Lutte contre les dicotylédones de printemps :Intercropping Byzantine Oats with Spring Fava Beans
Mikaël and Rémy Hily implemented this practice as part of an agronomic strategy for maximum spatial and temporal coverage of plots to limit weed pressure and with a goal of total autonomy for cattle feeding.
Context
- Farmer's name: Mikaël HILY – Rémy HILY
- Farm name: GAEC HILY
- Department: Finistère (29)
- UAA: 120 ha
- FTE: 2
- Livestock: 55 dairy cows – 390,000 kg milk/year. 30 beef cows
- Notable Crops: spring fava bean
- Irrigation: None
- Soil types: clay-sandy soils on Armorican sandstone and sandy-loamy soils on schist
- Soil work: mainly ploughing
- Crop sequence crops: temporary grassland, maize forage or beet, wheat or triticale, mixed cropping
- Farm in a Drinking Water Protection Zone (Zone d'Alimentation de Captage): No
- Other context elements: Farm in the watershed of Porzay green algae
- Practice within the cropping system: It complements a long and diversified rotation and is part of a global strategy of maximum soil cover in space (crop associations) and time (minimizing periods without soil cover).
Origin of the practice and farmer's approach
The practice fully fits into an agronomic strategy of maximum spatial and temporal coverage of plots and a goal of total autonomy for cattle feeding (no purchase of nitrogen concentrates or production concentrates). The trigger was the implementation of ensiled mixed crops on the farm and the observation of the benefit of associating a legume with a grass for strong soil cover early in the cycle to limit weed pressure. For grain harvest, the farmers then associated winter or spring fava bean with oat.
The technique
Objective
- Strongly limit weed infestation at the scale of the crop and rotation.
- Reduce herbicide IFT and weed control costs at the crop scale.
- Ensure grain production with oat, in case of failure or low yield of the fava bean crop.
Description
Start date of implementation: 2015.
2 sowing techniques
- Sowing winter oat (80 kg/ha) broadcast in August then stubble cultivation, line sowing of fava bean after winter (38 seeds/m²) with combined single-seed drill + rotary harrow.
- Broadcast sowing of Byzantine oat (50 kg/ha) after ploughing after winter, sowing of fava bean.
In both cases:
- Pre-emergence weed control at half the approved dose (Challenge + Prowl 400).
- Fungicide: one treatment at half the approved dose at early flowering + possibly one treatment 3 weeks later based on observation.
- Insecticide: one treatment based on observations if the aphid risk threshold is exceeded.
For winter oat sowing in August: destruction of oat in spring with a foliar anti-grass herbicide at 1/3 or 1/2 approved dose.
Fava bean yield: 28 to 50 q/ha.
Byzantine oat yield: 8 to 12 q/ha.
Farmer's expectations
Since his installation, Rémy sought to progressively increase the farm's feed autonomy. This pursuit was continued with his son Mikaël and resulted in a diversification of crops on the farm and a set of complementary solutions to achieve this autonomy.
At the same time, Rémy and Mikaël, both passionate about agronomy and attached to their decision autonomy for crops, developed practices leading to cost reduction notably by dose modulation. This was made possible by crop monitoring and observation, optimization of treatment practices (treatment conditions, low volume…) and lengthening of the rotation.
Advantages and disadvantages
Advantages
- Suppress and slow the emergence of spring dicot weeds (common orache, goosefoot, speedwell, black nightshade…) and reduce infestation at the end of the cycle. Thus reduce the pressure of these weeds in the rotation. This effect will be enhanced with early sowing.
- Secure fava bean weed control with reduced dose.
- Ensure a yield supplement on the plot with oat in years when climatic conditions are unfavorable to fava bean.
Disadvantages
- Additional work time and seed cost for sowing Byzantine oat
- Implementation of an additional tool during fava bean sowing for sowing in black oat: tooth cultivator at the front of the tractor and combined rotary harrow single-seed drill.
- Risk of difficult weed control at reduced dose in case of poor oat seed distribution during broadcast sowing.
