4. Air Seeder Principles and Functions
Basic Criteria for Effective Seeders
Opener Design & Seed/Fertilizer Placement
Managing Crop Residue
Soil Disturbance
Depth Control
Varying Conditions
Precision Agriculture
Energy Requirements
5. Channel Setting Instructions for ResponseCard RF
1. Press and release the "GO" or "CH" button.
2. While the light is flashing red and green, enter the 2 digit
channel code (i.e. channel 1 = 01, channel 21 = 21).
Channel is 41
3. After the second digit is entered, Press and release the "GO"
or "CH" button. The light should flash green to confirm.
4. Press and release the "1/A" button. The light should flash
amber to confirm.
6. Where is Your Home Area?
1 2 3 4 5 6
0 0 0000
1. North Dakota
2. South Dakota
3. Manitoba
4. Saskatchewan
5. Montana
6. Other
7. What is your Occupation?
1 2 3 4
0 000
1. Farmer/Rancher
2. Dealer Personnel
3. Factory Personnel
4. Other
9. Which crops do you grow?
1 2 3 4 5 6 7 8 9 10
0 0 0 0 000000
1. Oats
2. Potatoes
3. Rye
4. Safflower
5. Soybeans
6. Sugarbeets
7. Sunflower
8. Wheat, Durum
9. Winter Wheat
10. Other
10. What is your tillage system?
1 2 3 4 5
0 0 000
1. Intensive Tillage
2. Minimum Tillage
3. One-Pass System
4. No Till
5. Other
11. Basic Criteria for Effective Seeders
1. Precisely Meter Seeds
2. Plant Seed at Uniform Depth
3. Plant Through Residue
4. Function in Varying Soil Types
5. Durable
6. Economical
7. Correctly Place Fertilizer and Seed
12. Basic Criteria for Effective Seeders
1 2 3 4 5 6 7 8
0% 0% 0% 0%0%0%0%0%
1. Precisely Meter Seeds
2. Plant Seed at Uniform
Depth
3. Plant Through Residue
4. Function in Varying Soil
Types
5. Durable
6. Economical
7. Correctly Place Fertilizer
and Seed
8. Other
13. Factors Affecting Choice of Opener Type
• Soil Type and Conditions
• Crop Residue
• Amount, Type, Position
• Crops to Plant
• Producer Management Goals
15. What Type of Opener do you use?
1 2 3 4
0 000
1. Disc Opener
2. Hoe Opener
3. Combination
4. Other
16. Choice of Opener Type: Seed to Soil Contact
Water Transfer from Soil to Seed: The Role of Vapor Transport
Water Transfer from Soil to Seed: The Role of Vapor Transport
Stewart B. Wuest. USDA-ARS, Pendleton, OR
Vapor alone is sufficient to supply water for germination.
17. Choice of Opener Type: Seed to Soil Contact
Water Transfer from Soil to Seed: The Role of Vapor Transport
Water Transfer from Soil to Seed: The Role of Vapor Transport
Stewart B. Wuest. USDA-ARS, Pendleton, OR
Vapor alone is sufficient to supply water for germination.
Barley, pea, mustard,
and wheat were
tested for their ability
to germinate rapidly
with vapor alone.
18. Opener Design
Producer Management Goals: Hoe vs. Disc
Disc Openers – Leaves Residue Standing
• Slow Soil Warming (Cooling)
• Maintains Soil Moisture
Hoe Openers – Mixes Residue into Soil
• Promotes Soil Warming and Drying
• Promotes Residue Decomposition
• Place Seed into Moist Soil
19. Opener Design
Seed and Fertilizer Placement
• Factors Affecting Amount of N with the Seed
• Distance between Rows
• Distribution of Seed and Fertilizer
• Soil Texture, Soil pH
• Soil Moisture
• Fertilizer Placement
• Type of Fertilizer
• Crop
Greater risk of nitrogen
toxicity in sandy soils
than in clay soils
20. Opener Design
Separate Fertilizer Placement Systems
Banding Fertilizer
• Beside Seed
• Below Seed
Mid-row Banding - Fertilizer
Double Shooting Fertilizer
• Below and to Side of Seed
• Beside Seed
Barton™ Double-shoot
21. Opener Design
Separate Fertilizer Placement Systems
• 30 lb./acre of N - wheat
• 10-20 lb./a of N - Canola
• Mid-row banding
• P too far from the plants
to deliver a “starter”
effect to young plants?
