Stubble cultivation (shallow tillage)

Stubble cultivation, also known as shallow tillage, is the very first tillage operation of a new season. It is a shallow soil operation carried out immediately after harvest – and a lot depends on doing it right.

Important! Although shallow tillage should be done as soon as possible, it does not mean acting hastily or without a plan. Precision and timing matter.

What are the objectives of stubble cultivation?

Stubble consists of short stalks cut just above ground level. On its own, it does not protect the soil effectively against drying (excessive evaporation) or against erosion (wind erosion and water erosion). Straw left on the field helps to some extent, but combine harvesters rarely distribute it evenly. As a result, some areas have too much straw (yield losses occur there), while others have too little (the soil remains insufficiently protected).

Correctly performed shallow tillage serves several key purposes:
- Interrupting capillary evaporation of water. Before harvest, capillary pores connecting deeper soil layers with the root zone are beneficial – they allow crops to access water even without rainfall. After harvest, however, crop residues no longer need this water. Their role is to decompose and feed the next crop. Breaking capillaries limits moisture loss.
- Mixing residues with the topsoil. Covering straw and crop residues creates good conditions for their decomposition and mineralisation. This, in turn, “feeds” the humus layer and improves soil fertility and biodiversity (more in e-book 1).
- Stimulating the emergence of volunteer crops and weeds. Shallow tillage should trigger the germination of as many weeds and crop seeds as possible, which should then be eliminated as quickly as possible to avoid moisture loss. Otherwise, these seeds become a so-called soil seed bank, germinating uncontrollably and competing with the target crop. As a rule, emerged weeds should be removed 3–5 days after emergence, while volunteer cereals after 5–10 days.

Important! Chemical treatments (herbicide spraying) act only on plants that have already emerged and do not stimulate the germination of remaining unwanted seeds—unlike mechanical operations. Mechanical methods also allow even more effective control of weeds and volunteers, for example during a second pass.

Optimising shallow tillage – when and how deep?

First rule: carry out shallow tillage as soon as possible after harvest—ideally immediately after cutting and removing straw from the field. Delaying the operation means moisture loss from the soil and an increased risk of volunteer cereals and weeds.

Important! The optimal timing is right after harvest, when the soil still contains some moisture—breaking the stubble helps retain it for the next sowing.

Second rule: work shallow—usually 5–10 cm, maximum 12 cm. The aim is to cut the stubble and mix residues only in the topsoil, without disturbing deeper layers where valuable moisture is stored.

As a guideline, about 2–3 cm of working depth per tonne of straw is required. For example, after cereals yielding 7 t/ha, around 5–5.5 t of straw remains—so shallow tillage should be carried out at approximately 10–15 cm to mix such a large amount of material properly. If the soil is dry and heat persists, it is better to stay shallower (and consider chopping straw with the combine) than to cultivate too deep and dry out the profile. Importantly, on wetter soils depth should also be reduced—wet soil smears and compacts more easily. Shallower cultivation minimises the risk of structural damage under such conditions.

Important! The shallower the stubble is broken, the better—this is the essence of effective shallow tillage. No wonder ultra-shallow stubble cultivation (even 2–3 cm) is gaining popularity. Rolmako offers many tools for this purpose, such as knife rollers, rotary harrows and mulching harrows (note: the latter are best suited for preparing seedbeds for spring crops).

Third rule: generally, one solid cultivation pass is better than several poor ones—each additional operation causes unnecessary moisture loss. Excessive repeated shallow passes can over-dry the topsoil and delay straw decomposition.

Important! Correct shallow tillage requires driving the implement at an angle to the combine harvester’s direction—preferably 30–45°..

Tools for stubble cultivation

For stubble cultivation, disc harrows or stubble cultivators (grubbers) are most commonly used. Traditional stubble ploughs have largely disappeared due to low efficiency. Which is better—a disc harrow or a cultivator? There is no single perfect tool for all conditions and soils. When choosing equipment, farmers should consider many factors, including versatility, operating costs, farm size and preferred tillage system.

Disc harrows

A disc harrow consists of cutting discs set at an angle to the direction of travel. At higher speeds, they effectively cut stubble and mix residues with the soil. Disc harrows perform well even with large amounts of straw (they do not clog with long residues) and on slightly wetter, heavier soils—provided they have sufficient own weight.

High-quality tillage discs are very durable and can work on thousands of hectares, keeping operating costs relatively low. Rotating elements require less power—discs cut and roll, encountering less resistance than fixed cultivator tines (both rigid and spring-mounted types).

On smaller farms with low-power tractors, compact disc units are also effective. Their centre of gravity is closer to the tractor, allowing operation with lower horsepower. For such users, models like U693 (minimum 95 HP) and U622 (85 HP) are recommended.

Other Rolmako disc harrow models for stubble cultivation include:
- Disc harrow U652,SpeedCutter for ultra-shallow cultivation,
- SpeedCutter for ultra-shallow cultivation
- Heavy stubble disc harrow U671.

Stubble cultivators

A stubble cultivator (grubber) is equipped with several rows of tines fitted with goosefoot shares. It loosens soil, mixes residues without inversion and breaks weed roots. During operation, tines vibrate slightly, leaving a loosened surface with micro-cracks that promote a crumb soil structure.

Complete stubble cutting requires proper tine density—good grubbers usually have three or more rows, preventing untreated strips and straw clogging. Although more working elements increase power demand and machine length, they deliver better cultivation quality and levelling.

With well-matched equipment (working width suited to tractor power), shallow tillage with a cultivator is efficient and economical. Before entering the field, set the correct depth and check working parts (shares, points, edge discs, rollers, etc.)—worn components reduce performance.

Important! Important! Regardless of whether you choose a disc harrow or a cultivator, you must close the grooves left by discs or tines. A more uneven surface loses more water, so even a simple levelling section (levelling board, harrow or roller) is highly beneficial.

What does shallow tillage deliver?

Properly carried out shallow tillage immediately after harvest conserves valuable soil moisture. During summer drought, this can determine the success of emergence of winter oilseed rape, winter cereals or cover crops (where conditions allow). It is estimated that untreated stubble and weeds together can cause moisture losses of several to several dozen litres of water per square metre—enough to decide whether young plants establish and develop properly.