1. Off-Road Equipment Management TSM 262: Spring 2016
LECTURE 13: Tillage Systems
Off-Road Equipment Engineering
Dept of Agricultural and Biological Engineering

2. Homework

3. Lab and Technical Sessions

4. Tillage Systems: Class Objectives
Students should be able to:
Understand the relevant ASABE standards
Identify and apply soil textural classifications
Analyze primary and secondary tillage systems
Analyze the performance of tillage equipment
Identify factors that cause soil compaction

5. ASABE Standards ASABE EP291.3 FEB2005 (posted on compass)
Terminology and definitions for soil tillage and soil-tool relationships
Basic tillage goals
General tillage terms and kinds of tillage
Tillage systems
Specific tillage operation
Nomenclature for tillage tools and implements
Soil reaction nomenclature
Soil nomenclature
Soil and surface characteristics

6. ASABE Standards ASABE S414.2 MAR2009 (posted on Compass)
Terminology and definitions for agricultural tillage implements
Tillage implement categories
Implement hitch classification
Implement frame configurations
Definitions and illustrations
5.18 Combination tillage implement for strip tillage
5.19 Tillage components

7. Properties of Soil
Soil properties are very important consideration in tillage
Soil texture (clay, silt, sand): Effects on
Draft forces
Soil compaction
Crop growth
Physical properties (porosity, bulk density, water content)
Measures of readiness of soil for crop establishment and growth
Mechanical properties (shear strength, friction, adhesion)
Used to study mechanics and performance of tillage tools

8. Soil Textural Classification
Soil Classification
Clay, 2 micron, (0.002 mm)
Silt, – 0.05mm
Sand, 0.05 – 2mm
Gravel, mm
SAND
Textural Classification 8

9. Soil Physical Properties
Porosity (n) is the ratio of the void volume (Vv) to the total volume (V) of the soil
n = (Vv) / (V)
Void Ratio (e) is the ratio of the void volume (Vv) to the solid volume (Vs) of the soil
e = (Vv) / (Vs)
Water Content (w) is the ratio of the mass of water (mw) to the mass of solids (ms)
w = (mw) / (ms)*100
Degree of Saturation (Sr) is the percent of void space (Vv) occupied by water (Vw)
Sr = (Vw) / (Vv) *100
Field Capacity: Field capacity is the water content of a soil at which the gravitational pull on the water is matched by the capillary action (33 KPa).
Wilting Point: Is the moisture content at which the plant cannot remove any further water from the soil (1.5 MPa)
Air
(ma)
Water
(mw)
Soil
(ms) Vs Vw Va Vv V

10. Soil Physical Properties
Bulk Density (γ) is the total mass (m) of the soil divided by the total volume (V) of the soil
γ = (m) / (V) = (ms + mw) / V
Dry Bulk Density (γd) is the mass (ms) of the solid constituents in the soil divided by the total volume (V) of the soil
γd = (ms ) / V
Particle Density (γs) is the mass (ms) of the solid constituents in the soil divided by the solid volume (Vs) of the soil
γd = (ms ) / Vs
Particle density is approx. constant at 2.6 – 2.8 g/cm3
Sand/Silt ≈ 2.65 g/cm Clay ≈ 2.75 g/cm3
Organic Matter ≈ 1.37 g/cm3
Acceptable range for dry bulk density, g/cm3
Dry bulk density of 1.8 g/cm3 represents top end of bulk density
Air
(ma)
Water
(mw)
Soil
(ms) Vs Vw Va Vv V
Root Limiting Bulk Density
Sand ≈ 1.8 g/cm3
Loam ≈ 1.55 g/cm3
Clay ≈ 1.4 g/cm3

11. What is Tillage?
The practice to develop a desirable soil structure or soil tilth for crop growth.
Soil structure - the way in which soil particles are grouped or bound together to form lumps or aggregates.
Pores are controlling factors governing water, air and temperature and there should be optimum soil water and soil aeration.
Seedbed preparation
Post-emergence cultivation
Weed control
Residue management
Air
(ma)
Water
(mw)
Soil
(ms)

12. Seedbed Preparation Place where seeds germinate & nourish young plants
Seedbed must be firm to allow seed to come in contact with soil particles to absorb moisture
Must be porous to allow for air and water movement and root development
Have a crumb structure so that roots of seedling can penetrate it easily. The hard compact layer impedes root growth.
Water will not easily penetrate hard soil to reach roots
If soil is too loose, rain will wash away young plants
Some soils have excess water
Oxygen is needed by roots
Air and water conduct heat more rapidly than soil, looser soils warm up sooner
Plant residue on surface insulates, warms up slower, also provides buffer against wind

13. General Rules for Good Soil Tilth
Till at proper time to maintain proper aggregation
Too wet during tillage produces large clods
Too dry during tillage makes soil too fine and likely to blow away
Over tillage will destroy soil structure and lead to soil compaction

14. Types of Tillage (EP291.3) Tillage Conventional Primary/ Intensive
Secondary
Conservation
Minimum/
Reduced
Strip Till
No-Till

15. What is Primary Tillage?
First tillage operation of a season (after harvest)
Loosen soil to permit air and water to penetrate
Definitions
Equipment used to break and loosen soil for a depth of six to 36 inches (15 to 90 centimeters) may be called primary tillage equipment. It includes moldboard, disk, rotary, chisel, and subsoil plows
ASABE: Initial major soil working operation. Designed to reduce soil strength, cover plant materials, and re-arrange aggregates 15

16. Intensive Tillage (Primary)
Leave less than 15% crop residue cover or less than 500 pounds per acre (560 kg/ha) of small grain residue.
This system often involves multiple operations with implements such as a moldboard plow, disk, and/or chisel plow. 16

