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Replay of the webinar on intercropping

07 Jul 2022

This webinar will give you an update on interculture cover crops: expected benefits, management of annual cover crops through our research results & management of permanent cover crops.

View the replay on Terres Inovia's YouTube channel

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Some questions and answers from the webinar

Q : Hello, cabbage looper is exploding in some regions, the presence of crucifers in mixtures is a problem...
A : Hello, in addition to the oral answer, the table of constraints presented by Pierre does indeed include the fact of banning all crucifers in cover crops when there is a risk of clubroot on rapeseed. This constraint is included in the tools for choosing cover crops mentioned.

Q: If the carbon in a mixture with a high C/N is not humified, what happens to it? Destocked? No interest in growing EV?
A: In the short term, there is a risk of a net organisation of N at the destruction necessary for the humification of the residues, which can be detrimental to the following crop, with a fertilising effect that occurs late (about 6 months).

Q: Hello, is broadcast sowing compatible with straw harvesting? If so, what are the criteria for success?
A: This sowing method is rather adapted if the straw is returned, otherwise it makes the young plants more sensitive to dryness or heat. The straw replaces the soil.

Q: For cover crops, were you able to make observations related to varieties as well?
A: Yes, there are big differences between varieties, especially in terms of behaviour / adaptation to soil types. This is especially true for crucifers.

Q: Why rye and not oats? Advantage in cereal rotation?
A: Yes, oats are possible but rye has the advantage of making a lot of aerial biomass but also root biomass. Oats can also be a relay for aphids which are vectors of WNJ if they are close to cereals in the autumn.

Q: For short intercrops between 2 straws, are there any specificities?
A: Yes, short-cycle species should be favoured (flax, phacelia, sunflower, nyger, fodder pea). The aim is to produce the maximum biomass in the shortest possible time and, if possible, to be frost sensitive.

Q: For relay crops, have you observed a difference between sowing all the associated species with shredding in October or 2 sowings?
A: According to expert opinion, we have observed a positive effect of shredding on the availability of light for the relay. (This must be validated in comparison with a non-shredded control in our 2023 experiments). In addition, sowing the two simultaneously saves one sowing (especially at a time when winter cereals are being sown).

Q: There is a clear difference between SD tine and disc drills, although you talk about SD in a generic way. All your trials were done with a disc drill?
A: Yes, we have made a distinction between SD tines and discs with better results in TCS or SD tines compared to SD discs.

Q: What means do you use to assess and monitor residual soil moisture as you approach oilseed rape drilling?
A: We use moisture probes (3 depths).

Q: Apart from the date of destruction, is there a risk of disease when faba beans (or other pure legumes) are included in a 4-year rotation that includes soybeans? For faba beans and/or soya beans?
A: A somewhat "easy" answer is to recommend alternating species used as cover. This is because it requires a change in the practice of covering the soil.