Small Grain Research Menu

Results of Funded Research

No-Till Drill Performance Assessment for Wheat Stand Establishment Following Corn

Scott Shearer
Samuel McNeill
University of Kentucky

1999 Summary Report

OVERVIEW AND JUSTIFICATION
 
Kentucky wheat producers strive to establish good wheat stands in the fall to reduce winter kill and improve yield potential.  Desired crop rotation schedules encourage producers to use no-till practices for wheat into recently harvested cornfields, most of which contain high levels of residue.  In many locations, wheat is planted within a few days after corn harvest with green stalk material left in the field.  This compounds the residue problem and negatively impacts wheat stand establishment.  The two factors associated with corn residue that are thought to influence what stands are pinning and emergence suppression.  Pinning occurs when residue, uncut by the drill openers at planting, causes seed to be placed on top of the residue or soil surface.  This prevents good seed to soil contact and interferes with germination.  A second problem arises when the seed is sown at a sufficient depth only to be covered with heavy residue pushed aside by adjacent openers.  This movement and concentration of residue affects local soil temperature and the ability of emerging seedlings to grow through and above the residue.  Hence, the focus of the proposed work was to study the effects of no-till drill configurations with respect to cutting reside, residue flow and distribution, and depth control on wheat emergence and stand establishment.
 
OBJECTIVES
 
1.   To evaluate the performance of two no-till drills—one with a single-disc opener and another with a leading coulter and double-disc opener—by measuring stand establishment and seeding depth of wheat following high residue corn.
 
2.   To assess the role of residue in seed placement and emergence in no-till wheat following high residue corn.
 
METHODOLOGY
 
Drill trial test plots were established at three locations in the Commonwealth using two popular no-till drills.  Cooperators who participated in this investigation were Curtis Hancock in Hickman County, Don Halcomb in Logan County, and Mike Ellis in Shelby County.  Drills selected for this study represented two common configurations available today—a drill with single disc openers (John Deere 750 no-till drill) and one with coulters and double disc openers (Great Plains no-till drill).  Drill manufacturers were contacted to set-up and adjust the drills for wheat prior to planting.  Owner’s manuals were used to determine the initial settings for each drill.  These adjustments were fine-tuned at each location to assure proper seeding depth and seed slot closure.
 
Three wheat varieties were chosen for each location in consultation with each producer/cooperator.  Early, medium, and late maturing varieties selected were Clark, Pioneer 2552 or Foster, and Pioneer 2510 or 2540, respectively.  The wheat variety common to all sites was Clark.  Additional wheat varieties by site included Foster and Pioneer 2540 at Hickman County, Foster and Pioneer 2510 at Logan County, and Pioneer 2552 and 2510 at Shelby County.
 
A target seeding rate of 375 seeds/yd² (85 seeds/m in 7.5-inch rows) was chosen for all varieties after conferring with cooperators and representatives from Opti-Crop and Wheat Tech.  Germination and purity for each seed lot were taken into account when determining the desired seeding rates (see Table 1).  Both drills were calibrated to within 3.0 percent of the target seeding rate by collecting seeds from five drop tubes in a 200-ft test strip (see Table 2).
 
Table 1.  Seed data fro soft red winter wheat varieties used in 1997 no-till drill study.

Note:  Input values in bold are provided by the user to calculate the calibration seed drop needed for each variety to achieve the target rate.
 
Fields were laid out in strip plots that were oriented parallel to corn rows and at a 30º angle to corn rows at each location.  Plot widths varied relative to the size of the drill used at each location, but were between 200-ft and 1000-ft long.  With each variety, one drill pass was with each half of the 30-ft drills, but two drill passes were made with the 10-ft drills.  Hence, plot widths varied between 15 and 20 feet, which did not exceed the header width of the combines used at harvest.
 
Evaluations for each no-till drill included determination of residue management, furrow closure, seeding depth, and stand assessment.  All sample locations were flagged and sampled for soil moisture and fertility the same day they were planted.  Residue cover was estimated by isolating a 1.0-meter length by 2.5-meter width of test plot normal to the drilled seed row and then collecting, weighing, and determining the moisture content of the residue covering the plot at planting time.  The number of wheat seeds present on the soil or residue surface (pinning) was also counted at this time.  This process was replicated at 100-ft intervals within each of the Clark test strips for both orientations at each location.
 
Table 2.  Seeding rate calibration for 10-ft and 30-ft Great Plains and John Deere 750 no-till drills in 1997.

