Sowing catch crops before or during harvest saves time, reduces establishment costs, and maximizes vegetation duration, thus promoting cover crop growth. This document provides a summary of farmers' experiences who have adopted these techniques.
Common motivations among farmers practicing this technique are to successfully establish covers by anticipating their sowing while saving time. These practices allow moving the cover crop establishment work to a period generally less busy for farmers. Moreover, these no-till establishment techniques generally involve very low mechanization costs, due to:
very high work rates,
low to zero hourly fuel consumption depending on the technique,
almost no equipment wear.
Radish emergence under straw mulch (Hombleux (80) - August 2018)
The principle of these techniques consists of placing the seeds on the soil surface, then covering them with straw from the previous cereal crop. The seed benefits from the residual soil moisture, preserved either by the standing crop or by the straw mulch, to promote germination. Three distinct practices have been identified to carry out this type of sowing:
the use of a specific drill capable of spreading seeds over the working width of the sprayer,
the mounting of two small centrifugal drills on the booms of the sprayer,
Return and chop straw to cover the seed, retain moisture and thus promote germination.
Use this technique only in clean fields at harvest time (especially regarding perennials), to avoid proliferation of weeds and competition with the cover crop.
Adapt the technique according to the risk of residual herbicides from the previous crop; several farmers report risks related to spring weed control.
Choose species with low moisture requirements for germination (radish, phacelia, buckwheat, mustard, clover, vetch are among the most used). Some interesting species for cover crops (such as sunflower, faba bean or pea) are generally excluded due to their water needs. It is also necessary to favor species or varieties with late flowering, to limit the risk of bolting or the need for early destruction of the cover.
Some experiences of sowing before or during harvest
Cost of establishment technique (excluding depreciation)
€1.50/ha
Sowing date
In Brittany, the drill is provided free of charge to a CUMA by the water agency. In Hauts-de-France, a seed company conducts field tests. A sheet under the tractor prevents grain shedding of barley during sowing.
A sheet that connects front (covers weights or front linkage) and rear (lift arms) is fixed under the tractor to prevent barley grain shedding at sowing.
Mounting two centrifugal spreaders on the sprayer booms
Spreaders mounted on sprayer booms
Item
Detail
Context
Aisne
Objective
Early establishment of a cover between two wheat crops
Cost of establishment technique (excluding depreciation)
€1.00/ha
Sowing date
The drill is driven by the second power take-off of the combine harvester. Adjustment by splines, distribution by spreaders. Mounted on a metal frame welded to the header.
The advantage of this technique compared to using specific equipment is its low investment
Success of the technique
Farmers interviewed aim to produce very well-developed covers. In their context, this technique was chosen and retained because it most often led to more developed covers than with their previous practices. They explain these results either by the extension of the vegetation period allowed by earlier sowing or by faster cover emergence benefiting from residual soil moisture. Within the framework of the project "Multifunctionality of cover crops between crops", trials have been set up to identify the species and practices (sowing date, residue management) best suited to the regional context (See technical file: Summary of broadcast sowing trials )
Radish cover sown a few days before harvest (Vaux (02) - 25 September 2018)
Farmers surveyed have tested several species to develop their technique:
Feedback from surveyed farmers on species tested according to context and practices.
Source
Agro-Transfert Resources and Territories (2022). Summary of broadcast sowing trials, Project "Multifunctionality of cover crops between crops".
