Securing rapeseed sowing to increase robustness
Effective sowing means reducing uncertainties. The decision to sow rapeseed depends primarily on the weather: the start of sowing will be determined by whether rain is forecast. Sowing before rainfall of around 10 mm remains the ideal scenario, because sowing after rain disturbs and therefore dries the soil. For this, the soil must be prepared early (see article on Soil preparation//link//). In superficial, clay-limestone or clay soils with a low mineral nitrogen content, sowing must be particularly early, from 1 August. In deeper soils, the high availability of nitrogen makes it possible to sow a little later. “Rapeseed must be sufficiently robust and developed before winter, both at foliar and root level and with a suitable stand”, explains Philippe Charron, rapeseed expert product manager. “When the potential is well established before winter, we know that it will develop in spring”.
Adapt sowing density to soil moisture
The ideal sowing density for rapeseed is around 45 g/m2. The recommended sowing depth is 2 cm, to be adapted according to soil moisture. If the first 3 or 4 centimetres of soil are dry but there is fresh soil underneath, it is possible to sow at a maximum depth of 4 cm, in order to position the seed in contact with that fresh soil. If the soil remains dry for 5 cm and more, the sowing depth remains 2 cm as soon as 7-10 mm rainfall is forecast. The figure to bear in mind is that 1 to 1.5 mm of rain allows rewetting of 1 cm of soil. If the rainfall is less than 7 mm, the seed may dry out during germination, as the young root will have difficulty growing in a dry environment. With no actual or forecast rain by 20 August, the seed is sown at a depth of 3 cm, pending significant rainfall.
The Secure Install genetic driver
Regardless of pedoclimatic conditions, varieties with low sensitivity to elongation are still recommended to promote the development of robust rapeseed. Using varieties offering good development in the autumn, while ensuring good agronomic practices, secures the establishment phase and, ultimately, the success of the crop. “It is our responsibility, as a seed company, to offer varieties that promote the best possible establishment, whether in early or late sowing”, says Philippe Charron. The rapeseed varieties in the Secure Install range in our catalogue show the best autumnal establishments with good tolerance to bioaggressors, such as jaundice (also known as Turnip Yellows Virus), insects or phoma. Varietal selection is based on the development dynamic in the autumn, the recovery of available nitrogen, the ability to avoid larval pressure and resistance to jaundice. RGT OZZONE, RGT KANZZAS and RGT PARADIZZE have therefore been included in the Secure Install range.
What does robust rapeseed before winter imply?
In rapeseed, good establishment is crucial for achieving a robust plant that will express its full yield potential. Obtaining robust rapeseed before winter means:
– reaching the 4-leaf stage before early October (before the arrival of the cabbage-stem flea beetle);
– active growth during the autumn, with a biomass of 20 g/plant by mid-October;
– at least 8 leaves / plant by late autumn;
– a collar at least 8 mm in diameter;
– a minimum pivot length of 15 cm;
– a stand of 20 to 35 plants/m²;
– green weight between 1 and 1.5 kg/m² (45g/plant) by late autumn.
