Transcript of "About the necessity of adequately defining no-tillage - a discusssion paper. Rolf Derpsch"
About the necessity of adequately defining no-tillage - a discussion paper. Derpsch R. Friedrich T. Landers JN. Rainbow R. Reicosky DC. Sá JCM. Sturny WG. Wall P. Ward RC. Weiss K. 5 th WCCA Brisbane, 26. – 29.09.2011 Corresponding Author : Rolf Derpsch, firstname.lastname@example.org
Introduction What is no-till farming? This seems to be a simple question, but 50 years after its introduction in practical farming neither the scientific community, nor teaching institutions, nor the farming industry have yet agreed on a clear definition of this crop production system.
The key principles on which no-tillage is based are the same that have been defined by FAO (2011) to characterize Conservation Agriculture and are in this case rigorously implemented . - Minimum soil disturbance - Permanent organic soil cover - Crop rotation/association
The rigorous application of these principles in the no-tillage system implies that the additions of crop residues to the system must be at least greater than the output due to oxidation processes of organic matter.
No-tillage, zero tillage and no-till are used as synonymous by the authors of this paper.
Often no-tillage is defined as a production system with minimum soil disturbance. Minimum has to be very well defined if misunderstandings are to be avoided .
Common definition of no-till Soil is left undisturbed from harvest through planting.
Not tilling the soil Crop rotation Cover crops Permanent soil cover Sustainable Agriculture (Derpsch, 2001) No-tillage is a holistic cropping system Cropping Diversity
It is very important to formulate a science based and explicit definition of the no-tillage system if consistent and comparable results are to be achieved in the research community No-tillage.
Some people in this conference believe that there is no need to discuss this theme as the term Conservation Agriculture, which is well defined, is used today instead of no-tillage by many organizations. And there is no objection to that! Conservation Agriculture is indeed the preferred term for many institutions.
Can the term Conservation Agriculture be used as synonymous to NO-TILLAGE? Is the term NO-TILLAGE then superfluous? Can we just use the term Conservation Agriculture and forget the word NO-TILLAGE? Probably not .
How about naming a research treatment in an experiment like this? Conservation Agriculture compared to Conventional Tillage and Reduced Tillage? Is that realistic?
The question is if we can use the term CA when we are taking about research treatments in scientific investigations. To make it clear, what the authors of this paper are discussing is the adequate use of the term no-tillage a) in scientific research and b) other general uses.
When talking about equipment we most likely will continue to call it no-tillage seeding machine and not Conservation Agriculture seeding machine. When taking about experiment treatments we probably want to call it no-tillage treatment and not Conservation Agriculture treatment. Anyhow, manufacturers will most probably continue to call it no-till seeding equipment!
Our problem is that there is a very broad interpretation and understanding of what no-tillage is and how it should be performed.
Although almost everyone understands that no-tillage farming is agriculture without tillage, this is not precise enough when it comes to define a system with the aim of having COMPARABLE RESEARCH RESULTS.
All too often apples are not compared to apples Apples Apples
Instead they are compared to oranges Apples Oranges
Contrasting and contradicting research results are the consequence!. For example: some researchers assert that no-tillage does not sequester carbon in the soil (e.g.John Baker, et al 2007; Max Plank Institute at Müncheberg, Germany 2007), while other authors contend that no-tillage does sequester carbon in the soil. (e.g. Lal, et al., 1998; Reicosky, 1997; Sá, et al., 2009)
All too often conflicting and contradicting no-tillage research results are solely and exclusively the result of using local jargon, different definitions, dissimilar practices or dissimilar seeding equipment by different researchers.
Can this be called No-tillage? Fact is that many people do!
Soil surface disturbance following low disturbance (double-disc opener) and high disturbance (knife/rigid shank/hoe type openers) drills, planting into wheat stubble. Low carbon and water loss. >Tillage-induced carbon and water loss (Reicosky, 2004)
(Reicosky, 2004) Carbon and water loss from low versus high disturbance drills
Another issue is soil cover. A no-tillage system where crop residues from the previous crop have been removed, burned or eaten by livestock will result in lower yields compared to no-tillage with full retention of crop residues (Wall, 1999, Sayre et al., 2006). We know that almost all advantages of the no-tillage system come from the permanent cover of the soil and retaining all residues.
