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Tillage is the
agricultural Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled peopl ...
preparation of
soil Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former ...
by mechanical agitation of various types, such as digging, stirring, and overturning. Examples of human-powered tilling methods using
hand tool A hand tool is any tool that is powered by hand rather than a motor. Categories of hand tools include wrenches, pliers, cutters, files, striking tools, struck or hammered tools, screwdrivers, vises, clamps, snips, hacksaws, drills, an ...
s include shoveling, picking, mattock work,
hoeing A hoe is an ancient and versatile agricultural and horticultural hand tool used to shape soil, remove weeds, clear soil, and harvest root crops. Shaping the soil includes piling soil around the base of plants (hilling), digging narrow furrows ...
, and
raking Raking (also called "raking ratio estimation" or "iterative proportional fitting The iterative proportional fitting procedure (IPF or IPFP, also known as biproportional fitting or biproportion in statistics or economics (input-output analysis, etc ...
. Examples of draft-animal-powered or mechanized work include
plough A plough or plow ( US; both ) is a farm tool for loosening or turning the soil before sowing seed or planting. Ploughs were traditionally drawn by oxen and horses, but in modern farms are drawn by tractors. A plough may have a wooden, iron or ...
ing (overturning with moldboards or chiseling with chisel shanks), rototilling, rolling with
cultipacker A cultipacker is a piece of agricultural equipment that crushes dirt clods, removes air pockets, and presses down small stones, forming a smooth, firm seedbed. Where seed has been broadcast, the roller gently firms the soil around the seeds, en ...
s or other rollers, harrowing, and cultivating with
cultivator A cultivator is a piece of agricultural equipment used for secondary tillage. One sense of the name refers to frames with ''teeth'' (also called ''shanks'') that pierce the soil as they are dragged through it linearly. It also refers to ma ...
shanks (teeth). Tillage that is deeper and more thorough is classified as primary, and tillage that is shallower and sometimes more selective of location is 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 A row crop is a crop that can be planted in rows wide enough to allow it to be tilled or otherwise cultivated by agricultural machinery, machinery tailored for the seasonal activities of row crops. Such crops are sown by drilling or transplantin ...
fields that kills weeds while sparing the crop plants.


Definitions

''Primary tillage'' loosens the soil and mixes in
fertilizer A fertilizer (American English) or fertiliser (British English; see spelling differences) is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from ...
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 involving
herbicide Herbicides (, ), also commonly known as weedkillers, are substances used to control undesired plants, also known as weeds.EPA. February 201Pesticides Industry. Sales and Usage 2006 and 2007: Market Estimates. Summary in press releasMain page f ...
s. * The seedbed preparation can be done with harrows (of which there are many types and subtypes), dibbles,
hoe Hoe or HOE may refer to: * Hoe (food), a Korean dish of raw fish * Hoe (letter), a Georgian letter * Hoe (tool), a hand tool used in gardening and farming ** Hoe-farming, a term for primitive forms of agriculture * Backhoe, a piece of excavating ...
s, shovels,
rotary tiller A cultivator is a piece of agricultural equipment used for secondary tillage. One sense of the name refers to frames with ''teeth'' (also called ''shanks'') that pierce the soil as they are dragged through it linearly. It also refers to ma ...
s,
subsoiler A subsoiler or flat lifter is a tractor-mounted farm implement used for deep tillage, loosening and breaking up soil at depths below the levels worked by moldboard ploughs, disc harrows, or rototillers. Most such tools will break up and turn ov ...
s, ridge- or bed-forming tillers,
roller Roller may refer to: Birds *Roller, a bird of the family Coraciidae * Roller (pigeon), a domesticated breed or variety of pigeon Devices * Roller (agricultural tool), a non-powered tool for flattening ground * Road roller, a vehicle for compa ...
s, or
cultivator A cultivator is a piece of agricultural equipment used for secondary tillage. One sense of the name refers to frames with ''teeth'' (also called ''shanks'') that pierce the soil as they are dragged through it linearly. It also refers to ma ...
s. * 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 two mechanisms: uprooting them, burying their leaves (cutting off their
photosynthesis Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored in ...
), 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

