Title: Conservation Tillage
1Conservation Tillage
2Conservation Tillage
- portion of previous crop residue left
unincorporated on soil surface
3Conservation Tillage
- portion of previous crop residue left
unincorporated on soil surface - Opposite of conventional tillage (plowing)
- Plowing benefits good root zone, weed management
- Not plowing benefits erosion management
4Tillage Options
- Tillage (turn in everything)
- Top mowed and removed (root stubble left)
- Top mowed, but left as mulch (root stubble left)
- Planting into dead crop residues (nothing removed)
5Tillage and Crop Residue Management
100
NONE
SURFACE RESIDUE
TILLAGE INTENSITY
FREQUENT
0
6Tillage and Crop Residue Management
100
NONE
No tillage
SURFACE RESIDUE
TILLAGE INTENSITY
Minimum tillage Reduced tillage
FREQUENT
0
7Tillage and Crop Residue Management
100
NONE
No Tillage 90
SURFACE RESIDUE
TILLAGE INTENSITY
30 Minimum Tillage
FREQUENT
0
8Conservation Tillage
- portion of previous crop residue left
unincorporated on soil surface - Many different terms
- Reduced Tillage
- No Tillage
- Minimum Tillage
- Crop Residue Management
9Conservation Tillage
- Reduced Tillage
- No Tillage
- Minimum Tillage
- Crop Residue Management
- Many different terms, depending on relative
amounts of residues and varying degrees of
incorporation (cover crop mowed and used as
mulch, forage removed with stubble left in field,
etc.)
10Strip Tillage
- Crops planted into narrow tilled strip (4-12,
10-30 cm)
Residue on surface
Residue on surface
11Strip Tillage Planting into Crop Residue
12Rye Cover Crop Killed by Herbicide, Use Strip
Till Planter to Plant Crops
13Crops Strip Planted into Green Cover Crop, Cover
Killed Later with Herbicide
14Strip Till Peanut in Rye Mulch (double row)
15Strip Till Peanut in Rye Mulch (single row)
16Strip Till Corn in Rye Mulch
17Strip Till Cotton in Rye Mulch
18Conservation tillage in US increased rapidly
since 1980s
Schertz, 1994
19Advantages and Reasons for using Minimum Tillage
- Reduced erosion
- Economics
- Moisture conservation
- Stabilizes soil temperature
- Improved soil fertility and accessibility
- Improved quality of surface water
- Government regulations and programs
- Improved yields
20Relationship between Conservation Tillage (more
surface residue) and Reduction in Erosion
21Advantages and Reasons for using Minimum Tillage
- Reduced erosion
- Economics (reduced trips over field and fuel
costs, but more herbicide) - Moisture conservation (reduced evaporation rates)
- Stabilizes soil temperature
- Improved soil fertility and accessibility
- Improved quality of surface water
- Government regulations and programs
- Improved yields
22Relationship between Conservation Tillage (more
surface residue) and Moisture Conservation (less
evaporation)
23Advantages and Reasons for using Minimum Tillage
- Reduced erosion
- Economics
- Moisture conservation
- Stabilizes soil temperature
- Improved soil fertility and accessibility
(preserves OM) - Improved quality of surface water (reduced
erosion and runoff) - Government regulations and programs
- Improved yields
24Advantages and Reasons for using Minimum Tillage
- Reduced erosion
- Economics
- Moisture conservation
- Stabilizes soil temperature
- Improved soil fertility and accessibility
- Improved quality of surface water
- Government regulations and programs (Food
Security Act 1985 Minimum tillage considered
part of soil conservation program to reduce
erosion) - Improved yields
25Advantages and Reasons for using Minimum Tillage
- Reduced erosion
- Economics
- Moisture conservation
- Stabilizes soil temperature
- Improved soil fertility and accessibility
- Improved quality of surface water
- Government regulations and programs
- Improved yields ? --- Depends on soil types and
conditions.
26 Soybean Yield (bu/A)
Benefit from no-till in poor soils
From Johnson, 1994
27Improved Yields from Minimum Tillage?
- South US, dry soils greater yields
- North US lower yields (cooler temps.,
less DD in no-till)
28Problems with Minimum Tillage
- Weeds
- Weed pressure often severe in min. tillage
- Increased herbicide usage for weed control and
for killing crop residues - Roundup-Ready cultivars
- New weed problems K strategists, etc.
- Compaction -- varies
29US Pesticide Sales following Increase in
Conservation Tillage
Mostly herbicides
Johnson, 1994
30Effects of minimum tillage on physical and
biological factors
- Soil moisture
- Soil temperature
- Soil fertility
- Soil acidity
- Pests
31Effects of minimum tillage Soil Moisture
- Decreased evaporation and water loss
- improved water holding capacity on soils that
tend to dry - - - may delay drying in water-logged soils
32Effects of minimum tillageSoil Temperature
- Lowers soil temperature, depending on amount of
residue - for South US, tropics
- - - for north (soil warming may be delayed in
spring)
33Effects of minimum tillageSoil Fertility
- increased organic matter, reduced erosion
- - - N availability can be affected by residues
and lead to deficiency
Fertilizer placement and degree of incorporation
is important CN ratio of residue is
critical Placement important with other
nutrients (P, K) too
34Effects of minimum tillageSoil Fertility
- increased organic matter, reduced erosion
- - - N availability can be affected by residues
and lead to deficiency
Fertilizer placement and degree of incorporation
is important CN ratio of residue is
critical Placement important with other nutrients
(P, K) too
Strip Tillage can help with these fertilizer
placement problems !
35Effects of minimum tillageSoil Acidity
- Can increase with decomposition and organic acids
- Can affect nutrient availability
- Takes time to develop and may be confined in a
relatively narrow vertical strip
36Effects of minimum tillage Pests
- Weeds --- can be major problem
- Diseases
- Insects
37Effects of minimum tillage Diseases
- Varies with specific situations and ecology of
pathogens - Crop rotation important to eliminate residues of
the same crop (contaminated residues could be
source of disease inoculum) - Some seed pathogens worse with cooler soil
temperatures
38Effects of minimum tillage Insects
- Varies --- may favor pests or beneficials
- Favorable habitat and hiding places for crop
pests in residues (cutworms, snails, slugs) - May provide habitat for predators
39Tillage impacts larger organismsNo tillage
benefits earthworms, predators
Coleman and Crossley, 1996
40Seedbed Problems in Min. Tillage
- Problem in cool, moist soils
- Increased seedling mortality from
- Mulch layers
- Diseases (aggravated by cool temp. and moisture)
- Slow germination and establishment (lower DD if
soil is cool)
41References
- Text, Ch. 14, pp. 287-295.
- Altieri, 1987. Ch. 11.
- Coleman, D.C., and D.A. Crossley. 1996.
Fundamentals of Soil Ecology. Academic Press, San
Diego. - Johnson, R.R. 1994. Pp. 12-22 in P.J. Bauer and
W.J. Busscher, eds. Proc. of the 1994 Southern
Conservation Tillage Conference for Sustainable
Agriculture. USDA Coastal Plains Soil, Water, and
Plant Research Center, Florence, SC. - Schertz, D.L. 1994. Pp. 1-5 in Bauer and Busscher.