Seeding systems that till and mix more than 50% of the soil surface while seeding cannot be defined as no-tillage (Linke, 1998, Sturny et al., 2007). If the whole machine width of soil is disturbed even superficially, then the system is defined as Mulch Tillage (CTIC 2011)
Also a problem is that all too often researchers are not accurate in describing in materials and methods how they have carried out their no-tillage research. The absence of an adequate definition and the inaccuracy in describing how no-tillage research was performed leads to a situation where research results can become virtually meaningless.
A problem in defining no-tillage is that it is virtually impossible to define it in one sentence. Instead the system has to be described in detail because it is a complex system with many components. The description needs to include all the important concepts that characterize the no-till system.
Description of some of the implicit concepts Seeding directly into untilled soil. Using specialized low disturbance seeding equipment. Retaining crop residues on the soil surface as mulch. Opening a narrow slot into the residue covered soil which is only wide enough to put the seeds into the soil at proper depth and cover them with soil.
Description - some of the implicit concepts Performing integrated weed control including crop rotation and aggressive cover crops or associations and applying appropriate herbicides. Aiming at a balanced nutrient & pH status in the soil trough adequate nutrient management. Applying an integrated pest management strategy. Using the concept of permanence and continuity. Addition of crop residues must be > output (oxidation) Description of some of the implicit concepts Performing integrated weed control including crop rotation and aggressive cover crops or associations and applying appropriate herbicides. Aiming at a balanced nutrient & pH status in the soil trough adequate nutrient management. Applying an integrated pest management strategy. Using the concept of permanence and continuity. Addition of crop residues must be > output (oxidation)
In summary: No-tillage or zero tillage is a conservation farming system in which the seeds are deposited into untilled soil that has retained the crop residues from the previous crop by opening a narrow slot, trench or hole only of sufficient width and depth to obtain proper seed coverage. No other soil tillage is done. All aspects of the description of the no-tillage system undertaken in our paper are considered to be implicit in this definition.
No-tillage is being adopted on more than 170 Million ha worldwide and on > 70% of arable cropland by countries like Brazil, Argentina, Paraguay, Uruguay, Australia and New Zealand (Derpsch et al., 2010). But unfortunately there is no uniform understanding about this technology.
No-tillage is an increasingly popular production system that deserves an adequate international definition to be agreed on in order to avoid conflicting and contradicting RESEARCH results in future!
No-till is the only farming technology known today that fully meets the requirements of a sustainable agricultural production even under extreme soil and climate conditions.
A reminder to researchers: The common praxis of using laconic sentences in materials and methods of publications as for instance: “The experiment included three tillage treatments, conventional, minimum and no-tillage” or not describing in detail how the experiment and no-tillage was carried out needs to come to an end and to be energetically rejected.
If a researcher insists in using his own definition of no-tillage he may of course do that, but he should describe in DETAIL in materials and methods how he has carried out the experiment!!! Unfortunately this is seldom the case
Conclusions If among researchers a consensus for an accurate description and definition of no-tillage can not be achieved soon, then we will continue to “flounder” and have conflicting and contradicting research results about no-tillage at the national and the international level.
In other words, unless the scientific community agrees on an internationally recognized definition of no-tillage conflicting and contradicting research results will continue to fill the literature on tillage / no-tillage research.
About the necessity of adequately defining no-tillage - a discussion paper. Derpsch R. Friedrich T. Landers JN. Rainbow R. Reicosky DC. Sá JCM. Sturny WG. Wall P. Ward RC. Weiss K. Corresponding Author : Rolf Derpsch, email@example.com Thank you for your attention.
Alternative definitions Swiss no-till Swiss Soil Conservation Association http://www.no-till.ch/
Definition of a no-tillage system (1) (Swiss No-till, Wolfgang Sturny) NO-TILLAGE is a cropping system, in which seed is placed directly into an untilled soil covered by plants or plant residues – without any previous soil cultivation. By means of special openers such as a disc, hoe or cross slot just a slot is opened in the soil and closed instantaneously after seed placement. No more than 50% of the soil surface is being disturbed during the direct seeding operation. Fertilizer can be placed in the soil at the same time.
