Establishing Grass and Flower Strips in Plots

Technical articles

Permanent cover crops in arable farming Management of plant covers in arable farming Carbon cycle and GHG Climate resilience Soil cover Biodiversity Weeding in arable farming Soil regeneration

Establishing grassy strips will have several positive effects on biodiversity, water infiltration, reduction of soil erosion, and pollutant diffusion.

Description of the technique

Introducing grassy strips inside plots strengthens the role they play at the edges. The cover is generally sown but can also be spontaneous. The width (and spacing if multiple strips) depends on the working width of the equipment and regulations. Authorized species are generally regulated.

To limit pollutant transfers (nitrogen, pesticides), grassy strips should be placed at the bottom of valleys or perpendicular to the slope.

Beneficial organisms move a few dozen meters outside the grassy strip, so the denser the network, the more effective the system. The ecological corridor effect is improved if the arrangement is continuous with others (other strips, hedges, forest, etc.). The composition of the cover determines the favored plant or animal species.

Management of the grassy strip must prevent it from contributing to contamination of the adjacent plot (rapid growth after sowing, adapted mowing/shredding). Fertilization and spraying are prohibited on grassy strips.

The grassy strip helps to retain sediments from diffuse erosion, increase water infiltration, and reduce pollutant transfer.

Example of implementation

Example taken from the Phytoma article (see bibliography) presented for edge-of-plot devices. The effect would likely be the same (and improved) for grassy strips within plots: for creating borders along beet fields, it has been shown that the preferential use of orchardgrass and fescues enhances the presence of beneficial organisms useful for controlling aphids harmful to beet, without providing these aphids with an attractive food source. Management elements are proposed.

Implementation period and installation

During the intercrop period or on an established crop.
At a period when grass grows rapidly (rainy periods) and when runoff risks are minimal (upstream plots covered) : from March to June or from August to September.
Sow at a high density of about 30kg/ha.
Varieties : turf-type mix for easy maintenance, perennial grasses as in meadow : tall fescue, ryegrass, Kentucky bluegrass,…

Their effectiveness and low establishment cost (250€/ha in 2016) and maintenance cost (50€/ha in 2016) require them to be permanent. However, regulations allow annual destruction, while still mentioning mandatory vegetation cover periods. It is also possible to evolve the specific composition of permanent grassy strips.

Location

Grassy strips can be implemented at the plot, farm, or territorial level.

The implementation of these arrangements depends on the targeted objective. Their effectiveness generally increases with the spatial scale, from plot to territory.

Maintenance

For maintenance, an annual or biannual mowing (above 15 cm) in late spring or early summer is sufficient, followed by removal of the biomass. It is sometimes possible to use a harrow if there is a strong accumulation of sediments.

Application of the technique to...

All crops. Not mandatory for perennial crops (and to be planned before planting in this case).

All soil types and all climatic contexts. Choose species adapted to the local context, or allow spontaneous cover to develop.

Regulations

The "nitrates" directive requires grassy strips 10 to 15m wide along hydrographic elements. In the decree of 12 September 2006 relating to the marketing and use of plant protection products, the width of untreated zones depends on the presence of grassy strips (minimum 5m). The "BCAE maintenance of topographical elements" standard requires a minimum surface of topographical elements. Directive "nitrates"; decree of 12 September 2006 relating to the marketing and use of plant protection products; "BCAE Protection and water management" standard; "BCAE Maintenance of topographical elements" standard, DGFAR/SDEA/C2003-5001-DPEI/SPM/MGA/C2003-4010 of 24 March 2003 for environmental and wildlife fallows, EEC Regulation 2078/92 for green fallow (aid for afforestation of agricultural land).

Ecological Focus Area (EFA) : 1 linear meter of grassy strip = 9m² EFA with 5 < width < 10m.

Effects on the sustainability of the cropping system

"Environmental" criteria

Effect on air quality : Pesticide emissions are reduced.

Effect on water quality : Increased thanks to the protection of watercourses via the reduction of runoff speed and volume. Pollutant transfers (N, P, pesticides,...) to waters are reduced due to reduced pesticide use (which is also prohibited on grassy strips) by promoting beneficial organisms in the plots.

Effect on soil quality : Reduced erosion, increased water infiltration.

