Soil preparation: anticipate in order to effectively establish rapeseed crops
Tilling the soil is like preparing an athlete: you cannot neglect anything if you want to get off on the right foot, in terms of timing and setting the right pace”, explains Philippe Charron, rapeseed expert product manager. “So, as soon as I have a slot, I can start off in good conditions”. With rapeseed, good establishment requires anticipation. Obtaining robust rapeseed crops that are less vulnerable to attacks by pests and diseases, and to climatic hazards, remains the major objective of good establishment. To achieve this, it is essential to anticipate interventions, the first being soil preparation.
Early preparation of the soil, while limiting tillage
Preparation starts the day after the previous harvest in order to be able to sow from early August and benefit from rainfall that will allow the rapeseed to emerge. Two conditions are essential to promote rapeseed emergence: a sufficiently fine and broken up seedbed, with maximum moisture in the soil. To achieve these objectives, which may seem contradictory, the solution consists in adopting reasonable tillage by limiting it to what is strictly necessary and to do it as soon as possible after harvesting the previous crop, in order to reduce drying out.
Do not till the soil in the fortnight preceding sowing
Depending on the soil characteristics of the field, tillage and tools differ. If there are no structural problems at the 0-20 cm depth, surface work is recommended, at a depth of 5 cm, ideally with a double cross-pass within 24 hours after harvesting. Rolling after each action will be beneficial to limit drying due to evaporation.
On clay soils it is advisable to plough-in the stubble and follow this up with light tillage, with rolling in between. The objective is to promote rewetting in the event of rain, to limit evaporation and to give the soil good structure.
Where there is compaction, a working depth of 15 cm will be sufficient. In any case, the soil must not be tilled in the fortnight preceding sowing, in order to take full advantage of any rainfall.
For lighter soils, interventions before sowing can be considered with tine tillage or deep tillage. Moisture raised by ploughing can also facilitate the germination of rapeseed.
Combination sowing with a rotating harrow or power tool is strongly discouraged for the establishment of rapeseed, because the consequences are unfavourable: significant drying of the soil, or micro-clods.
