No-till farming

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No-till farming, also known as conservation tillage or zero tillage is a way of growing crops from year to year without disturbing the soil through tillage. Once called chemical farming, the reference was subdued in order to promote the idea of no-till being more natural. It is becoming more common as researchers study its effects and farmers uncover its economic benefits.

Contents

[edit] Process

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, arthropods, and earthworms; and soil erosion where topsoil is blown or washed away. No-till farming thus avoids these unfavorable effects by reducing or excluding the use of conventional tillage.

[edit] Effects on Soil

In no-till farming the soil is left intact and crop residues are left in the fields. Variations of the conservation tillage method involve some working of the soil with attention paid to keeping soil compaction and carbon loss at a minimum. These variations include reduced tillage, aka strip-tillage, in which small strips may be plowed to allow space for planting seeds. As defined by the USDA-Natural Resources Conservation Service strip-tillage should till no more than 1/3 of the field area. Strip-tillage is primarily used in areas where the soil profile contains a natural hard pan that creates a barrier preventing plant roots from moving deeper into the profile to access water and nutrients. Strip-tillage also creates a more suitable seed bed for crops where the harvestable portion is produced below the surface, such as peanuts. Other terms, such as incomplete tillage and minimal tillage may be used.

[edit] Pros and Cons

There are benefits and drawbacks to no-till and reduced tillage. The benefit currently receiving much scientific attention is the potential for carbon sequestration in the soil of crop fields. When soil is tilled with machinery, carbon is released from the soil into the atmosphere. This, in addition to the emissions from the farm equipment itself, increases the carbon dioxide content of the atmosphere. Carbon sequestration, in soil or elsewhere, is a proposed method of reducing these greenhouse gases. Cropland soil is an ideal carbon sink, since in most areas it has been depleted of its necessary carbon content. Traditional farming practices that rely on tillage have removed carbon from the soil ecosystem. Removal of crop residues also deprives a field of a good source of carbon. By reducing tillage, leaving crop residues to decompose where they lie, and growing winter cover crops such as grains or alfalfa, a farmer can slow carbon loss from a field while doing a small part to transfer carbon from the atmosphere to the soil.

[edit] Further Benefits

Other benefits of no-till include increasing soil quality (soil function), protecting the soil from erosion, evaporation of water, and structural breakdown. 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. A reduction in tillage passes helps prevent the soil aggregates from being crushed and/or compacted. Less tillage of the soil reduces labor and related fuel and machinery costs. Less soil plowing means less airborne dust, which is a serious pollutant in some agricultural areas. No-till fields often have more beneficial insects and annelids, a higher microbial content, and a greater amount of soil organic material. As sustainable agriculture becomes more socially 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.

[edit] Disadvantages

[edit] Yield

Yields are often immediately impacted negatively by inexperienced no-till farmers. A combination of technique, equipment, pesticides, crop rotation, fertilization, and irrigation has to be found which is optimal for the particular native conditions. However, dropping the need to till, fertilize excessively, and organize the soil into rows and drainage ditches is often cited as increasing profit by reducing costs and labor, even with an initial diminished yield and the other headaches of no-till farming.

Certain crops, like corn, do not tolerate the increased competition in early life well, and are not suitable for complete no-till agriculture. These types of plants are currently grown most successfully in a hybrid fashion by cultivating 7-inch-wide strips of fertilized bare soil spaced out with no-till mowed areas. This combines most of the environmental and labor benefits of no-till agriculture with very close to conventional corn cultivation.


With precision fertilizer and seed placement yields are never compromised.

[edit] Equipment

The primary disadvantage of no-till farming is the need for specialized seeding equipment designed to plant seeds into undisturbed soil and crop residues. Often, the combination of machinery has to be custom-tailored to the condition of the native soil. However, today many types of no-till seeding equipment are readily available.

[edit] Chemicals

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 mentally associated with increased chemical use in comparison to traditional tillage based methods of crop production.

In reality, attacking hardy weeds individually while mowing sporadically in between crops is a suitable substitute for that type of practice in most cases, and mixed with certain elements of a conventional herbicide regime can often serve to reduce herbicide load as well as soil fatigue from herbicide toxicity since it's directly applied, instead of mixed throughout the soil. Likewise, fertilizer use is drastically reduced as it is directly applied to the seed hole, usually in liquid form.

Crop rotation is also more important in no-till farming, as soil conditions change, and some no-till farmers utilize a wide variety of crop cycles to exploit their particular soil condition at the time and their weed situation at the time for maximum yields.

[edit] Erosion

Long-term erosion is sometimes considered a problem - while much less soil is displaced, drainage gulleys that do form get deeper every year instead of disappearing. This may necessitate either sod drainways or permanent drainways in extreme circumstances. Because there is often a slight increase in soil bulk density associated with no-till farming 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.

[edit] 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 excessive 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.

[edit] See also

[edit] External links

[edit] Further reading

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

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