Tillage

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.

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 fields that kills weeds while sparing the crop plants.

Fendt Tractor Ripping up Kulin
Cultivating after an early rain

History of tilling

Tilling with Hungarian Grey cattles
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, in addition to pigs, whose natural instincts are to root the ground regularly if allowed to. 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.

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, in order to incorporate fertilizers, reduce the soil to a finer tilth, level the surface, or control weeds.[1]

Reduced tillage

Ploughtilling the field
Plough tilling the field

Reduced tillage[note 1] 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[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),[2][3] 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. 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[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. Additionally, conservation tillage has been found to benefit predatory arthropods that can enhance pest control.[4] 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.[3]

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.[5]

  • No-till – Never use a plow, disk, etc. ever again. Aims for 100% ground cover.
  • Strip-Till – Narrow strips are tilled where seeds will be planted, leaving the soil in between the rows untilled.[6]
  • Mulch-till
  • Rotational Tillage – Tilling the soil every two years or less often (every other year, or every third year, etc.).[6]
  • 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 problems and to improve internal soil drainage.[7] 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 aides in postponement of the warming of the soil and crop growth in Northern climates, zone tillage creates approximately a strip approximately five inches wide that simultaneously breaks up plow pans, assists in warming the soil and helps to prepare a seedbed.[8] 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.[9] Some specific states where zone tillage is currently in practice are Pennsylvania, Connecticut, Minnesota, Indiana, Wisconsin, and Illinois.

Unfortunately, its use in the Northern Cornbelt states lacks consistent yield results; however, there is still interest in deep tillage within the agriculture industry.[10] In areas that are not well-drained, deep tillage may be used as an alternative to installing more expensive tile drainage.[11]

Effects of tillage

Positive

Plowing:

  • Loosens and aerates the top layer of soil or horizon A, which facilitates planting the crop.[12]
  • Helps mix harvest residue, organic matter (humus), and nutrients evenly into the soil.[12]
  • Mechanically destroys weeds.[12]
  • Dries the soil before seeding (in wetter climates tillage aids in keeping the soil drier).[12]
  • When done in autumn, helps exposed soil crumble over winter through frosting and defrosting, which helps prepare a smooth surface for spring planting.[12]

Negative

  • Dries the soil before seeding.[12]
  • Soil loses nutrients, like nitrogen and fertilizer, and its ability to store water.[12][note 2]
  • Decreases the water infiltration rate of soil. (Results in more runoff and erosion[12][13] since the soil absorbs water more slowly than before)[note 3]
  • Tilling the soil results in dislodging the cohesiveness of the soil particles thereby inducing erosion.
  • Chemical runoff.[12][note 3]
  • Reduces organic matter in the soil.[12][note 4]
  • Reduces microbes, earthworms, ants, etc.[14]
  • Destroys soil aggregates.[12][14]
  • Compaction of the soil, also known as a tillage pan.[12][14][note 2][note 3]
  • Eutrophication (nutrient runoff into a body of water).[note 3]
  • Can attract slugs, cut worms, army worms, and harmful insects to the leftover residues.[15]
  • Crop diseases can be harbored in surface residues.[15]

General comments

  • The type of implement makes the most difference, although other factors can have an effect.[16]
  • 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.[17]
  • 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.[16][18]

Definitions

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 involving herbicides.

  • The seedbed 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.

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).[19]

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,[20] and in the temperate region of North America generally.[21]

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.[22]

Changes in soil chemical properties associated with burning include significantly increased pH, which Macadam (1987)[20] 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.[23] 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.[24]

Even a broadcast slash fire in a clearcut does not give a uniform burn over the whole area. Tarrant (1954),[25] 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.[20] 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[26] 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,[20][26][27] though concentrations in remaining forest floor were found by Macadam (1987)[20] 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)[28] 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 hazard on harvested sites.[29] 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).[30] 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 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.[31] 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)[32] 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)[32] recommended that sheltered plantation site preparation should be used.

