No-till farming

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 is an emergent agricultural technique which can increase the amount of water in the soil and decrease erosion. It may also increase the amount and variety of life in and on the soil but may require increased herbicide usage.

Background

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 and other organisms including mycorrhiza, arthropods, and earthworms; and soil erosion where topsoil is blown or washed away. No-till farming avoids these effects by excluding the use of tillage. 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. Continuous no-till has yield-limiting factors during the transition years, that is, the first years of no-till following a history of intensive conventional tillage. Some of the problems involve residue management and increased weed and disease infestations. The judicious use of crop rotations, cover crops and some soil disturbance may help reduce agronomic risks. No-till was developed in part by Masanobu Fukuoka.

Issues

Profit/economics/yield

Studies have found that no-till farming can be more profitable if performed correctly.

Less tillage of the soil reduces labour, fuel, irrigation and machinery costs. 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.

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. 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 no-till farming can increase organic matter.

Environmental

Carbon (air and soil)

No-till has carbon sequestration potential through storage of soil organic matter in the soil of crop fields. 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 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, protecting the soil from erosion, evaporation of water, 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. 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 previous 6 centuries. By using no-till methods these structures can be preserved and can be properly investigated instead of being destroyed.

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).

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. 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 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. However, there are many agroecological alternatives to increased chemical use, such as winter cover crops and the mulch cover they provide, solarization or flaming.

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. As with any production system, if no-till isn't done correctly, yields can 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). Farmers experimenting with organic no-till use cover crops instead of tillage for controlling 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.

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, but not necessarily at a higher or lower rate than conventional tillage.

The cardboard method

Some farmers who prefer to pursue a chemical-free management practice often rely on the use of normal, non-dyed corrugated cardboard for use on seed-beds and vegetable areas. Used correctly, cardboard placed on a specific area can A) keep important fungal hyphae and microorganisms in the soil intact B) prevent recurring weeds from popping up C) increase residual nitrogen and plant nutrients by top-composting plant residues and D) create valuable topsoil that is well suited for next years seeds or transplants. The plant residues (left over plant matter originating from cover crops, grass clippings, original plant life etc.) will rot while underneath the cardboard so long as it remains sufficiently moist. This rotting attracts worms and other beneficial microorganisms to the site of decomposition, and over a series of a few seasons (usually Spring-->Fall or Fall-->Spring) and up to a few years, will create a layer of rich topsoil. Plants can then be direct seeded into the soil come spring, or holes can be cut into the cardboard to allow for transplantation. Using this method in conjunction with other sustainable practices such as composting/vermicompost, cover crops and rotations are often considered beneficial to both land and those who take from it.

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.

Equipment

It is very important to have planting equipment that can properly penetrate through the residue, into the soil and prepare a good seedbed. 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.

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. 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.

Residue

On some crops, like continuous no-till corn, the thickness of the residue on the surface of the field can become a problem without proper preparation.

Yield

Yields can decrease the first few years of no-till. 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. This can be fixed by adding extra fertilizer during this period. The second reason why yields drop is because of soil aggregates. 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. 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

Although no-till farming often causes a slight increase in soil bulk density, periodic tillage is not necessary to “fluff” the soil back up. There are millions of acres of land that have not been 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 closely than any other method of farming, in that the soil is left undisturbed except to place seeds in a position to germinate.

Similar terms

No-till farming is not equivalent to conservation tillage or strip tillage. Conservation tillage is a group of practices that reduce the amount of tillage needed. No-till and strip tillage are both forms of conservation tillage.

Potential

Research by both institutions and farmers continues into developing organic no-till farming methods that utilize the rolling/crimping of cover crops 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

Conventional tillage

Do Nothing Farming

Masanobu Fukuoka, one of the pioneers of no-till grain cultivation

No-dig gardening

Permaculture

Soil erosion

Strip-till

References

Further reading

Wright, Sylvia. "Paydirt". UC Davis Magazine Winter 2006, pp 24–27.

Dirt: The Erosion of Civilizations, by David R. Montgomery, University of California Press (May 14, 2007). ISBN 978-0-520-24870-0.

Category:Agronomy Category:Agricultural soil science Category:Energy conservation Category:Sustainable agriculture