Field Notes for the John Deere 750 no-till drill:
 
Little disturbance of the soil surface.
More space for residue to flow through the unit.
Few problems with residue build-up on openers at all locations including standing, uncut stubble (Shelby Co.), flail chopped stalks (Logan Co.), and disked and weathered stalks (Hickman Co.).
Seed placed on soil surface near corn row (opener and gage wheel rode over stalks and roots at base of plant instead of cutting through standing residue—more pronounced in dry conditions).
Worked well in moist soil although slot was not always closed.
Relatively low variation of discharge between seed metering cups, with different variations between 10-foot and 30-foot drills.
Some pinning observed with moist residue (opener did not cut through moist stalks, leaves and stalk ‘stumps’).
Able to maintain desirable ground speeds for all soil and residue conditions encountered at all locations.
 
Field Notes for the Great Plains no-till drill:
 
Moderate soil disturbance and movement by nature of design (Turbo coulter with double disc opener).
Less unobstructed area for residue to flow through seed openers and closing wheels.
Drill seemed to perform better in dry soil and crop residue conditions.
Severe bunching of residue observed at one location (flail chopped residue was matted and tended to collect on the coulter in moist conditions, thereby causing the operator to reduce ground speed by half).
Dirt clods observed to hinder seed emergence in heavy, moist soil.
Relatively high variation of discharge between seed metering cups with different variations between 10-ft and 30-ft drills.
Some pinning observed with moist stalks.
 
Plant emergence and seeding depth were evaluated three to four weeks after the planting date and are summarized in Table 3.  A one-meter length of drill row was selected at 100-ft intervals within the Clark test strips.  Emergence was assessed at each location by counting the number of viable plants as shown in Table 4.  Seeding depth was determined by physical measurements from drill rows that were selected at random.  A metal scale was used to measure the distance from the soil surface to the top of the seed to the nearest 1.0-mm which are recorded in Table 5.
 
Four to five head counts were made at random within a 38.4-inch row length (2 square foot area) at 100- to 200-ft intervals within the Clark test strips.  Measurements were made on May 21 in Logan County, May 28 in Hickman County, and June 3 in Shelby County.  Data from each location are given in Tables 6 - 8 and summarized in Table 3.
 
Wheat plots were harvested after the last variety had ripened and dried below 15% moisture content.  Harvest dates were June 22 for Logan County, June 23 for Hickman County, and June 25 for Shelby County.  Gross weight from each plot was measured with a weigh wagon in Hickman and Logan Counties while a yield monitor was used in Shelby County.  A composite grain sample was collected at the Hickman and Logan County locations and analyzed for moisture content and test weight.  Harvest data was then adjusted for moisture and calculated on a 60-lb bushel for each location and shown in Tables 9 - 11.  Equipment used to harvest each plot is described in the notes on each table.  Stripper headers were used at Logan and Shelby Counties.
 
RESULTS
 
Drill Calibration
 
Initially, the drill calibration procedure was approached in a traditional manner.  Seed was collected from a metering cup as the drill was operated over a 200-ft distance.  However, on examination of the data from several metering cups, significant differences were found.  The calibration procedure was amended to include collection of seed from five metering cups somewhat evenly distributed over the width of the drill.  Differences in the coefficient of variation between manufacturers and between drills from the same manufacturer were observed.    The coefficient of variation for the drills and seed size in this investigation ranged from 1.1 to 3.4% for the John Deere 750 drill and 2.8 to 9.2% for the Great Plains drill (see Table 2).  The average coefficient of variation for the John Deere drills was 2.1% versus 4.8% for the Great Plains drills.  The most meaningful conclusion to be drawn from this data is that producers who want to sow seed to within 5% of a target rate should use three or more metering cups when calibrating their drills.
 
Drill Performance
 
Soil moisture contents for the top 4.0 inches of soil averages 25.4% in Hickman County, 19.7% in Logan County, and 15.4% in Shelby County.  With the exception of the Shelby County site, good seeding conditions were encountered at planting.  Drill penetration at Shelby County was limited, particularly with the John Deere machine.  Although 900 lbs of additional weight was added to the John Deere drill frame, the down pressure of the openers was limited to the level recommended in the operator’s manual.  In the wetter soils down pressure on the John Deere drill was not a problem.  The Great Plains drill appeared to perform well in dry soil, with some residue flow problems encountered in the wetter soil where the residue was flail chopped.   In this condition, residue accumulated on the top of the Turbo coulters causing the operator to reduce ground speed to overcome this problem.
 
