No-till planting under cover crops

Technical articles

Crop association in arable farming Permanent cover crops in arable farming Management of cover crops in arable farming Carbon cycle and GHG Climate resilience Soil cover Biodiversity Grazable cover crops Soil regeneration

No-till farming under cover crop (NTC) is an agricultural production technique that combines the absence of soil tillage (no plowing) with permanent soil cover.

What is it?

This technique comes from conservation agriculture whose founding principles are non-disturbance of the soil, permanent vegetative cover, and diversity of crops in association and rotation. Particularly developed overseas (Brazil, United States), these techniques have been expanding in Europe and France for about twenty years.

Eliminating soil tillage and maintaining vegetative cover requires very good technical mastery, regular observations, and a certain adaptability from the farmer. Beyond purely technical aspects, no-till seeding under cover crop requires a holistic approach to the cropping system and the farm.

However, there is no miracle recipe and each farmer, depending on the soil-climate context of their farm and the crops they wish to produce and market, must adapt their rotation and practices. When well mastered and stabilized, this technique aims to achieve good yields, optimal product quality while maintaining soil fertility, control of crop diseases, pests, and weeds.

This technique can be implemented on the crop (cover destroyed in the crop) or at the rotation level (cover maintained for several years).

The main principles of no-till seeding under cover crop

Eliminate all deep soil tillage. The establishment of cover crops and main crops is done directly using a seeder, most often with discs, which allows placing the seed without working the soil.

Establish and/or maintain a vegetative soil cover in which the main crop(s) will be sown. The cover crop between crops can serve several functions during the season: protecting the soil against erosion, capturing then releasing mineral elements, limiting evaporation and maintaining soil moisture, limiting the development of weeds, plants targeted by certain pests… The choice of cover crop(s) is therefore essential regarding species, possible mixtures, dates of establishment, destruction, and obviously the costs of seed purchase and implementation.

Manage the cover crops. The dead cover technique is probably the most widespread. It consists of establishing a cover immediately after the crop harvest and destroying it before sowing the next crop. However, in some constraining situations: lack of irrigation to make covers germinate, presence of stones, impossibility to use chemicals to control the cover,... it is necessary to adapt cover management. Establishing and maintaining the same cover over several successive crops is possible. The cover is established at a favorable time (sufficient rainfall) and intended to remain in place for several years. The successive cash crops on the plot are thus sown in a living cover and carefully managed to allow crop development. Regulating the cover is important so that it develops when there is no crop and does not hinder emergence and growth when the crop is present: competition for water, mineral elements, or simply light and space. For this, various control techniques are possible: mechanical control by mowing, cutting, grazing or rolling (obviously no plowing or shallow soil tillage), chemical control (herbicide), or climatic control: frost or drought.

Adapt the sequence of cover crops / cash crops to optimize and benefit from the positive effects of each plant. Beneficial effects on fertilization, weed control, pests, and soil moisture can be obtained through judicious choices. Of course, these choices must also consider economic and climatic criteria.

Fertilize at the right time and in the right amount. The absence of mechanical tillage and the presence of vegetative cover increase the amount of carbon stored in the soil. Mineralization of organic matter is also slower. Organic or mineral nitrogen fertilization must therefore be adapted (precocious) to both allow the transformation of organic matter (decomposition of cover crop residues) and fertilization of the crops.

Points of caution

Implementing no-till seeding under cover is not to be taken lightly. It is above all a profound change in farm practices that can lead to failure if all conditions are not met.

Many interested parties approach no-till primarily from the angle of simplifying practices, reducing energy and input consumption, and first think about equipment: which seeder to choose? But a successful transition to no-till is above all a change in how one approaches their cropping system and especially putting agronomy, observation, and knowledge of soil and crops back at the center of the farming profession.

From a technical point of view, the choice of cover crops, crop sequences, destruction or control of covers, pest management, and fertilization are the main points of vigilance. However, there are no ready-made recipes and everyone must adapt to their farm conditions. What works for some does not necessarily work for others.

Soil response time is also an important parameter. The positive effects of transitioning to no-till under cover crop are only observed after a few years (3 to 5 years minimum). Patience and perseverance are therefore necessary. However, the farm must continue to operate and generate income for the farmer. The economic dimension must therefore be considered and anticipated (reflection on current or future equipment investments).

If there is one investment not to neglect, it is the human investment through training, exchanges, peer visits, social networks, … It is clear that we are still far from a widespread adoption of these techniques and pioneers have managed on their own driven only by their motivation and conviction that they were on the right path. Currently, the Ministry of Agriculture, through the Agroecological Project, offers new perspectives for technical and financial support of no-till under cover techniques. Research and development organizations increasingly integrate no-till under cover in their work programs and more broadly conservation agriculture. Nevertheless, the pioneer spirit must be maintained and exchanges of experiences, results, or failures between farmers must continue.

