Technical articles

Crop association in arable crops Management of cover crops in arable crops Climate resilience Soil cover Biodiversity Soil regeneration

Diversify crops and cultivated varieties across a territory and distribute plots carrying the same species or varieties by spacing them apart (spatial and temporal diversification of crops)

Presentation

Technique characterization

Technique description :

Marie Gosme	INRA	marie.gosme(at)grignon.inra.fr	Grignon (78)
Julien Halska	INRA	julien.halska(at)grignon.inra.fr	Dijon (78)
Julien Papaix	INRA	julien.papaix(at)jouy.inra.fr	Jouy en Josas (78)
Paul Van Dijk	ARAA	p.vandijk(at)bas-rhin.chambagri.fr	Schilltigheim (67)

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. This technique can be implemented individually but is more effective if coordinated across the entire territory. The relevant scale depends on objectives: for example, a watershed to limit erosion, or a scale related to the movement distance of pests and/or natural enemies targeted by this technique. The contribution of plot arrangement (with equal crop proportions) to crop protection stems from general principles not always demonstrated for different plant-pest systems.

Example of implementation : Historically CETIOM, and now Terres Inovia offer on their site a tool to assist in choosing rapeseed varieties based on the history of the plot and neighboring plots for a prophylactic goal and resistance durability management. Example: if the plot or a neighboring plot has had a variety with specific resistance in the last three years, it is advised to choose a variety with very low sensitivity to quantitative resistance.

Technique details :

Spatial diversification of crops across a territory means diversifying crops in rotations present on that territory. Thus, all organisms manageable by rotation are concerned by this technique. However, for clarity, only organisms influenced by the fact that crops are diversified on a territory in a given year are listed here. Low-mobility organisms (soilborne pests and diseases) are therefore not covered by this fact sheet.

Implementation period On established crop

Spatial scale of implementation Territory

Diversification can be done at the farm scale, but in some cases, it will be more effective at the territorial scale (especially if the farm's plots are not grouped).

Application of the technique to...

All crops : Sometimes difficult to generalize

Crops with territorial distribution advice are rare.

Beet : Avoid proximity to grassland, which can be sources of crane flies and do not sow within 500m of cereals attacked by the cabbage root fly.

Winter rapeseed : Academic references exist for phoma of winter rapeseed. Principles are to distance inoculum sources and rapeseed plots as much as possible, considering prevailing wind directions.

Flax fiber winter - Flax fiber spring - Flax seed winter - Flax seed spring : Avoid proximity to grassland, which can be sources of crane flies.

Alfalfa : Crop serving as refuge for ladybugs in winter. From alfalfa plots, they can colonize nearby crops.

Maize silage - Maize grain : The fewer maize fields in the landscape, the lower the densities of corn rootworms, and the more spotted ladybugs are present.

Potatoes : Do not sow within 500m of cereals attacked by the cabbage root fly. Against late blight, simulations show the effectiveness of reducing the proportion of host plants on a territory. Effects of field distribution are less clear.

Grasslands : Grasslands can be sources of crane flies (notably pests of flax), but also of natural enemies.

All soil types : Easily generalizable

Depending on soil types, crop choice and diversification possibilities differ and may be limited. However, pedological characteristics of the territory can limit crop distribution possibilities.

All climatic contexts : Easily generalizable

Depending on the pedoclimatic zone, crop choice and diversification possibilities differ and may be limited. Possibly consider constraints linked to microclimates of the territory.

Effects on cropping system sustainability

"Environmental" criteria

Effect on air quality : Variable

Phytosanitary emissions : DECREASE

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, phyto ...) : Decrease

By reducing phytosanitary product use, transfer risk is reduced (depending on active substance characteristics). Reduced runoff risk also limits pesticide and phosphorus transfer (adsorbed on soil particle surfaces). Nitrogen transfer risk may increase if runoff limitation increases leaching (increased infiltration).

Pollutant transfer to air (N, P, phyto ...) : Decrease

By reducing phytosanitary product use, transfer risk is reduced (depending on active substance characteristics).