Biomass yields ranged from approximately 4700 lbs/ac to 9200 lbs/ac for the three sites.  Much of the difference in the amount of residue between sites was due to the difference between the corn harvest date and wheat planting date.  In Shelby County, only a few days separated the two events, but in Hickman County the time span was close to four weeks.  This difference partially contributed to the difference in soil and residue moisture during wheat planting but at this point no attempt has been made to correlate biomass and stand or biomass and consistency of seeding depth.  Nonetheless, data from each location was treated both separately and collectively in the statistical analysis.
 
The average fall stand count, seeding depth, and head count for Clark wheat with both drills/orientations and all locations is shown in Table 3.  Recall that a stand of 375 plants per square yard required 85 plants per meter of drill row at 7.5-inch spacing.  When comparing average stands for both drills and orientations, stands at Hickman County (71) were significantly higher than those at Logan County (65) (LSD = 4.5).  Both drills had virtually the same average stand (68.3 for the Great Plains versus 67.9 for the John Deere).
 
            The difference in fall stand counts between drills and orientations at Hickman County were both significant, where the John Deere had 73.8 plants per meter versus 68.3 for the Great Plains drill (LSD = 4.5).  Not reflected in this data, however, was the observation that the Great Plains produced an earlier, more uniform stand while the John Deere plots had more noticeable ‘skips.’  The difference between the drill angle with corn rows was also significant (72.5 plants per meter of drill row length at a 30º  angle compared with 67.2 when parallel).
 
            Different results were found at the Logan County site where neither drill nor orientation contributed significantly to the variations in stand count.  However, a significant difference was observed between orientations for the Great Plains drill only (73 for parallel rows versus 59 at a 30º angle).  Comparative values for the John Deere drill were 61 plants per meter for both orientations.  Obviously, stands from both the John Deere and Great Plains drills fell short of the intended goal which meant that the plants would have to produce several tillers to approach maximum yield potential.  Nonetheless, a high seeding rate seems to be a cost-effective method of reaching yield goals.
 
            Observed differences in seeding depth were unaffected by orientation with corn rows, which was a bit surprising.  The overall mean and standard deviation for both drills was virtually the same (27.6 and 7.4 mm, respectively for the John Deere drill compared with 29.3 and 8.7 mm for the Great Plains drill).  Both were very close to the target depth of one-inch (25.4-mm).  When evaluated by location, however, significant differences were found.  The Great Plains planted deeper at Hickman County (33.8 mm versus 25.3 mm for the John Deere), but the opposite was found at Logan County (30.4 mm for the John Deere compared with 24.0 mm for the Great Plains).  Hopefully, the second year of study will provide more information on this interesting observation.
 
            Head count data from Hickman, Logan, and Shelby Counties are given in Table 6, 7, and 8, respectively, and summarized in Table 3.  Drill type significantly influenced head counts (LSD = 3.6 heads/2 ft²) with the John Deere exhibiting a slightly higher average value for all locations and orientations (110 heads/2 ft² or 495 heads/yd²) compared with the Great Plains 105 heads/2 ft² or 473 heads/yd²).  When scrutinized by location, significant differences were found between drills and corn angle at Hickman County and for drills only in Logan County, but for neither variable in Shelby County.  Mean values were higher for the John Deere drills at all locations.  Head counts for wheat drilled parallel with corn rows were slightly higher in Hickman and Logan Counties.
 
Table 3.  Summary of mean fall stand counts, seed depth, and head counts for Clark wheat plots at all locations with both no-till drills and orientations with corn rows.

Yield data for Hickman, Logan, and Shelby Counties are given in Tables 9, 10, and 11, respectively.  Grain moisture and test weight data were also recorded for varieties from the Logan and Hickman County plots.  Adjusted yields account for the differences between row units on each drill trip, which varied at each location.  When all data was combined, location and variety contributed significantly to the observed differences in adjusted yield whereas the drill and angle of planting did not.  At individual test locations, significant differences were found between varieties and drills only at the Hickman County site.
 
Please note that these findings are preliminary!  While some trends appear, more data is needed from a second year of study to determine if they are reproducible.
 
OTHER PROJECT ACTIVITIES
 
These findings have been presented as a work in progress at UK Wheat Field Days in Logan, Henderson, and Fulton Counties in May 1998 (prior to harvest).  A poster presentation that summarized this data was also given at the National Association of Wheat Growers meeting in Nashville in February 1999.  Additionally, an extension publication for calibrating wheat drills has been drafted by the investigators and is under review.
 
