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No-till farming

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No-till farming (sometimes called zero tillage) is a way of growing crops from year to year without disturbing the soil through tillage. No-till increases the amount of water in the soil, decreases erosion, increases the amount and variety of life in and on the soil and it increases herbicide usage.

Background

Producing crops usually involves regular tilling that agitates the soil in various ways, usually with tractor-drawn implements. Tilling is used to remove weeds, mix in soil amendments like fertilizers, shape the soil into rows for crop plants and furrows for irrigation, and prepare the surface for seeding. This can lead to unfavorable effects, like soil compaction; loss of organic matter; degradation of soil aggregates; death or disruption of soil microbes including mycorrhiza, arthropods, and earthworms[1]; and soil erosion where topsoil is blown or washed away. No-till farming thus avoids these unfavorable effects by excluding the use of tillage.

There is evidence that repeated tillage destroys the soil resource base and causes adverse environmental impacts. Tillage degrades the fertility of soils, causes air and water pollution, intensifies drought stress, consumes fuel, and contributes to global warming[2][3]. Today, farmers are expected to produce food in ever greater quantities. This is becoming more difficult to do in view of declining soil quality, which can be caused by soil tillage. It is becoming well known that no-till is an effective technique to reduce the degradation of soil. With this way of farming, crop residues or other organic amenities are retained on the soil surface and sowing/fertilizing is done with minimal soil disturbance.

A major obstacle that farmers often face with change to continuous no-till is overcoming yield-limiting factors during the transition years, that is, the first years of no-till following a history of intensive conventional tillage[4] Some of the problems involve residue management and increased weed[5] and disease infestations. Farmer experience seems to indicate that many problems during the transition are temporary and become less important as the no-till system matures and equilibriates. The judicious use of crop rotations, cover crops and some soil disturbance may help reduce agronomic risks. Farmers switching to continuous no-till must often seek new knowledge and develop new skills and techniques in order to achieve success with this different way of farming[6]. Answers to these questions are urgently needed to provide strategies for promoting no-till as a way to enhance agricultural sustainability for future generations.

Advantages


Profit/Economic/Yield

Studies that try to identify whether or not it is more profitable have found that it can be[7] [8] if performed correctly.

Less tillage of the soil reduces labour[9], fuel[10], irrigation [11] and machinery costs[12]. No-till can increase yield because of higher water content and much lower erosion rates. Another benefit of no-till is that because of the higher water content, instead of leaving a field fallow it can make economic sense to plant another crop instead. This potentially earns more money, because even though each individual crop earns less the total amount earned can be larger since more crops are produced in the same amount of time[13].

As sustainable agriculture becomes more popular, monetary grants and awards are becoming readily available to farmers who practice conservation tillage. Some large energy corporations which are among the greatest generators of fossil-fuel-related pollution are willing to purchase carbon credits to encourage farmers to engage in conservation tillage[14][15]. The farmers' land essentially becomes a carbon sink for the power generators' emissions. This helps the farmer in several ways, and it helps the energy companies meet demands for reduction of pollution.

Environmental

Carbon (Air and Soil)

No-till has carbon sequestration potential through storage of soil organic matter in the soil of crop fields [16]. Tilled by machinery, the soil layers invert, air mixes in, and soil microbial activity dramatically increases over baseline levels. The result is that soil organic matter is broken down much more rapidly, and carbon is lost from the soil into the atmosphere. This, in addition to the emissions from the farm equipment itself, increases carbon dioxide levels in the atmosphere.

Cropland soils are ideal for use as a carbon sink, since it has been depleted of carbon in most areas. It is estimated that 78 billion metric tones of carbon that was trapped in the soil has been released[17] because of tillage. Conventional farming practices that rely on tillage have removed carbon from the soil ecosystem by removing crop residues such as left over corn stalks, and through the addition of chemical fertilizers which have the above mentioned effects on soil microbes.

By eliminating tillage, crop residues decompose where they lie, and growing winter cover crops field carbon loss can be slowed and eventually reversed.

