Tillage is the agricultural preparation of soil by mechanical
agitation of various types, such as digging, stirring, and
overturning. Examples of human-powered tilling methods using hand
tools include shovelling, picking, mattock work, hoeing, and raking.
Examples of draft-animal-powered or mechanized work include ploughing
(overturning with moldboards or chiseling with chisel shanks),
rototilling, rolling with cultipackers or other rollers, harrowing,
and cultivating with cultivator shanks (teeth). Small-scale gardening
and farming, for household food production or small business
production, tends to use the smaller-scale methods, whereas medium- to
large-scale farming tends to use the larger-scale methods. There is a
fluid continuum, however. Any type of gardening or farming, but
especially larger-scale commercial types, may also use low-till or
no-till methods as well.
Tillage is often classified into two types, primary and secondary.
There is no strict boundary between them so much as a loose
distinction between tillage that is deeper and more thorough (primary)
and tillage that is shallower and sometimes more selective of location
(secondary). Primary tillage such as ploughing tends to produce a
rough surface finish, whereas secondary tillage tends to produce a
smoother surface finish, such as that required to make a good seedbed
for many crops. Harrowing and rototilling often combine primary and
secondary tillage into one operation.
"Tillage" can also mean the land that is tilled. The word
"cultivation" has several senses that overlap substantially with those
of "tillage". In a general context, both can refer to agriculture.
Within agriculture, both can refer to any kind of soil agitation.
Additionally, "cultivation" or "cultivating" may refer to an even
narrower sense of shallow, selective secondary tillage of row crop
fields that kills weeds while sparing the crop plants.
1.1 Reduced tillage
1.2 Intensive tillage
1.3 Conservation tillage
2 Zone tillage
3 Effects of tillage
4 General comments
6 History of tilling
7 Alternatives to tilling
8 Site preparation of forest land
8.2 Ameliorative intervention
8.6 Orientation of linear site preparation
9 See also
12 Further reading
13 External links
Plough tilling the field
Reduced tillage[note 1] leaves 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. See the
general comments below to see how they can affect the amount of
Intensive tillage[note 1] leaves less than 15% crop residue cover or
less than 500 pounds per acre (560 kg/ha) of small grain residue.
This type of tillage is often referred to as conventional tillage but
as conservational tillage is now more widely used than intensive
tillage (in the United States), it is often not appropriate to
refer to this type of tillage as conventional. Intensive tillage often
involves multiple operations with implements such as a mold board,
disk, and/or chisel plow. Then a finisher with a harrow, rolling
basket, and cutter can be used to prepare the seed bed. There are many
Conservation tillage[note 1] leaves at least 30% of crop residue on
the soil surface, or at least 1,000 lb/ac (1,100 kg/ha) of
small grain residue on the surface during the critical soil erosion
period. This slows water movement, which reduces the amount of soil
erosion. Conservation tillage also benefits farmers by reducing fuel
consumption and soil compaction. By reducing the number of times the
farmer travels over the field, farmers realize significant savings in
fuel and labor. In most years since 1997, conservation tillage was
used in US cropland more than intensive or reduced tillage.
However, conservation tillage delays warming of the soil due to the
reduction of dark earth exposure to the warmth of the spring sun, thus
delaying the planting of the next year's spring crop of corn.
No-till - Never use a plow, disk, etc. ever again. Aims for 100%
Strip-Till - Narrow strips are tilled where seeds will be planted,
leaving the soil in between the rows untilled.
Tillage - Tilling the soil every two years or less often
(every other year, or every third year, etc.).
Zone tillage is a form of modified deep tillage in which only narrow
strips are tilled, leaving soil in between the rows untilled. This
type of tillage agitates the soil to help reduce soil compaction
problems and to improve internal soil drainage.
Zone tillage is designed to only disrupt the soil in a narrow strip
directly below the crop row. In comparison to no-till, which relies on
the previous year’s plant residue to protect the soil and aides in
postponement of the warming of the soil and crop growth in Northern
climates, zone tillage creates approximately a 5-inch-wide strip that
simultaneously breaks up plow pans, assists in warming the soil and
helps to prepare a seedbed. When combined with cover crops, zone
tillage helps replace lost organic matter, slows the deterioration of
the soil, improves soil drainage, increases soil water and nutrient
holding capacity, and allows necessary soil organisms to survive.
