1. Presentation

Characterization of the technique

Description of the technique:

Plowing is a deep soil work (20 to 25 cm) with inversion of the worked layer. In this respect, it constitutes an alternative to the use of glyphosate during the intercrop period (destruction of intercrop covers) and for the destruction of temporary grasslands. It is recommended to distribute plowing operations in the crop sequence by performing at least one plowing in the rotation and preferably an odd number of plowings between two crops sown at the same time. Systematic plowing, due to its effect of inverting the worked horizons, can cause difficulties in managing weeds (species with persistent seeds) or diseases (residues from the previous crop carrying pathogens). Plowing should not be too shallow (to bury the top five centimeters at more than 5 cm depth).

Example of implementation: Example taken from the sheet by Laure Gran Aymerich (see bibliography), for a sequence winter soft wheat 1 / winter soft wheat 2 / winter barley / maize: 1) if spring flora dominates, perform a plowing between two crops of choice; 2) if autumn flora dominates, perform three plowings: one before each wheat and one before or after the maize. Example taken from the Agro-Transfert Picardie leaflet for a sequence rapeseed / winter soft wheat / beet / winter soft wheat / protein pea: place one plowing between wheat and pea and another between wheat and beet.

Details on the technique:

Plowing enhances the effectiveness of early sowing and can improve that of the harrow by freeing the soil from plant debris. Permanent no-till requires increased use of other agronomic levers such as false seedbeds, late sowing of winter cereals, diversification of rotations, establishment of intermediate covers, or even direct seeding, etc.

Strong effectiveness on weeds with low seed bank persistence: grasses (blackgrass, ryegrass English, Italian ryegrass, brome, etc.) and dicotyledons (cleavers, etc.) with autumn germination.

Low effectiveness on weeds with very persistent seed banks (spring-germinating weeds such as knotweeds and amaranths).

Implementation period During the intercrop

On established crop

Spatial scale of implementation Plot

Application of the technique to...

All crops: Easily generalizable

All rotated crops: Garlic, diploid Oat, Winter oat, Spring oat, Beet, Durum wheat, Winter soft wheat, Spring soft wheat, Camelina, Carrot, Hemp, Forage cabbage, Cauliflower autumn and winter, Summer cauliflower, Winter rapeseed, Spring rapeseed, Einkorn, Emmer, Fenugreek, Winter Faba bean, Spring faba bean, Vetch, Bean, Green bean, Lettuce, Lentil, Winter Flax fiber, Spring flax fiber, Winter flaxseed, Spring flaxseed, Winter sweet white Lupin, Spring white lupin, Spring blue lupin, Alfalfa, Sweet corn, Silage maize, Grain maize, Sweet clover white or yellow, Melon, Millet, Miscanthus, Sorghum sudanense, Winter Mustard, Spring mustard, Autumn Turnip, Summer turnip, Rapeseed, Niger, Onion, Winter barley, Spring barley, Poppy (cornflower), Pea, Phacelia, Leek, Chickpea, Winter pea, Spring pea, Potato, Grassland, Radish, English ryegrass, Italian ryegrass, Rice, Sainfoin, Buckwheat, Winter Rye, Soybean, Sorghum silage, Sorghum grain, Tobacco, Industrial Tomato, Sunflower, White clover, Alexandrian clover, Micheli clover, Persian clover, Crimson clover, Purple clover, Winter Triticale, Spring triticale, Common vetch

Carrot, lettuce, soybean: plowing acts against Sclerotinia.

Potato: to bury straw from the previous crop against Streptomyces scabies (common scab).

All soil types: Generalization sometimes delicate

In clay soils, winter plowings are performed to benefit from the restructuring of the soil by climate (due to shrink-swell and humification/drying properties of clays). Plowings can cause problems in very stony or very shallow soils (tool wear) or in soils sensitive to wind or water erosion (steep slopes for example).

All climatic contexts: Easily generalizable

Attention to conditions of passage: soil must be dry enough to avoid plow pans.

Regulation

2. Services provided by the technique

3. Effects on the sustainability of the cropping system

"Environmental" criteria

Effect on air quality: Decreasing

Phytosanitary emissions: DECREASE

GHG emissions: INCREASE

Effect on water quality: Decreasing

Pesticides: DECREASE

Turbidity: INCREASE

Effect on fossil resource consumption: Increasing

Fossil energy consumption: INCREASE

Other: No effect (neutral)

Air: Reduction of phytosanitary emissions by reduced use (depending on molecule characteristics). Increase in CO2 emissions, plowing requires significant fuel consumption. Moreover, plowing promotes mineralization of organic matter, which releases carbon. N2O emissions are lower in plowed systems, but the difference decreases over time if no-till is maintained (beware of occasional plowings).

Water: Reduction of phytosanitary transfer by reduced use, especially herbicides (depending on molecule characteristics, herbicides frequently detected in water).

Fossil energy: Increase, plowing is a fuel-intensive operation.

Erosion risk: Increase, dilution of organic matter linked to plowing reduces structural stability and may increase erosion risk in sensitive soils.

Risk of pollutant transfer to surface waters: Increase, via increased erosion risk.

"Agronomic" criteria

Productivity: Increasing

Plowing generally secures yields (but attention to plowing quality).

Soil fertility: Increasing

Improvement of soil structure (restructuring in case of compaction) by plowing, but dilution of organic matter. Risk of plow pan formation (if done in wet conditions) and capillarity break. Difficult operation in too dry or too wet conditions.

Water stress: No effect (neutral)

Functional biodiversity: Decreasing

Plowing strongly disturbs soil fauna (macrofauna, earthworms, bacteria and fungi of the soil) and especially beneficials (notably ground beetles). Effect depends on plowing frequency in the rotation.

