1. Presentation

Characterization of the technique

Description of the technique:

Martine Despreaux-Robelin	CA 71	mdespreaux(at)sl.chambagri.fr	St Germain du Bois (71)
Jean-Robert Moronval	LEGTA E de Chambray	jean-robert.moronval(at)educagri.fr	Gouville (27)
Pierre mulliez	CA 49	pierre.mulliez(at)maine-et-loire.chambagri.fr	Angers (49)
Estelle Meslin	INRA	estelle.meslin(at)rennes.inra.fr	Rennes (35)
Rémy Ballot	INRA	remy.ballot(at)grignon.inra.fr	Grignon (78)

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Promote water flow in hydromorphic plots by installing deep drains. Draining a plot requires a preliminary soil study and topographic survey to determine the technical implementation details (spacing of drains, collectors...) and identify any potential wetlands.

Details on the technique:

Draining one or more plots represents a significant investment. The effectiveness of the operation must therefore be evaluated beforehand.

Implementation period On established crops

Drainage of a plot is a long-lasting operation.

Spatial scale of implementation Plot

Drainage can be done at the plot scale, or even in a coordinated manner at the watershed scale.

Application of the technique to...

All crops: Sometimes difficult to generalize

On drained plots, precautions must be taken for crops with taproot systems (notably rapeseed) which may pose risks of drain clogging.

All soil types: Easily generalizable

However, drainage is only justified on soils sensitive to hydromorphy. A prior pedological study is essential.

All climatic contexts: Easily generalizable

Regulation

NEGATIVE influence

The Water Law requires declaration of drainage projects from a cumulative drained area of 20 ha since 1993 and subjects project implementation to authorization from 100 ha. These areas are reduced to 0.1 ha for declaration and 1 ha for authorization in wetland zones. Modifications in the minor bed of watercourses may also require declaration or authorization.

Water Law and wetlands

2. Services provided by the technique

3. Effects on the sustainability of the cropping system

"Environmental" criteria

Effect on air quality: Variable

GHG emissions: VARIABLE

Effect on water quality: Variable

N.P.: VARIABLE

Pesticides: DECREASE

Effect on fossil resource consumption: Variable

Fossil energy consumption: VARIABLE

Other: No effect (neutral)

Air: The drainage operation itself involves greenhouse gas emissions due to fuel consumption. But in the long term, fuel consumption and related greenhouse gas emissions can be reduced thanks to more favorable soil working conditions. Moreover, drainage limits nitrous oxide emissions by denitrification.

Water: Drainage can promote nitrogen transfer to water. The risk is particularly high in the first years following drainage, when accumulated organic matter is mineralized. Conversely, drainage would limit the transfer of phosphorus and pesticide residues to water by reducing runoff.

Flood risk: Increase

Drainage accelerates water transfer to watercourses and can thus amplify the risk of flooding following rainfall events.

Fossil energy: The drainage operation itself consumes energy, but in the long term, drainage can limit fuel consumption related to crop establishment by maintaining favorable soil working conditions.

"Agronomic" criteria

Productivity: Increasing

Drainage improves the yield potential of hydromorphic plots by maintaining favorable conditions for crop development.

Soil fertility: Increasing

Drainage of hydromorphic plots has a positive effect on soil nitrogen supply by promoting mineralization. Furthermore, it prevents the accumulation of toxic elements in the soil (ferrous, sulfurous, manganese ions…).

Water stress: Decreasing

Drainage promotes root exploration of the soil and thus better utilization of the available water reserve.

Functional Biodiversity: Variable

Drainage is unfavorable for species dependent on wet environments and anaerobic microorganisms. Conversely, it favors aerobic microorganisms.

"Economic" criteria

Operating costs: Variable

Drainage can reduce the need for fungicide protection and nitrogen fertilization. But the use of inputs and associated operating costs may increase to meet the increased yield potential.

Mechanization costs: Decreasing

Drainage can reduce fuel consumption due to better soil working conditions.

Margin: Increasing

Drainage generally improves system profitability by increasing plot potential.

Other economic criteria: Variable

Fuel consumption: Decrease

The drainage operation itself consumes fuel but can reduce fuel consumption due to better soil working conditions.

Land charges: Increase

Drainage implementation represents a significant cost: on average €1600/ha excluding preliminary studies.

"Social" criteria

Working time: No effect (neutral)

Peak period: Decreasing

Drainage of hydromorphic plots allows better spreading of work, enabling wider intervention windows.

Observation time: No effect (neutral)

4. Organisms favored or disfavored

Favored Bioagressors

Organism	Impact of the technique	Type	Details

Disfavored bioagressors

Organism	Impact of the technique	Type	Details

Favored Auxiliaries

Organism	Impact of the technique	Type	Details

Disfavored Auxiliaries

Organism	Impact of the technique	Type	Details

Favored climatic and physiological accidents

Organism	Impact of the technique	Details

Disfavored climatic and physiological accidents

Organism	Impact of the technique	Details

5. For further information

Drainage
-Trouche G.

Les mots de l'agronomie, Website, 2014

Page

La carotte, practical guide.
-Villeneuve, F.

CTIFL Edition, Book, 1992

Drainage and drained soils
-Mulliez P. (CA 49)

Anjou Cultures n°127, Press article, 2008

Diseases of lettuce. Identification, knowledge and control.
-Blancard, D.

INRA Edition, Book, 2003

Phytophthora diseases worldwide
-Erwin

The American Phytopathological Society Press ed, Book, 1996

6. Keywords

Bioagressor control method: Cultural control

Mode of action: Mitigation

Type of strategy regarding pesticide use: Redesign

Annexes

Drainage of plots

Contents