It has been successfully used on farms in the mid-west and west for
over 40 years and is currently used on more than 36% of the U.S.
farmland. Some specific states where zone tillage is currently in
practice are Pennsylvania, Connecticut, Minnesota, Indiana, Wisconsin,
Unfortunately, there aren't consistent yield results in the Northern
Cornbelt states; however, there is still interest in deep tillage
within the agriculture industry. In areas that are not
well-drained, deep tillage may be used as an alternative to installing
more expensive tile drainage.
Effects of tillage
Rice tillage. Valencian Museum of Ethnology.
Loosens and aerates the top layer of soil or horizon A, which
facilitates planting the crop
Helps mix harvest residue, organic matter (humus), and nutrients
evenly into the soil
Mechanically destroys weeds
Dries the soil before seeding (in wetter climates tillage aids in
keeping the soil drier)
When done in autumn, helps exposed soil crumble over winter through
frosting and defrosting, which helps prepare a smooth surface for
Dries the soil before seeding
Soil loses a lot of nutrients, like nitrogen and fertilizer, and its
ability to store water[note 2]
Decreases the water infiltration rate of soil. (Results in more runoff
and erosion since the soil absorbs water slower than
Tilling the soil results in dislodging the cohesiveness of the soil
particles thereby inducing erosion.
Chemical runoff[note 3]
Reduces organic matter in the soil[note 4]
Reduces microbes, earthworms, ants, etc.
Destroys soil aggregates
Compaction of the soil, also known as a tillage pan[note
Eutrophication (nutrient runoff into a body of water)[note 3]
Can attract slugs, cut worms, army worms, and harmful insects to the
left over residues.
Crop diseases can be harbored in surface residues
The type of implement makes the most difference, although other
factors can have an effect.
Tilling in absolute darkness (night tillage) might reduce the number
of weeds that sprout following the tilling operation by half. Light is
necessary to break the dormancy of some weed species' seed, so if
fewer seeds are exposed to light during the tilling process, fewer
will sprout. This may help reduce the amount of herbicides needed for
Greater speeds, when using certain tillage implements (disks and
chisel plows), lead to more intensive tillage (i.e., less residue is
on the soil surface).
Increasing the angle of disks causes residues to be buried more
deeply. Increasing their concavity makes them more aggressive.
Chisel plows can have spikes or sweeps. Spikes are more aggressive.
Percentage residue is used to compare tillage systems because the
amount of crop residue affects the soil loss due to erosion.
Primary tillage loosens the soil and mixes in fertilizer and/or plant
material, resulting in soil with a rough texture.
Secondary tillage produces finer soil and sometimes shapes the rows,
preparing the seed bed. It also provides weed control throughout the
growing season during the maturation of the crop plants, unless such
weed control is instead achieved with low-till or no-till methods
The seed bed preparation can be done with harrows (of which there are
many types and subtypes), dibbles, hoes, shovels, rotary tillers,
subsoilers, ridge- or bed-forming tillers, rollers, or cultivators.
The weed control, to the extent that it is done via tillage, is
usually achieved with cultivators or hoes, which disturb the top few
centimeters of soil around the crop plants but with minimal
disturbance of the crop plants themselves. The tillage kills the weeds
via 2 mechanisms: uprooting them, burying their leaves (cutting off
their photosynthesis), or a combination of both. Weed control both
prevents the crop plants from being outcompeted by the weeds (for
water and sunlight) and prevents the weeds from reaching their seed
stage, thus reducing future weed population aggressiveness.
History of tilling
Tilling with Hungarian Grey cattles
Tilling was first performed via human labor, sometimes involving
slaves. Hoofed animals could also be used to till soil by trampling.
The wooden plow was then invented. It could be pulled with human
labor, or by mule, ox, elephant, water buffalo, or similar sturdy
animal. Horses are generally unsuitable, though breeds such as the
Clydesdale were bred as draft animals. The steel plow allowed farming
in the American Midwest, where tough prairie grasses and rocks caused
trouble. Soon after 1900, the farm tractor was introduced, which
eventually made modern large-scale agriculture possible.
