Planting nitrate trap species mixed with autumn crops
Autumn cereals with straw are crops with low capacity to trap nitrogen in autumn. The establishment of "nitrate trap" species that are frost-sensitive and weakly competitive (buckwheat, mustard...) mixed with autumn cereals with straw allows the uptake of part of the available nitrogen without limiting the development of the autumn cereal (limited needs at this period). The companion plant will disappear during winter.
The sowing of the companion cover can be done simultaneously with that of the cash crop (seeder with separate hoppers) or precede it (broadcast sowing of the nitrate trap species followed by row sowing of the cash crop).
If the cover is established early (before early September), this technique corresponds to the establishment of an intermediate crop before the autumn cereal and the "direct" sowing of this cereal into the cover which will be destroyed after sowing by frost (rolling in December - January is always possible to facilitate this cover destruction).
Example of implementation:
Sowing of mustard at 4-5 kg/ha in association with winter wheat
Sowing of buckwheat at 15 kg/ha in association with winter soft wheat
Sowing of mustard at 8 kg/ha in September and sowing of soft wheat under cover.
Implementation period During the intercrop period
On established crop
depending on the date of establishment of the companion cover
Spatial scale of implementation Field
Application of the technique to...
All crops: Sometimes difficult to generalize
This technique has already been tested with winter oilseed rape. It seems generalizable to all autumn cereals with straw. The companion cover must meet certain criteria (frost-sensitive, moderate competitiveness if established simultaneously with the cereal, rapid development, ...).
All soil types: Easily generalizable
All climatic contexts: Easily generalizable
If the climate does not allow the frost of the cover, it will be destroyed, in conventional farming, by a herbicide application in "post-winter".
Regulation
2. Services provided by the technique
3. Effects on the sustainability of the cropping system
"Environmental" criteria
Effect on water quality: Increasing
N.P.: DECREASE
pesticides: DECREASE
turbidity: DECREASE
Effect on fossil resource consumption: Variable
fossil energy consumption: VARIABLE
phosphorus consumption: VARIABLE
Other: No effect (neutral)
The establishment of nitrate trap species mixed with autumn cereals with straw helps limit the amount of potentially leachable mineral nitrogen during drainage periods, thus limiting the risk of nitrate transfer to water.
The establishment of nitrate trap species mixed with autumn cereals with straw may require an additional pass if sowing is split, thus higher fuel consumption. However, nitrogen returns in spring may reduce mineral fertilizer inputs, thus reducing fossil energy consumption related to their manufacture.
The establishment of nitrate trap species mixed with autumn cereals with straw may require an additional pass if sowing is split, thus higher fuel consumption and increased greenhouse gas emissions related to it. However, nitrogen returns in spring may reduce mineral fertilizer inputs, thus greenhouse gas emissions related to their manufacture.
"Agronomic" criteria
Productivity: No knowledge on impact
The establishment of nitrate trap species in association with autumn cereals with straw may have a competitive effect on the cash crop.
Soil fertility: Increasing
Improvement of soil structure and possible limitation of crusting (physical fertility); favorable to soil life (higher root density, biological fertility); remobilization of elements (chemical fertility), …
Water stress: Variable
In "dry" years, the presence of a cover may increase competition for water and reduce water available for the autumn cereal
Functional Biodiversity: Increasing
Intra-field biodiversity is increased.
Other agronomic criteria: Decreasing
Control of autumn bio-aggressors (aphids, weeds): Decrease
The companion plant helps reduce the presence of weeds by increasing competitiveness. As with "associated oilseed rape", companion plants may lead to a decrease in "insects" pressure in autumn, even some diseases of cereals if they have "bio-fumigation" properties (see intermediate crop). These effects of companion plants still need to be specified.
"Economic" criteria
Operational costs: Variable
The establishment of nitrate trap species in association with autumn cereals with straw involves additional costs for seed purchase. However, nitrogen returns in spring, reduced use of herbicides or insecticides may "offset" the cost incurred by the cover.
Mechanization costs: Variable
The establishment of nitrate trap species mixed with autumn cereals with straw may require an additional pass if sowing is split, thus increasing mechanization costs.
Margin: Variable
Current knowledge does not allow to conclude on the impact of this technique on the margin of the crop or rotation. The balance will depend on the impact of the cover on bio-aggressors, nitrogen and cereal yield, and the management costs of the cover (seeds, mechanization).
Other economic criteria: Variable
Fuel consumption: variable
The establishment of nitrate trap species mixed with autumn cereals with straw may require an additional pass if sowing is split, thus higher fuel consumption.
"Social" criteria
Working time: Variable
The establishment of nitrate trap species mixed with autumn cereals with straw may require an additional pass if sowing is split.
Peak period: Variable
The establishment of nitrate trap species mixed with autumn cereals with straw may require an additional pass if sowing is split.
Observation time: No effect (neutral)
Observation time is identical to a "conventional management".
4. Favored or disadvantaged organisms
Favored Bioagressors
| Organism | Impact of the technique | Type | Details |
|---|
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. To learn more
6. Keywords
Bioagressor control method: Cultural control
Mode of action: Mitigation
Type of strategy regarding pesticide use: Redesign
Annexes
La version initiale de cet article a été rédigée par Julien Halska, Sébastien Minette et Rémy Ballot.
| Laurence Guichard | INRA | laurence.guichard(at)grignon.inra.fr | Grignon (78) |
|---|---|---|---|
| Julien Halska | INRA | julien.halska(at)grignon.inra.fr | Epoisses (21) |
| Sébastien Minette | CRA Poitou-Charentes | sebastien.minette(at)poitou-charentes.chambagri.fr | Lusignan (86) |
| Rémy Ballot | INRA | remy.ballot(at)grignon.inra.fr | Grignon (78) |
