False seedbed, how effective is it?

Technical articles - Structure:Centre National d'Agroécologie - Conserwa - Weeds

Field crops Field crops Mechanical weeding

Tractor performing false seedbed preparation

False seedbed preparation consists of stimulating weed emergence with superficial soil work to destroy them before the crop, thus reducing the seed bank. Its effectiveness depends on species and climatic conditions.

False seedbed preparation is used against annuals with low dormancy such as crop volunteers (oilseed rape, cereals), ryegrass, blackgrass, pansies, poppies, lamb's quarters, knotweeds, cleavers, chamomiles, …

Weed regulation options (infloweb)

Weed	Diverse rotation	False seedbed (before next crop)		Sowing date shift (except oilseed rape)	Occasional plowing
Goosegrass	Medium / irregular effectiveness	In April		Medium / irregular effectiveness	Medium / irregular effectiveness
Brome grasses	Medium / irregular effectiveness	In summer and autumn		Medium / irregular effectiveness	Good effectiveness
Wild oats	Good effectiveness	In October		Insufficient / variable effectiveness	Insufficient / variable effectiveness
Ryegrass	Insufficient / variable effectiveness	Late summer-early autumn		Medium / irregular effectiveness	Medium / irregular effectiveness
Blackgrass	Good effectiveness	Late summer-early autumn		Good effectiveness	Good effectiveness
Lamb's quarters	Medium / irregular effectiveness	In April		Insufficient / variable effectiveness
Poppy	Medium / irregular effectiveness	In autumn		Null / not relevant effectiveness	Medium / irregular effectiveness
Jimsonweed	Good effectiveness	In spring		Null / not relevant effectiveness	Insufficient / variable effectiveness
Geraniums	Good effectiveness	Late August-early September		Insufficient / variable effectiveness	Medium / irregular effectiveness
Chamomiles	Insufficient / variable effectiveness	Late summer		Null / not relevant effectiveness	Medium / irregular effectiveness
Annual mercury	Medium / irregular effectiveness	Spring		Medium / irregular effectiveness	Insufficient / variable effectiveness
Field mustard	Null / not relevant effectiveness	Before late spring crop		Insufficient / variable effectiveness	Medium / irregular effectiveness
Ivy-leaved speedwell	Good effectiveness	Insufficient / variable effectiveness		Insufficient / variable effectiveness	Medium / irregular effectiveness
Persian speedwell	Null / not relevant effectiveness	Late summer-early spring		Null / not relevant effectiveness	Medium / irregular effectiveness
				Null / not relevant effectiveness
				Insufficient / variable effectiveness
				Medium / irregular effectiveness
				Good effectiveness

Implementation

1. Identify the weeds you want to eliminate to gather information on:

• their germination depth
• germination timing
• techniques that stimulate germination

1. Soil preparation

• Work the surface (generally less than 5 cm deep but this can be deeper depending on the weeds) of a fresh, moist, and firmed soil (rolling may be relevant), as for preparing a seedbed.

The goal is to stimulate weed germination.

1. Destroy the weeds chemically or mechanically; in the latter case, care must be taken not to work the soil deeply to avoid bringing new weed seeds to the surface.
2. Sow the crop 2 - 3 weeks after the last false seedbed preparation without deep soil working.

Several false seedbeds can be done in succession, it is then recommended to leave 2 to 3 weeks between each false seedbed and always keep the same soil working depth.

Advantages

• Reduction of weed emergence potential thanks to the decrease of the seed bank in the soil.
• Possible reduction in the use of phytosanitary products.

Limitations

• The success of the technique depends on climatic conditions.
• Does not allow control of perennials.
• Requires a sufficient intercrop period.

What about weed emergence during the following crop?

False seedbed preparation certainly causes grasses to emerge and thus reduces the seed bank, but this does not guarantee a reduction in weed infestation afterwards.

This phenomenon is partly explained by the difference in magnitude between weeds emerging during the intercrop period (24 to 1600 plants/m²) and the number of seeds returned to the soil during a campaign (23,000 seeds/m²). It is easy to imagine that the number of seeds eliminated thanks to false seedbed preparation actually represents only a tiny fraction of the weed seed bank in the soil.

One solution would be to repeat several successive false seedbeds to exhaust the seed bank, especially in particularly weedy fields. However, the reduction of the seed bank is nuanced by Merfield (2015), who estimates the potential impact of a false seedbed at 0.7% of the seed bank, considering that 10% of seeds are non-dormant at any time and that only 7% of these are in the top 3 cm of soil, i.e., in germination conditions. If false seedbeds are irrigated (40 mm/week), seed bank reduction is much more effective, 40% reduction with four successive false seedbeds versus 3% without irrigation.

Cost of a false seedbed

A pass with an cultivator with independent discs costs about €25/ha (varies between €20 and €35/ha depending on the model).

Costs of cropping operations

Experimentation

False seedbed against ryegrass/blackgrass

Ryegrass and blackgrass emergence is higher after superficial work / false seedbed (here, rotary harrow at 5 cm) than after deep work (here, independent disc cultivator at 20 cm).

Weed management during intercrop: false seedbed tested - Perspectives-agricoles.com 2019

False seedbed before a spring crop

Spring false seedbed is fully justified; it allows a real reduction of weed pressure in the crop as shown in the graph below:

ECOHERBI trial

It is noted that there is no clear difference in effectiveness between the different modalities.

False seedbeds reduce weeds in the crop by a factor of 4 compared to no false seedbed.

Sources

• Arvalis. 2022. Practicing false seedbed to reduce the seed bank in fields. [26/01/2026]. https://www.arvalis.fr/infos-techniques/pratiquer-les-faux-semis-pour-diminuer-le-stock-semencier-des-parcelles
• Arvalis. 2022. Soil work: controlling weeds during intercrop. [26/01/2026]. https://www.arvalis.fr/infos-techniques/pratiquer-les-faux-semis-pour-diminuer-le-stock-semencier-des-parcelles
• Bayer. 2021. False seedbed: an effective control method before sowing. [26/01/2026]. https://www.arvalis.fr/infos-techniques/pratiquer-les-faux-semis-pour-diminuer-le-stock-semencier-des-parcelles
• Bayer. 2023. False seedbed, a real solution to control weeds. [26/01/2026]. https://www.arvalis.fr/infos-techniques/pratiquer-les-faux-semis-pour-diminuer-le-stock-semencier-des-parcelles
• Réussir. 2023. What if we took advantage of summer to “false seed”? [26/01/2026]. https://www.arvalis.fr/infos-techniques/pratiquer-les-faux-semis-pour-diminuer-le-stock-semencier-des-parcelles

La version initiale de cet article a été rédigée par Jasmin Razongles. ar:البذر الجزئي