Stubble cultivation: to be carried out all year round

A shallow tillage operation

Stubble cultivation is a shallow tillage method which consists of pulling up and burying emerged plants and fallen seeds, as well as stubble from fallow land, uncultivated land, an intermediate crop, or the previous crop. It takes one or several passes to carry out this operation. Working depth depends on objectives and equipment.

The purpose of stubble cultivation

There are many purposes:

• to facilitate the decomposition of crop or intermediate-crop residues,
• to contribute to weed control,
• to make it easier to sow the following crops,
• to air and structure the soil better.

Its agronomic value is now well established, which is no doubt why it has grown in popularity in recent years. It is also a cultivation technique that saves time and fuel compared to ploughing, for example.

Burying and mixing in crop residues

Throughout history, stubble cultivation has been carried out to bury and mix in crop residues through the depths of the worked soil, following the combine harvester. Straw and residues mixed in with the soil are subject to an initial moistening process before the organic matter is mineralised and decomposed. As a result, there is less plant debris on the surface which deprives certain pests, such as slugs, of shelter in which to reproduce.

Did you know? Two passes with a stubble cultivator reduces the amount of straw on the surface threefold.

Organic soil enriching agents (liquid manure, manure, and compost) are also buried by  stubble cultivators.

Weed control 

Weed biology: Most grasses have a germination capacity that decreases after a year and a maximum life expectancy of a few years, whereas broadleaf weed seeds are often more persistent.

For effective mechanical weeding, the 1st pass with the stubble cultivator should be at a depth of approximately 2 to 5cm, otherwise the seeds could go dormant.

While mechanical stubble cultivation is effective for destroying annual weeds and crop regrowth, care must be taken with perennials not to split the rhizomes of couch grass, bindweed, thistle, and docks, with the stubble cultivator, particularly the version with discs.

Improving the structure of the soil and preserving water reserves

Stubble cultivation improves the structure of the soil and aerates it. A pass with a stubble cultivator prevents slaking, increases the soil’s water-retention capacity and deeper water infiltration. By disrupting the capillary continuity of the surface soil, stubble cultivation reduces water evaporation from the soil.

In rainy weather, and especially during violent storms, water penetrates into the soil better when the field has been worked by a stubble cultivator. The tool also partly eliminates the problem of packing caused by harvesting machines.

The soil is thus aerated and supplied with water to boost biodiversity.

The different types of stubble cultivation:

• Shallow stubble cultivation between 2 and 5cm: just after harvest as a means of pre-sowing to enhance weed emergence and seedlings from the previous crop. At the same time, the machine mixes in straw residues to accelerate decomposition.
• Intermediate stubble cultivation between 5 and 15cm: to plant cover crops, for example, at the end of the summer, and create a seedbed by mechanically destroying any weeds.

Which to choose, a stubble cultivator with tines or discs?

Different machines are suitable and should be chosen according to soil type, weather conditions, and the required result:

Why choose a stubble cultivator with discs and tines?

In practice, it may be a good idea to alternate between discs (to cut weeds) and tines (to uproot weeds).
Some machines are multi-purpose with rows of discs and tines (the PERFORMER range). The discs cut residues and roots while the tines mix the residues in deep down.

Get more insights: What are the advantages of carbide points for your stubble cultivators with tines?

If pre-sowing is the objective

Good stubble cultivation should create fine surface soil to encourage germination. In this case, it is advisable to till as soon as possible after the harvest (with cereals) to reap the benefit of the cool soil. An OPTIMER-type tool with discs can be used for shallow cultivation to around 5cm. It is also possible to use a tool like the PROLANDER with fairly light tines.

If destroying weeds and /or crop residues is the objective

In this case, the stubble cultivator needs to be capable of scalping the soil and uprooting weeds. A tool with tines that can work at depths of 5 to 10-12cm to reach the roots. Tine tools from the PROLANDER or CULTIMER ranges meet these requirements.

If mixing in straw or crop residues is the objective

In this case, the stubble cultivator should facilitate straw decomposition. Tools with discs, such as in the OPTIMER range, that work at depths of between 5 and 10cm will ensure that vegetation is mixed in well.

If limiting water evaporation is the objective

Tools equipped with tines or discs can be used to work the surface of the field to 5cm deep. To optimise the operation, combining it with a roller is recommended in order to close the soil. Most KUHN stubble cultivators are equipped with rollers.

If structuring the soil is the objective

It is possible to mix straw deep into the first 20 centimetres of the soil to ensure better decomposition, using tine tools such as the CULTIMER or Performer. This is usually done before planting a spring crop, or sometimes in the autumn before planting a winter crop. In order to loosen plough pans and compacted soil, caused by tractor wheels, stubble cultivators such as the CULTIMER, Performer or the DC Sub Soiler can be used. Their finer rows of tines can work to depths of 30 to 35cm.

Stubble cultivation and seeding at the same time: to save time and fuel, seeding can be carried out at the same time as stubble cultivation. This practice is developing particularly for planting inter-crops in the autumn. Machines with discs and tines as well as a roller are suited to this type of operation.
 

4-seasons stubble cultivation

A lot of stubble cultivation in the summer

Stubble cultivation is mainly carried out in the summer after harvesting cereal crops and rapeseed, as well as in the autumn after maize. The objective is to facilitate the decomposition of stubble, combat weeds and slugs, and make it easier to plant the next crop. As well as regenerating the soil, stubble cultivation reduces the need to use herbicides.

Preparing the field with the stubble cultivator in the autumn

This cultivation method is developing for autumn operations to prepare the land for cover crops or even cereal crops planted using Minimum Tillage Methods.

Stubble cultivation to bury plant cover after the winter

Soil and weather conditions permitting, plant cover can be destroyed at the end of winter. This protects the soil for longer and increases the amount of biomass to bury, returning more nutrients to the soil. If the soil has settled sufficiently, a stubble cultivator can be used to destroy plant cover. It may be necessary to pass with a shredder first if there is a lot of cover.

Improve the structure of the soil in spring with a stubble cultivator

In spring, tillage operations structure the soil and prepare for spring sowing by accelerating soil warming. 

To sum up, stubble cultivation is no longer limited to the sole objective of burying stubble by shallow cultivating. The technique also traps nitrates in the soil for the future crop by mixing in residues.

Stubble cultivation limits the spread of harvest fires

During the summer season, it is advisable to keep a tractor-mounted stubble cultivator close to the field in case a firebreak is needed. It will restrict fires by reducing flames.