Soil and Water

No-till improves soil quality (soil function), carbon, organic matter, aggregates[18], protecting the soil from erosion[19], evaporation of water[20], and structural breakdown. A reduction in tillage passes helps prevent the compaction of soil.

Crop residues left intact help both natural precipitation and irrigation water infiltrate the soil where it can be used. The crop residue left on the soil surface also limits evaporation, conserving water for plant growth. Since there is less soil compaction and no tillage-pan, soil absorbs more water and plants are able to grow their roots deeper into the soil and suck up more water.

Tilling a field reduces the amount of water, via evaporation, around 1/3 to 3/4 inches (0.85 to 1.9cm ) per pass[21]. By no-tilling, this water stays in the soil, available to the plants.

Soil Biota/Wildlife/Etc.

In no-till farming the soil is left intact and crop residue is left on the field. Therefore, soil layers, and in turn soil biota, are conserved in their natural state. No-tilled fields often have more beneficial insects and annelids[22], a higher microbial content, and a greater amount of soil organic material. Since there is no ploughing there is less airborne dust.

No-till increases the amount and variety of wildlife[23]. This is the result of the improved cover because of surface residue and because the field is disturbed less often than conventional fields.

Preserving Artifacts

Tilling regularly damages ancient structures under the soil such as long barrows. In the UK, half of the long barrows in Gloucestershire and almost all the burial mounds in Essex have been damaged. According to English Heritage modern tillage techniques have done as much damage in the last 6 decades as traditional tilling did in the 6 centuries. By using no-till methods these structures can be preserved and can be properly investigated instead of being destroyed. [24]

Disadvantages

Cost

Equipment

No-till requires specialized seeding equipment designed to plant seeds into undisturbed crop residues and soil. Purchasing new equipment (seed drills for example) is expensive and while the cost could be offset by selling off plows, etc. doing so is not usually done until the farmer decides to switch completely over (after trying it out for a few years). This results in more money being invested into equipment in the short term (until old equipment is sold off)[25].

Drainage

If a soil has poor drainage, it may need drainage tills or other devices in order to help with the removal of excess water under no-till.

Gullies

Gullies can be a problem in the long-term. While much less soil is displaced by using no-till, any drainage gulleys that do form will get deeper each year since they aren't being smoothed out by plowing [26]. This may necessitate either sod drainways, waterways, permanent drainways, etc.

Has to be Managed Differently

See management section.

Increased Chemical Use

One of the purposes of tilling is to remove weeds. No-till farming does change weed composition drastically. Faster growing weeds may no longer be a problem in the face of increased competition, but shrubs and trees may begin to grow eventually.

Some farmers attack this problem with a “burn-down” herbicide such as glyphosate[27] in lieu of tillage for seedbed preparation and because of this, no-till is often associated with increased chemical use in comparison to traditional tillage based methods of crop production.

Artifact recovery

Prior to no-till farming's rise in popularity, the annual tilling of the soil often exposed arrowheads and other artifacts. Other artifacts include bullets, medals, and buttons, coins and other metal items from destroyed houses and barns.

Management

No-till requires some different skills in order to do it successfully. If no-till isn't done correctly, yields will drop. A combination of technique, equipment, pesticides, crop rotation, fertilization, and irrigation have to be used for local conditions.

Cover Crops

Cover crops are used occasionally in no-till to help control weeds and increase nutrients in the soil (by using legumes)[28]. Farmers experimenting with organic no-till use cover crops instead of tillage for controling weeds, and are developing various methods to kill the cover crops (rollers, crimper, choppers, etc.) so that the newley planted crops can get enough light, water, nutrients, etc. [29][30]

Disease/Pathogens/Insects

With no-till, residue from the previous years crops lie on the surface of the field, cooling it and increasing the moisture. This can cause increased or decreased or variations of diseases that occur[31], but not necessarily at a higher or lower rate than conventional tillage[32].