Tilling was first performed via human labor, sometimes involving
slaves Slavery and enslavement are both the state and the condition of being a slave—someone forbidden to quit one's service for an enslaver, and who is treated by the enslaver as property. Slavery typically involves slaves being made to perf ...
. Hoofed animals could also be used to till soil by trampling, in addition to pigs, whose natural instincts are to
root In vascular plants, the roots are the organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into the plant body, which allows plants to grow taller and faster. They are most often below the su ...
the ground regularly if allowed to. The wooden
plow A plough or plow ( US; both ) is a farm tool for loosening or turning the soil before sowing seed or planting. Ploughs were traditionally drawn by oxen and horses, but in modern farms are drawn by tractors. A plough may have a wooden, iron or ...
was then invented. It could be pulled with human labor, or by
mule The mule is a domestic equine hybrid between a donkey and a horse. It is the offspring of a male donkey (a jack) and a female horse (a mare). The horse and the donkey are different species, with different numbers of chromosomes; of the two po ...
, ox,
elephant Elephants are the largest existing land animals. Three living species are currently recognised: the African bush elephant, the African forest elephant, and the Asian elephant. They are the only surviving members of the family Elephantida ...
,
water buffalo The water buffalo (''Bubalus bubalis''), also called the domestic water buffalo or Asian water buffalo, is a large bovid originating in the Indian subcontinent and Southeast Asia. Today, it is also found in Europe, Australia, North America, So ...
, or a similar sturdy animal. Horses are generally unsuitable, though breeds such as the Clydesdale were bred as draft animals. The
steel Steel is an alloy made up of iron with added carbon to improve its strength and fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels that are corrosion- and oxidation-resistan ...
plow allowed farming in the
American Midwest The Midwestern United States, also referred to as the Midwest or the American Midwest, is one of four census regions of the United States Census Bureau (also known as "Region 2"). It occupies the northern central part of the United States. I ...
, where tough prairie grasses and rocks caused trouble. Soon after 1900, the farm tractor was introduced, which eventually made modern large-scale
agriculture Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people ...
possible. Tilling could at times be very labor-intensive. This aspect is discussed in the 16th-century French agronomic text written by Charles Estienne:


Types


Primary and secondary tillage

Primary tillage is usually conducted after the last harvest, when the soil is wet enough to allow plowing but also allows good traction. Some soil types can be plowed dry. The objective of primary tillage is to attain a reasonable depth of soft soil, incorporate crop residues, kill weeds, and to aerate the soil. Secondary tillage is any subsequent tillage, to incorporate fertilizers, reduce the soil to a finer tilth, level the surface, or control weeds.


Reduced tillage

Reduced tillage leaves between 15 and 30% crop 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 residue.


Intensive tillage

Intensive tillage 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, or chisel
plow A plough or plow ( US; both ) is a farm tool for loosening or turning the soil before sowing seed or planting. Ploughs were traditionally drawn by oxen and horses, but in modern farms are drawn by tractors. A plough may have a wooden, iron or ...
. After this, a finisher with a harrow, rolling basket, and cutter can be used to prepare the seed bed. There are many variations.


Conservation tillage

Conservation tillage 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 Soil erosion is the denudation or wearing away of the upper layer of soil. It is a form of soil degradation. This natural process is caused by the dynamic activity of erosive agents, that is, water, ice (glaciers), snow, air (wind), plants, a ...
period. This slows water movement, which reduces the amount of soil erosion. Additionally, conservation tillage has been found to benefit predatory arthropods that can enhance pest control. Conservation tillage also benefits farmers by reducing fuel consumption and soil compaction. By reducing the number of times the farmer travels over the field, significant savings in fuel and labor are made. Conservation tillage is used on over 370 million acres, mostly in South America, Oceania and North America. 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 – plows, disks, et cetera are not used. Aims for 100% ground cover. * Strip-till – Narrow strips are tilled where seeds will be planted, leaving the soil in between the rows untilled. *
Mulch-till In agriculture mulch tillage or mulch-till fall under the umbrella term of conservation tillage in the United States and refer to seeding methods where a hundred percent of the soil surface is disturbed by tillage whereby crop residues are mixed ...
- Soil is covered with mulch to conserve heat and moisture. 100% soil disturbance. * Rotational tillage – Tilling the soil every two years or less often (every other year, or every third year, etc.). * Ridge-till