Fertilizer banded more than a few inches
from the seed row may not be available to
the plant until the tillering stage when crown
roots develop (Washington State University)
22. Opener Design
Paired-row vs. Single Row Spacing
• Wheat Plant
Lateral spread - 5 inches
Depth–6inches
30 days after planting
Early fertilizer access improves tiller survival where
soils have low nutrient levels.
Yield increases in
wheat by banding
below the seed
compared to banded
between seed rows.
23. Opener Design
Paired-row vs. Single Row Spacing
• Wheat Plant
Lateral spread - 5 inches
Depth–6inches
30 days after planting
Paired-row
• Fertilizer band between wheat rows within
2” to 3” of each seed row
• 2” below seed
24. Opener Design Preferences?
1 2 3 4 5 6
0% 0% 0%0%0%0%
1. Separate Fertilizer
Placement
2. Starter Fertilizer with
Seed
3. All Fertilizer with
Seed
4. Paired Row - Fertilizer
Between Rows
5. Fertilizer Below Seed
6. Other
25. Managing Crop Residue
• Residue is a Resource to
Conserve and Use.
• Limits Evaporation
• Preserves Moisture
• Maintains Humidity in Soil
• Food for Beneficial Fungi,
Bacteria, Insects
26. Managing Crop Residue at Harvest Time
• Spread Straw Uniformly
• Harrows
• Incorporate Weeds Seeds
• Increases Seed Longevity
• Disc Openers
• Leave Tall Stubble
• How Opener – Shorter Stubble
• Residue No Longer than Planter Row Width
27. Managing Crop Residue
Effect of Corn Residue Placement on Wheat Yield
Residue Placement Wheat Yield (bu/ac)
random coverage 73.8
0.25 inches away 75.4
0.50 inches away 73.1
0.75 inches away 75.0
1.25 inches away 72.0
Bare Soil 81.9
Residue Placement to Improve Yields of No-Tillage
Winter Wheat Following Corn
John H. Grove and Christopher E. Kiger, Agronomy Dept., Univ.
of KY 1987
28. one
NDSU Residue Management Project
Golden Valley
County
Stutsman County Cass County
Soil name Amor loam Barnes-Buse loam Glyndon silt loam
Tillage System No-till (20+ years) No-till 10 years Conventional
Crop Rotation wheat-corn-pea-
wheat
wheat-soybean-
soybean-wheat-
soybean-soybean-
corn-dry bean-corn
sugarbeet-wheat-
soybean or corn
• Started in 2010
• Electronic Sensors
• Data on Internet
• Updated Daily
31. NDSU Residue Management Project
Short
Medium
35 to 40% Standing
13% Standing
Tall
100% Standing
32. Data Transfer
• Cellular Modem
• Remote Computer calls Modem
• FTP Data to NDSU Server Computer
• Updated Data on Internet
http://www.ageng.ndsu.nodak.edu/farmmonitor
35. -20
-10
0
10
20
30
40
50
Average Temperatures
Stutsman County
Dec. 1 - March 1
2011-12
Air Temperature Tall Stubble Temperature
Medium Stubble Temperature Short Stubble Temperature
Average Temp 22°F Average Temp 29°F
Average Temp 29°F Average Temp 29°F
Crop Residue – Winter Temperature 2011-12
-20
-10
0
10
20
30
40
50
Average Temperatures
Cass County
Dec. 1 - March 1
2011-2012
Air Temperature Medium Stubble Temperature
Short Stubble Temperature Chisel Plowed Temperature
Ridge Tilled Temperature
Average 22°F Average 29°F
Average 27°F Average 28°F
Average 25°F
-10
0
10
20
30
40
50
60
Average Temperatures
Golden Valley County
Dec. 1 - March 1
2011-2012
Air Temperature Tall Stubble Temperature
Medium Stubble Temperature Short Stubble Temperature
