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Vue d'ensemble de parcelles de différentes variétés de céréales : catalogue variétal des blés tendres d'hiver et des orges. La Minière (Yvelines).. © INRA, FOUCHARD Marc

Innovative Agricultural Systems: System Experiments

Grignon: new environmental objectives

Reducing fossil fuel use and greenhouse gas (GHG) emissions have become new environmental goals. Researchers now have the methodological tools to integrate these concerns into crop and livestock systems. While examples here are drawn from the system experiment at Grignon, in the Parisian Basin, the issues are of worldwide importance.

Since 2008, INRA’s System Under Constraints system experiment evaluates three systems of field crops, each one subject to a major constraint, be it to forgo pesticide use, to halve fossil fuel consumption, or to halve GHG emissions.

Biological factors such as soil microflora and earthworm, ground beetle, and weed populations will be used to measure the effects of the systems on their environment.. © Caroline Cohenne, Caroline Cohenne
Biological factors such as soil microflora and earthworm, ground beetle, and weed populations will be used to measure the effects of the systems on their environment. © Caroline Cohenne, Caroline Cohenne

Ambitious yet achievable objectives

Initial research findings show that constraints and environmental objectives have been satisfactorily met and that yields are largely in line with projections. The system halving GHG emissions produced the same yields as the control system. Yields from the pesticide-free system, although certainly lower than the control system, were 10 to 20% higher than other organic farming in the region. The system halving fossil fuel use produced yields that were on average 20% less than the control system. The limit imposed on fossil fuel use reduced the amount of nitrogen fertilisers that could be applied, which directly impacts yields.

Over the long term, biological factors such as soil microflora and earthworm, ground beetle, and weed populations will be used to measure the effects of the systems on their environment. More complete results can be expected in 2020 following two full rotation cycles.

“We set the bar quite high” says Thierry Doré from the Agronomy Joint Research Unit. “But the idea was really to push limits. Although complete findings are yet to come, we have demonstrated that these ambitious objectives are attainable and that they are attainable for typical Parisian Basin crop systems with acceptable productivity levels, even though productivity was never our priority.”

System Rotations Key drivers Yields**(t/ha)
Control system (1)

5 years

Winter horsebean – soft winter wheat – winter rape – soft winter wheat – mustard – spring barley

  • Resistant varieties
  • Sowing date and desity
  • Legumes
  • One ploughing

Wheat: 7.9

Rape: 3.1

Spring barley: 6.2

Horsebean: 3.4

No pesticide use

(2)

6 years

IC* – spring horsebean – soft winter wheat – IC* – hemp – triticale – IC* – maize – soft winter wheat

  • Mechanical weeding
  • Alternation of winter and spring species
  • Alfalfa for two consecutive years in cases of weeds

Wheat: 5.5

Maize: 6.5

Triticale: 5.0

Hemp: 8.0

50% less fossil fuel use

(2)

6 years

Winter horsebean – soft winter wheat – winter linseed – mix of soft winter wheat and white clover – white clover – spring oats

  • Legumes
  • Production reduced
  • Nitrogen-efficient species (oats, linseed) (Reduced nitrogen fertilizers)
  • No ploughing

Wheat: 6.3

Oats: 3.8

Linseed: 1.8

Horsebean: 3.4

50% less greenhouse gas emissions

(2)

6 years

IC* – spring horsebean – winter rape – regrowth + IC* – soft winter wheat – IC* – winter barley – IC* – maize – triticale

  • Small grain crops
  • High output
  • No ploughing (carbon sequestration)

Wheat: 7.9

Rape: 3.1

Winter barley: 7.2

Triticale: 7.1

 

IC*: Intermediate crop not decided
**: on 2009–2011 harvests.

(1)     The control system is environment-sensitive high yield; specified environmental criteria must be met, while yields must remain relatively high.

(2)     In these systems, as in the control system, adjustments are made in the choice of plant varieties and to sowing densities.

Complex design phase

There is a hierarchy of objectives. First, the major constraint must be met. Second come a number of other agroenvironmental criteria that must be satisfied. The last objective is to maximise yields using what leeway remains.

When designing the experiment, system prototypes were created by combining a variety of technical drivers used by agricultural professionals and researchers (see table). Researchers then calculated a number of variables such as fossil fuel consumption and greenhouse gas emissions, along with a dozen other agroenvironmental indicators as defined by INRA’s Indigo© method. These indicators look at things such as nitrate, phosphorous, and organic material levels in the soil and the presence of pesticides in the air, water, and soil. If the prototype system does not achieve all objectives, it is adapted and re-evaluated until all objectives are met. Many design–evaluation–redesign cycles are necessary to develop a system that can then be field-tested.

 

For more information:

Agronomy Joint Research Unit, INRA/AgroParisTech, in partnership with the Grignon AgroParisTech farm