Adapting and Integrating Conservation Tillage to
Cropping Systems in the Northeast
A field becomes exhausted by constant tillage – Ovid
A conservation tillage system is any system that maintains at least 30% of plant
residues on the soil surface.
Figure 1. Residue cover of varying concentration.
Figure 2. Conservation tillage across the United States.
Table 1. Description of standard tillage practices in the United States.
Tillage
Management
Chisel plow
Moldboard plow
Mulch tillage
No-till
Ridge tillage
Definition
Full field tillage. Significantly more residue remaining
on the soil surface relative to moldboard plow.
Full field tillage. Incorporation of nearly all residues.
Restricted tillage system. Surface residues remain on
the soil surface until just prior to planting. After tillage
at least 30% of the residues are on or near the surface.
Restricted tillage system. Creates the least disturbance.
Planting creates a small zone of disturbance as seeds
are planted.
Restricted tillage system. Tillage creates a ridge used
Strip tillage
Zone tillage
Reduced tillage
as a seed bed. About 30% residues are incorporated
when the ridges are created.
Restricted tillage system. Tillage is restricted to the
seed bed. Residue is removed with trash wheels. Out of
season a shank is used to overcome compaction
problems.
Restricted tillage system. Tillage is restricted to the
seed bed. Residue is removed with trash wheels.
Any restricted tillage system that results in 30% or
more residues on the soil surface.
Conservation tillage became an effective management practice once weed
management and farm equipment were adapted to systems with surface
residues. Conservation systems produce equivalent or higher crop yields than
moldboard plow while conserving soil, time and fuel.
Figure 4. No-till planters cut a narrow, uniform slit that serves as a seed bed.
Fewer field operations reduce soil compaction particularly on heavy poorly
drained soils. Frequent passes with field equipment can result in plow pans.
Figure 5. Compaction in a sugar beet field resulting in a plow pan.
Farmers played a critical role in research and development of conservation
systems. Farmers and manufacturers developed equipment that allowed for
planting of seeds in residues. Growers designed new physical methods for cover
crop suppression and weed control. Zone-till was a Michigan farmer’s adaptation
of no-till to wet poorly drained soils.
Conservation tillage practices were designed to reduce soil erosion. These
practices have significantly reduced soil erosion and can help reduce runoff.
Universal Soil Loss Equation A=RKLSCP
A = predicted soil loss
R = rainfall erosivity
K = soil erodibility
L = slope length
S = slope
C = cover management
P = erosion control practice
Factors that effect erosion that are not affected by management include:
Rainfall intensity and patterns
Wind velocity
Percent slope and length
Soil texture, soil erodibility
Factors that effect erosion and can be modified through management
include:
Soil surface roughness
Vegetative residue cover
Soil organic matter content
Tillage systems affect vegetative residue cover, soil surface roughness, and
long-term soil organic matter contents.
Tillage systems effects on soil loss are incorporated into factor c = cover and
management. C is based on cropping sequence, surface residue, surface
roughness, and canopy cover, which are weighted by the % of erosive rainfall
during the six crop stages. Combines these factors into a table of soil-loss ratios,
by crop and tillage scheme. See Table 17.3 (Brady and Weil, 2002).
A Conservation tillage system is any system that maintains at least 30% of plant
residues on the soil surface. Erosion was reduced by 75 to 80% when ground
cover was at 30% Fig 17.12. Soil loss was reduced by more than two thirds when
conservation tillage systems were compared to a moldboard plow (conventional
tillage) system on a silt loam. See Figure 17.20 (Brady and Weil, 2002).
Types of Tillage Systems and the Percent Residue Cover
Remaining in Each
Zone-tillage is used on row crops and recognizes the benefits of some further
soil disturbance of the soil in the plant row and uses multiple fluted coulters
mounted on the forward frame of the planter to develop a fine seedbed of
approximately 4 x 4 inches. It also uses trash wheels to move residue away from
the row, thereby improving seed placement and soil warming. (pg 20 Cornell
Guide)
Moldboard plow is generally the least desirable practice because it is energy
intensive, leaves little residue on the surface and often requires multiple
secondary tillage passes. (Magdoff and van Es, 2000) It also tends to create
plow pans (Figure 5.).