Other agronomic criteria: Variable

Intervention window for sowing: Variable

Plowing increases the duration of intervention windows for sowing in case of surface moisture. However, it seems that no-till also allows increasing sowing windows (effect of organic matter accumulation in the long term?).

Soil leveling and cleaning: Increase

Plowing allows leveling the soil and removing any plant debris, which can facilitate mechanical weed control.

Effect of false seedbeds on the crop following plowing: Decrease

On crusting soils with low bearing capacity, plowings are sometimes done just before sowing. In this case, they can reduce the effectiveness of false seedbeds possibly done earlier during the same intercrop by bringing seeds back to the surface. However, false seedbeds will have effectively reduced the overall seed bank.

"Economic" criteria

Operational costs: Increasing

Variable effect depending on balance between fuel consumption and pesticide use reduction (20 to 30 liters of fuel per hectare needed for one plowing).

Mechanization costs: Increasing

Purchase, maintenance or replacement of the plow, need for a powerful tractor.

Margin: Variable

Depends on balance between plowing costs and pesticide savings. The balance also depends on plowing frequency in the rotation. A group of Picardy farms reduced plowing share and better distributed these operations, which allowed economic and labor time gains (considering plowing plus stubble cultivation, cf. bibliography).

"Social" criteria

Working time: Increasing

Increase (about one hour of work per hectare).

A group of Picardy farms reduced plowing share and better distributed these operations, which allowed economic and labor time gains (considering plowing plus stubble cultivation, cf. bibliography).

Observation time: No knowledge on impact

4. Favored or disadvantaged organisms

Favored Bioagressors

Organism	Impact of the technique	Type	Details
clubroot of crucifers		pathogen (bioagressor)

Disadvantaged bioagressors

Organism	Impact of the technique	Type	Details
White amaranth	LOW	weeds	Weed with very persistent seed bank, spring germination.
Prostrate amaranth	LOW	weeds	Weed with very persistent seed bank, spring germination.
Lying amaranth	LOW	weeds	Weed with very persistent seed bank, spring germination.
Hybrid amaranth	LOW	weeds	Weed with very persistent seed bank, spring germination.
Reflecting amaranth	LOW	weeds	Weed with very persistent seed bank, spring germination.
Sterile brome	HIGH	weeds	Grass with low seed bank persistence, autumn germination.
botrytis cinerea		pathogen (bioagressor)
common bunt of wheat	MEDIUM	pathogen (bioagressor)	For rhynchosporium: remove infected residues before plowing as burying them increases disease severity on the following crop. Less soil disturbance favors less disease.
corn rootworm	MEDIUM	pest, predator or parasite
ergot	MEDIUM	pathogen (bioagressor)
fusariosis	MEDIUM	pathogen (bioagressor)	Fusariosis on ears
cleavers	HIGH	weeds	Dicotyledon with low seed bank persistence, autumn germination.
common scab		pathogen (bioagressor)	In potato, bury straw from previous crop against Streptomyces scabies (common scab)
cockchafer	MEDIUM	pest, predator or parasite
slug	MEDIUM	pest, predator or parasite
phoma of crucifers	MEDIUM	pathogen (bioagressor)
phoma of sunflower	MEDIUM	pathogen (bioagressor)
take-all	LOW	pathogen (bioagressor)
English ryegrass	HIGH	weeds	Grass with low seed bank persistence, autumn germination.
Italian ryegrass	HIGH	weeds	Grass with low seed bank persistence, autumn germination.
terrestrial form of amphibious knotweed	LOW	weeds	Weed with very persistent seed bank, spring germination.
bird knotweed	LOW	weeds	Weed with very persistent seed bank, spring germination.
bindweed knotweed	LOW	weeds	Weed with very persistent seed bank, spring germination.
persicaria knotweed	LOW	weeds	Weed with very persistent seed bank, spring germination.
patience-leaf knotweed	LOW	weeds	Weed with very persistent seed bank, spring germination.
rhynchosporium	MEDIUM	pathogen (bioagressor)	Remove infected residues before plowing as burying them increases disease severity on the following crop. Less soil disturbance favors less disease.
sclerotinia	MEDIUM	pathogen (bioagressor)	carrot, lettuce, soybean
scutigera	MEDIUM	pest, predator or parasite
septoria leaf blotch	MEDIUM	pathogen (bioagressor)
septoria tritici blotch	MEDIUM	pathogen (bioagressor)
septoria linicola	MEDIUM	pathogen (bioagressor)
blackgrass	HIGH	weeds	Grass with low seed bank persistence, autumn germination.

Favored Beneficials

Organism	Impact of the technique	Type	Details

Disadvantaged beneficials

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 further information

Using soil work to fight autumn grasses
-Bonin L.

ARVALIS-Plant Institute, Website, 2014

Environmental impacts of reduced tillage systems: positive effects on air quality and greenhouse effect.
-Germon J.C. (INRA); Nicolardot B. (Agrosup Dijon); Métay A. (Montpellier Supagro); Labreuche J. (Arvalis)

Agricultural Perspectives No. 347, July-August 2008, pp 40-45, Press article, 2008

Alternative weed control in vegetable farming - Preventive measures
-Ferrier J-D.

Chamber of Agriculture of Ain, Technical brochure, 2016

See page 16

6. Keywords

Bioagressor control method: Cultural control

Mode of action: Action on the initial stock

Type of strategy regarding pesticide use: Redesign

Annexes

Est complémentaire des leviers

Collect fine straw during harvest

Favorise les bioagresseurs suivants

Clubroot of crucifers

Défavorise les bioagresseurs suivants

Distribute the ploughings in the rotation

Contents