Promoting Regrowth After Harvest
1. Presentation
Characterization of the technique
Description of the technique:
Promote the development and growth of regrowth to trap available nitrogen before the start of leaching and limit the amount of nitrate leached in autumn and winter. Well "developed" and fairly homogeneous regrowth has an effect comparable to cover crops sown for this purpose (mustard, oat).
Example of implementation:
In the case of a succession "soft wheat => winter barley", the combine harvester must be equipped with a chaff spreader to ensure a homogeneous distribution of seeds. Stubble cultivation followed by rolling after wheat harvest and coinciding with the return of precipitation promotes the emergence of regrowth.
Conversely, in the case of a succession "oilseed rape => soft wheat", better results are obtained without stubble cultivation, as losses by shedding before harvest allow a sufficiently homogeneous distribution of regrowth. Moreover, in the case of oilseed rape, a two-month delay without destroying regrowth is necessary to trap 50 units of nitrogen. This delay can be difficult to respect, especially in northern France (later oilseed rape harvest and earlier sowing of the following wheat). It is therefore preferable not to delay the growth and development of regrowth by stubble cultivation, which risks destroying regrowth from seeds fallen before harvest (unless the presence of weeds requires stubble cultivation).
In both cases (regrowth of cereal straw or oilseed rape before winter crop), regrowth must be destroyed at the end of September to allow sowing of the following crop (wheat or barley) in October.
Implementation period On established crop
Spatial scale of implementation Plot
Application of the technique to...
All crops: Sometimes difficult to generalize
The technique can be applied to all crops harvested in early summer but is all the more effective when the amount of seeds returned before or at harvest is sufficient and distributed over the entire surface and not only on the windrows.
All soil types: Easily generalizable
All climatic contexts: Sometimes difficult to generalize
The success of the technique depends on sufficient rainfall between July and September to allow regular emergence of regrowth. However, in pedo-climatic contexts subject to strong summer water deficits (Midi-Pyrénées, Poitou-Charentes), this technique may be more appropriate than sowing a cover crop in August or September after soil work that has dried the soil.
Regulation
POSITIVE influence
The 4th action program of the nitrate directive requires, in most departments, total soil cover during winter in vulnerable zone by 2012. Oilseed rape regrowth can be considered as cover, with constraints on destruction date and minimum biomass to be justified in some departments.
Nitrate directive
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: Increasing
N.P.: DECREASE
pesticides: DECREASE
Effect on fossil resource consumption: Variable
fossil energy consumption: VARIABLE
Other: No effect (neutral)
Pollutant transfer to water (N, P, phytosanitary products ...): Decrease-
Maintaining regrowth limits the transfer of nitrogen and phosphorus to water (and possibly phytosanitary products).
Pollutant transfer to air (N, P, phytosanitary products ...): no effect (neutral)
Fossil energy consumption: variable
Maintaining regrowth after harvest has a variable impact on fossil energy consumption, depending on whether stubble cultivation is performed to homogenize distribution or not.
GHG emissions: variable
Maintaining regrowth after harvest has a variable impact on greenhouse gas emissions, depending on whether stubble cultivation is performed to homogenize distribution or not. Moreover, biomass production through regrowth growth contributes to carbon storage in the soil.
"Agronomic" criteria
Productivity: No effect (neutral)
If destruction is too late, the regrowth cover can cause depressive effects on the following crop (water and nitrogen availability). However, few crops are sensitive to autumn nitrogen deficiencies and it remains possible to adapt nitrogen fertilization to available nitrogen and crop needs.
Soil fertility: Variable
Depending on rainfall during the intercrop period, maintaining regrowth can lead to higher nitrogen availability for the following crop (wet years) or lower (dry years) compared to bare soil.
Water stress: Increasing
Maintaining regrowth can increase water deficit by 20 to 40 mm at sowing of the following crop, but with very limited impact on yield.
