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Yields of rapeseed, soya and protein crops: what conclusions can be drawn from the climatic events of 2019?

Crédit photo : L Jung – Terres Inovia « Changement climatique : quelles conséquences pour le colza ? »

Whilst the instances of rain and mild temperatures seen in the final weeks of winter led to the first applications being brought forward, what conclusions can be drawn from the climatic events which had a significant impact on the previous season? Extreme and variable environmental conditions which seem likely to be repeated this year and which led to the crop operations being brought forward during the shooting phase of the rapeseed.  

Late frosts, wide temperature ranges, droughts during sowing and at the end of the cycle, etc. The variations in temperature seen during the 2019 season changed the crops a little bit more each year. Events that are more and more frequent and unevenly distributed according to researchers at Terres Inovia, who estimate a 30% [1] reduction of the soil for rapeseed due to this drought, coupled with difficulty managing the devastation of autumn.

Contrasting results for different crops

For rapeseed, the extension of the dry ground period, the increase in average temperatures and the number of hot days led to uneven, failed or late germination of the plants[2]. Furthermore, this increase in temperatures not only caused the number of seed pods, as well as the number of seeds per pod. Numerous climatic factors which seem likely to be repeated, according to experts, and which in part explain the falls in yields, down from 353 kg/ha in 2017 to 287 kg/ha in 2018 and 286 kg/ha in 2019[3].

Results remained the same for soya crops, where yield went from 260 kg/ha in 2018 to 251 kg/ha in 2019[3]. In fact, the flowering period crucial for determining yield. For the soya crop, this stage occurs at the start of summer: a critical period where high temperatures and a lack of water could have a negative effect on the growth of pods and may also lead to the failure of flowers and losses of yield.

The figures for 2019 were more reassuring for protein crops. In fact, favourable weather for the key stages of the development of the crops, together with good agricultural practices and an increase in the surface area linked to the turnover of rapeseed plots in particular, led to favourable conditions for the successful growth of plants and pods. These yields are borne out by broad beans and peas, which respectively went from 248 kg/ha to 282 kg/ha and from 353 kg/ha to 397 kg/ha between 2018 and 2019[3].

Preventing permanent stresses with biostimulants

However, even the most minor stresses can have some impact on the crops. For Benjamin Albert, R&D project manager for plant biostimulation and bionutrition at Agrauxine by Lesaffre, biostimulation solutions represent an effective response, not only for combating a fresh occurrence of these climatic variations but also for stimulating the crops:

« 2019 has been a particularly tricky year in terms of climatic conditions, affecting numerous crops, given the varied nature and high frequency of these variations throughout last year. The application of biostimulation at key stages is a valued addition to farmers’ technical itinerary and is of great interest for reducing the impact of these abiotic stresses. As their name suggests, these solutions naturally stimulate plants and their metabolism, inducing intrinsic responses at different levels of the plant to protect themselves or to combat against these unfavourable conditions. In fact, these latter are the source of physiological problems or disturbances, such as osmotic, oxidative or light stress for the plant, for example. Therefore, the biostimulants protect the crops, ensuring their develop correctly and lastly preventing potential negative consequences for yield. »

Biostimulants cannot, therefore, be simply described as stimulation products for crops to only be used in the event of significant climatic variations. As plants are constantly affected by these stresses, it is recommended that these solutions are applied each year, in order to optimise the yield of the crops.

Anticipating and reviewing operations in 2020

The start of this year has clearly demonstrated this with the first instances of long, consecutive rainfall: the climatic conditions for the 2020 season will once again cause stresses that will have a negative effect on the crops.

To prevent this, it will be necessary to better anticipate and review the different operations, particularly during flowering where these stresses are more harmful for the plants. In addition it will be necessary to correctly prepare the soil, with sowing underway and stocks with sufficient organic matter, it would be advisable to favour stimulation solutions for plants throughout their growth, in order to combat these climatic variations and ensure that the crops’ growth is dense and regular.

For more information about the right biostimulation solutions for your crops, please get in touch with our teams.


[1] Sources : Terres Inovia, Climate change: what are the consequences for rapeseed?
[2] Sources : Terres Inovia, Climate change: what are the consequences for rapeseed?
[3] Sources : Terre-Net, Yields, production, land: summary of figures for all production
Photo credit: “Climate change: what are the consequences for rapeseed? “