Mechanical

Up to 1970, no "sophisticated" site preparation equipment had become operational in Ontario,[33] 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),[33] 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)[33] 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 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),[34] 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)[34] 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.[35] 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.[36] 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

Notes

  1. ^ 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.
  2. ^ a b However, see zone tillage
  3. ^ a b c d However, see conservation tillage
  4. ^ However, see cover crops

References

  1. ^ "Types of tillage". Knowledge Bank. Retrieved 24 February 2019.
  2. ^ "CONSERVATION TILLAGE IN THE UNITED STATES: AN OVERVIEW". okstate.edu. Institute of Agriculture and Natural Resources, University of Nebraska – Lincoln. p. Figure 2. Retrieved 8 July 2013.
  3. ^ a b "National Crop Residue Management (CRM) Survey Summary (various years)". ctic.purdue.edu. Conservation Technology Information Center.
  4. ^ Tamburini, G., De Simone, S., Sigura, M., Boscutti, F., Marini, L. and Kleijn, D. (2016), Conservation tillage mitigates the negative effect of landscape simplification on biological control. Journal of Applied Ecology, 53: 233–241. doi:10.1111/1365-2664.12544
  5. ^ "Strip Till for Field Crop Production". Ag.ndsu.edu. 14 November 2012. Retrieved 20 December 2012.
  6. ^ a b "Best Management Practices for Conservation/Reduced Tillage" (PDF). Texas Cooperative Extension, The Texas A&M University System. Archived from the original (PDF) on 10 August 2014.
  7. ^ [1], University of Massachusetts Amherst. Vegetable Program. "Deep Zone Tillage", 2012.
  8. ^ "Archived copy". Archived from the original on 13 May 2013. Retrieved 3 August 2013.CS1 maint: archived copy as title (link) Pennsylvania State University. "Evaluation of Zone Tillage for Corn Production", 2002.
  9. ^ "Archived copy". Archived from the original on 22 May 2013. Retrieved 3 August 2013.CS1 maint: archived copy as title (link), Boucher, J. University of Connecticut. "Soil Health and Deep-Zone Tillage", 2008.
  10. ^ [2], "Fall Zone Tillage Conserves Soil, Yields Well", 1999.
  11. ^ [3], DeJong-Hughes, J. Johnson, J. Plant Management Network. 2009.
  12. ^ a b c d e f g h i j k l Ray Hilborn. "Soils in Agriculture" (PPT—available as non-PPT by searching the path through a search engine). University of Washington. Retrieved 28 August 2013.
  13. ^ Gebhardt_et_al. 1985
  14. ^ a b c "Soil Compaction and Conservation Tillage". Conservation Tillage Series. PennState – College of Agricultural Sciences – Cooperative Extension. Retrieved 26 March 2011.
  15. ^ a b Dr. Tarlok Singh Sahota CCA (September 2008). "Alternative tillage systems to save time and fuel*" (PDF). Retrieved 20 June 2018.
  16. ^ a b Conservation Tillage and Residue Management to Reduce Soil Erosion University of Missouri: Extension
  17. ^ "Nightmare in Tilling Fields – a Horror for Weed Pests". Ars.usda.gov. Retrieved 5 July 2012.
  18. ^ Mahdi Al-Kaisi; Mark Hanna; Michael Tidman (13 May 2002). "Methods for measuring crop residue". Iowa State University. Retrieved 28 December 2012.
  19. ^ 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.
  20. ^ a b c d e 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.
  21. ^ Kiil, A.D.; Chrosciewicz, Z. 1970. Prescribed fire – its place in reforestation. For. Chron. 46:448–451.
  22. ^ Scott, J.D. 1970. Direct seeding in Ontario. For. Chron. 46(6):453–457.
  23. ^ Holt, L. 1955. White spruce seedbeds as related to natural regeneration. Pulp Paper Res. Instit. Can., Montreal QC. 28 p.
  24. ^ 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.
  25. ^ 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.
  26. ^ a b Taylor, 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.
  27. ^ 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.
  28. ^ 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.
  29. ^ Kiil, A.D. 1965. Weight and size distribution of slash of white spruce and lodgepole pine. For. Chron. 41:432–437.
  30. ^ 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.
  31. ^ Ronco, F. 1975. Diagnosis: sunburned trees. J. For. 73(1):31–35. (Cited in Coates et al. 1994).
  32. ^ a b 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.
  33. ^ a b c Hall, J. 1970. Site preparation in Ontario. For. Chron. 46:445–447.
  34. ^ a b 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).
  35. ^ 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.
  36. ^ 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.

