Establishing a vegetable crop in cover crop residues
As part of the GIEE "zero weed control" coordinated by MSV Normandy, we share with you a state of the art on an innovative weed management technique : planting a vegetable crop in a rolled cover crop.
Introduction
The benefits of a cover crop are numerous and frequently cited in the scientific literature (GAB IdF, 2021; Mazollier & Vedie, 2008; Pousset, 2011). However, planting a vegetable crop in crushed or rolled cover crop residues raises technical difficulties (FNAB, 2019). First, it is necessary that the cover produces a dry biomass greater than 10 t/ha to be properly flattened by a roller of the “faca” type and reduce the pressure of spontaneous flora by creating a thick mulch (FNAB, 2019). Consequently, “faca” rollers adapted to market gardening systems were built, with the help of the Atelier Paysan, during the “Buzuk” (L’Atelier Paysan (a), 2015) and “Solveig” (L’Atelier Paysan (b), 2015) projects.
FACA Roller
The purpose of a FACA roller is to lay down a green manure and break its stems. The passage of the FACA roller creates a quality mulch. This surface mulch will be beneficial to preserve the soil, retain freshness, but also slow down weed development.
The "Buzuk" project enabled the development of a Rolo FACA adapted to a context of permanent ridged beds in market gardening (L’Atelier Paysan (a), 2015). You can find the downloadable plans by clicking on this link.
Here is another self-built model during the MARCO project: a cage roller to which metal rods were welded. 120 kg of weights were added to the 2m wide cage roller to properly “pinch” the entire biomass of the cover crop. Experience shows that if the cover is cut, then the weight of the added masses on the roller must be reduced. If the cover stands back up after rolling, then either the cover plants are not at the right stage, or the cover is not dense enough, or weeds dominate the cover and are not managed by rolling" (Menard, 2023).
Planting Cane
Seeding and planting canes are ideal manual tools for sowing seeds (beans, peas, corn, etc.) or planting your plugs and shrubs. Designed to facilitate work, these canes are ergonomic and essential tools for your plantings. Thanks to its tip and sharp edge, the planting cane’s beak cleanly cuts through cover crop residues allowing easy placement of plant plugs. The beak opens using a pedal mounted on a spring which carefully releases the plants.
Direct Seeder Combined with Strip-Till
The mulch produced by the cover crop must be pushed aside or cut so that a seeder or planter can operate without residues clogging the parts and preventing proper functioning. Therefore, there are “strip-till” type seeders that clear the seed line by performing shallow soil work (< 5 cm) using goosefoot-shaped tines. This type of seeder has been adapted for vegetable sowing through several projects. For example, a strip-till for tool bar was developed during the SEFerSOL project (EPLEFPA, 2018; YouTube (a), 2019). In parallel, the “Buzuk” project also developed a strip-till seeder used in combination with the “faca” roller attached to the front of the tractor to simultaneously roll and sow (L’Atelier Paysan (c), 2017).
Note also that farmers self-build their own tools, like Jacky Berland who sows carrots in finely crushed wheat mulch with a modified Ribouleau NG 3+ seeder (TCS, 2020).
The GAB guide on green manure (GAB IdF, 2021) mentions the use of a disc marker modified by the farmer to sow or plant in the trench made in the cover. However, the guide does not indicate whether the farmer performed a sowing, if emergence was uniform, or if yields were satisfactory.
In conclusion, there is a variety of already built tools allowing sowing in cover crop residues; however, all tools must be tractor-drawn to operate. Additionally, most reported results concern transplanting vegetables in crops residues (Adamko-Sevestre & Buard, 2021; GAB IdF, 2021). The only technical report mentioning vegetable sowing in a rolled cover comes from the MARCO project led by GRAB. Indeed, the report mentions a corn sowing with their self-built strip-till in spring 2022, but results have not yet been communicated.
Seeder Wheel
To date, there is no study aiming to sow a vegetable crop after a green manure with total no-till and without using a tractor. Currently, the only example of sowing in mulch produced by a green manure is documented by a market gardener on living soil. Indeed, Fabrice Meyer conducted trials on a model of seeder wheel imported from China for 3 years (AliExpress, 2023).
Fabrice obtained good emergence with large seeds but the seeder wheel, being made of plastic, broke after 3 years (YouTube (b), 2023). One problem with this wheel is that sometimes seeds block the roller, which must then be unblocked by moving it back and forth. Do not force it to avoid breaking a plastic gear. This tool works well for peas and beans, aside from this blocking issue. Fava beans pass but it’s borderline and broad beans are too large (possibility to DIY an adapted wooden roller).
It is recommended to use a configuration with a maximum of 8 beaks (or a 10-beak model) for a depth of 5-6 cm because if closer, the beaks perform a “soil work” on the row by “lever effect” lifting soil and mulch, which results in poor work. With 8 beaks, you can barely see that sowing has been done; the work row and mulch remain intact!
