Growing smothering species

Crop Association in Arable Farming Carbon Cycle and GHG Biodiversity

Introduce one or more smothering species into the rotation: these crops are characterized by a high potential for spatial coverage, as well as rapid growth and good establishment capacity. The objective is to establish strong competition for light to the detriment of weeds. These crops can be annual, perennial, or integrated into intermediate covers.

Authors:

Rodriguez	Alain	ACTA	Baziège (31)
Guichard	Laurence	INRA	Grignon (78)
Munier-Jolain	Nicolas	INRA	Dijon (21)
Cherifi	Alexandra	EPLEFPA 89	Auxerre (89)
Halska	Julien	INRA	Dijon (21)
Bernicot	Marie-Hélène	INRA	Dijon (21)

Presentation

Characterization of the technique

Description of the technique:

This involves integrating certain crops into the rotation, targeting certain weeds to be disadvantaged by their competition: for example alfalfa against thistle (well documented) or bindweed (less documented). They can be grown pure or in mixtures. High-density sowing with reduced spacing increases the smothering power (see complementary techniques). The chosen crop(s) must develop rapidly and cover the soil well before it becomes infested. Smothering crops: alfalfa, mixed cereal-legume association (for example pea-wheat each at 75% of their pure crop density), hemp, buckwheat, mustard, vetch, triticale, winter oat, rye, winter barley, etc. Annual legumes are generally poor competitors.

Example of implementation: Example taken from the ENDURE network document. Farm located in Burgundy (limestone plateau, shallow soils, degraded oceanic climate), initial rotation: winter oilseed rape - winter soft wheat - winter barley. Weed management is one of the priorities in designing a new cropping system. The proposed new rotation is: winter oilseed rape - winter soft wheat - spring barley - alfalfa - alfalfa - winter soft wheat - mustard as cover crop - sunflower - triticale. The smothering crops introduced are thus alfalfa, mustard as cover crop, and triticale.

Details on the technique:

The effect on weeds depends on the covers and rotations. Nevertheless, it is reasonable to think that ubiquitous species (found in wide and varied territories), composites, willows and grasses are less disadvantaged by this technique than other species. These are pioneer species with intense and rapid development in early stages, as well as those that germinate year-round or those that are not demanding in terms of pedoclimatic conditions.

Application of the technique to...

Implementation period On established crop

Spatial scale of implementation Plot

All crops: Easily generalizable

All soil types: Easily generalizable

All climatic contexts: Easily generalizable

Effects on the sustainability of the cropping system

Expected reduction in the use of herbicides (and possibly other phytosanitary products) and low level of inputs required by smothering crops. The transfer of phytosanitary products depends on the physico-chemical characteristics of the molecules. Possible reduction in the number of sprayer passes, but variable balance depending on the technical itineraries of the introduced crops. Possible reduction in nitrogen fertilizer inputs if pure or associated legumes are introduced. Furthermore, if smothering crops diversify rotations, a reduction in the use of fungicides and insecticides can also be expected due to interruption of cycles of other pests than weeds.

"Environmental" criteria

Effect on air quality: Variable

Phytosanitary emissions: DECREASE

GHG emissions: VARIABLE

Effect on water quality: Increasing

Eutrophication: DECREASE

Pesticides: DECREASE

Effect on fossil resource consumption: Variable

Fossil energy consumption: VARIABLE

GHG emissions: variable, at the CO2 level, possible reduction in the number of herbicide passes, but variable balance depending on the technical itineraries of the introduced crops. No knowledge for N2O.

"Agronomic" criteria

Productivity: Variable, the previous effect of the introduced crop can improve or deteriorate the yield of the following crop. However, the physico-chemical fertility of the soil is maintained or even improved, as well as the control of pest development.

Soil fertility: Increasing, varied crops explore different soil compartments and different resources.

Water stress: No effect (neutral)

Functional Biodiversity: Increasing, increase in cultivated biodiversity, and likely associated wild biodiversity (more varied habitats and resources).

Other agronomic criteria: Decreasing, pest pressure: Decrease, if smothering crops diversify rotations, a reduction in pressure from insects and diseases can be expected due to interruption of cycles of other pests than weeds.

"Economic" criteria

Finding buyers may be difficult for some crops depending on the local context and volumes produced. However, economic risks can also be considered reduced thanks to the existence of varied outlets.

Operating costs: Decreasing, evolution depending on the introduced crops (increased costs for cover crops, but possible compensation if they provide nitrogen to the system). Possible reduction in phytosanitary costs due to reduced pressure from certain pests in the cover (effect of diversification of rotations).

Mechanization costs: Variable, variable evolution depending on the chosen species and associated technical itineraries.

Margin: Variable, the evolution of margins on the rotation will depend on the introduced crop (potential margin of the crop and previous effect). However, if current rotations are economically optimized, there is a risk that diversification tends to affect margins negatively. But there are counter-examples. Phytosanitary costs are reduced.

"Social" criteria

Working time: Variable depending on the introduced crop(s).

Peak period: Decreasing, diversification does not imply a systematic increase in overall workload. It can limit workload peaks by spreading out operations (sowing, harvesting). Farmers often feel an increase in workload which actually comes from a different distribution. The system is however more complex, some activities take more time (tool adjustment for example).

Observation time: Increasing, each crop requires specific observations. Introducing smothering crops partly means diversifying crops, which implies more observation time.

Need for farmer training: increasing, managing a greater number of crops requires more know-how, necessitates learning, etc.