Bibliography

Further reading

  • Brady, Nyle C.; R.R. Weil (2002). The nature and property of soils, 13th edition. New Jersey: Prentice Hall. ISBN 0-13-016763-0.

External links

1875 State of the Union Address

The 1875 State of the Union Address was given by Ulysses S. Grant, the 18th President of the United States on Tuesday, December 7, 1875. It was written by him, but not presented to the 44th United States Congress by him. He said, "In submitting my seventh annual message to Congress, in this centennial year of our national existence as a free and independent people, it affords me great pleasure to recur to the advancement that has been made from the time of the colonies, one hundred years ago. We were then a people numbering only 3,000,000. Now we number more than 40,000,000. Then industries were confined almost exclusively to the tillage of the soil. Now manufactories absorb much of the labor of the country." The Industrial Revolution had begun.

Agroecology

Agroecology is the study of ecological processes applied to agricultural production systems. Bringing ecological principles to bear in agroecosystems can suggest novel management approaches that would not otherwise be considered. The term is often used imprecisely and may refer to "a science, a movement, [or] a practice". Agroecologists study a variety of agroecosystems. The field of agroecology is not associated with any one particular method of farming, whether it be organic, integrated, or conventional, intensive or extensive. However, it has much more in common with organic and integrated farming.

Cappawhite

Cappawhite is maybe seen as spelled Cappaghwhite (Irish: An Cheapach or Ceapach na bhFaoiteach, meaning "White's tillage plot") is a village in County Tipperary, Ireland and is located on the R505 regional road from Cashel to County Limerick. Close major towns near the village include Tipperary Town which is 12 kilometres south of the village and Cashel which is 24 kilometres east of the village.

Ceres (mythology)

In ancient Roman religion, Ceres ( SEER-eez, Latin: [ˈkɛreːs]) was a goddess of agriculture, grain crops, fertility and motherly relationships. She was originally the central deity in Rome's so-called plebeian or Aventine Triad, then was paired with her daughter Proserpina in what Romans described as "the Greek rites of Ceres". Her seven-day April festival of Cerealia included the popular Ludi Ceriales (Ceres' games). She was also honoured in the May lustratio of the fields at the Ambarvalia festival, at harvest-time, and during Roman marriages and funeral rites.

Ceres is the only one of Rome's many agricultural deities to be listed among the Dii Consentes, Rome's equivalent to the Twelve Olympians of Greek mythology. The Romans saw her as the counterpart of the Greek goddess Demeter, whose mythology was reinterpreted for Ceres in Roman art and literature.

Contour plowing

Contour bunding or contour farming or Contour ploughing is the farming practice of plowing and/or planting across a slope following its elevation contour lines. These contour lines create a water break which reduces the formation of rills and gullies during times of heavy water run-off; which is a major cause of soil erosion. The water break also allows more time for the water to settle into the soil. In contour plowing, the ruts made by the plow run perpendicular rather than parallel to the slopes, generally resulting in furrows that curve around the land and are level. This method is also known for preventing tillage erosion. Tillage erosion is the soil movement and erosion by tilling a given plot of land. A similar practice is contour bunding where stones are placed around the contours of slopes.Contour ploughing helps to reduce soil erosion.

