On 26 February 2017, Christian Huyghe, INRA's Scientific Director for Agriculture, will participate in a meeting on conservation agriculture at the Paris International Agribusiness Show (SIMA). This report on conservation agriculture reviews the question of tillage.
For several decades now, conservation agriculture is increasingly prevalent in crop systems throughout the world, and is gaining ground in France as well.
In 2001, the Food and Agriculture Organization of the United Nations officially defined conservation agriculture as having three core principles: maximum soil coverage, elimination of tillage, and prolonged and diversified crop rotations.
In theory, these three principles must be applied simultaneously, for in the absence of tillage, maximum soil coverage and diversified crop rotations is what helps keep weeds and pests in check. Ideally, conservation agriculture leads to an agro-ecosystem in which ecological regulations minimize the need to resort to artificial means (eg inputs, soil tillage). It should be noted, however, that this implies a radical departure from traditional farming practices.
Concept or slogan?
Conservation agriculture is naturally linked to the notion of ecological intensification, and to the closely-related notion of agro-ecology, which relies heavily on the use of biological and ecological processes rather than on inputs. Conservation agriculture therefore implies a very different approach to production. As such, it can be considered a sociological phenomenon as well, invested with certain values and rallying the support of environmental activists. The absence of tillage is the defining feature of conservation agriculture, underpinned for many farmers by a rejection of a purely technical approach in favour of one that is more in synch with nature.
A wide variety of systems
Defining conservation agriculture leaves a wide margin for interpretation. In reality, its principles are often only partially applied, for different reasons, be they historic or economic: tillage is replaced by varying degrees of topsoil disturbance without permanent soil coverage or prolonged crop rotations. The result is that conservation agriculture has come to be associated with a wide variety of systems, the common denominator being the absence of tillage. These include anywhere from simplified models of large crops combining direct seeding and the use of non-selective herbicides, to truly innovative systems such as direct seeding under perennial cover (eg wheat beneath alfalfa cover, rapeseed beneath clover, etc).
Conservation agriculture is a complex idea that has generated much debate. This report shows, through several findings, that research can shed light both on its technical and sociological implications.
This report is the product of many joint interviews. Special thanks to Frédérique Angevin, Michel Bertrand, Jean Boiffin, Hubert Boizard, Hélène Brives, Yvan Capowiez, Caroline Colnenne, Stéphane de Tourdonnet, Patricia Garnier, Gilles Grandeau, Christian Huyghe, Eric Justes, Fabrice Martin, Nicolas Munier-Jolain, Sylvie Recous, Guy Richard, Anaïs Tibi, and Nicolas Urruty.
Conservation agriculture in France
In 2006, 34% of large crops in France used a no-till system, more than half of which involved large farms of more than 300 ha, or 17% of arable land (source HTV Expert Report, 2012). Nevertheless, in 2011, direct seeding represented a mere 4% of land used for growing common and durum wheat, 1% for barley and sunflower, 0.5% for rapeseed (source Agreste).