Favored or disadvantaged organisms

Disfavored Bioagressors

Organism	Impact of the technique	Type	Details
Amaranth white		weeds
Amaranth blite		weeds
Amaranth prostrate		weeds
Amaranth hybrid		weeds
Amaranth reflective		weeds
Brome sterile		weeds
Chenopodium polyspermum		weeds
Wild oat		weeds
Abutilon theophrasti		weeds
Yarrow		weeds
Agrostis capillaris		weeds
Agrostis stolonifera		weeds
Field lady's mantle		weeds
Ambrosia artemisiifolia		weeds
Ammi majus		weeds
Anthriscus sylvestris		weeds
Anthemis cotula		weeds
Anthemis arvensis		weeds
Anthemis tinctoria		weeds
Thlaspi arvense		weeds
Artemisia vulgaris		weeds
Atriplex patula		weeds
Avena sterilis ssp. ludoviciana		weeds
Avena fatua		weeds
Barbarea intermedia		weeds
Bidens tripartita		weeds
Centaurea cyanus		weeds
Calepina irregularis		weeds
Capsella bursa-pastoris		weeds
Cardamine hirsuta		weeds
Carex		weeds
Daucus carota		weeds
Silybum marianum		weeds
Cynodon dactylon		Cynodon dactylon
Elymus repens		weeds
Chrysanthemum segetum		weeds
Chenopodium album		weeds
Chenopodium murale		weeds
Chenopodium hybridum		weeds
Crepis capillaris		weeds
Cuscuta		weeds
Cerastium glomeratum		weeds
Cerastium arvense		weeds
Datura stramonium		weeds
Digitaria sanguinalis		weeds
Diplotaxis tenuifolia		weeds
Erodium cicutarium		weeds
Euphorbia exigua		weeds
Euphorbia helioscopia		weeds
Foeniculum vulgare		weeds
Ranunculus ficaria		weeds
Fumaria officinalis		weeds
Fumaria parviflora		weeds
Galium aparine		weeds
Galactites tomentosa		weeds
Lathyrus tuberosus		weeds
Lithospermum arvense		weeds
Geranium columbinum		weeds
Geranium dissectum		weeds
Geranium molle		weeds
Geranium rotundifolium		weeds
Geranium pusillum		weeds
Helminthotheca echioides		weeds
Holcus mollis		weeds
Lolium rigidum		weeds
Juncus bufonius		weeds
Sonchus arvensis		weeds
Sonchus asper		weeds
Lactuca scariola		weeds
Lamium amplexicaule		weeds
Lamium purpureum		weeds
Sicyos angulatus		weeds
Lapsana communis		weeds
Linaria vulgaris		weeds
Linaria minor		weeds
Linaria elatine		weeds
Convolvulus arvensis		weeds
Calystegia sepium		weeds
Lychnis dioica		weeds
Matricaria chamomilla		weeds
Matricaria discoidea		weeds
Malva sylvestris		weeds
Mentha suaveolens		weeds
Mercurialis annua		weeds
Solanum nigrum		weeds
Stellaria media		weeds
Sinapis arvensis		weeds
Brassica nigra		weeds
Myosotis arvensis		weeds
Nigella		weeds
Orobanche ramosa		weeds
Panicum capillare		weeds
Panicum miliaceum		weeds
Panicum crus-galli		weeds
Panicum dichotomiflorum		weeds
Paspalum distichum		weeds
Poa annua		weeds
Poa trivialis		weeds
Papaver argemone		weeds
Papaver rhoeas		weeds
Papaver rhoeas		weeds
Venus comb		weeds
Viola arvensis		weeds
Petroselinum crispum		weeds
Phalaris paradoxa		weeds
Phytolacca decandra		weeds
Picris hieracioides		weeds
Taraxacum officinale		weeds
Plantago lanceolata		weeds
Plantago major		weeds
Potentilla reptans		weeds
Portulaca oleracea		weeds
Portulaca oleracea		weeds
Equisetum giganteum		weeds
Equisetum		weeds
Poa annua		weeds
Poa pratensis		weeds
Raphanus raphanistrum		weeds
Raphanus raphanistrum		weeds
Lolium perenne		weeds
Lolium multiflorum		weeds
Ranunculus arvensis		weeds
Ranunculus palustris		weeds
Ranunculus repens		weeds
Persicaria amphibia		weeds
Polygonum aviculare		weeds
Fallopia convolvulus		weeds
Persicaria maculosa		weeds
Persicaria lapathifolia		weeds
Rumex crispus		weeds
Rumex acetosella		weeds
Rumex obtusifolius		weeds
Reseda phyteuma		weeds
Sherardia arvensis		weeds
Sisymbrium officinale		weeds
Sorghum halepense		weeds
Cyperus esculentus		weeds
Spergula arvensis		weeds
Specularia perfoliata		weeds
Stellaria media		weeds
Senecio vulgaris		weeds
Setaria glauca		weeds
Setaria viridis		weeds
Setaria verticillata		weeds
Thlaspi arvense		weeds
Torilis arvensis		weeds
Torilis nodosa		weeds
Helianthus annuus		weeds
Trifolium		weeds
Tussilago farfara		weeds
Erigeron sumatrensis		weeds
Verbena officinalis		weeds
Vulpia myuros		weeds
Vulpia bromoides		weeds
Veronica persica		weeds
Veronica arvensis		weeds
Veronica lucida		weeds
Veronica hederifolia		weeds
Epilobium tetragonum		weeds
Ethusa cynapium		weeds