Alternatives to tilling
Modern agricultural science has greatly reduced the use of tillage.
Crops can be grown for several years without any tillage through the
use of herbicides to control weeds, crop varieties that tolerate
packed soil, and equipment that can plant seeds or fumigate the soil
without really digging it up. This practice, called no-till farming,
reduces costs and environmental change by reducing soil erosion and
diesel fuel usage.
Site preparation of forest land
Site preparation is any of various treatments applied to a site in
order to ready it for seeding or planting. The purpose is to
facilitate the regeneration of that site by the chosen method. Site
preparation may be designed to achieve, singly or in any combination:
improved access, by reducing or rearranging slash, and amelioration of
adverse forest floor, soil, vegetation, or other biotic factors. Site
preparation is undertaken to ameliorate one or more constraints that
would otherwise be likely to thwart the objectives of management. A
valuable bibliography on the effects of soil temperature and site
preparation on subalpine and boreal tree species has been prepared by
McKinnon et al. (2002).
Site preparation is the work that is done before a forest area is
regenerated. Some types of site preparation are burning.
Broadcast burning is commonly used to prepare clearcut sites for
planting, e.g., in central British Columbia, and in the temperate
region of North America generally.
Prescribed burning is carried out primarily for slash hazard reduction
and to improve site conditions for regeneration; all or some of the
following benefits may accrue:
a) Reduction of logging slash, plant competition, and humus prior to
direct seeding, planting, scarifying or in anticipation of natural
seeding in partially cut stands or in connection with seed-tree
b) Reduction or elimination of unwanted forest cover prior to planting
or seeding, or prior to preliminary scarification thereto.
c) Reduction of humus on cold, moist sites to favour regeneration.
d) Reduction or elimination of slash, grass, or brush fuels from
strategic areas around forested land to reduce the chances of damage
Prescribed burning for preparing sites for direct seeding was tried on
a few occasions in Ontario, but none of the burns was hot enough to
produce a seedbed that was adequate without supplementary mechanical
Changes in soil chemical properties associated with burning include
significantly increased pH, which Macadam (1987) in the Sub-boreal
Spruce Zone of central British Columbia found persisting more than a
year after the burn. Average fuel consumption was 20 to 24 t/ha and
the forest floor depth was reduced by 28% to 36%. The increases
correlated well with the amounts of slash (both total and ≥7 cm
diameter) consumed. The change in pH depends on the severity of the
burn and the amount consumed; the increase can be as much as 2 units,
a 100-fold change. Deficiencies of copper and iron in the foliage
of white spruce on burned clearcuts in central British Columbia might
be attributable to elevated pH levels.
Even a broadcast slash fire in a clearcut does not give a uniform burn
over the whole area. Tarrant (1954), for instance, found only 4%
of a 140-ha slash burn had burned severely, 47% had burned lightly,
and 49% was unburned. Burning after windrowing obviously accentuates
the subsequent heterogeneity.
Marked increases in exchangeable calcium also correlated with the
amount of slash at least 7 cm in diameter consumed.
Phosphorus availability also increased, both in the forest floor and
in the 0 cm to 15 cm mineral soil layer, and the increase
was still evident, albeit somewhat diminished, 21 months after
burning. However, in another study in the same Sub-boreal Spruce
Zone found that although it increased immediately after the burn,
phosphorus availability had dropped to below pre-burn levels within 9
Nitrogen will be lost from the site by burning, though
concentrations in remaining forest floor were found by Macadam
(1987) to have increased in 2 of 6 plots, the others showing
decreases. Nutrient losses may be outweighed, at least in the short
term, by improved soil microclimate through the reduced thickness of
forest floor where low soil temperatures are a limiting factor.