Average 24°F Average 28°F
Average 27°FAverage 27°F
Similar
Soil Temperatures
without Snow
Ridge Till
Coldest
36. -20
-10
0
10
20
30
40
50 Air Temperature Tall Stubble Temperature
Medium Stubble Temperature Short Stubble Temperature
Strip Till Temperature
Average 8°F
Average 32°F
Average 33°F
Average 30°F
Average 32°F
Average Temperatures
Cass County
Dec. 1 - March 1
2010-2011
Crop Residue – Winter Temperature 2010-11
-30
-20
-10
0
10
20
30
40
50
Average Temperature
Golden Valley County
Dec. 1 - March 1
2010-2011
Air Temperature Tall Stubble Temperature
Medium Stubble Temperature Short Stubble Temperature
Average 14°F Average 32°F
Average 31°F Average 26°F
-20
-10
0
10
20
30
40
50
Air Temperature Tall Stubble Temperature
Medium Stubble Temperature Short Stubble Temperature
Average Temp 12°F Average Temp 32°F
Average Temp 32°F Average Temp 32°F
Average Temperatures
Stutsman County
Dec. 1 – March 1
2010-2011
Similar
Soil Temperatures
with Snow
37. Crop Residue – Spring 2011 Soil Temperature
0
10
20
30
40
50
60
70
Soil Temperature
Golden Valley County
April 1-30
2011
Tall Stubble Temperature Medium Stubble Temperature Short Stubble Temperature
Average 40 Average 41 Average 42
0
10
20
30
40
50
60
Soil Temperatures
Stutsman County
April 1-30
2011
Tall Stubble Temperature Medium Stubble Temperature Short Stubble Temperature
Average 39 Average 42 Average 39
0
10
20
30
40
50
60
Soil Temperatures
Cass County
April 1-30
2011
Tall Stubble Temperature Medium Stubble Temperature
Short Stubble Temperature Strip Till Temperature
Average 42 Average 41
Average 40 Average 42
Soybeans
Sugarbeets
Prevent Plant
No Difference in
Temperatures
38. Crop Residue – Spring 2011 Soil Moisture
0.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
40.00
45.00
50.00
Soil Moisture
Stutsman County
Apr. 1 - June 30
2011
Tall Stubble Moisture Medium Stubble Moisture Short Stubble Moisture
Average 32% VWC Average 31% VWC Average 30% VWC
0
5
10
15
20
25
30
35
40
Soil Moisture
Golden Valley County
Apr. 1 - June 30
2011
Tall Stubble Moisture Medium Stubble Temperature Short Subble Moisture
Average 18% VWC Average 17% VWC Average 18% VWC
0
10
20
30
40
50
60
Soil Moisture
Cass County
Apr. 1 - June 30
2011
Tall Stubble Moisture Medium Stubble Moisture
Short Stubble Moisture Strip Till Moisture
Average 38% VWC
Average 46% VWC
Average 41% VWC
Average 34% VWC
Soybeans
Sugarbeets
Prevent Plant
Short Stubble
Drier
Strip Till
Drier
Similar
39. 0.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
40.00
45.00
10/1/11 10/8/11 10/15/11 10/22/11 10/29/11 11/5/11 11/12/11
Soil Moisture
Stutsman County
Oct. 1 - Nov. 15
2011
Tall Stubble Moisture Medium Stubble Moisture Short Stubble Moisture
Crop Residue – Fall 2011 Soil Moisture
Average 33 % VWC Average 37 % VWC Average 37 % VWC
0
5
10
15
20
25
30
35
40
45
10/4/2011
10/5/2011
10/6/2011
10/7/2011
10/8/2011
10/9/2011
10/10/2011
10/11/2011
10/12/2011
10/13/2011
10/14/2011
10/15/2011
10/16/2011
10/17/2011
10/18/2011
10/19/2011
10/20/2011
10/21/2011
10/22/2011
Soil Moisture
Cass County
Oct. 4 - Oct 22
2011
Medium Stubble Moisture Short stubble Moisture
Chisel Plowed Moisture Ridge Tilled Moisture
