No-till is a way of growing crops without plowing. There is no soil disturbance and fields retain a good cover of living or decaying plant material throughout the year. This protects against erosion and encourages a healthy, well-structured soil for growing crops. The system is also known as zero-tillage or direct drilling
Source: Conservation Technology Information Center1
Crop remains play an essential role in maintaining or improving soil quality. Stubble and straw, which is best chopped and spread evenly over the field, guard against erosion by wind and rain, provide a habitat for wildlife and ultimately help to maintain soil organic matter levels, as do crop roots.
The impact that no-till can have on greenhouse gas emissions has been of particular interest recently. Around 20% of all greenhouse gas emissions, including most methane and nitrous oxide come from agriculture and the burning of unwanted wood from deforestation.2
No-till systems use much less fuel, which will obviously reduce emissions. However, this is a relatively small effect compared to the enhanced potential of no-till soils to sequester carbon in organic matter.
In Europe (the continent, excluding the former USSR), it has been estimated that if all cropland were to be no-tilled, there would be potential to sequester more than 150 million tonnes of carbon dioxide per annum.3 In addition, savings in diesel fuel consumption would reduce emissions of carbon dioxide by nearly 12 million tonnes every year. To put this into perspective, a family car typically emits about 4 tonnes of carbon dioxide in a year’s travel.
A breakdown of fuel use under various cultivation systems in Illinois (USA) showed that, although some gains from lower fuel use under no-till are clawed-back by more fuel used to plant and spray, no-tilling corn used 14% less fuel, and no-tilling soybeans used 49% less fuel.4
Table 3. Fuel used in growing corn and soybeans in Illinois under conventional and no-till systems.4
DescriptionAlso known as conservation tillage or zero tillage is a way of growing crops from year to year without disturbing the soil through tillage ie cultivating the soil usually with tractor-drawn implements.
Authoritative On-line References and ResourcesNo-till.com: A portal for on-line information about no-till farming. and is one of a number of crop production practices that are included in the overall concept of conservation tillage
DescriptionAny tillage and planting system that covers 30 percent or more of the soil surface with crop residue after planting to reduce soil erosion by water.
Authoritative On-line References and ResourcesPurdue University-based Conservation Technology Information Centre.. There are many benefits that result from creating and maintaining a healthy soil. The global demand for food is forecast to double by 2050 and many more people will want to eat meat. Food energy in beef, for example, requires up to eight times more cropland than an equivalent vegetarian diet. So, more than ever, the pressure is on to increase agricultural productivity and to use land wisely. Protecting the soil is essential for sustainable agricultural production. Weed control is a fundamental issue in no-till because weeds are not buried by plowing. Although various weed control practices are used in no-till, including the use of cover crops
DescriptionCover crops are primarily planted not to be harvested for food but to reduce soil erosion, control weeds and improve soil quality. They are usually plowed or tilled under before the next food crop is planted, in which cases the "cover crop" is used as a soil amendment and is synonymous with "green manure crop."
Authoritative On-line References and Resourceshttp://attra.ncat.org/attra-pub/covercrop.html ATTRA is the US National Centre for Appropriate Technology's Sustainable Agriculture Information Centre., non-selective
DescriptionA chemical product used for eliminating all types of weeds (annual and perennial grasses and broadleaved weeds).
Authoritative On-line References and Resourceshttp://www.weeds.iastate.edu/ An invaluable source of contemporary information about herbicides and weeds from Iowa State University. herbicides such as paraquat play a key role in an integrated approach to weed management. This article covers what no-till is, where it is successfully being employed, its benefits and the role of paraquat.
Conservation tillage systemsThe place of no-till amongst other tillage systems is shown in Table 1. Soil-type and condition often dictate whether no-till can be readily adopted. However, with preparation and commitment (eg control of problem weeds, adequate drainage) the system can be used successfully in a wide variety of situations. The key objectives of all conservation tillage systems are to minimize the number of passes over the field and to maximize the amount and duration of vegetative cover of the soil. Table 1. Definitions of no-till and other conservation tillage systems.
|System||Cultivations||Width||Vegetative residue cover|
|Conventional||Plowing, inverting soil, or other deep cultivations with several passes||Full||Less than 15%|
|No-till (zero tillage, direct drilling)||None||None||More than 30%|
|Reduced (minimum) tillage||Shallow cultivations with eg, discs or tines||Full||15 – 30%|
|Strip-till||Shallow soil disturbance when planting seed in rows||Strips up to 1/3 row width||More than 30%|
|Ridge-till||Similar to strip-till, but soil is left in ridges with seed planted on clean tops||Ridges up to 1/3 row width||More than 30%|
|Mulch-till||Shallow cultivations with eg, discs or tines||Full||More than 30%|
No-Till BenefitsThe many benefits of no-till are listed in Table 2 below. There are practical solutions to the few problems sometimes encountered, but skill and appreciation of the soil’s needs are vital to successful no-till. Examples of how these benefits are being achieved in no-till systems using paraquat are given in the final section of this article. Table 2. Summary of benefits and problems usually associated with no-till.