Chisel plowing results in conditions similar to that of moldboard plow. Chisels
allow for flexibility of chisel depth (5 to 12 in) and additional tools to go deeper.
(Magdoff and van Es, 2000)
The most obvious and important distinction between tillage managements is the
percent surface covered with residue. Table 17.10 provides an estimate of
residue cover in 6 different tillage system (Brady and Weil, 2002). While it is true
that no-till systems have greater cover than chisel-plow, the table provides only
part of the story. The crop grown can have a significant impact on the percent
ground cover (see Table 1. Extension Bull. E-2738). Corn always has greater
surface residue coverage than sugar beets irrespective of tillage. Chisel plowed
corn has greater residue cover (29%) than zone-tilled sugar beets (6%).
When calculating potential erosion in a field, keep in mind that secondary tillage
practices and field implements can displace or remove residue cover similar to
tillage. (Secondary tillage includes finishing disks, tine or tooth, harrows, rollers,
packers, and drags.) I have provided you with a comprehensive table that you
can refer to Estimated Percent Cover after Secondary Tillage, Use of
Specific Field Implements and Field Operations Table 3. Cornell Guide.
How to Choose the Best Conservation Tillage System(s) for Your Farm
Factors to consider:
Soil texture - Soils with fine sand and silt fractions are most susceptible to
erosion. Therefore, reduced tillage prevents erosion in a coarse textured soil,
such as a sandy loam to a greater degree than in a finer textured clayey soil.
Soils with high clay content resist erosion. Fine textured soils stick together and
retain more water. Greater water content and cool temperatures can retard seed
germination. Therefore, ridge-till or zone-till may be more appropriate than no-till
in finer textured soils of temperate climate.
Weed management – Biennial weed management is more difficult in no-till if
pesticides are not being applied. New methods of mechanical cultivation and use
of cover crops can help reduce weed pressure. Weed pressure typically
decreases after several years of reduced tillage management.
Plant pathogens – residues from no-till and other minimum tillage systems can
prevent splashing of soil onto foliage during rainfall events. Splashing of soil
often transmits soil borne diseases. In other instances, residues may need to be
buried or burned to prevent over wintering of fungal spores in residues. Crop
rotations may be as effect as tillage depending on the pathogen.
Insect – European corn borer, cutworms, and armyworms over winter in corn
residues. Rotations can break pest cycles. European corn borer can also be
managed by avoiding the planting of early maturing varieties. Insects can only
infect the plant if it is in the proper growth stage.
Nutrient stratification – Surface application of nutrients can result in nutrient
stratification and acidification. In some instances, deliberate stratification of
nutrients has improved yields. Example, Brazilian soybeans grown in no-till
management on Oxisols. However, stratification and acidification associated with
minimum tillage are typically detrimental and may require periodic tillage
(approximately once a decade). Phosphorus fertilizers in minimum tillage
systems are often broadcast but can be knifed into the soil. Surface applications
can limit plant available P. Conservation tillage systems reduce P loss to erosion
and runoff. See Table 14.3 (Brady and Weil, 2002). Conservation tillage systems
often contain higher P levels although not all is plant available. Urease enzyme
activity is also greater in no-till and reduced tillage systems. Urease increases
urea-N availability from urea fertilizer applications. See photo of no-till fertilizer
injection system.
Application of organic amendments – manure application in conservation
tillage requires investment in manure injection tools. Surface application of
manure allows for ammonia volatilization and is a potential nuisance due to odor.
Figure 6. Injection equipment for fertilizer and animal slurries are important
adaptation to conservation tillage systems.
The affect of conservation tillage practices on a number of soil physical
and biological properties.
Tillage disturbs worm burrows and fungal hyphae and reduces organic matter.
Long-term increases in soil organic matter improve:
water holding capacity
aggregation
infiltration rates
and increase the number and diversity of soil organisms
See Figure 17.21 & Table 11.11 (Brady and Weil, 2002)
Soil organic matter and plant residues (debris) are an integral part of the soil food
web. The amount of residues and their placement effect fungal populations and
mesofauna such as earthworms. Tillage disrupts fungal hyphae and removes
residues from the surface. Fungi require aerobic conditions (high oxygen levels).