Application of the technique

Generalizing this technique to all crops, soil types, and climates can sometimes be delicate.

The right association must be chosen to avoid competition with the cash crop and pathogen transmission. The cover must be defined and optimized according to soil type (hydromorphy, available water capacity, …).

Be careful if there are water availability issues (limited available water capacity) because the cover can compete with the crop for water availability and thus penalize it.

Environmental criteria

Air: Establishing crops under cover crop reduces energy consumption and related greenhouse gas emissions compared to planting after plowing or conventional no-till techniques. Compared to no-till, seeding under cover also allows carbon storage through cover crop growth.

Water: The cover takes up mineral elements from the soil solution, limiting their leaching. Moreover, the cover also limits runoff, preventing the transport of phosphorus or pesticide residues adsorbed on soil particles. However, seeding under cover may involve the use of herbicides to control or destroy the cover, which can increase the risk of transfer to water.

Fossil energy: Establishing crops under cover crop reduces energy consumption compared to planting after plowing or conventional no-till techniques. However, the impact on energy consumption is negligible compared to no-till.

Biodiversity: Maintaining a "permanent" (or long) soil cover favors macrofauna (game), but also soil biological activity (root activity).

Agronomic criteria

Productivity: The cover improves soil fertility (organic matter and biological activity) and limits weed competition. Positive effects depend on the ability to limit competition exerted by the cover on the crop: species choice and cover management (slowing cover growth and/or destruction) and levels of mineral element return (variable depending on species used for the cover).

Soil fertility: In quantity, diversity, and availability of elements but visible effects require time.

Water stress: Depends on water resources available year-round (climate). The cover can limit water availability for the cash crop.

Functional biodiversity: The cover provides refuge and food for beneficial insects and pollinators at a time of year when resources are limited.

Weed pressure: The cover can reduce weed competition.

Soil crusting surface sealing: The presence of a cover between crops reduces soil exposure to crusting and erosion (reduced bare soil duration over the rotation).

Economic criteria

Operating costs: Establishing crops under cover crop may involve increased use of herbicides to destroy/slow the cover compared to planting after plowing or simplified cropping techniques. Compared to no-till, the cost of cover crop seed can be considered negligible.

Mechanization costs: Compared to planting after plowing or Simplified cropping techniques, seeding under cover crop, like no-till, reduces mechanization costs.

Margin: The effect of seeding under cover crop is variable. Compared to planting after plowing or simplified cropping techniques, it reduces mechanization costs but may cause yield reduction and increased herbicide costs. Compared to no-till, the effect on profitability is difficult to estimate.

Fuel consumption: Establishing crops under cover crop reduces fuel consumption compared to planting after plowing or conventional no-till techniques. However, the impact on fuel consumption is negligible compared to no-till.

Social criteria

Working time: Establishing crops under cover crop reduces workload compared to planting after plowing or conventional no-till techniques. However, the impact on workload is negligible compared to no-till.

Observation time: Cover management + cash crop management.

Sources

This article is largely inspired by the project "No-till seeding under cover crop" of the Chamber of Agriculture PACA. ^[1] and from Practicing seeding under cover crop from the GECO database ^[2]

Videos on the subject

Keywords

Bioaggressor control method

Cultural control

Mode of action

Action on initial stock

Type of strategy regarding pesticide use

Redesign

Annexes

Est complémentaire des leviers

Establishing legumes in intercrop

S'applique aux cultures suivantes

Défavorise les bioagresseurs suivants

↑ "No-till seeding under cover crop" (https://paca.chambres-agriculture.fr/fileadmin/user_upload/Provence-Alpes-Cote_d_Azur/020_Inst_Paca/CA04/Documents/Publications/Productions_vegetales/Projet_semis_direct_sous_couvert_CASDAR.pdf)
↑ Practicing seeding under cover crop (https://geco.ecophytopic.fr/geco/Concept/Pratiquer_Le_Semis_Sous_Couvert_Vegetal)

[PDF_Semis_direct_CA_PACA-1] "No-till seeding under cover crop" (https://paca.chambres-agriculture.fr/fileadmin/user_upload/Provence-Alpes-Cote_d_Azur/020_Inst_Paca/CA04/Documents/Publications/Productions_vegetales/Projet_semis_direct_sous_couvert_CASDAR.pdf)

[Semis_direct_GECO-2] Practicing seeding under cover crop (https://geco.ecophytopic.fr/geco/Concept/Pratiquer_Le_Semis_Sous_Couvert_Vegetal)

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