Zone tillage

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 In geotechnical engineering, soil compaction is the process in which stress applied to a soil causes densification as air is displaced from the pores between the soil grains. When stress is applied that causes densification due to water (or othe ...
problems and to improve internal soil drainage.
University of Massachusetts Amherst The University of Massachusetts Amherst (UMass Amherst, UMass) is a public research university in Amherst, Massachusetts and the sole public land-grant university in Commonwealth of Massachusetts. Founded in 1863 as an agricultural college, ...
. Vegetable Program. "Deep Zone Tillage", 2012.
It 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 aids in postponement of the warming of the soil and crop growth in Northern climates, zone tillage produces a strip approximately five inches wide that simultaneously breaks up plow pans, assists in warming the soil and helps to prepare a seedbed.
Pennsylvania State University The Pennsylvania State University (Penn State or PSU) is a public state-related land-grant research university with campuses and facilities throughout Pennsylvania. Founded in 1855 as the Farmers' High School of Pennsylvania, Penn State becam ...
. "Evaluation of Zone Tillage for Corn Production", 2002.
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 Midwest and West for over 40 years, and is currently used on more than 36% of the U.S. farmland., Boucher, J.
University of Connecticut The University of Connecticut (UConn) is a public land-grant research university in Storrs, Connecticut, a village in the town of Mansfield. The primary 4,400-acre (17.8 km2) campus is in Storrs, approximately a half hour's drive from H ...
. "Soil Health and Deep-Zone Tillage", 2008.
Some specific states where zone tillage is currently in practice are Pennsylvania, Connecticut, Minnesota, Indiana, Wisconsin, and Illinois. Its use in the Northern Corn Belt states lacks consistent yield results; however, there is still interest in deep tillage within agriculture.
"Fall Zone Tillage Conserves Soil, Yields Well", 1999.
In areas that are not well-drained, deep tillage may be used as an alternative to installing more expensive tile drainage.
DeJong-Hughes, J. Johnson, J. Plant Management Network. 2009.


Effects


Positive

Plowing: * 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 spring planting. * Can reduce infestations of slugs, cut worms, army worms, and harmful insects as they are attracted by leftover residues from former crops. * Reduces the risk of crop diseases which can be harbored in surface residues.


Negative

* Dries the soil before seeding. * Soil loses
nutrients A nutrient is a substance used by an organism to survive, grow, and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi, and protists. Nutrients can be incorporated into cells for metabolic purposes or excr ...
, like
nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...
and fertilizer, and its ability to store water. * Decreases the water infiltration rate of soil. (Results in more runoff and erosion as the soil absorbs water more slowly than before) * Tilling the soil results in dislodging the cohesiveness of the soil particles, thereby inducing erosion. * Chemical runoff. * Reduces organic matter in the soil. * Reduces microbes, earthworms, ants, etc. * Destroys soil aggregates. * Compaction of the soil, also known as a tillage pan. *
Eutrophication Eutrophication is the process by which an entire body of water, or parts of it, becomes progressively enriched with minerals and nutrients, particularly nitrogen and phosphorus. It has also been defined as "nutrient-induced increase in phyt ...
(nutrient runoff into a body of water).


Archaeology

Tilling can damage ancient structures such as long barrows. In the UK, half of the long barrows in
Gloucestershire Gloucestershire ( abbreviated Glos) is a county in South West England. The county comprises part of the Cotswold Hills, part of the flat fertile valley of the River Severn and the entire Forest of Dean. The county town is the city of ...
and almost all the burial mounds in
Essex Essex () is a Ceremonial counties of England, county in the East of England. One of the home counties, it borders Suffolk and Cambridgeshire to the north, the North Sea to the east, Hertfordshire to the west, Kent across the estuary of the Riv ...
have been damaged. According to
English Heritage English Heritage (officially the English Heritage Trust) is a charity that manages over 400 historic monuments, buildings and places. These include prehistoric sites, medieval castles, Roman forts and country houses. The charity states that i ...
in 2003, ploughing with modern powerful tractors had done as much damage in the last six decades as traditional farming did in the previous six centuries.


General comments

* The type of implement makes the most difference, although other factors can have an effect.Conservation Tillage and Residue Management to Reduce Soil Erosion
University of Missouri: Extension
* 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 weed control. * 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.