Erosion and Gullies

No-till dramatically reduces the amount of erosion in a field. While much less soil is displaced, any gullies that do form will get deeper each year instead of being smoothed out by regular plowing. This may necessitate either sod drainways, waterways, permanent drainways, etc.[33]

Equipment

It is very important to have planting equipment that can properly penetrate through the residue, into the soil and prepare a good seedbed[34]. Switching to no-till reduces the maximum amount of power needed from farm tractors, which means that a farmer can farm under no-till with a smaller tractor than if he/she was tilling[35].

Crop Rotations

Crop rotations are commonly used in no-till situations.

Soil Temperature

Another problem that growers face is that in the spring the soil will take longer to warm and dry, which may stall planting to a less ideal future date. One reason why the soil is slower to warm is that the field absorbs less solar energy as the residue covering the soil is a much lighter color than the black soil which would be exposed in conventional tillage. This can be managed by using row cleaners on a planter[36]. Since the soil can be cooler, harvest can occur a few days latter than a conventionally tilled field. Note: A cooler soil is also a benefit because water doesn't evaporate as fast.

Yield

Yields can decrease the first few years of no-till[37]. There are several reasons this can occur. Yields will decrease because of nitrogen being immobilized in the crop residue, which can take a few months to several years to decompose, depending on the crop[citation needed]. This can be fixed by adding extra fertilizer during this period. The second reason why yields drop is because of soil aggregates[citation needed]. Tilling the soil destroys soil aggregation and it can take years for soil aggregates to rebuild. So when a field is switched to no-till, it takes the plants, microbes, worms, etc. several years to create new aggregates. Without aggregation, soil is harder making it tougher for plants to grow and tougher for water to penetrate the soil. Luckily, these yield reductions are only temporary.

Yield will be lower on poorly drained soils because of the lower evaporation rate[38]. Drainage problems should be fixed if possible before going into no-till.

Yields can also be higher, because of increased water availability. Yields will eventually be higher because of the prevention of soil loss.

Misconceptions

Need to Fluff the Soil

Because no-till farming often causes a slight increase in soil bulk density, there is a misconception that periodic tillage is necessary to “fluff” the soil back up. There are millions of acres of land that have been no-tilled for over 20 years where water infiltration, biologic activity, soil aggregate stability, and productivity have all increased well beyond nearby traditionally tilled land. No-till farming mimics the natural conditions under which most soils formed more so than any other method of farming in that the soil is left undisturbed except to place seeds in a position to germinate.

Conservation Tillage

A common misconception is that conservation tillage = no-till or vice versa. Conservation tillage is a group of practices that reduce the amount of tillage needed. No-till is technically a form of conservation tillage, but no-till isn't conservation tillage.

Strip Tillage

No-till is not strip tillage. Strip tillage tills the soil, no-till doesn't.

Potential

Research by both institutions and farmers continues into developing organic no-till farming methods that utilize the rolling/crimping of cover crops [39] and diverse crop rotations to suppress weeds, insects, and diseases. Current organic farming methods often rely on tillage to control these pests at the expense of soil quality. The marriage of no-till and organic has the potential to produce both the healthiest food and the healthiest soil at the same time.