Average 26% VWC Average 33% VWC
Average 31% VWC Average 9% VWC
0
5
10
15
20
25
30
35
40
Soil Moisture
Golden Valley County
Sept. 29 - Nov. 15
2011
Tall Stubble Moisture Medium Stubble Temperature Short Subble Moisture
Average 14% VWC Average 10% VWC Average 2% VWC
Tall is
Driest
Ridge Till
Is Driest
Tall is
Wettest
Tall is
Wettest
40. Equipment and Cost
• SolarStream Cellular Modem - $750
• Cellular Service - $180/year
• Data Logger - $500
• Sensors
• Temperature $100
• Moisture $140
• Wind $240
• Rainfall $400
41. Depth Control
• Influences Seedling Emergence and Yield
• Important Factors
• Independent Pressure
• Gauge Wheels
• Shank Linkage
• Castor Wheels
Accurate and controllable methods of depth
placement are more important in small-seeded
crops because seeds usually are planted
shallower than in larger-seeded crops.
42. Depth Control
WHEAT PLANTING DEPTH STUDY
Jim Herbek, John James, and Dottie Call
Dept. of Agronomy, Univ. of KY. 2001
43. HOW PERFECT DO WHEAT STANDS NEED TO BE?
Lloyd Murdock, Jim Herbek, John James, and Dottie Dept. of
Agronomy, Univ. of KY. 2001
Effects of Skips on Wheat Yields
• Method:
• Plants removed to make skips
• Skips 6”, 12”, or 18” long
• Results:
• Length of Skip – No Yield Effect
• No Yield Effect if:
• -10% Skip - all Varieties
• -20% Skip -Tillering Varieties
Depth Control
44. Varying Conditions
• No Openers Work as Well in Wet Soils
• Compacts Soil
• Buildup on Packer
Wheels
• “Glazed” Furrow
46. Soil Disturbance
• Disc Openers Cause Less Soil Disturbance
• More Residue on Surface
• Less Soil Temperature Change
• Less Soil Erosion
• Conserve Soil Moisture
47. Soil Disturbance
Soil disturbance and fuel consumption for various types of openers
Opener configuration Soil surface
disturbance
STIR*
factor
Fuel consumption
to seed one acre
(spacing in inches) % gallons/acre
Double disc (7-10) 65 6.33 0.34
D disc separate fertilizer opener (7-12) 85 13.8 0.43
Double disc – fluted coulters (7-10) 55 7.2 0.43
Double disc – narrow offset 25 4.9 0.32
D disc – very heavy direct seeding one pass 85 16.6 1.1
D disc – very heavy direct /row cleaners 90 17.5 1.3
Hoe in heavy residue (10-15) 65 16.9 0.74
Hoe (6-12) 90 23.4 0.74
Inverted tee,.e.g., cross-slot (7-10) 15 1.9 0.40
Single disc (7-10) 15 2.4 .035
S disc with separate fertilizer opener (7-10) 35 5.7 .048
49. • Seed/Fertilizer Placement
• Depends on Seedbed Utilization
• Increase Yield with Optimum Fertilizer Placement
• 30 lb. Nitrogen with Wheat Seed
• Uniform Depth – Not as Critical
• Crop Residue
• Standing Stubble Warms and Dries Earlier in Spring
• Bare Soil Warmer and Drier
• Stubble Height
• No Influence on Winter Soil Temperature
• Short Stubble – Drier Spring and Fall
Summary
50. • Planting Depth
• 3”+ Reduces Wheat Yield
• Depth Critical for Small-seeded Crops
• Effects of Skips on Yield
• -10% Skip ok with Wheat
• Soil Disturbance and Energy Consumption
• Hoe in heavy residue – 65% Disturbance, 0.74
gal/acre
• Single disc – 15% Disturbance, 0.35 gal/acre
Summary
The average day-night temperature has increased 2 degrees Fahrenheit between 1903 and 2010. During the same period, the growing season has lengthened by 12 days at that location.
