1. Presentation

Characterization of the technique

Description of the technique:

This involves increasing the sowing density of crops by 10 to 15% to ensure the development of a dense stand in order to limit the space available for the development of weeds. Combining with complementary techniques is strongly recommended (row spacing, competitive ability of the variety or varieties, etc.).

Implementation period On established crop

Spatial scale of implementation Plot

Application of the technique to...

All crops: Easily generalizable

All soil types: Easily generalizable

All climatic contexts: Generalization sometimes delicate

In mild climates, the risk of diseases is higher with dense sowing. It is then preferable to choose varieties tolerant / resistant to diseases, and possibly sow a mixture of several varieties (especially soft wheat).

Regulation

2. Services provided by the technique

3. Effects on the sustainability of the cropping system

"Environmental" criteria

Effect on air quality: Increasing

phytosanitary emissions: DECREASE

Effect on water quality: Increasing

pesticides: DECREASE

Effect on fossil resource consumption: Decreasing

fossil energy consumption: DECREASE

Other: No effect (neutral)

This technique contributes to reducing the use of herbicides. However, be careful not to favor diseases too much and thus not increase the use of fungicides. The use of seed treatments can degrade this criterion, due to the use of a larger quantity of seeds.

"Agronomic" criteria

Productivity: Variable

An increase in sowing density, as a component of yield, can lead to an increase in yield. However, increasing density does not systematically improve yield, as it depends on the crops sown and can for example lead to lodging or the appearance of foliar diseases.

Therefore, sowing density is reasoned according to sowing date, soil type, and sowing conditions.

Water stress: Increasing

Other agronomic criteria: Variable

Disease risk: link=|alt=red face size 10

The risk of diseases is higher for dense sowing, especially in regions with mild winters (Picardy, regions of the West).

Risk related to certain pests: link=|alt=green face size 10

Damage caused by pests causing plant losses can be limited (grey fly, seed fly, wireworms, etc.).

Sensitivity to lodging: link=|alt=red face size 10

Especially in case of sensitive variety and high availability of nitrogen. Variety mixtures can limit this risk.

"Economic" criteria

Operating costs: Increasing

Increase in seed costs and possibly fungicides, but reduction in herbicide use.

Margin: Variable

It depends on the balance between the increase in seed costs (possibly fungicides) and savings in herbicides.

"Social" criteria

Working time: No effect (neutral)

4. Organisms favored or disadvantaged

Favored Biotic stressors

Organism	Type	Details
brown rust	pathogen (biotic stressor)	Disease development can be earlier at high density.
yellow rust	pathogen (biotic stressor)	Disease development can be earlier at high density.
septoria leaf blotch	pathogen (biotic stressor)	Greater vegetative mass and humidity within the canopy.

Disadvantaged biotic stressors

Organism	Impact of the technique	Type	Details
Annual weeds	MEDIUM	weeds	Moderately effective technique if used alone (also concerns some occasional perennial weeds)
perennials	LOW	weeds	Weakly effective technique if used alone

Favored Auxiliaries

Organism	Impact of the technique	Type	Details

Disadvantaged auxiliaries

Organism	Impact of the technique	Type	Details

Favored climatic and physiological accidents

Organism	Impact of the technique	Details

Disadvantaged climatic and physiological accidents

Organism	Impact of the technique	Details

5. For more information

Sowing of soft wheat: Review dates and densities to avoid drought
-Gate P.; Gouache D.; Garcia C. (Arvalis)

Perspectives Agricoles no. 337, September 2007, pp 48-51, Press article, 2007

Link to article

Agronomic solutions limiting herbicide use
-Gran Aymerich L.

Ministry of Agriculture and Fisheries, Professional report, 2006

Link to report. Sheet no. 9 largely inspired this technical sheet.

Smothering weeds
-Pierre Mischler (Agro-Transfert)

Agro-Transfert resources and Territories, Press article, 2011