Functional Biodiversity: Increasing
Regrowth can provide shelter for various organisms (insects, small game…)
Other agronomic criteria: Variable
Pest pressure: Increase
Oilseed rape regrowth favors flea beetles; it can increase the risk of damage on neighboring oilseed rape plots.
"Economic" criteria
Operational costs: Decreasing
With the obligation of soil cover, maintaining regrowth reduces operational costs compared to sowing an intermediate crop (seeds).
Mechanization costs: Variable
Maintaining regrowth after harvest has a variable impact on mechanization costs, depending on whether stubble cultivation is performed to homogenize distribution or not.
With the obligation of soil cover, maintaining regrowth reduces operational and mechanization costs compared to sowing an intermediate crop (seeds, sowing technique).
Margin: Variable
The impact on the margin of the crop or rotation varies depending on the practices replaced by maintaining regrowth; increase in margin compared to establishing intermediate crops, or decrease compared to no intercrop interventions.
Other economic criteria: Variable
"Social" criteria
Working time: Variable
Maintaining regrowth after harvest has a variable impact on workload, depending on whether stubble cultivation is performed to homogenize distribution or not.
Observation time: No effect (neutral)
4. Favored or disadvantaged organisms
Favored Bioagressors
| Organism | Impact of the technique | Type | Details |
|---|---|---|---|
| flea beetle (oilseed rape) | MEDIUM | pest, predator or parasite | Oilseed rape regrowth |
| lupin anthracnose | MEDIUM | pathogen (bioagressor) | Legume regrowth |
| pea anthracnose | pathogen (bioagressor) | Legume regrowth | |
| faba bean anthracnose | MEDIUM | pathogen (bioagressor) | Legume regrowth |
| aphanomyces | MEDIUM | pathogen (bioagressor) | Legume regrowth |
| botrytis cinerea | MEDIUM | pathogen (bioagressor) | Legume regrowth |
| botrytis fabae | MEDIUM | pathogen (bioagressor) | Legume regrowth |
| slug | MEDIUM | pest, predator or parasite | |
| small flea beetle | MEDIUM | pest, predator or parasite | Oilseed rape regrowth |
| autumn aphid | MEDIUM | pest, predator or parasite | |
| pea green aphid | MEDIUM | pest, predator or parasite | |
| crucifer aphids | MEDIUM | pest, predator or parasite | |
| brown rust | MEDIUM | pathogen (bioagressor) | Cereal regrowth |
Disadvantaged bioagressors
| Organism | Impact of the technique | Type | Details |
|---|
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 further information
- Oilseed rape brochures
- -Cetiom
Technical brochure, 2011
- Sheet n°9 - Management of the intercrop
- -Coufourier N., Lecomte V., Le Goff A. (CA76), Pivain Y. (CA27), Lheriteau M., Ouvry J.F. (AREAS)
AREAS, Technical brochure
- Nitrate nitrogen leaching in cereal rotations with oilseed rape: a diagnosis based on the analysis of multi-year experimental results and modeling.
- -Reau R. Champolivier L. (CETIOM), Bouthier A. (arvalis)
OCL vol 13 n°6, p403-412, Press article, 2008
- Better management of the intercrop for agronomic and environmental benefit
- -Minette S. (CRA Poitou-Charentes)
Technical brochure, 2005
- Cereal-oilseed rape rotation: Early establishment and regrowth against leaching
- -Bouthier A. (Arvalis) Reau R. (INRA), Champolivier L. (Cetiom)
Agricultural Perspectives n°339, p12-15, Press article, 2007
- Using regrowth of cereal straw as an intermediate cover crop to trap nitrate
- -Reau R. Champolivier L. (CETIOM), Bouthier A. (arvalis)
OCL vol 13 n°6, p403-412, Technical brochure, 2008
6. Keywords
Bioagressor control method:
Mode of action:
Type of strategy regarding pesticide use:
Annexes
S'applique aux cultures suivantes
Favorise les bioagresseurs suivants