Conservation tillage is part of a system of crop production designed to minimize soildisturbance, maintain previous crop residue on or near the soil surface and minimizethe number of field operations. Weeds primarily are controlled with herbicides andfertilizers are applied in ways that minimize soil disturbance. Conservation tillageseeding equipment often is designed as a “one-pass” system, combining minimumtillage with the planting operation or completely eliminating the need for tillage.The primary reasons crop producers adopt conservation tillage practices are:1) labor and fuel savings by reducing the number of passes across a field,2) equipment cost savings and 3) yield increases. A number of studies have beenconducted in North Dakota comparing conventional tillage systems to reduced andno-tillage systems.
Which Opener Design?The two basic opener designs used on conservation tillage seeders are disc and hoe openers. “Hybrids” of these two opener designs incorporate some of the same features of both disc and hoe type openers. Disc openers can be single or double disk, with gauge wheels mounted beside and in contact with the disc openeror with a trailing packer wheel functioning as a gauge wheel. Hoe openers are available in various widths from less than 1-inch-wide spikes to 10-inch-wide sweeps. Some hoe openers are bolted on to the shank and others are “knock-on” without bolts. The importance of the type and designs of openers and packer wheels varies, depending on soil type and conditions, the amount and type of crop residue, the crop being planted and the producer’s management goals.
Selected openers to illustrate disturbance. The first number listed for each opener illustrated is the surface area of the soil disturbed by the opener. The STIR rating is a three dimensional rating that was derived from university tests and compiled by USDA – NRCS. The ratings in white font are for drill configurations that are not placing fertilizer in a separate ban from the seed. The yellow are ratings for drill configurations that are capable of placing seed and fertilizer in separate bands. Openers from high-disturbance to low-disturbance are Anderson Hoe Opener, offset double disc openers, JD Single Disc Opener, Cross-slot opener.
Seed-soil contact has been assumed to be the most important factor for rapid transfer of water from soil to seed. Recent research demonstrated that seeds are capable of germinating without soil contact, and that 85 percent or more of the water absorbed by seeds can be directly attributed to vapor. A new appreciation for the capacity of soil atmosphere to supply water vapor to seeds will help in future efforts to improve seeding equipment.Knowing that vapor is sufficient to quickly germinate seed should help guide future improvements in seeding equipment. Placement at a desirable depth near moist soil is still important, but pressing the seed into firm soil is only helpful if it helps maintain high relative humidity near the seed. Seed should germinate just as quickly in loose moist soil as in firm moist soil, if it has adequate protection from the drying effects of wind and sun.The distance that water vapor travels from the liquid source to the seed is critical, as shown in Figure 5. Wheat suspended very close to the water surface in the sealed test tubes germinated in about 3 days. The seed on the right, suspended about one-half inch from the water surface, required about 9 days to germinate. It is surprising to most people that seed can germinate without any contact with liquid water. It is also surprising that a closed vessel with water in the bottom does not have uniform 100 percent relative humidity in the air space above the water surface. These non-intuitive relationships may be why scientists have underestimated the role of vapor in seed germination.
Knowing that vapor is sufficient to quickly germinate seed should help guide future improvements in seeding equipment. Placement at a desirable depth near moist soil is still important, but pressing the seed into firm soil is only helpful if it helps maintain high relative humidity near the seed. Seed should germinate just as quickly in loose moist soil as in firm moist soil, if it has adequate protection from the drying effects of wind and sun.
Crop producers usually have specific management goals that relate to the amount of residue to be maintained on the soil surface and the position of the residue after planting. Disc openers are superior to hoe openers if the producer’s goal is toleave most of the crop residue from the previous year standing after planting. Hoe openers result in more of the crop residue mixed into the soil.Hoe openers push residue aside to place seed in moist soil near the surface. Hoe openers cause more soil disturbance, which can promote both soil warming and drying similarly to a tillage operation. Hoe openers may cause bunching if the residue is wet or unevenly spread. More vertical clearance of the seeder helps prevent bunching.Disc openers generally disturb soil less than hoe openers, maintaining moisture in the seed zone. However, this may slow soil warming after planting.