Soil erosion prevention practices such as this can drastically decrease negative effects associated with soil erosion such as reduced crop productivity, worsened water quality, lower effective reservoir water levels, flooding, and habitat destruction. Contour farming is considered an active form of sustainable agriculture.

Crop rotation

Crop rotation is the practice of growing a series of dissimilar or different types of crops in the same area in sequenced seasons. It is done so that the soil of farms is not used for only one set of nutrients.

It helps in reducing soil erosion and increases soil fertility and crop yield.

Growing the same crop in the same place for many years in a row (monocropping) gradually depletes the soil of certain nutrients. With rotation, a crop that leeches the soil of one kind of nutrient is followed during the next growing season by a dissimilar crop that returns that nutrient to the soil or draws a different ratio of nutrients. In addition, crop rotation mitigates the buildup of pathogens and pests that often occurs when one species is continuously cropped, and can also improve soil structure and fertility by increasing biomass from varied root structures.

Crop cycle is used in both conventional and organic farming systems.

Cultivation

Cultivation may refer to:

The state of having or expressing a good education (bildung), refinement, culture, or high culture

Gardening

Agriculture, the cultivation and breeding of animals, plants and fungi

Fungiculture, the process of producing food, medicine, and other products by the cultivation of mushrooms and other fungi

Horticulture, the cultivation of plants

Tillage, the cultivation of soil

Animal husbandry, the cultivation of livestock

Microbiological culture, a method of multiplying microbial organisms

Cultivation, a video game by Jason Rohrer

Cultivation theory, George Gerbner's model of media effects

Cultivation, a 2006 album by Gram Rabbit

Cultivate (store)

Cultivator

A cultivator is any of several types of farm implement 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. Another sense refers to machines that use rotary motion of disks or teeth to accomplish a similar result. The rotary tiller is a principal example.

Cultivators stir and pulverize the soil, either before planting (to aerate the soil and prepare a smooth, loose seedbed) or after the crop has begun growing (to kill weeds—controlled disturbance of the topsoil close to the crop plants kills the surrounding weeds by uprooting them, burying their leaves to disrupt their photosynthesis, or a combination of both). Unlike a harrow, which disturbs the entire surface of the soil, cultivators are designed to disturb the soil in careful patterns, sparing the crop plants but disrupting the weeds.

Cultivators of the toothed type are often similar in form to chisel plows, but their goals are different. Cultivator teeth work near the surface, usually for weed control, whereas chisel plow shanks work deep beneath the surface, breaking up hardpan. Consequently, cultivating also takes much less power per shank than does chisel plowing.

Small toothed cultivators pushed or pulled by a single person are used as garden tools for small-scale gardening, such as for the household's own use or for small market gardens. Similarly sized rotary tillers combine the functions of harrow and cultivator into one multipurpose machine.

Cultivators are usually either self-propelled or drawn as an attachment behind either a two-wheel tractor or four-wheel tractor. For two-wheel tractors they are usually rigidly fixed and powered via couplings to the tractors' transmission. For four-wheel tractors they are usually attached by means of a three-point hitch and driven by a power take-off (PTO). Drawbar hookup is also still commonly used worldwide. Draft-animal power is sometimes still used today, being somewhat common in developing nations although rare in more industrialized economies.

Daikon

Daikon (大根, literally 'big root'), Raphanus sativus L. var. longipinnatus Bailey, also known by many other names depending on context, is a mild-flavored winter radish usually characterized by fast-growing leaves and a long, white, napiform root. Originally native to Southeast or continental East Asia, daikon is harvested and consumed throughout the region, as well as in South Asia, and is now available internationally.

Drumbegger

Drumbegger (possibly from Irish Druim Beagair, meaning 'ridge of the little tillage') is a townland situated in County Fermanagh, Fermanagh and Omagh district, Northern Ireland. It is part of the civil parish of Boho in the old barony of Magheraboy and contains the sub-townland known as Oubarraghan.This area was designated an Area of Special Scientific Interest (ASSI 322, 17 August 2009) as a consequence of species-rich wet grassland.

