Using the sandwich method to manage weeds in orchards
1. Presentation
Characterization of the technique
Description of the technique:
Information initially from the Guide for designing fruit production systems that are economical in phytosanitary products (2014) / Technical sheet n°9 - For more information: see link
Principle
The sandwich method is a technique for controlling weeds present in the tree row of fruit orchards without using herbicides. This method consists of working the soil on each side of the row (minimum 40 cm, up to 1 m for wide plantings in stone fruit trees) with a simple tool while leaving the central strip of the planting row grassed over a minimum width of 20 cm. This technique is an alternative to chemical weeding of the row (with glyphosate for example).
Equipment and implementation
Implementing this lever requires usual tools adapted for localized soil work (discs, subsoiler, cultivator). The absence of a clearance system to avoid obstacles (trees, trellising) reduces the purchase and maintenance costs of the equipment and allows much higher working speeds than mechanical weeding with clearance.
The grassing of the central strip can be:
- Spontaneous and maintained by mowing with an offset tool
- Sown: manual sowing or with a seeder (at the end of the first leaf stage, in the autumn following tree planting). In this case, it is recommended to choose low-competition ground cover plant species or those interesting from an agronomic point of view (e.g., with allelopathic effect such as mouse-ear hawkweed Hieracium pilosella).
Example of implementation:
Example taken from the technical brochure "Sandwich system - Arboriculture" from FIBL (see bibliography): Installation of the sandwich system with mouse-ear hawkweed (Pilosella officinarum). Mouse-ear hawkweed is an allelopathic plant that inhibits the root growth of weeds by secreting toxins at the root level. The production of stolons allows rapid establishment and dense soil cover. It has high ecological value as it limits the use of herbicides and reduces soil work. Installation: - Soil preparation by mechanical weeding in the tree line (width 40 cm) - Planting (sowing is random): from April until the end of August if irrigated or until mid-October - Sowing density: 3 potted plants per linear meter. Single row planting is sufficient. It is also possible to replant clumps taken from older plantations.
Maintenance during establishment: - Mow 1 to 2 times depending on weed development, above the leaves of the mouse-ear hawkweed (preferably avoiding the 2 flowering periods of the hawkweed) - Remove vigorously growing grasses, thistles and other weeds likely to shade the plants.
Maintenance of the sandwich system:
- Work on the central mulch strip: In the presence of grasses and/or tall herbs, mow 1 to 2 times/year to prevent vegetation from shading the plants. No maintenance needed when the mouse-ear hawkweed is well established and covers the soil.
- Work on the worked strips on each side: Hoeing the lines to the left and right of the tree line, over a width of 40-50 cm on each side with a hoe or usual tools adapted for localized soil work (tines, goosefoot cultivators). Fertilization or compost only on the worked strips. Do not cover the mouse-ear hawkweed.
Details on the technique:
The irrigation system must be compatible (suspended or buried).
The timing of passes is based on observations of regrowth of the weed flora. During the flowering period of weeds, an additional mowing is planned if phytosanitary products are applied during this period.
This technique is well suited to controlling large-growing weeds present in the row or those likely to multiply from rhizomes (perennials such as horsetail, sorghum, bindweed).
Soil work on each side of the row can disturb voles by destroying superficial galleries and herbaceous cover, while the small grassed strip on the row can promote the presence of beneficials near the trees.
Implementation period
On established crop
Spatial scale of implementation
Plot
Application of the technique to...
All crops:
Easily generalizable
Easily generalizable
This method can be used in most mature orchards but attention must be paid to the necessary ground clearance (branch sagging under fruit weight) for equipment passage.
In cider orchards, where harvest is done on the ground, this technique is no longer possible from production start (3rd leaf) in muddy soil conditions.
All soil types:
Generalization sometimes delicate
Generalization sometimes delicate
No major constraints. However, on risky soils and during harvest period, possibility of worsening compaction by trampling.