The success of a continuous no-tillage system is comparable to continuous grassland with durable renouncement of soil movement, permanent soil cover, reduced mechanical soil stress as well as enhanced water conservation, nitrogen and energy efficiency. Definition of a no-tillage system (2) (Swiss No-till, Wolfgang Sturny)
Alternative definitions University of Nebraska http://cropwatch.unl.edu/web/tillage/notillman
No-till uses a systems approach to crop production where crops are grown with minimal soil disturbance and the soil is kept covered with crop residue to conserve soil and water. Continuous no-till and crop rotation, intensity, and diversity are keys to making no-till successful, building the soil system while minimizing potential problems. Too often, producers think that no-till is planting a crop one year without doing tillage. No, it’s continuously planting crops, every year, without tillage to get the full benefits of no-till. Residue management, crop rotation, nutrient management, integrated pest management, equipment and its proper operation, and many other cropping practices must be part of the systems approach. When no-till is properly managed, the soil structure and its biological life will improve; runoff, erosion, fuel, and labor will decrease; and infiltration, productivity, and profitability will increase. Without the systems approach, planting a crop without tillage will have problems and the producer will likely fail, blaming no-till, not the lack of management.
Description and definition of the no-tillage concept If needed to be read during the discussion 3 PPT pages, 582 Words 5 – 6 minutes reading time
Description and definition of the no-tillage concept No-tillage or zero tillage is a conservation farming system in which the seeds are placed at proper depth directly into untilled soil that has retained the previous crop or cover crop residues. It is also referred to as no-till. It is considered to be the important element in Conservation Agriculture. Special no-till seeding equipment with discs (low disturbance) or narrow tines/coulters (higher disturbance) open a narrow slot into the residue-covered soil which is only wide enough to put the seeds into the soil at proper depth and cover them with soil. The aim is to move as little soil as possible in order to preserve the surface residues and to reduce potential weed seeds from reaching the soil surface to germinate. No other soil tillage operation is done. The residues from the previous crops will remain largely undisturbed at the soil surface as mulch. Seeding systems that till and mix more than 50% of the soil surface while seeding cannot be defined as no-tillage (Linke, 1998, Sturny et al., 2007). If the whole machine width of soil is disturbed even superficially, then according to CTIC (2011), the system is defined as mulch tillage.
A successful no-tillage system has to have adequate weed control. Weed control in no-tillage is performed through the adoption of appropriate crop rotations including the use of adapted, aggressive species of cover crops or crop associations, mechanical non soil engaging tools like the knife roller and also by applying appropriate herbicides. Adequate nutrient management, including replacement of nutrients exported by crops that are in short supply in the soil and integrated pest management are parts of the system. Some of the environmentally-relevant effects of no-tillage, such as erosion control, improvement of water quality, increased water infiltration (leading also to reduced flood hazard and greater dry season flows), climate related consequences (through carbon sequestration in the soil and lower emissions of other GHGs), will become important only after several years of continuous, uninterrupted practice, generating substantial off-farm benefits for society (Landers et al., 2001). Returning enough plant biomass to the system year by year is a condition for all these environmental benefits to become effective.
The success of no-tillage as a conservation production system, embraced by Conservation Agriculture, is based on its continuous, permanent usage, similar to a permanent pasture (Sturny et al., 2007) and on direct biological diversification through crop rotation and cover crops associated with non disturbance of soil. Indirect diversification also occurs especially in the soil micro- and meso-biota, but also in the surface fauna, such as birds and mammals. The system mimics nature where soil loosening is performed by roots of plants and soil fauna as well as by diversified biological activity. Special requirements of the system must be satisfied to avoid failures and the necessary steps towards a successful transition to no-till need to be followed (Duiker and Myres, 2006, Derpsch, 2008). The fact that the soil is not tilled and remains permanently covered with crop residues leads to reduced soil erosion, to soil sequestration of atmospheric carbon, to increased biological activity in the soil, to better conservation of water, to better efficiency of applied nutrients and increased nutrient availability from biological activity, to improved energy efficiency (Sturny et al., 2007) and to higher economic returns through time (Derpsch et al., 2010). Moreover, no-till is the only farming system known today that fully meets the requirements of a sustainable agricultural production even under extreme soil and climate conditions.
No-tillage is the specific technology that makes Conservation Agriculture possible!
A minimum of items to be recorded and to be mentioned in materials and methods when doing tillage / no-tillage research are: Percentage of soil surface covered with residues after seeding. Percentage of the soil surface that has been disturbed while seeding Crop sequences and/or rotations that have been used Herbicides and rates that have been used for weed control Brand name and model of no-tillage seeding equipment used Configuration of the furrow opener and closing devices of the seeder Additional N applications for no-tillage in the initial phase Counting of number of plants germinated per m 2 in each treatment Weed development and weed control in each treatment Pest and diseases development and control.