History of Long Term Tillage Study
Early evaluation of reduced tillage systems in the Midwest centered on well-drained and/or erosive soils. Due to reduced water erosion and savings in soil moisture, systems leaving 70% or more of the soil surface covered with residue often increased yield potential on these soils. These findings could not be generalized, however, to the dark silty clay loam soils of the Eastern Corn Belt where soil moisture and erosion were less severe problems.
Beginning in 1975, a range of tillage systems have been compared annually on Chalmers silty clay loam soil (4% OM) at the Purdue Agronomy Center for Research and Education (ACRE) in West-central Indiana. Our goals are to determine long-term yield potential of the different systems and to determine changes in soil characteristics and crop growth that could be associated with yield differences. Plow, chisel, ridge-till (discontinued in 2008) strip-till, and no-till systems are compared for continuous corn, corn following soybeans, soybeans following corn, and continuous soybeans. There are 4 replications; individual plots are 30-feet wide and 150-feet long.
Don Griffith planting with Ford 8000 tractor and a Buffalo-Till planter on ridges. (1970’s)
Soil and Crop Management
Cultural practices have been relatively consistent since the study began. Plowing and chiseling were done in the fall with 1 disking and/or 1 or 2 field cultivation passes for spring seedbed preparation. For the ridge system, ridges were made at the time of inter-row cultivation in corn and after harvest in soybeans. (The ridge system was replaced with strip-till for 2010 and beyond.) Row width for corn is 30-inches. Both moldboard and chisel plowed corn plots were also inter-row cultivated until 2008. No-till has never been inter-row cultivated. Row width for soybeans was 30-inches for soybeans in all treatments from 1975 to 1994. Starting in 1995, soybeans were drilled in 7.5-inch rows for plow, chisel and no-till treatments, but the ridge treatment remained at 30-inches. Due to the threat of soybean rust disease, all soybean treatments were switched back to 30-inch rows starting in 2005. We concluded that the mechanical damage to plants during possible fungicide application(s) most likely would have greatly reduced yield in the harvest area of drilled soybeans. Soybean plots have not been inter-row cultivated since 2004.
Starter fertilizer was used for all corn plots (except in 2010), but not for soybeans. Placement was 2-inches to the side and 2-inches below the seed. The nitrogen source for corn was anhydrous ammonia through 2000 (either pre-plant or side-dress) and liquid UAN (28%) (always side-dress applied) starting in 2001. Total nitrogen applied generally exceeded 180 lbs/acre of actual N. Phosphorus, potassium and lime were surface-applied as needed.
Corn planting dates ranged from April 5 to May 31 and soybean dates from April 25 to June 21; however, all tillage treatments were planted on the same day each year. One-inch fluted, 2-inch fluted or bubble coulters were used ahead of planter disk openers from 1975 to 1996. Starting in 1997, no coulters were used ahead of disk openers as per planter manufacturer recommendation; however, tined row cleaners were used in no-till corn treatments. For ridge planting, horizontal disks were used to scrape ridges at planting from 1980 to 1996 and then we switched to planter-mounted, double-vertical disks in 1997. Strip-till, which replaced ridge-till in 2010, was accomplished with a Remlinger brand toolbar equipped with row cleaners, a shank set for 8-inches deep, and concave disks to catch soil from the shank and deposit it on the shank track.
Burndown herbicides were applied to control existing vegetation when needed. Pre-emergence herbicides were applied with the planting pass from 1975 through 1996. Starting in 1997, pre-emergence herbicides were applied after planting in a separate operation. Post-applied herbicides were used for weed escapes. Where needed, plots were hand weeded to ensure that weed control did not limit yield. Insecticides were applied at planting for corn rootworm control until 2008 when we switched to genetically modified corn hybrids. Chemical control for cutworms, stalk borers, bean leaf beetle, rodents, and spider mites was applied as needed.
Hiniker ridge-till cultivator used through 2008.
The ridge-till treatment was discontinued after harvest in the fall of 2008. These plots were chisel plowed and disked to destroy the ridges after fall harvest and then strip-tilled in March of 2009. Heavy rains in April and May of 2009 leveled the strips to the point of being unrecognizable. We decided to use 2009 as a set-up year and to field cultivate once more before planting in 2009. Strips were successfully established in the fall of 2009 with 2010 becoming the first data year for strip-till.
Fourteen corn hybrids and 19 soybean varieties have been used during the 44 years of this project.
Dr. Jerry V. Mannering, Harry Galloway and Donald R. Griffith initiated the experiment in 1975 and continued to direct it until their respective retirements in 1989, 1980, and 1995. Terry D. West has managed the experiment from 1979 until present. Dr. Tony J. Vyn became involved in 1998, after moving from Canada where he had been involved in tillage research for 20 years.
Numerous faculty and graduate students have conducted research on this experiment over the years. Most of the efforts were directed towards soil physical properties (Drs. Mannering, Kladivko and Steinhardt), soybean diseases (Drs. Abney and Westphal), corn and soybean production (Griffith and Dr. Swearingin), agricultural engineering (Dr. Parsons), soil microbiology (Drs. Nakatsu, Turco and Brouder), soil fertility (Dr. Mengel) and entomology (Bledsoe).
The Journal of Production Agriculture article titled “Effect of Tillage and Rotation on Agronomic Performance of Corn and Soybean: Twenty-Year Study on Dark Silty Clay Loam Soil” gives a detailed report of this research project. This article can be found in volume 9, no. 2, page 241 to 248, 1996.
Jerry Mannering educating a youngster.
Terry West, Tony Vyn, and Alicia West.
Planting with John Deere 1780 planter, 2013 to present
Case-IH 5240 tractor and model 955 Cyclo planter (1997 through 2013).