CA-CoP CONSERVATION AGRICULTURE COMMUNITY OF PRACTICE
for sustainable production intensification
Dear Subscribers,
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URL: www.fao.org/ag/caThe recent paper on CA (primarily no-till ) showing lower yields with no till than conventional till should serve as a “wake-up call” to the CA community for improved definitions of methods used in CA research and better communication of the environmental benefits to the broader community. The paper also points to the need of more basic research to understand the interactions in this complex system. A few additional points and questions:
1. The paper did confirm and provided proof that no-till alone as CA does not work. Much of the research reported in the article provided the data, lessons and impetus to consider continuous crop residue cover and diverse crop rotations and/or cover crop mixes to provide a proper carbon balance in the CA system.
2. A primary concern is the definition of no-tillage in previous research. The definition of no-tillage has been used very loosely and inconsistently over the last 40 years. To some, no-till simply means no plow. To others, the terms of minimum tillage, mulch tillage, reduced tillage, strip tillage, rotational tillage, vertical tillage, conservation tillage, etc., etc. can be lumped into the category of no-tillage; which do not meet the criteria of “minimum soil disturbance” in CA. The definition of conservation tillage with minimum of 30% residue cover is not adequate for CA.
3. How do progressive farmers learn faster and get positive results with their type of CA? The progressive CA farmers promote both the economic and environmental benefits and will tell you that it is a truly sustainable production system. The progressive farmers see and understand the soil and environmental degradation associated with intensive tillage.
4. Why are the yields from large field, on-farm research studies as good as or better than inversion tillage agriculture on large fields, but not on small research plots?
5. What type and how much more detail do we in the scientific community need to accurately characterize CA research methods and materials to enable us to compare “apples to apples, not apples to oranges”?
6. What can we do to learn from and better understand the historical results of the last 40-50 years of research to continue the development and improvement of sustainable agriculture production systems?
Your candid thoughts with a science foundation on this subject would be appreciated.
Don
No-tillage is looked upon by many as a way to enable sustainable cropping intensification to meet future agricultural demands. Although no-tillage suggests merely the absence of tillage, in reality several components need to be applied to a conservation agriculture system to guarantee equal or higher yields and better environmental performance than with conventional tillage systems.
We contend that broad understanding is lacking of what
conservation agriculture systems research means. This has led to a situation of
conflicting research results because different technologies, methodologies, and
definitions of conservation agriculture systems have been applied. The term
no-tillage has been used despite considerable soil movement in the previous
crop, to inject fertilizer or to establish the current crop. Similarly, the
term no-tillage has been used for systems with very little or no crop mulch
cover, extended fallow periods, alternating tillage and no-tillage, or crops
grown in monoculture. By not performing no-tillage research in a systems
approach, many problems can be encountered such as reduced yields, high
erosion, low infiltration, elevated fertilizer and high pesticide use.
Rolf Derpsch
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