay loam, Agronomy Research Center, West Lafayette, IN. Tillage system1975–19941980–19941975–19941980–1994--------------------bu/acre--------------------------Continuous corn Corn after soybean Fall plow170.4a†173.3a178.3a183.8aFall chisel165.7b169.0a179.0a184.5aRidge--‡169.9a--186.3aNo-till146.6c143.1b173.3b177.4bContinuous soybean Soybean after corn Fall plow48.1a48.5a52.4a52.8aFall chisel45.7b45.7b50.9b50.5bRidge--46.4b--50.3bNo-till45.7b46.8b48.5c49.0b†Within mtation, data followed by the same letter are not significantly different according to Student-Newman-Kuels Test (P = 0.05). ‡Planter was not properly equipped to stay on ridge tops for first 5 yr.