See also

References

  1. ^ http://attra.ncat.org/new_pubs/attra-pub/soilmgmt.html
  2. ^ Brady, N.C. and R.R. Weil. 2002. Soil Organic Matter pp.353-385 in Elements of the Nature and Properties of Soils. Pearson Prentice Hall, Upper Saddle River, NJ.
  3. ^ http://www.notill.org/KnowledgeBase/Reicosky_WC01.PDF
  4. ^ Lal, Rattan "NO-TILL FARMING OFFERS A QUICK FIX TO HELP WARD OFF HOST OF GLOBAL PROBLEMS" http://researchnews.osu.edu/archive/notill.htm
  5. ^ http://www.ars.usda.gov/research/publications/publications.htm?seq_no_115=176317
  6. ^ http://www.dakotalakes.com/Publications/asa10_98.pdf
  7. ^ D.L. Beck, J.L. Miller, and M.P. Hagny "Successful No-Till on the Central and Northern Plains " http://www.dakotalakes.com/Publications/asa10_98.pdf
  8. ^ http://www.notill.org/KnowledgeBase/03_economics_derpsch.pdf
  9. ^ Time savings from no-till are the result of fewer passes over a field being needed and less time for each pass (its faster to pull a sprayer over a field than a plow through it).
  10. ^ http://ecat.sc.egov.usda.gov/Fuel.aspx
  11. ^ http://cropwatch.unl.edu/input$/notill_irrigation.htm
  12. ^ Derpsch, Rolf "Economics of No-till farming. Experiences from Latin America." http://www.notill.org/KnowledgeBase/03_economics_derpsch.pdf
  13. ^ http://www.agmanager.info/crops/prodecon/production/No-till%20handbook%20--%20Chapter%205.pdf
  14. ^ http://www.extension.umn.edu/extensionnews/2005/carboncredits07.html
  15. ^ http://nfu.org/issues/environment/carbon-credits
  16. ^ Carbon sequestration in two Brazilian Cerrado soils under no-till Bayer, C | Martin-Neto, L | Mielniczuk, J | Pavinato, A | Dieckow, J Soil and Tillage Research [Soil Tillage Res.]. Vol. 86, no. 2, p.237-245. Apr 2006.
  17. ^ http://researchnews.osu.edu/archive/notill.htm
  18. ^ http://www.extension.umn.edu/distribution/cropsystems/components/7399_02.html
  19. ^ http://www.monsanto.com/biotech-gmo/asp/topic.asp?id=ConservationTillage
  20. ^ http://cropwatch.unl.edu/input$/notill_irrigation.htm
  21. ^ http://cropwatch.unl.edu/input$/notill_irrigation.htm
  22. ^ K. Y. Chan, An overview of some tillage impacts on earthworm population abundance and diversity -- implications for functioning in soils, Soil and Tillage Research, Volume 57, Issue 4, January 2001, Pages 179-191, http://www.sciencedirect.com/science/article/B6TC6-423R93X-1/2/d2452be1f1ed377e472fb7144dc63403
  23. ^ http://www.jswconline.org/content/39/5/327.abstract
  24. ^ www.english-heritage.org.uk/upload/pdf/030725_RippingUpHistory.pdf July 2003 English Heritage - "Ripping Up History"
  25. ^ "Kansas No-till handbook" Chapter 5 http://www.agmanager.info/crops/prodecon/production/No-till%20handbook%20--%20Chapter%205.pdf
  26. ^ http://deltafarmpress.com/news/water-management-0801/
  27. ^ http://oregonstate.edu/weeds/articles/CBARC%20Spec%20Rpt%202008.pdf
  28. ^ "TIPS FOR NO-TILL PLANTING INTO COVER CROPS" Penn. State University http://agguide.agronomy.psu.edu/cm/sec10/sec104.cfm
  29. ^ http://www.rodaleinstitute.org/no-till_revolution
  30. ^ http://attra.ncat.org/attra-pub/organicmatters/conservationtillage.html
  31. ^ http://extension.missouri.edu/xplor/agguides/crops/g04080.htm
  32. ^ https://topcropmanager.annexweb.com/index.php?option=com_content&task=view&id=914&Itemid=182
  33. ^ Elton Robinson "Tilling ephemeral gullies can cost you soil" http://deltafarmpress.com/news/water-management-0801/
  34. ^ "Soybeans: No-Till and Minimum Till Guidelines" http://msucares.com/pubs/infosheets/is1129.htm
  35. ^ Casady, William W. "G1236 Farming With One Tractor" http://extension.missouri.edu/publications/DisplayPub.aspx?P=G1236
  36. ^ "Converting To Continuous No-Till" http://www.lesspub.com/cgi-bin/site.pl?332&ceNews_newsID=5873
  37. ^ Dick Tremain "26-Year-Old Farmer Builds Successful Operation with No-Till"http://www.extension.iastate.edu/ilf/pdf%20files/Nate%20Ronsiek_feature.pdf
  38. ^ http://msucares.com/pubs/infosheets/is1163.htm
  39. ^ http://www.rodaleinstitute.org/no-till_revolution

Further reading

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