On low fertility soils, risk of loss of vigor and yield in the first years if grassing of the row is established on young trees (risk of competition).
On sloping areas, risk of erosion on the worked strips.
All climatic contexts:
Easily generalizable
Easily generalizable
No major constraints but in non-irrigated orchards and in low rainfall areas, risk of loss of vigor and yield in the first years if grassing of the row is established on young trees (risk of water competition).
Regulation
No specific regulation for this technique.
2. Services provided by the technique
3. Effects on the sustainability of the cropping system
"Environmental" criteria
Effect on air quality:
Variable
phytosanitary emissions: DECREASE
GHG emissions: VARIABLE
Effect on water quality:
Increasing
pesticides: DECREASE
Effect on fossil resource consumption:
Variable
fossil energy consumption: VARIABLE
Other:
No effect (neutral)
Fossil energies: average energy cost
Water: No water pollution by herbicides.
"Agronomic" criteria
Productivity:
Variable
Variable
No trunk wounds or suckers near the trunk caused by soil work.
Prevents phytotoxicity problems induced by chemical herbicides on young orchards.
Possible development of perennials (example of Sorghum halepense) at the base of trees.
Vigor and yield equivalent to mechanical weeding on mature trees.
Quality of production:
Variable
Variable
No risk of herbicide residues in fruits
Soil fertility:
Increasing
Increasing
Better porosity in the grassed part compared to the worked part.
More abundant and diverse soil fauna (mesofauna, microbial).
Depending on the developed weeds, the soil is covered in winter.
However, compaction at the bottom of the worked layer if intervention on too wet soil.
Water stress:
Variable
Variable
In non-irrigated orchards, risks of water competition between trees and the central grassed strip. These risks are nevertheless reduced compared to full grassing.
Functional biodiversity:
Increasing
Increasing
Increase in floral biodiversity favorable to beneficials.
"Economic" criteria
Operational costs:
Increasing
Increasing
Need for investment to purchase specific equipment. Moreover, this technique requires more passes and working time per hectare.
Mechanization costs:
Variable
Variable
Simple soil working equipment sufficient (cost reduction compared to soil work on the row).
Investment for soil working equipment on the row is around €7,000 to €12,000 (2015 prices).
"Social" criteria
Working time:
Variable
Variable
Soil work much faster than in a system with full mechanical weeding.
Grassing establishment on the row with seeder: 2h/ha Maintenance of worked strips: 2 to 6 h/ha with 3 to 6 passes per year Maintenance of the central strip: 3 to 5 h/ha with 1 mowing per year
Mowing of flowering weeds if phytosanitary product application is essential. This also applies to the inter-row.
4. Favored or disadvantaged organisms
Favored bioagressors
Disadvantaged bioagressors
Favored beneficials
Disadvantaged beneficials
Favored climatic and physiological accidents
Disadvantaged climatic and physiological accidents
5. For more information
- Arboriculture - Sandwich System
- -Tschabold J.-L. Agridea, Technical brochure, 2012 link to brochure
- Soil management file in organic farming. Alternatives to soil work on the row and soil management in arboriculture.
- -Garcin A., Bussi C., Corroyer N., Dupont N., Ondey S.-J., Parveaud C.-E. Alter Agri, 116, 19-21., Technical brochure, 2012 link to brochure
- Integrated fruit production guide
- -Regional Chamber of Agriculture PACA, La Pugère Station Technical brochure, 2014 Objectifs Info Arbo, 30-32.
- The sandwich system
- -Chamber of Agriculture of Dordogne Technical brochure, 2010
6. Keywords
Bioagressor control method:
Cultural control
Mode of action:
Mitigation
Type of strategy regarding pesticide use:
Substitution
Annexes
S'applique aux cultures suivantes
Favorise les bioagresseurs suivants
Favorise les auxiliaires
Favorise les accidents climatiques
Défavorise les bioagresseurs suivants