|Soil||Straw and other unharvested plant materials reduce erosion by wind and water. Organic matter accumulates to provide structure and nutrients.||Causes lower soil temperatures in spring. Strip-till (clearance of a narrow strip along crop rows during planting) provides a solution.|
|Water||Good structure allows better retention and drainage of excess.||Slow spring growth in colder soils in more marginal areas and possible yield reductions. Strip-till avoids the problem (see above).|
|Biodiversity||Habitats for flora, fauna and microorganisms on and in soil.||Occasionally disease fungi are encouraged.|
|Crop||Good environment for root growth and supply of nutrients. Better drought tolerance. Less susceptible to waterlogging.|
|Energy||Reduced use of fuel.|
|Climate||Reduced emissions from fewer farm operations. Carbon sequestration in organic matter.||Possible increase in nitrous oxide emissions if soil structure is not good and soil is waterlogged.|
|Farm economics||Lower costs in fuel and machinery, greater profitability.|
|Operation||Diesel Fuel Use (US gallons/acre)|
Adoption of no-till systemsThe first experiments on no-till systems started to be conducted in the US in the late 1940s. However, it was not until the 1960s when paraquat became available that adoption by farmers really began. A decade later, no-till started to be practised in Brazil, spreading to Argentina, Paraguay and Uruguay, in particular.5 Fastest adoption rates have been in S. America, where in some regions more than 70% of fields are permanently no-tilled. Over the past 20 years, global rates of adoption have been estimated as growing by about 6 million hectares each year.6 The main barriers to adoption are:
- Lack of knowledge
- Cultural preferences for traditional methods
- Lack of suitable machinery
- Problems with weed control
Advantages of paraquatIn no-till, weeds are not controlled by plowing, so its success relies on the use of non-selective herbicides like paraquat. Paraquat is the best choice when fast action and rainfastness are needed. Paraquat has no soil residual activity because it is deactivated by extremely strong adsorption immediately on contact with soil. New flushes of germination are, therefore, unaffected. A naturally regenerated and managed weed flora provides a vegetative cover to the soil performing a similar function to crop remains spread over the field. Paraquat also contributes to minimizing soil erosion by only destroying shoot growth. Roots are left intact and provide an anchoring effect. Many field experiments have shown how using no-till and paraquat can markedly reduce soil erosion. Some typical results are shown in Fig. 1. (Read more ...) In addition, paraquat is an essential component when rotating herbicides to avoid weed resistance.
Controlling herbicide resistant weedsOther non-selective herbicides are widely used in no-till, especially glyphosate, which although slow acting has the advantage of controlling perennial weeds
DescriptionWeeds that return year after year. Some die back in the winter but their roots remain alive and shoots reappear in spring; some don't die back and grow in size and stature the next season.
Authoritative On-line References and ResourcesThe International Weed Science Society represents individual associations around the world.. However, glyphosate resistant weeds have become a serious issue as a result of over-reliance on this herbicide, particularly in no-till soybeans, cotton and other GM field crops that are tolerant to glyphosate. To avoid or mitigate these situations it is essential to adopt an integrated approach to weed control, using a variety of agronomic methods (eg crop rotations, different sowing dates) and herbicides with different modes of action. Paraquat’s distinctive mode of action means that it is the ideal candidate to use for burndown of weeds prior to planting, whether alone or as a follow-up to glyphosate to remove any surviving weeds.
Other articles about no-till in the Paraquat Information CenterYou can read about how no-till systems have been successfully introduced around the world in other articles on this website:
Paraquat system saves soil in the PhilippinesIn the five year Sagip-Lupa project, the production of crops of corn, rice, potatoes and cabbage has been investigated on five sites using rotations common in each region. Farmers’ traditional methods of hand or mechanical weed control were compared to using paraquat and no-till. Read more …
No-till rice reduces methane emissionsMethane is one of several gases that have been shown to cause global warming. Field experiments examined the effects of different irrigation systems as well as different tillage systems and showed that no-till systems reduced methane emissions by 43% compared to conventional practice in Indonesia’s wet season. Read more …
Brazil’s no-till boom fights climate changePlans to increase the area of no-till farming feature strongly in the Brazilian Ministry of Agriculture's ABC program (Agricultura de Baixo Carbono) launched in 2010 to target reductions in greenhouse gas emissions. The goal is to slash more than 160 million tonnes from carbon dioxide equivalent emissions per annum by 2020. Read more …
Birds benefit from no-tillBirds are benefiting when fields are not plowed or only lightly cultivated in conservation tillage systems. Leaving stubble and chaff from the previous crop on the soil surface, and undisturbed soil, provides habitats for invertebrates and small wildlife. Whether bird species feed on spilled grain and weed seeds, insects or small mammals, greater numbers are often present. Read more …
Developing no-till maize in China with paraquatFarmers in southwest China are adopting no-till maize production using paraquat for weed control. A large proportion of crops in the region are grown by smallholder farmers on hillside fields. Soil erosion and loss of fertility are serious problems. The traditional methods of hand and mechanical weed control have very high labor demands and often cannot be done in a timely manner to achieve the best yields. Read more …
India: No-till riceField demonstrations in West Bengal prove that using paraquat and no-till plus ‘thrown seedling technology’ in paddy rice is enhancing productivity. Paraquat and no-till are providing a solution that minimizes the cost and number of days required for rice cultivation. Read more …
- Conservation Technology Information Center
- Venterea, R T, et al (2005). Nitrogen oxide and methane emissions under varying tillage and fertilizer management. Journal of Environmental Quality, 34, 1467-1477
- Smith, P et al (1998). Preliminary estimates of the potential for carbon mitigation in European soils through no-till farming. Global Change Biology, 4, 679-685
- University of Illinois (2006). Farmdoc Newsletter, April 19 2006
- Huggins, D R & Reganold, J P. No-till: the quiet revolution. Scientific American, July 2008, pp 70-77
- Derpsch, R, et al (2010). Current status of adoption of no-till farming in the world and some of its main benefits. International Journal of Agricultural and Biological Engineering, 3, (1), 1-26
- Horowitz, J et al. (2010). No-till farming Is a growing practice. USDA ERS Economic Information Bulletin No. (EIB-70) 28 pp, November 2010
- USDA (2006). Energy and Agriculture. 2007 Farm Bill Theme Paper