Environmental impact of agriculture

The environmental impact of agriculture is the effect that different farming practices have on the ecosystems around them, and how those effects can be traced back to those practices. The environmental impact of agriculture varies based on the wide variety of agricultural practices employed around the world. Ultimately, the environmental impact depends on the production practices of the system used by farmers. The connection between emissions into the environment and the farming system is indirect, as it also depends on other climate variables such as rainfall and temperature.

There are two types of indicators of environmental impact: "means-based", which is based on the farmer's production methods, and "effect-based", which is the impact that farming methods have on the farming system or on emissions to the environment. An example of a means-based indicator would be the quality of groundwater, that is effected by the amount of nitrogen applied to the soil. An indicator reflecting the loss of nitrate to groundwater would be effect-based. The means-based evaluation looks at farmers' practices of agriculture, and the effect-based evaluation considers the actual effects of the agricultural system. For example, the means-based analysis might look at pesticides and fertilization methods that farmers are using, and effect-based analysis would consider how much CO2 is being emitted or what the Nitrogen content of the soil is.The environmental impact of agriculture involves a variety of factors from the soil, to water, the air, animal and soil variety, people, plants, and the food itself. Some of the environmental issues that are related to agriculture are climate change, deforestation, genetic engineering, irrigation problems, pollutants, soil degradation, and waste.

Minimum tillage

Minimum tillage, also called conservation tillage, is a soil conservation system like Strip-till with the goal of minimum soil manipulation necessary for a successful crop production. It is a tillage method that does not turn the soil over. It is contrary to intensive tillage, which changes the soil structure using ploughs.

In it primary tillage is completely avoided and only secondary tillage is practiced to a small extend.

No-till farming

No-till farming (also called zero tillage or direct drilling) is a way of growing crops or pasture from year to year without disturbing the soil through tillage. No-till is an agricultural technique that increases the amount of water that infiltrates into the soil, the soil's retention of organic matter and its cycling of nutrients. In many agricultural regions, it can reduce or eliminate soil erosion. It increases the amount and variety of life in and on the soil, including disease-causing organisms and disease organisms. The most powerful benefit of no-tillage is improvement in soil biological fertility, making soils more resilient. Farm operations are made much more efficient, particularly improved time of sowing and better trafficability of farm operations.

Tillage remains relevant in agriculture today, but the success of no-till methods in many contexts keeps farmers aware that multiple options exist. In some cases low-till methods combine aspects of till and no-till methods. For example, some approaches may use a limited amount of shallow disc harrowing but no plowing.

Philomelus

Philomelus (Greek: Φιλόμηλος, romanized: Philómēlos) or Philomenus was a minor Greek demi-god, patron of Husbandry, Tillage/Ploughing and Agriculture, the son of Demeter and Iasion, and the brother of Plutus. Plutus was very wealthy, but would share none of his riches to his brother. Out of necessity, Philomenus bought two oxen, invented the wagon or plough, and supported himself by ploughing his fields and cultivating crops. His mother, admiring him for this, put him in the heavens as the constellation Boötes, his wagon or plough being the constellation Ursa Major.

Philomelus's son Parias gave his name to the Parians and the city of Parion (a town in Mysia on the Hellespont).