Effect on fossil energy consumption: Slight variation in fuel consumption due to change in technical itinerary between commercial crop and grassy strip, depending on whether the cover is harvested or not, and decrease due to prohibition of fertilizer inputs on grassy strips. Overall evaluation is complex.

Effect on greenhouse gas (GHG) emissions: No knowledge on overall impact. For CO2, there is a slight reduction in fossil energy consumption, but the grassy strip allows carbon storage. No knowledge for N2O.

Effect on biodiversity : Increase in biodiversity due to habitats and resources offered and thanks to the ecological corridor effect. However, landscape floral covers can reduce biodiversity by replacing native species initially present at field edges with exotic species that have no ecological function in our environments (no consensus on this). Increasing biodiversity is not initially part of the objectives of regulations on grassy strips. There is also an increase in the diversity of landscape elements through the creation of semi-natural zones.

"Agronomic" criteria

Productivity : Loss of commercial production on the grassy area (but production of a non-commercial cover), but potential yield increases on the periphery of the cultivated area compared to yield without grassy strip (less compacted soil, complete fertilizer inputs up to the crop edge).

Soil fertility : Increase via erosion reduction, development of soil microfauna, both contributing to improved soil structure at the grassy strip and, at best, a few centimeters around.

Water stress : Water infiltrates better in the grassy strip and is better retained there, but is no longer available for the crop.

Functional biodiversity : Increase in biodiversity, particularly functional biodiversity (beneficial organisms, pollinators). However, the role is weak regarding soil microfauna and microflora, which are less mobile.

Other agronomic criteria : Flowering and/or grassy strips can also serve as reservoirs for pests (e.g., Sterile brome, couch grass, slugs). Minimum monitoring is therefore necessary, for example for thistle or ergot on weeds.

"Economic" criteria

Operational costs : Increased quantified for fuel and seeds at about 0.5 euros/linear meter/year for maintenance and about 7 euros/linear meter for establishment. Conversely, expenses are avoided because the grassy strip area does not bear commercial crops (no fertilizer, no pesticides, etc.).

Mechanization costs : Increased quantified for mechanization at about 4 euros/linear meter/year for maintenance and 8 to 13 euros/linear meter for establishment. Conversely, expenses are avoided because the grassy strip area does not bear commercial crops.

Margin : Decrease due to establishment and maintenance costs and the possible replacement of the crop by a non-productive area (commercially speaking). The cost of grassy strips sown at edges has been estimated at 350 to 850 euros/ha of grassy strip in the year of installation and 125 to 640 euros/ha in subsequent years. At the farm scale, these costs are low.

Other economic criteria :

Fuel consumption: Depends on the variation in fuel needs between an area bearing a commercial crop and the same area bearing a grassy strip (generally fewer passes, so slight decrease, except establishment year).
Productive areas : Conversion of productive areas is not always necessary as many reservoir zones can be made from existing uncultivated areas.
Need for specific equipment: Acquisition, rental, or use in CUMA of specific equipment may be necessary for shredding grassy strip vegetation.

"Social" criteria

Working time : Grassy strips require less work than commercial productions (except establishment year), but specific passes are generally needed. For some, the increase in working time is very limited and mainly related to establishment; for others, this increase is significant (training, planning of establishment and management of grassy strips, etc.).

Effect on health and image quality of the agricultural environment: Improvement of the agricultural environment's image due to environmental measures taken and landscape changes, provided the public is informed about farmers' involvement in implementing these devices.

Observation time : No effect, except additional observations in the grassy strip (beneficial organisms, weeds), except close monitoring in grassy strips to, for example, improve the initial mix.

Favored or disadvantaged organisms

Disadvantaged pests

These pests are targets of beneficial organisms favored by the technique. They are therefore indirectly disadvantaged :

Favored beneficial organisms


Organism	Impact of the technique	Details
Spiders	Average if the technique is used alone, to be combined.	Certain species.
Ground beetles predatory and granivorous	Average if the technique is used alone, to be combined.
Fungi (beneficial)	Average if the technique is used alone, to be combined.	Untreated areas from fungicides.
Green lacewings and antlions	Average if the technique is used alone, to be combined.	If melliferous plants are present in the grassy strip.
Ladybugs	Average if the technique is used alone, to be combined.	Certain species.
Predatory birds	Average if the technique is used alone, to be combined.	Trees, hedges, groves, and gaps in vegetation are important.
Parasitoids	Average if the technique is used alone, to be combined.
Predatory bugs or granivorous	Average if the technique is used alone, to be combined.	Predatory bugs need an environment close to natural state (ecological compensation areas, rich accompanying flora).
Rove beetles	Average if the technique is used alone, to be combined.
Predatory hoverflies	Average if the technique is used alone, to be combined.	If melliferous plants are present in the grassy strip.