Alternatives

Modern
agricultural science Agricultural science (or agriscience for short) is a broad multidisciplinary field of biology that encompasses the parts of exact, natural, economic and social sciences that are used in the practice and understanding of agriculture. Profession ...
has greatly reduced the use of tillage. Crops can be grown for several years without any tillage through the use of
herbicide Herbicides (, ), also commonly known as weedkillers, are substances used to control undesired plants, also known as weeds.EPA. February 201Pesticides Industry. Sales and Usage 2006 and 2007: Market Estimates. Summary in press releasMain page f ...
s to control weeds, crop varieties that tolerate packed soil, and equipment that can plant seeds or
fumigate Fumigation is a method of pest control or the removal of harmful micro-organisms by completely filling an area with gaseous pesticides—or fumigants—to suffocate or poison the pests within. It is used to control pests in buildings (s ...
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 Diesel fuel , also called diesel oil, is any liquid fuel specifically designed for use in a diesel engine, a type of internal combustion engine in which fuel ignition takes place without a spark as a result of compression of the inlet air and ...
usage.


Site preparation of forest land

Site preparation is any of various treatments applied to a site 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 Boreal may refer to: Climatology and geography *Boreal (age), the first climatic phase of the Blytt-Sernander sequence of northern Europe, during the Holocene epoch *Boreal climate, a climate characterized by long winters and short, cool to mild ...
tree species has been prepared by McKinnon et al. (2002).McKinnon, L.M.; Mitchell, A.K.; Vyse, A. 2002. The effects of soil temperature and site preparation on subalpine and boreal tree species: a bibliography. Nat. Resour., Can., Can. For. Serv., Victoria BC, Inf. Rep. BC-X-394. 29 p. Site preparation is the work that is done before a forest area is regenerated. Some types of site preparation are burning.


Burning

Broadcast burning is commonly used to prepare clearcut sites for planting, e.g., in central British Columbia,Macadam, A.M. 1987. Effects of broadcast slash burning on fuels and soil chemical properties in the sub-boreal spruce zone of central British Columbia. Can. J. For. Res. 17(12):1577–1584. and in the temperate region of North America generally.Kiil, A.D.; Chrosciewicz, Z. 1970. Prescribed fire – its place in reforestation. For. Chron. 46:448–451. 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 systems. :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 by wildfire. 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 site preparation.Scott, J.D. 1970. Direct seeding in Ontario. For. Chron. 46(6):453–457. 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.Holt, L. 1955. White spruce seedbeds as related to natural regeneration. Pulp Paper Res. Instit. Can., Montreal QC. 28 p. 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.Ballard, T.M. 1985. Spruce nutrition problems in the central interior and their relationship with site preparation. Proc. Interior spruce seedling performance: state of the art Symposium. Northern Silviculture Committee Workshop, Feb. 1985, Prince George BC. Even a broadcast slash fire in a clearcut does not give a uniform burn over the whole area. Tarrant (1954),Tarrant, R.F. 1954. Effect of slash burning on soil pH. USDA, For. Serv., Pacific Northwest For. and Range Exp. Sta., Portland OR, Res. Note 102. 5 p. 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 studyTaylor, S.W.; Feller, M.C. 1987. Initial effects of slashburning on the nutrient status of Sub-boreal Spruce Zone ecosystems. ''In'' Papers presented at the Fire Management Symposium, April 1987, Prince George BC, Central Interior Fire Protection Committee, Smithers BC. 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 months. Nitrogen will be lost from the site by burning,Little, S.N.; Klock, G.O. 1985. The influence of residue removal and prescribed fire on distribution of forest nutrients. USDA, For. Serv., Res. Pap. PNW-333. though concentrations in remaining forest floor were found by Macadam (1987) to have increased in two out of six 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)Endean, F.; Johnstone, W.D. 1974. Prescribed fire and regeneration on clearcut spruce–fir sites in the foothills of Alberta. Environ. Can., Can. For. Serv., Northern For. Res. Centre, Edmonton AB, Inf. Rep. NOR-X-126. 33 p. 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.