Therefore, retaining residues on the soil surface typically favors fungi.
Figure 7. Choice of tillage management influences the soil food web.
Choice of conservation tillage systems should be based on potential for erosion,
soil moisture, pest management, and nutrient availability. Prior to use of
moldboard plow for control of pests or nutrient stratification, growers should
make use of rotations, mechanical cultivation, flaming and pesticides (where
appropriate) to control pests, as well as, knifing or injection of nutrient materials
to improve nutrient availability. There are instances where temporary use of
intensive tillage is required to reduce compaction, pests, or improve nutrient
availability. Poorly drained clay soils may experience sub soil compaction due to
wheel traffic. These soils may require deep tillage, sub soiling, or use of zonebuilders. Conservation tillage practices such as ridge-tillage confine field traffic to
follow rows increasing compaction in some areas while minimizing traffic and
compaction in ridges.
Where grows? Where grows it not? If vain our toil. We ought to blame the
culture, not the soil. – Alexander Pope
References and Further Reading
Brady, N.C. and R.R. Weil. 2002. The Nature and properties of soils. 13th ed.
Prentice Hall, Upper Sadle River, NJ.
Cornell guide for integrated field crop management. 2001. Jerome H. Cherney,
William J. Cox, Russell R. Hahn, Ellen Z. Harrison, Quirine M. Ketterings, Murray
B. McBride, William S. Reid, Robert R. Schindelbeck, Harold M. van Es,
Department of Crop & Soil Sciences; Elson J. Shields, Department of
Entomology; Margaret E. Smith Einarson, Julie L. Hansen, Department of Plant
Breeding & Genetics; Gary C. Bergstrom, Department of Plant Pathology; Karl J.
Czymmek, PRO-Dairy; and J. Keith Waldron, NYS IPM Program. Designed and
edited by Raj Smith and Pam Kline. Cornell Cooperative Extension, Ithaca, NY.
Magdoff, F. and H. van Es. 2000. Building soils for better crops. Sustainable
Agriculture Network, National Agricultural Library, Beltsville, MD.
Sanchez, J., R.R. Harwood, J. LeCureux, J. Shaw, M. Shaw, S. Smalley, J.
Smeenk, and R. Voelker. 2001. Integrated cropping system for corn-sugar beetdry bean rotation: The Experience of the innovative farmers of Michigan. MSU
Ext. Bull. E-2738.
Steel in the field: a farmer’s guide to weed management tools. 1997. G.I.
Bowman (ed.) Sustainable Agriculture Network, National Agricultural Library,
Beltsville, MD.
URLs for Photos Used in Bulletin
www.mo.nrcs.usda.gov Photos Figure 1.
www.nrcs.usda.gov Figure 2.
http://reveg-catalog.tamu.edu/images/07-Site-Prep/02Moldboard%20Plow.JPG Figure 3. a.
http://www.maes.msu.edu/ressta/saginawvalley/Pic_Tour/14C23chisel_plo
w.jpg Figure 3. b.
http://www.epa.gov/glnpo/image/vbig/110.jpg Figure 3. c.
http://www.plant.uoguelph.ca/faculty/bdeen/assests/tractor.jpg Figure 3. d.
http://www.ipm.iastate.edu/ipm/icm/2003/4-28-2003/checkequip.html Figure 4.
http://www.maes.msu.edu/ressta/saginawvalley/Research/Sec_tillage&plow
_pan.jpg Figure 5.
www.hort.cornell.edu Zone-till cart
http://www.oznet.ksu.edu/notill/images/equip_liquid_injection.jpg Figure 6.
a. fert injection
http://agronomyday.cropsci.uiuc.edu/2003/liquid_manure/robert-fig-1.gif Figure 6.
b. slurry injection
http://soils.usda.gov/sqi/concepts/soil_biology/images/A-3.jpg
Figure 7. soil food web
Web Based Resources
http://www.nrcs.usda.gov/technical/land/meta/m4124.html
http://www.ctic.purdue.edu/CTIC/CTIC.html
http://attra.ncat.org/attra-pub/organicmatters/conservationtillage.html
http://www.sare.org