Regarding small seeds: There are leaks in the distribution system, especially for very small seeds like carrots, even beets are not ideal (depending on varieties, some have smaller seeds than others). Same for turnips, Radish... Prefer for small seeds the other model of seeder wheel equipped with hole distributors: https://french.alibaba.com/p-detail/Farm-60757166006.html?spm=a2700.details.0.0.63f66789osDDl2
Adjustment advice:
For carrot: - Depth 3 cm - Configuration 20 beaks for 9 cm spacing on the row - Choose the seed selector to have 2-3 carrot seeds per beak - For denser sowing, perform a back and forth with the second pass slightly offset from the first to avoid disturbing the first sowing line
For carrots without irrigation (test carried out at Jardin de Manspach in 2019 and 2020 with an 8-beak seeder wheel) Sowing without irrigation behind a cover tarp after rain to retain soil moisture (depending on soil texture, in my case, soil with 25% clay 70% silt, zero tillage), carrots buried at 5-6 cm depth manage to germinate without any watering or rain after 6 weeks of heatwave. – Maximum depth: 6.5 cm – Configuration 10 beaks (I think 20 beaks at 6.5 cm are too close and will perform “soil work” by “lever effect” on the row causing soil drying, the goal of this method being to conserve soil moisture and place the seed deep enough to benefit from deep soil moisture)
Other seeds: Possibility to sow all kinds of small round seeds I think (beets, turnips, radishes, rutabaga, etc.) To check the minimum seed quantity needed in the wheel to ensure good distribution
Remarks: Personally, I do a lot of broadcast sowing for small seeds, however, this method requires irrigation if no precipitation, possibly a lot of irrigation for long-emerging seeds like carrot.
Burying seeds saves water, reduces water needs or even eliminates irrigation depending on soil nature and crop rotation organization (requires covering after rain plots that will not be cultivated until sowing, and thus having the necessary surface). Interesting in certain situations and depending on water availability.
To check the efficiency and durability of the beaks in stony soil
Bibliography
Adamko-Sevestre & Buard, 2021. Marco-Market gardening on cover crops without herbicide. Technical report. Available at : https://www.grab.fr/wp-content/uploads/2022/11/L21Bret0904.pdf
AliExpress, 2023. Seeder Wheel for large seeds. Commercial site. Available at : https://cutt.ly/jwlhLG3E
EPLEFPA, 2018. Les Sillons de Haute-Alsace innovate in agroecology in their territory. Article. Available at : https://polemaraichage.com/wp-content/uploads/2018/09/SEFerSol_ArticleADTVF2_mai2018.pdf
FNAB, 2019. Cover crops : Planting crops in a cover. Technical sheet. Available at : https://www.produire-bio.fr/articles-pratiques/couverts-vegetaux-implanter-des-cultures-dans-un-couvert/
GABB IdF, 2021. Green manures in organic market gardening. Technical guide. Available at : https://www.produire-bio.fr/articles-pratiques/guide-technique-sur-les-engrais-verts-en-maraichage-bio/
L’Atelier Paysan (a), 2015. ROLO FACA (BUZUK). Article. Available at : https://www.latelierpaysan.org/Rolo-FACA-issu-du-groupe-BUZUK4
L’Atelier Paysan (b), 2015. ROLO FACA (GRAB). Article. Available at : https://www.latelierpaysan.org/Rolo-FACA-GRAB
L’Atelier Paysan (c), 2017. Buzuk Project. 3-year report. Article. Available at : https://www.latelierpaysan.org/IMG/pdf/bilan_3_ans_projet_buzuk.pdf
Mazollier C., Vedie., H. 2008. Green manures in organic market gardening. Market gardening technical sheet. TECHN’ITTAB. 1-4. Available at : https://occitanie.chambre-agriculture.fr/fileadmin/user_upload/Occitanie/076_Inst-Occitanie/Documents/Productions_techniques/Agriculture_biologique/Espace_ressource_bio/Maraichage_bio/Pluri-espece/Fertilisation/EngraisVerts-PACA-2010.pdf
Pousset., J. 2011. Green manures and soil fertility. Agronomic principles. Agricultural practices. 3rd edition. Paris : GROUPE FRANCE AGRICOLE.
TCS, 2020. Plant material to limit plastic and gain fertility. Issue 106. Magazine. Available at : https://polemaraichage.com/wp-content/uploads/2020/03/2020.02-TCS106_Autres-productions.pdf
YouTube, 2019. [PROTOTYPE] Strip Till BPO - July 2019. Available at : https://www.youtube.com/watch?v=z7Pq5_UmYk4
YouTube, 2023. MSV-Seeder wheel-Drill sowing & other ITK large seeds-Jardin de Manspach-Fabrice Meyer. Available at : https://www.youtube.com/watch?v=S9ZgHODLczM&t=351s