Soil compaction (agriculture)

Soil compaction, also known as soil structure degradation, is the increase of bulk density or decrease in porosity of soil due to externally or internally applied loads. Compaction can adversely affect nearly all physical, chemical and biological properties and functions of soil. Together with soil erosion, it is regarded as the "costliest and most serious environmental problem caused by conventional agriculture."In agriculture, soil compaction is a complex problem in which soil, crops, weather and machinery interact. External pressure due to the use of heavy machinery and inappropriate soil management can lead to the compaction of subsoil, creating impermeable layers within the soil that restrict water and nutrient cycles. This process can cause on-site effects such as reduced crop growth, yield and quality as well as off-site effects such as increased surface water run-off, soil erosion, greenhouse gas emissions, eutrophication, reduced groundwater recharge and a loss of biodiversity.Unlike salinization or erosion, soil compaction is principally a sub-surface problem and therefore an invisible phenomenon. Special identification methods are necessary to locate, monitor and manage the problem appropriately.

Top soil compaction is considered partly reversible and its occurrence controllable. Subsoil compaction, however, is regarded as the major problem because it can be permanent, meaning the pore functions can potentially not be restored after deterioration. Since farmers in modern intensive agriculture depend on heavy machinery and therefore cannot completely avoid compaction, soil compaction management approaches focus on mitigation. Attempts to mitigate soil compaction include biological, chemical and technical approaches. Long-term public policies can tackle the underlying reasons for soil compaction. For instance, subsidies for low-tech agriculture may decrease heavy machinery use on the field, and educational programs aiming at slowing population growth can lower the pressure on agriculture caused by population size.

Soil conservation

Soil conservation is the prevention of soil loss from erosion or prevention of reduced fertility caused by over usage, acidification, salinization or other chemical soil contamination.

Slash-and-burn and other unsustainable methods of subsistence farming are practiced in some lesser developed areas. A sequel to the deforestation is typically large scale erosion, loss of soil nutrients and sometimes total desertification. Techniques for improved soil conservation include crop rotation, cover crops, conservation tillage and planted windbreaks, affect both erosion and fertility. When plants die, they decay and become part of the soil. Code 330 defines standard methods recommended by the U.S. Natural Resources Conservation Service. Farmers have practiced soil conservation for millennia. In Europe, policies such as the Common Agricultural Policy are targeting the application of best management practices such as reduced tillage, winter cover crops, plant residues and grass margins in order to better address the soil conservation. Political and economic action is further required to solve the erosion problem. A simple governance hurdle concerns how we value the land and this can be changed by cultural adaptation.

Soil management

Soil management is the application of operations, practices, and treatments to protect soil and enhance its performance (such as soil fertility or soil mechanics). It includes soil conservation, soil amendment, and optimal soil health. In agriculture, some amount of soil management is needed both in nonorganic and organic types to prevent agricultural land from becoming poorly productive over decades. Organic farming in particular emphasizes optimal soil management, because it uses soil health as the exclusive or nearly exclusive source of its fertilization and pest control.

Strip-till

Strip-till is a conservation system that uses a minimum tillage. It combines the soil drying and warming benefits of conventional tillage with the soil-protecting advantages of no-till by disturbing only the portion of the soil that is to contain the seed row. This type of tillage is performed with special equipment and can require the farmer to make multiple trips, depending on the strip-till implement used, and field conditions. Each row that has been strip-tilled is usually about eight to ten inches wide.

Tilth

Soil tilth is its physical condition of soil, especially in relation to its suitability for planting or growing a crop. Factors that determine tilth include the formation and stability of aggregated soil particles, moisture content, degree of aeration, rate of water infiltration and drainage. Tilth can change rapidly, depending on environmental factors such as changes in moisture, tillage and soil amendments. The objective of tillage (mechanical manipulation of the soil) is to improve tilth, thereby increasing crop production; in the long term, however, conventional tillage, especially plowing, often has the opposite effect, causing the soil to break down and become compacted. Soil with good tilth has large pore spaces for air infiltration and water movement. Roots only grow where the soil tilth allows for adequate levels of soil oxygen. Such soil also holds a reasonable supply of water and nutrients.Tillage, organic matter amendments, fertilization and irrigation can each improve tilth, but when used excessively, can have the opposite effect. Crop rotation and cover crops can positively impact tilth. A combined approach can produce the greatest improvement.

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