The Picea/Abies forests of the Alberta foothills are often
characterized by deep accumulations of organic matter on the soil
surface and cold soil temperatures, both of which make reforestation
difficult and result in a general deterioration in site productivity;
Endean and Johnstone (1974) describe experiments to test
prescribed burning as a means of seedbed preparation and site
amelioration on representative clear-felled Picea/Abies areas. Results
showed that, in general, prescribed burning did not reduce organic
layers satisfactorily, nor did it increase soil temperature, on the
sites tested. Increases in seedling establishment, survival, and
growth on the burned sites were probably the result of slight
reductions in the depth of the organic layer, minor increases in soil
temperature, and marked improvements in the efficiency of the planting
crews. Results also suggested that the process of site deterioration
has not been reversed by the burning treatments applied.
Slash weight (the oven-dry weight of the entire crown and that portion
of the stem < 4 inches in diameter) and size distribution are major
factors influencing the forest fire hazard on harvested sites.
Forest managers interested in the application of prescribed burning
for hazard reduction and silviculture, were shown a method for
quantifying the slash load by Kiil (1968). In west-central
Alberta, he felled, measured, and weighed 60 white spruce, graphed (a)
slash weight per merchantable unit volume against diameter at breast
height (dbh), and (b) weight of fine slash (<1.27 cm) also
against dbh, and produced a table of slash weight and size
distribution on one acre of a hypothetical stand of white spruce. When
the diameter distribution of a stand is unknown, an estimate of slash
weight and size distribution can be obtained from average stand
diameter, number of trees per unit area, and merchantable cubic foot
volume. The sample trees in Kiil's study had full symmetrical crowns.
Densely growing trees with short and often irregular crowns would
probably be overestimated; open-grown trees with long crowns would
probably be underestimated.
The need to provide shade for young outplants of Engelmann spruce in
Rocky Mountains is emphasized by the U.S. Forest Service.
Acceptable planting spots are defined as microsites on the north and
east sides of down logs, stumps, or slash, and lying in the shadow
cast by such material. Where the objectives of management specify
more uniform spacing, or higher densities, than obtainable from an
existing distribution of shade-providing material, redistribution or
importing of such material has been undertaken.
Site preparation on some sites might be done simply to facilitate
access by planters, or to improve access and increase the number or
distribution of microsites suitable for planting or seeding.
Wang et al. (2000) determined field performance of white and black
spruces 8 and 9 years after outplanting on boreal mixedwood sites
following site preparation (Donaren disc trenching versus no
trenching) in 2 plantation types (open versus sheltered) in
southeastern Manitoba. Donaren trenching slightly reduced the
mortality of black spruce but significantly increased the mortality of
white spruce. Significant difference in height was found between open
and sheltered plantations for black spruce but not for white spruce,
and root collar diameter in sheltered plantations was significantly
larger than in open plantations for black spruce but not for white
spruce. Black spruce open plantation had significantly smaller volume
(97 cm³) compared with black spruce sheltered (210 cm³),
as well as white spruce open (175 cm³) and sheltered
(229 cm³) plantations. White spruce open plantations also had
smaller volume than white spruce sheltered plantations. For transplant
stock, strip plantations had a significantly higher volume
(329 cm³) than open plantations (204 cm³). Wang et al.
(2000) recommended that sheltered plantation site preparation
should be used.
Up to 1970, no "sophisticated" site preparation equipment had become
operational in Ontario, but the need for more efficacious and
versatile equipment was increasingly recognized. By this time,
improvements were being made to equipment originally developed by
field staff, and field testing of equipment from other sources was
According to J. Hall (1970), in Ontario at least, the most widely
used site preparation technique was post-harvest mechanical
scarification by equipment front-mounted on a bulldozer (blade, rake,
V-plow, or teeth), or dragged behind a tractor (Imsett or S.F.I.
scarifier, or rolling chopper). Drag type units designed and
constructed by Ontario's Department of Lands and Forests used anchor
chain or tractor pads separately or in combination, or were finned
steel drums or barrels of various sizes and used in sets alone or
combined with tractor pad or anchor chain units.