Implementation and success conditions
The choice of oat associated with fava bean is important. Black oat is interesting to keep the plot clean between an autumn harvest and fava bean sowing after winter. However, it can be competitive with the protein crop and at worst cause lodging. This requires an additional intervention for its chemical destruction with a foliar anti-grass herbicide whose dose will be modulated. Hence the interest of replacing black oat with Byzantine oat, which is shorter, less water-demanding, less prone to lodging and has good tolerance to rust. However, this requires positioning the crop after a late harvest such as fodder beet if one wants to avoid establishing an intercrop after cereals.
Farmer's testimony
"Growing fava bean in association also reduces or eliminates attacks by sitones early in the cycle, avoiding a specific treatment if the damage threshold is exceeded. However, it has no positive or negative effect on the development of diseases of fava bean."
"Since we use the grain directly for supplementing silage maize in dairy cow feeding, harvesting two species together does not require extra sorting work. And joint harvesting of the two species poses no problem for threshing at harvest, both for the mix of Byzantine oat and fava bean, and for fava bean alone."
Improvements and other envisaged uses
"To speed up the start of spring fava bean, we plan to apply localized phosphorus at sowing (super triple). For sowing the associated cereal at the end of summer, rye which is more covering and faster to develop early in the cycle could replace oat. However, this would require using a disc drill for maize establishment."
Farmer's advice
- It is necessary to test the technique under the pedoclimatic conditions of one's plots.
- It is important to sow as early as possible, possibly from mid-January, to limit spring weed pressure… and to limit yield losses in case of dry spring.
For further information
Starting from an already low initial value, a steady decrease in herbicide IFT at GAEC Hily with fluctuations linked to climatic conditions and crop rotations.
A total IFT stabilizing around 0.8, a 36% reduction compared to the initial total IFT.
With a diversity of crops including grassland and a long rotation, the cropping system shows strong resilience allowing it to limit IFT variations without being strongly impacted by the year's conditions.
Result indicators
| Satisfaction level
/ performance |
Farmer's comments | |
| Weed control | 
|
Reduction of dicot pressure in the rotation |
| Pest control |
|
Better control of sitones |
| Disease control | 
|
Neutral effect |
| IFT of the concerned crop(s) |
|
Secures weed control at reduced dose |
| IFT of the cropping system |
|
Reduction of herbicide IFT |
| Yield |
|
Equivalent for fava bean with Byzantine oat |
| Work time in the plot |
|
Work for sowing Byzantine oat |
| Observation time |
|
Little impacted by the association |
| Mechanization costs |
|
Slight increase with Byzantine oat |
| Semi-net margin of the system |
|
Compensation of herbicide costs – mechanical costs |
| Risk-taking |
|
Reduced competition with Byzantine oat |
Farmer satisfaction level:
Satisfied
Moderately satisfied
Not satisfied
Farmer's takeaway
"The reduction of pesticides is not spectacular with this technique and this is not the primary goal: what is more important is medium and long-term control at the rotation scale of weeds and especially spring weeds.
From this point of view, it is crucial to sow as soon as soil conditions allow from mid-January. In plots with limited useful water reserve, this also ensures good grain filling, even with limited rainfall at the end of the cycle. And in drying conditions, oat provides a yield supplement always appreciated."
DEPHY engineer's opinion
Fava bean cultivation is one of the solutions developed by GAEC Hily to achieve feed autonomy in energy and protein. Meeting needs relies on combining optimized grazing, grass ensiling, cultivation of cereals, maize, beet, alfalfa, ensiled mixed crops and protein crops.
This diversified strategy reduces risks and ensures forage system security. Thus, fava bean is grown both as winter and spring crop, allowing compensation in case of poor success of one of the crops. Finally, chemical weed control options are few for fava bean, especially for catch-up: success of pre-emergence treatment is essential, while dose reductions with these products are limited by the risk of significant loss of persistence and efficacy.
Leviers évoqués dans ce système
Matériel évoqué dans ce retour d'expérience
Bioagresseurs évoqués dans ce retour d'expérience