Fertilizing Hard Red Spring Wheat and DurumD.W. Franzen, NDSU Extension Soil Specialist
Separate fertilizer delivery systems can be used to place fertilizer in a band to the side and below the seed. With disc openers, a separate disc can be mounted between two seed rows to place fertilizer in a band shared by two seed rows. This is called midrow banding. Midrow bands deliver nitrogen products safely.Some hoe seeders are designed with a fertilizer tube next to the seed tube that places fertilizer below and to the side of the seed row. This is referredto as double-shooting. Low-draft, double-shooting openers place seed and fertilizer at the same depth, which is designed to reduce power required to pull the seeder.The air seed delivery system needs to have enough air to move the correct amount of seed to the farthest ends of the seeder but not blow seed out of the seed slot or cause damage to the seeds. This is accomplished by incorporating an air dissipation system in the air delivery system prior to the seed discharge into the opener.
The separation of fertilizer from the seeds needs to be greater in some soil conditions, such as in dry, cloddy soils. The risk of stand reduction is greater from nitrogen toxicity in sandier soils than in clayey soils. More than 20 to 30 pounds per acre (lbs/acre) of nitrogen fertilizer placed with seeds can result in reduced germination, low seedling emergence and poor stands, with subsequent yield loss.However, midrow banding places phosphorus materials too far away from the plants to deliver a “starter” effect to young plants. A separate system to deliver phosphorus in or near the seed row is required to achieve “starter” phosphorus effects.
Paired-row vs. Single Row Spacing. Roger Veseth. PNW CONSERVATION TILLAGE HANDBOOK SERIES. Chapter 6 - Fertility, No. 7, Winter 1987 (Oregon)http://pnwsteep.wsu.edu/tillagehandbook/chapter6/060787.htm
Paired-row vs. Single Row Spacing. Roger Veseth. PNW CONSERVATION TILLAGE HANDBOOK SERIES. Chapter 6 - Fertility, No. 7, Winter 1987 Paired-row – place fertilizer band between rows so that it is within 2 to 3 inches of each seed row. Fertilizer band should also be at least 2 inches below seed because of the 30 to 45 degree downward growth angle of the pairs of seminal roots.Seminal roots extend laterally 2 to 4” by the start of tillering. The roots initially grow downward 30 to 45 degrees before growing straight down. So, fertilizer banded more than a few inches from the seed row may not be available to the plant until the tillering stage when crown roots develop.
The previous crop residue is a resource to conserve and use. Crop residue limits evaporation from the soil surface and maintains humidity levels in undisturbed soils at between 90 percent and 100 percent, which is ideal for germinating seed. Even with excellent soil seed contact, at least 85 percent of the water enters the germinating wheat seed in the form of vapor. In dry conditions, low disturbance, no-till planting systems preserve moisture in the seedbed, allowing uniform germination and plant establishment to occur. Crop residue also provides a food source for beneficial fungi, bacteria, insects and weed seed predators.Managed properly, the beneficial aspects outweigh the negative aspects of crop residue in conservation tillage systems. When left in place, crop residue will protect the crop from wind damage during establishment and will continue protecting the soil if the crop fails to establish due to drought or flood. Crop residue readily decays and is incorporated into soils by earthworms and fungi once the growing crop canopies cover the inter-row space.
Previous research by Flerchinger et al. 2003, suggests that standing stubble in the spring warms and dries 5 to 9 days earlier in the spring than flat residue. Long term no-till soils exhibit structure allowing greater and faster infiltration of water than soils that have been disturbed through tillage or with high disturbance seeding and weed control operations (Arshad et al., 1999, Pierce et al., 1994). With low disturbance no-till openers and tall residue left undisturbed in long-term no-till fields, producers should be able to seed and establish high yielding crops within a few days of tilled fields.