Ameliorative intervention

Slash weight (the oven-dry weight of the entire crown and that portion of the stem less than four inches in diameter) and size distribution are major factors influencing the
forest fire A wildfire, forest fire, bushfire, wildland fire or rural fire is an unplanned, uncontrolled and unpredictable fire in an area of combustible vegetation. Depending on the type of vegetation present, a wildfire may be more specifically identi ...
hazard on harvested sites.Kiil, A.D. 1965. Weight and size distribution of slash of white spruce and lodgepole pine. For. Chron. 41:432–437. 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).Kiil, A.D. 1968. Weight of the fuel complex in 70-year-old lodgepole pine stands of different densities. Department of Forestry and Rural Development, Forest Research Laboratory, Calgary, Alberta. Departmental Publication 1228. 13 p. 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 the high
Rocky Mountains The Rocky Mountains, also known as the Rockies, are a major mountain range and the largest mountain system in North America. The Rocky Mountains stretch in straight-line distance from the northernmost part of western Canada, to New Mexico ...
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.Ronco, F. 1975. Diagnosis: sunburned trees. J. For. 73(1):31–35. (Cited in Coates et al. 1994). 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.


Access

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)Wang, G.G.; Siemens, A.; Keenan, V.; Philippot, D. 2000. Survival and growth of black and white spruce seedlings in relation to stock type, site preparation and plantation type in southeastern Manitoba. For. Chron. 76(5):775–782. 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.


Mechanical

Up to 1970, no "sophisticated" site preparation equipment had become operational in Ontario,Hall, J. 1970. Site preparation in Ontario. For. Chron. 46:445–447. 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 increasing. 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 Hardwood is wood from dicot trees. These are usually found in broad-leaved temperate and tropical forests. In temperate and boreal latitudes they are mostly deciduous, but in tropics and subtropics mostly evergreen. Hardwood (which comes from ...
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 Finland.


Mounding

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),Draper, D.; Binder, W.; Fahlman, R.; Spittlehouse, D. 1985. Post-planting ecophysiology of Interior spruce. Interior Spruce Seedling Performance: State of the Art. Northern Silvic. Committee, Prince George BC. 18 p. (mimeo). 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 microsites. 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 Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored in ...
, 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 Topography is the study of the forms and features of land surfaces. The topography of an area may refer to the land forms and features themselves, or a description or depiction in maps. Topography is a field of geoscience and planetary sc ...
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.Burton, P.; Bedford L.; Goldstein, M.; Osberg, M. 2000. Effect of disk trench orientation and planting spot position on the ten-year performance of lodgepole pine. New For. 20:23–44. 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 orientation. 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.Clausen, J.C.; Mace, A.C., Jr. 1972. Accumulation and snowmelt on north–south versus east–west oriented clearcut strips. Univ. Minnesota, Coll. For., St. Paul MN, Minn. For. Res. Notes No. 34. 4 p. 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 100 years.


See also

* Advance sowing *
Land development Land development is the alteration of landscape in any number of ways such as: * Changing landforms from a natural or semi-natural state for a purpose such as agriculture or housing * Subdividing real estate into lots, typically for the purpos ...
* Optimum water content for tillage * Site preparation *
Soybean management practices Soybean management practices in farming are the decisions a producer must make in order to raise a soybean crop. The type of tillage, plant population, row spacing, and planting date are four major management decisions that soybean farmers must cons ...
* SWEEP (Soil and Water Environmental Enhancement program) *
TERON (Tillage erosion) TERON is a foundation dedicated to the assessment of tillage related erosion in Europe. See also * Conservation biology * Environmental protection * Habitat conservation * Natural environment * Natural resource * Sustainability * Tillage erosion ...
* Tillage erosion


Notes


References


Bibliography

* Cook, R.L., H.F. McColly, L.S. Robertson, and C.M. Hansen. 1958. Save Money – Water – Soil with Minimum Tillage. Extension Bulletin 352. Cooperative Extension Service, Michigan State University, East Lansing. * Sprague, Milton A., and Glover B. Triplett. 1986. ''No-tillage and surface-tillage agriculture: the tillage revolution''. New York, Wiley. * Troeh, Frederick R., J. Arthur Hobbs, Roy L. Donahue. 1991. ''Soil and water conservation for productivity and environmental protection'', 2nd ed. Englewood Cliffs, N.J., Prentice-Hall. * Soil Science of America. 2009. Glossary of Soil Science Terms. nline Available at https://www.soils.org/publications/soils-glossary (28 September 2009; verified 28 September 2009). Soil Science of America, Madison, WI.
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Further reading

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External links


"Illustrated Guide of Tilling and Weaving: Rural Life in China"
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