17. Residue Coverage
75%
25%
50%
90%
CORN RESIDUE

18. Typical Equipment for Intensive Tillage (S414.2)
Moldboard Plows (Mouldboard Ploughs)
Gunnel, Share, Shin, Moldboard, Landside, Heel
Down Suction from the plow
Disk Plows
Gang Angle, Disk Angle(42-45 deg), Tilt Angle (15-25 deg), kg/disk
Hard soils, non-scouring soils
Chisel Plow / Subsoiler
Shanks, straight shanks, curved shanks
V-Frame
Rotary Tillers
PTO driven, High Power Requirements, Low Traction requirements
Single pass operation 18

19. Moldboard Plow Typically bury 90-95% of the residue on each trip.
These plows turn the surface soil upside down leaving only 5-10% surface residues. 19

20. Problems with Moldboard Plowing
Moldboard plowing has become increasingly recognized as a highly destructive farming practice rapidly depleting soil resources.
Foremost is the formation of hardpan, or the calcification of the sub layer of soil.
Hardpan is impenetrable to the roots of plants and restricts growth and yields.
Hardpan becomes impenetrable to water, leading to flooding and the drowning of crops.
Rapidly depletes the organic matter content
Promotes erosion
Leads to increased soil compaction and loss of pore space within the soil. 20

21. Disk Plows 21

22. Chisel Plow and Subsoiler
Series
Type
No. of Shanks
Weight Lbs
Track/Belted DBHP
Wheel Tractor PTO-HP
VRT
towed
5 or 7
6,610-8,050 22

23. Rotary Tiller High PTO power required High wear part consumption
Excellent residue incorporation 23

24. Secondary Tillage Objectives:
Tillage that can take place on its own or after primary tillage and is less than 6" deep
Objectives:
Refine the seed bed – create a smoother surface with less clods
Shape rows if necessary
Control weeds
Incorporate chemicals
Manage residue 24

25. Cultivation Tillage Systems
Post plant and shallow tillage Objectives:
Weed control
Aerate soil (moisture or crust)
S-tine
C-shank
rolling

26. Secondary Tillage Equipment
Harrows
Disk
Spring Tooth
Cultivators
Rotary Hoes
Cultipackers

27. Disk Harrow

28. Spring Tooth Harrow
Purpose: Final seedbed preparation, post-planting operations to break up soil crust and remove weeds

29. Cultivator

30. Rotary Hoe
Purpose: Weed control in row crops, breaking soil crusts for better seed emergence, and mixing of fertilizer

31. Cultipackers
Purpose: Break up hard clods and conserve soil moisture for better seed germination by increasing soil density in top few centimeters of soil

32. Conservation Tillage
Leave minimum of 30% of crop residue on soil surface or at least 1,000 lb/ac (1,100 kg/ha) of small grain residue on surface during critical soil erosion period
Slows water movement
Reduces the amount of soil erosion
Warms soil, enabling next year’s crop to be planted earlier in the spring
Reduces fuel consumption
Reduces soil compaction
Reduces field traffic 32

33. Reduced Tillage Systems
Leave between 15 and 30% residue cover on the soil or 500 to 1000 pounds per acre (560 to 1100 kg/ha) of small grain residue during the critical erosion period.
This may involve the use of a chisel plow, field cultivators, or other implements
25% 33

34. Strip Till
Combines soil drying and warming benefits of conventional tillage with soil-protecting advantages of no-till by disturbing only the portion of the soil that is to contain the seed row
Requires special equipment
Each row that has been strip-tilled is usually about eight to ten inches wide.
Benefit of strip-tilling is that farmer can apply chemicals and fertilizer at the same time as tillage 34

35. Strip Till (S414.2)
Leave surface ready for planting
Loosen soil below row to be planted
Cut surface residue
Move surface residue away from seed row
Planter can be attached to rear of machine for single pass tillage/planting operation

36. No Till Pros Increasing soil quality (soil function),
Protecting the soil from erosion, evaporation of water, and structural breakdown.
Residues left intact help both natural precipitation and irrigation water infiltrate the soil where it can be used.
Residue left on the soil surface also limits evaporation, conserving water for plant growth.
Reduction in tillage passes
Reduced labor and related fuel and machinery costs.
Less airborne dust,
Often have more beneficial insects and annelids, a higher microbial content, and a greater amount of soil organic material. 36

37. No Till Cons Yield Equipment
Yields can be impacted negatively. However, lower overhead cost may offset lower production, thus higher profits.
Crops, like corn, do not tolerate the increased competition in early life well, and are not suitable for complete no-till agriculture.
With precise fertilizer and seed placement, yields are never compromised.
Equipment
Requires specialized seeding equipment 37

38. No Till Cons Chemicals Erosion
One of the purposes of tilling is to remove weeds.
No-till farming does change weed composition drastically.
Shrubs and trees may begin to grow eventually.
Crop rotation is also more important
Erosion
Long-term erosion, drainage gulleys that do form get deeper every year
Slight increase in soil bulk density 38

39. Management Goals of Tillage
Minimize soil compaction
rearrangement of soil particles and aggregate to reduce pore space and increase soil bulk density
Soil Properties are a key factor
soil composition - Sand, silt, clay
soil texture - % sand, silt, clay
soil aggregates
Compaction
clay soils are most compactible

40. Management Goals of Tillage
Crop Residue Management
Benefits
erosion control
soil tilth : improves both physical and chemical properties
water holding capacity
CEC is increased
Conservation tillage (> 30% on surface)