Conclusions: We removed corn residues prior to seeding the wheat, then returned residues, at a rate of 6300 lb/ac (equal to about 150 bu/ac corn crop), in specific "placements" to each plot. We removed residues prior to seeding to take out any effect of residue on the drill's ability to establish the crop. In our "placement" treatments, we had one where the full rate of residue was randomly scattered over the entire plot area, four treatments where the residue was placed a set distance (0.25, 0.50, 0.75, and 1.25 inches) away from either side of the row, and a control treatment (bare) where none of the residue was returned. The row spacing was 7 inches. Yields were not influenced by residue placement treatments; only complete residue removal had a positive effect on yield (Table 1). Measurements of soil and air temperatures during the fall emergence and tillering period showed that residues tended to "buffer" against quick temperature changes. This keeps the soil warmer during cooling trends, and cooler during warming trends, and causes greater differences in temperature between the soil and air at such times. This greater "shear" between air and root zone temperatures might be contributing to stress during shoot development.
Uniform depth placement of both the seed and fertilizer influences seedlingemergence and, ultimately, crop yield. Factors influencing uniformity of seeding depth include independent hydraulic pressure on each opener assembly, gauge wheels, shank linkage and caster wheels. Individual opener down force can be controlled by adding or removing depth stops from each cylinder. Depth control wheels and packer wheels on seeders improve uniform seed depth placement.Packer/gauge wheels mounted close to the point of seed release will place seed more consistently at the proper depth, compared with wheels mounted farther behind orin front of the release point.
RESULTS:The wheat planting depth study results are shown in Table 1. Wheat emergence was affected by planting depth. Based on 50% emergence data, it took 2½ to 3½ days longer for the two deepest planting depths to emerge as compared to the recommended planting depth of 1-1½ inches. Likewise, the shallowest planting depth (1/2 inch) emerged 1 day later and can be attributed to drier conditions at the soil surface. Good stand establishment was achieved at all planting depths. The % stand achieved, based on a seeding rate of 35 seeds/ft2, was over 90% for the two intermediate planting depths and 85% for the deepest planting depth. Even though the shallowest planting depth (1/2 inch) had a significantly lower stand than the deeper planting depths, the final stand of 27 plants/ft2 is still adequate to achieve a high yield potential. The lower stand achieved at the shallow planting depth can be attributed to drier conditions near the soil surface. Although rainfall totaled 2.8 inches for the 3-week period prior to planting, (10-16-00), none of the rainfall occurred in the 10 days preceding planting. Likewise, no measurable rainfall was recorded for the 3-week period after planting. A planting delay would have further reduced germination and emergence at the shallow planting depth. Wheat head numbers were the highest and very similar (47-49 heads/ft2) at planting depths of 2-2½ inches or less. The deepest planting depth (3-3½ inches) had significantly fewer head numbers. These results verify that wheat plants emerging from deeper depths have reduced tillering. Highest wheat yields were obtained at planting depths of 1½ inches or less.A planting depth of 2-2½ inches reduced yields slightly. The deepest planting depth (3-3½ inches) significantly reduced yields by ~ 3 bu/acre and can be related to reduced tillering (fewer heads).CONCLUSIONS:Wheat seed should be planted 1-1½ inches deep if soil moisture is adequate. In this study, a planting depth of 1-1½ inches had the best overall wheat performance (faster emergence, excellent stands, high head counts, and high yields). A slightly deeper depth (2 inches) is justified if soil moisture isdeficient. Shallow seed placement (< 1 inch) can result in reduced and uneven germination and emergence under dry soil conditions. Shallow seed placement also has the potential for more winter injury and greater susceptibility to heaving which can further reduce stands. Conversely, deep seed placement (as shown in this study) delays emergence, can reduce stand, and emerged plants have less vigor and reduced tillering (less yield). When seed is planted deeper than 2 inches, there can also be a differential response among varieties. Wheat emergence is more difficult for varieties that have short coleoptiles or small seed.