ACKNOWLEDGMENTS
 
Funding for this research was provided through a grant sponsored by the Kentucky grain growers association.  The assistance of Dottie Call, John Earnest, and Derek Hall with collecting field data was deeply appreciated.  The investigators also wish to express their sincere appreciation and gratitude to the cooperators that include Curtis Hancock in Hickman County, Don Halcomb in Logan County, and Mike Ellis in Shelby County.

Table 4.  Stand counts for SRW wheat into corn stubble at Hickman and Logan Co. during the fall of 1997 with Great Plains (10-ft & 30-ft) & John Deere 750 (10-ft & 30-ft) drills.

Table 5.  Seed depths for SRW wheat into corn stubble at Hickman61 and Logan Co. during the fall of 1997 with Great Plains (10-ft & 30-ft) & John Dee53re 750 (10-ft & 30-ft) drills (12/23/97 and 12/17/97, respectively).

Table 6.  Head counts for SRW wheat plots at Hickman Co. with Great Plains (10-ft) & John Deere 750 (30-ft) drills (5/2/98).

Table 7.  Head counts for SRW wheat plots at Logan Co. with Great Plains (10-ft) & John Deere 750 (10-ft) drills (5/21/98).

Table 8.  Head counts for SRW wheat plots at Shelby Co. with Great Plains (30-ft) & John Deere 750 (10-ft) drills (6/3/98).

Table 9.  Yield, moisture, and test weight data for Hickman County no-till drill plots harvested 6/23/98.

Notes:  All plots were harvested with a ‘98 JD 9610 w/ 30-ft conventional header at ~ 4.5 mph.
* Harvested weight multiplied by 1.014 to account for corner trimmed by combine.
Larry Reber’s weigh wagon used to weigh harvested grain and transfer into grain cart.
Moisture adjustment made by shrink equation: [(100-mc) / (100-13.5)].
Yields adjusted for moisture and based on 60 lb/bu--not adjusted for test weight.
Overall mean adjusted yield for orientations was 74.8 and 73.2 for the 0 and 30 degree angle, respectively (LSD = 4.7).
Overall mean adjusted yield for drills was 71.5 and 76.6 for the GP and JD, respectively (LSD = 4.7).
Overall mean adjusted yield for varieties was 81.7, 71.5, and 68.8 for the P2540, Foster, and Clark, respectively (LSD = 5.8).
 
Table 10.  Yield, moisture, and test weight data for Logan County no-till drill plots harvested 6/22/98.

Notes:  all 1000-ft plots and four of the 330 ft plots were harvested with a ‘97 JD 9600 w/ 22-ft stripper header at ~ 5.5 mph.
*Weight from these plots were multiplied by 1.23 (16/13) because the spray coupe mashed 3 out of 16 rows.
The last two 330-ft plots were harvested with a NH TR85 (twin rotor) combine with an 18-ft stripper header (17.5 ft cut).
Quantum Seeds’ weigh wagon used to weigh harvested grain.
Moisture adjustment made by shrink equation:  [(100-mc) / (100-13.5)].
Yields adjusted for moisture and based on 60 lb/bu--not adjusted for test weight.
Overall mean adjusted yield for orientations was 55.4 and 51.4 for the 0 and 30 degree angle, respectively (LSD = 6.2).
Overall mean adjusted yield for drills was 51.3 and 55.5 for the GP and JD, respectively (LSD = 6.2).
Overall mean adjusted yield for varieties was 57.0, 52.1, and 51.2 for the Foster, Clark, and P2510, respectively (LSD = 7.6).
 
Table 11.  Yield data from Shelby Co. no-till drill plots harvested 6/25/98.

Notes:  Green Star yield monitor used to measure grain moisture and yield.
Trip #1 in both sub-plots was a buffer used to calibrate the yield monitor with a weigh wagon.
All plots were harvested with a /97 JD 9600 w/ 30-ft stripper header at ~ 5.5 mph.
Overall mean adjusted yield for orientations was 68.8 and 69.7 for the 0 and 30 degree angle, respectively (LSD = 9.5).
Overall mean adjusted yield for drills was 71.0 and 67.5 for the GP and JD, respectively (LSD = 9.5).
Overall mean adjusted yield for varieties was 73.1, 68.6, and 66.1 for the P2510, Clark, and P2552, respectively (LSD = 11.6).

TOP