For more information

Beneficial organisms : Management of the edges of cultivated areas : French Association for Plant Protection, coordination : Jean-Louis Bernard. French Association for Plant Protection. AFPP guide working group, provisional document as of 12 February 2011, Technical brochure, 2011. http://French Association for Plant Protection

Beneficial organisms : management of reservoir zones : French Association for Plant Protection, coordination : Jean-Louis Bernard. French Association for Plant Protection. AFPP guide working group, provisional document as of 12 February 2011, Technical brochure, 2011.French Association for Plant Protection

Grassy strips :
- Ibis, Technical brochure, 2011. Seine Normandy Water Agency. Technical brochure. Concerns reduction of pollutant transfers. [1]
- Grassy strips : it costs, but it’s good for the image and nature. Caillaud L. AgroDistribution n°198, October 2009, Press article, 2009.
- Grassy strips. Biodiversity but safe. Cordeau S. (INRA). Biju-Duval L. (INRA); Chauvel B. (INRA). Phytoma, n°643, April 2011, Press article, 2011. Shows that the risk of introducing weeds into plots via grassy strips is limited. Phytoma Plant Health

Consequences of establishing grassy strips on weed flora. Cordeau S. (INRA, University of Burgundy). INRA, University of Burgundy, Academic work, 2010. Thesis. Includes articles by the author listed in this bibliography. Consequences of establishing grassy strips on weed flora evolution.

Effect of grassy tramlines on hoverfly populations in arable farming. Francis F.; G. Fadeur; E. Haubruge, University Faculty of Agronomic Sciences of Gembloux, Unit of Functional and Evolutionary Entomology. Faunal notes of Gembloux 2005 56, 7-10, Peer-reviewed article, 2005. Scientific journal article.

Farmers' fears and agro-economic evaluation of sown grass strips in France. Cordeau S. (INRA); Reboud X. (INRA); Chauvel B. (INRA). Agronomy for sustainable development, volume 31, issue 3, pages 463-473, July 2011, Peer-reviewed article, 2011. Scientific journal article. Provides cost elements given in the effects section of the sheet. Agronomy for sustainable Development

Flora of borders, aphids and beneficial organisms in beet culture. Bernard J.L. (Syngenta agro S.A.S.); Ythier E. (Syngenta agro S.A.S.).

Phytoma n°556, January 2003, Press article, 2003. Phytoma Plant Health

To prevent water pollution, I establish a grassy strip. Chamber of Agriculture of Seine Maritime. Chamber of Agriculture of Seine Maritime and Seine Normandy Water Agency, Technical brochure, 2006. Technical brochure. Concerns reduction of pollutant transfers.

Chamber of Agriculture 76

What are grassy strips? Environmental and biological consequences. Cordeau S. and Chauvel B. (INRA). Bourgogne Nature, journal of the Society of Natural Sciences of Burgundy. 7, 97-108, Press article, 2008.

Keywords

Pest control method : Biological control .

Mode of action : Action on the initial stock .

Type of strategy regarding pesticide use : Redesign.

Contacts

Julien Halska	INRA	julien.halska(at)grignon.inra.fr	Dijon (21)
Stéphane Cordeau	ESA	s.cordeau(at)groupe-esa.com	Angers (45)
Etienne Gaujour	Agrosup Dijon	e.gaujour(at)agrosupdijon.fr	Dijon (21)
Régis Wartelle	Regional Chamber of Agriculture Picardy	r.wartelle(at)picardie.chambagri.fr	Amiens (80)

La version initiale de cet article a été rédigée par Julien Halska, Stéphane Cordeau, Etienne Gaujour et Régis Wartelle.

Sources

Appendices