Fossil energy consumption : Variable

Depends on species choice on the territory. Any crop highly dependent on mineral fertilizer use will increase fossil energy consumption in the rotation. Conversely, any crop more autonomous regarding nitrogen (e.g., legumes) will improve this impact. Plot distribution can influence travel length and number between plots.

GHG emissions : Variable

Depends on species choice. In arable systems, GHG emissions mainly come from CO2 and N2O. CO2 is linked to energy consumption (and indirectly fertilizer manufacture). N2O is linked to nitrogen fertilizer spreading. GHG emissions magnitude strongly depends on nitrogen fertilizer quantity used. Plot distribution can influence travel length and number between plots (CO2 emissions).

"Agronomic" criteria

Productivity : Increasing

Production quality : Increasing

By maintaining or improving soil physico-chemical fertility and better control of pests. Depends on previous effects and crop complementarity regarding resource exploitation.

Soil fertility : Increasing

Varied crops explore different soil compartments and do not exploit the same resources.

Water stress : No effect (neutral)

Functional biodiversity : Increasing

Increased landscape heterogeneity means sufficiently mobile organisms can more easily move from one crop to another, depending on resources and habitats suitable for them.

Other agronomic criteria : Decreasing

Resistance durability : Increasing

Inoculum reduction induced notably by appropriate plot distribution can contribute to increasing durability of monogenic or quantitative resistances. Varying resistance genes across a territory hinders pathogen adaptation (notably for rapeseed phoma where preserving monogenic resistances is crucial).

Certain pest populations : Increasing

In some cases, a high proportion of host plants dilutes pest populations. Example: pollen beetles and stem weevils (see bibliography).

"Economic" criteria

Operating costs : Variable

Evolution depends on rotation crops and their technical itineraries. Lower pest pressure in the cover should reduce costs related to phytosanitary product use.

Mechanization costs : Increasing

Dispersed plots of the same crop imply increased travel between plots. Also depends on territory crops and their technical itineraries.

Margin : Variable

Variable depending on pesticide savings and increased costs.

Other economic criteria : Variable

Market opportunities : Decreasing

Finding buyers may be difficult for some crops depending on local context and volumes produced.

"Social" criteria

Working time : Increasing

Possibly increased travel time between plots of the same crop.

Peak period : Increasing

Working time may increase due to crop diversification (managed with different technical itineraries). However, diversification may also limit work peaks (sowing, harvesting). Increased travel time between plots of the same crop.

Need for coordination among neighboring farmers : Increasing

This collaboration may be necessary since the technique is more effective at a territorial scale.

Observation time : Increasing

Each crop requires specific observations. Diversifying crops implies more observation time.

Need for farmer training : Increasing

Managing more crops requires more know-how, learning, etc.

Favored or disadvantaged organisms

Favored pests

Organism	Technique impact	Type	Details
Stem weevil		pest, predator or parasite
Pollen beetle		pest, predator or parasite
Crane fly	MEDIUM	pest, predator or parasite	On flax and beet

Disadvantaged pests

Organism	Technique impact	Type	Details
Corn rootworm	MEDIUM	pest, predator or parasite	Reducing maize proportion reduces corn rootworm densities on maize.
Late blight	LOW	pathogen (pest)	Against late blight, simulations show effectiveness of reducing host plant proportion (potatoes) on a territory. Effects of field distribution are less clear.
Phoma of crucifers	LOW	pathogen (pest)	Rapeseed phoma

Favored natural enemies

Organism	Technique impact	Type	Details
Ladybugs	MEDIUM	Natural enemies of pests	Intensity note given for Coleomegilla maculata, favored by reducing maize proportion in the landscape.

Keywords

Pest control method : Cultural control

Mode of action : Avoidance

Strategy type regarding pesticide use : Redesign

Appendices

Favorise les bioagresseurs suivants

Favorise les auxiliaires

Ladybugs

Défavorise les bioagresseurs suivants

Cultivating Diverse Species and Varieties at the Territorial Scale

Contents