J. Hall's (1970) report on the state of site preparation in
Ontario noted that blades and rakes were found to be well suited to
post-cut scarification in tolerant hardwood stands for natural
regeneration of yellow birch. Plows were most effective for treating
dense brush prior to planting, often in conjunction with a planting
machine. Scarifying teeth, e.g., Young's teeth, were sometimes used to
prepare sites for planting, but their most effective use was found to
be preparing sites for seeding, particularly in backlog areas carrying
light brush and dense herbaceous growth. Rolling choppers found
application in treating heavy brush but could be used only on
stone-free soils. Finned drums were commonly used on jack
pine–spruce cutovers on fresh brushy sites with a deep duff layer
and heavy slash, and they needed to be teamed with a tractor pad unit
to secure good distribution of the slash. The S.F.I. scarifier, after
strengthening, had been "quite successful" for 2 years, promising
trials were under way with the cone scarifier and barrel ring
scarifier, and development had begun on a new flail scarifier for use
on sites with shallow, rocky soils. Recognition of the need to become
more effective and efficient in site preparation led the Ontario
Department of Lands and Forests to adopt the policy of seeking and
obtaining for field testing new equipment from Scandinavia and
elsewhere that seemed to hold promise for Ontario conditions,
primarily in the north. Thus, testing was begun of the
Brackekultivator from Sweden and the Vako-Visko rotary furrower from
Site preparation treatments that create raised planting spots have
commonly improved outplant performance on sites subject to low soil
temperature and excess soil moisture. Mounding can certainly have a
big influence on soil temperature. Draper et al. (1985), for
instance, documented this as well as the effect it had on root growth
of outplants (Table 30).
The mounds warmed up quickest, and at soil depths of 0.5 cm and
10 cm averaged 10 and 7 °C higher, respectively, than in
the control. On sunny days, daytime surface temperature maxima on the
mound and organic mat reached 25 °C to 60 °C, depending on
soil wetness and shading. Mounds reached mean soil temperatures of
10 °C at 10 cm depth 5 days after planting, but the control
did not reach that temperature until 58 days after planting. During
the first growing season, mounds had 3 times as many days with a mean
soil temperature greater than 10 °C than did the control
Draper et al.'s (1985) mounds received 5 times the amount of
photosynthetically active radiation (PAR) summed over all sampled
microsites throughout the first growing season; the control treatment
consistently received about 14% of daily background PAR, while mounds
received over 70%. By November, fall frosts had reduced shading,
eliminating the differential. Quite apart from its effect on
temperature, incident radiation is also important photosynthetically.
The average control microsite was exposed to levels of light above the
compensation point for only 3 hours, i.e., one-quarter of the daily
light period, whereas mounds received light above the compensation
point for 11 hours, i.e., 86% of the same daily period. Assuming that
incident light in the 100-600 µEm‾²s‾1 intensity range is the
most important for photosynthesis, the mounds received over 4 times
the total daily light energy that reached the control microsites.
Orientation of linear site preparation
With linear site preparation, orientation is sometimes dictated by
topography or other considerations, but the orientation can often be
chosen. It can make a difference. A disk-trenching experiment in the
Sub-boreal Spruce Zone in interior British Columbia investigated the
effect on growth of young outplants (lodgepole pine) in 13 microsite
planting positions: berm, hinge, and trench in each of north, south,
east, and west aspects, as well as in untreated locations between the
furrows. Tenth-year stem volumes of trees on south, east, and
west-facing microsites were significantly greater than those of trees
on north-facing and untreated microsites. However, planting spot
selection was seen to be more important overall than trench
In a Minnesota study, the N–S strips accumulated more snow but snow
melted faster than on E–W strips in the first year after
felling. Snow-melt was faster on strips near the centre of the
strip-felled area than on border strips adjoining the intact stand.
The strips, 50 feet (15.24 m) wide, alternating with uncut strips 16
feet (4.88 m) wide, were felled in a Pinus resinosa stand, aged 90 to
Optimum water content for tillage
Soybean management practices
Soil and Water Environmental Enhancement program)
^ a b c Since each type of tillage type has more than one type of
equipment that may be used, the tillage types may be referred to in
the plural by adding the term "systems" ie: Reduced tillage systems,
intensive tillage systems, conservation tillage systems.
^ a b However, see zone tillage
^ a b c d However, see conservation tillage
^ However, see cover crops
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Plow Farmers Save Our Soil
I will teach the world farming without oil
Manufacturer of Agricultural Zone Till
Subsoiler with Photos
(umequip.com by Unverferth Equipment)
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