Yield CompensationIn order for the yields to remain the same with some areas skipped,the yields of plants around the skip must increase. The compensation of thewheat plants surrounding the skips can come from more heads, more grainsper head or more weight per grain. Head counts made near harvest in 1999-2000 indicated that the compensation was not made by increased heads dueto increased tillering. However, head counts made in 2000-2001 (Table 3)show many more heads in the plants surrounding the skipped areas. Theincreases were in the order of 35 to 45% more heads/ft2.SUMMARY:This trial will continue in order to try to verify what has been found to thispoint. At present, it appears that the length of a skip has no effect on grainyield. When the amount of area skipped is 10% or less, there is no effect onyield regardless of variety. There is also no effect on yield with varieties thattiller prolifically if the area skipped is as high as 20%.Image: University of Kentucky College of Agriculture
Neither hoe nor disc openers work as well in wet soils as in drier soils. Soils too wet to till are too wet to seed. Seeding or tilling wet soils compacts soil, damaging the rooting environment, which results in reduced crop growth and yield. Clay soils pack well but can become hard when they dry. Clay can build up on packer wheels, changing the seeding depth. Openers can create a “glazed” furrow sidewall in wet conditions, which slows germination.Packer wheels help firm soil around seeds and increase the likelihood that the seeds are in contact with soil in very wet seeding conditions. Machine weight can influence seedingdepth when soil is firm. Some seeders are built heavier than others and some are designed to include added weight. Greater downward pressure requires positive depth control, which usually is accomplished with a gauge wheel running next to or directly behind the opener.Seeders need to be flexible to function properly on irregular soil surfaces and sloping fields. Seeders with rigid frame sections larger than 12 to 14 feet generally do not follow the soil contour on sloping fields and when crossing drainage ditches, resultingin seed being placed too shallowly or unevenly on the soil surface.
Parallel linkage has been used on row-crop planters for a number of years, andonly recently has this innovation been applied to drills. Parallel linkage onindividual openers operating independently of each other allow the opener to track soil surface more accurately, giving a more uniform placement of seed at the desired depth.
Generally, reducing the amount of soil disturbance during crop production lowers carbon losses from soil. The Natural Resources Conservation Service (NRCS) has developed a Soil Tillage Intensity Rating (STIR), which assigns a numerical value toeach tillage operation (Table 3). Crop management decisions implemented for a particular field affect the rating value. Lower numbers indicate less overall disturbance to the soil layer.To qualify for NRCS no-till incentive programs, a STIR value of 10 or less is required. Values may range from 0 to 200, with lower scores preferred. The NRCS indicates other benefits of low STIR values, which include increasing organic-matter (OM) content of the soil, less OM breakdown and improved water infiltration rates. Under most soil conditions, disc-type openers cause less soil disturbance than hoe openers. Disc openers on seeders generally cause less soil disturbance and maintain more residue on thesoil surface, resulting in less soil temperature change, less soil erosion potential and a greater potential to conserve existing soil moisture, compared with hoe openers.Hoe openers generally cause more soil disturbance than disc openers by partially burying straw and bringing soil to the surface. Disturbed soil exposed to solar radiation will warm sooner than undisturbed soil, but it also will cool faster. Low-disturbance, angle discs on seeders have shown significant advantages in both wet and dry years in reducing weed germination. Increasing soil disturbance increased competition from weeds anddecreased crop density. Weed seeds left on the soil surface are exposed to predation and environmental extremes, resulting in fewer viable seeds to germinate and infest the next crop. When low-disturbance no-till is used in combination with diverse crop rotations and appropriately selected and timed herbicide application, weed control costs can be reduced by 50 percent because lower weed density reduces the need for herbicides.
Source: NRCS RUSLE2 Version 1.26 and Soil Tillage Intensity Worksheet, http://stir.nrcs.usda.gov/*STIR factor calculated for seeding spring wheat using a drill with the specified opener following sunflower in a four-year rotation of spring wheat-winter wheat-corn (grain)-sunflower in southwestern North Dakota. The overall STIR rating for the entire four-year no-till rotation will differ from that shown for each specific opener.