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Post-harvest cultivation, known as stubble cultivation, is an important agrotechnical procedure

The fundamental principle applied post-harvest of cereals and rapeseed using a combine harvester is post-harvest cultivation, primarily aimed at mitigating soil evaporation. Shallow stubble breaking offers several advantages. Bare stubble fields should be managed more carefully than those covered with straw cut and distributed by the combine harvester. Selecting the appropriate tool can be challenging. How can this be achieved effectively?

The arable plow is now considered outdated for stubble fields

Historically, stubble plows were utilized for post-harvest cultivation. However, they have largely been supplanted by other tools that precede plowing or facilitate simplified cultivation without plowing. The benefits of simplified tillage are increasingly persuading farmers to adopt it. Transitioning from plow technology necessitates equipment changes. Larger farms, typically those exceeding 100 hectares, are more inclined to adopt simplified cultivation due to the financial capacity to invest in new machinery. Consequently, instead of a plow, other machines will be required, and it may also be necessary to upgrade to a more powerful tractor.

Retain water and prevent weed growth

The primary benefit of using stubble aggregates is the reduction of water evaporation from the soil. Cultivation itself also leads to water loss, though it is significantly less than if the field were left uncultivated. It is estimated that water loss during shallow cultivation is approximately 3 liters per square meter, whereas plowing results in twice this amount. Immediate post-harvest cultivation is recommended to avoid allowing weeds to self-sow for an extended period. Weeds reaching a height of 10 cm can cause water loss of 12 liters per square meter, an amount essential for emerging rapeseed.

Rapid decomposition of plant residues

Post-harvest tillage advantages include uniform distribution and accelerated decomposition of residues, and reduction of disease and pest risks. Additionally, it creates suitable conditions for sowing cover crops and enables straw use as fertilizer. Traditional stubble cultivation involves turning the furrow and covering crop residues, while the current approach mixes these residues with the soil. Stubble aggregates also demonstrate higher efficiency compared to plows.

Shallow stubble cultivation

Shallow stubble cultivation is increasingly gaining popularity. The market offers units designed for cultivation to a depth of up to 5 cm. Another approach is ultra-shallow cultivation to a depth of 2-3 cm, which can be combined with sowing catch crops. This type of cultivation employs knife rollers, compact disc harrows, grubbers for shallow cultivation, and mulch harrows. These tools can be equipped with leveling bars and rollers mounted before or after the main working section. Generally, two types of stubble cultivation can be distinguished in shallow stubble cultivation: coulter and disc. These tools are available in various configurations and working widths, making them suitable for both small and large-scale farms. Farmers thus have a wide choice of these tools.

Which tool wastes more water: a cultivator or a disc harrow?

The intensity of evaporation results from the depth of work and the degree of compaction, not the type of tool used. Compact disc harrows with large diameter discs can work almost as deep as most stubble cultivators. Closing the grooves after the discs or cultivator legs pass is of great importance here. More water is lost through a more undulating surface. Therefore, each, even the simplest, additional section (cultivator drag, cultivator's comb, string or pipe roller) that helps level the ground is very useful.

How to reduce water losses from the soil immediately after harvesting cereals and rapeseed?

Numerous tests indicate that straw cut by a combine harvester and scattered on the ground serves as the best insulating layer to prevent water evaporation. Many older textbooks recommend the quick removal of capillaries through shallow tillage to prevent uncontrolled evaporation. However, this is applicable only to sites where the entire straw crop is collected, leaving the soil completely bare.

Which approach retains more water: several shallow passes or alternating between shallow and deep?

If post-harvest cultivation needs to be expedited for winter crops, particularly rapeseed, repeated shallow tillage dries the top soil layer and delays straw decomposition. In plowed fields, this is less critical, as the plow will eventually bring sufficient moisture to the surface for rapeseed and early-sown cereals germination. However, in no-plough cultivation, it is crucial to ensure that shallow straw does not obstruct seed-soil contact.

Is a mulch harrow sufficient for the first tillage and can it retain water?

Utilizing a mulch harrow is efficient. However, this tool only scratches the field's surface, which does not qualify as stubble breaking. It aids in water conservation to some extent, and the seeds of grassy weeds and fallen rapeseed germinate well since they are not deeply buried. However, a period of time is needed to use this harrow again. The rate of straw decomposition is very low. Therefore, repeated treatments with this tool are primarily effective for areas intended for spring plants.

Should I spread the lime on the stubble or later?

The reactivity of each calcium fertilizer depends on its contact with the soil. The earlier it is spread, the more often it will be mixed with the soil. Calcium also has a beneficial effect on soil microflora, as it creates conditions for increased activity, promoting faster decomposition of crop residues. Therefore, there is no better time for liming than on stubble and scattered straw. Maintaining even distances between passes of the spreader is somewhat difficult, but manageable without a GPS satellite guidance system. Start working from the side of the field where sowing of the harvested crop commenced, using rows of cut plants, combine harvester traces, or driving paths as guides.

Working Depth

The stubble field should be cultivated shallowly enough not to loosen and dry the soil too deeply, but also to such a depth that the residues are well mixed. In theory, therefore, the recommendation to perform undercutting at a depth of 5 cm is difficult to achieve, especially with smaller and lighter tools. Heavy cultivators or disc harrows maintain the set working depth much better, which is also easier to set on such equipment. It is assumed that for each ton of straw, you should work at a depth of 2-3 cm. This means that winter barley yielding at a level of 7 t/ha will produce about 5-5.5 t/ha of straw. Therefore, the working depth should be 10-15 cm. In our example, the cultivator had to work at 15 cm. The depth also depends on the soil moisture. The more moist it is, the shallower we should perform undercutting. However, with a large mass of straw, shallow cultivation is not entirely possible, as you might not achieve the effect of mixing the straw with the soil at all.

Agricultural Equipment for Stubble Cultivation

With technological progress, stubble plows have been replaced by stubble cultivators and disc harrows, which are now the most frequently used machines for this type of work and are found on nearly every farm. Utilizing these machines for stubble work saves a significant amount of time due to their relatively high speed and width, and they are considerably less expensive than using a plow. However, it is challenging to definitively determine which is superior, as much depends on field conditions and the models of the machines used. Despite similarities, tools for stubble cultivation often differ in construction details that impact the quality and ease of work. It is crucial to inspect our equipment before entering the field. Depending on the type of device (disc harrow, stubble cultivator), one should check the condition of plowshares, discs, rollers and coulters. Winter is the best time to inspect agricultural machinery, but the pre-harvest period, when the farmer has time to "breathe," is also an opportunity to prepare cultivation equipment. Efficient and well-maintained machines are essential for productive cultivation in dynamic modern agriculture.

Stubble cultivator - a universal machine

The popularity of stubble cultivators stems from their versatility. This machine enables both shallow and deep cultivation, reaching depths of up to 25-30 cm. Some models feature working elements that allow for additional side wings on the coulter for shallow cultivation, which can be removed for deeper cultivation. Compared to two-beam models, three-beam grubbers are more expensive, heavier, and require a more powerful tractor. The stubble cultivator, commonly known as a grubber, has become a staple in farm machinery.

Coulter Stubble Units

Rolmako offers a wide range of stubble cultivators. These tools effectively lift stubble across the entire working width and mix it into the upper soil layer, providing excellent crop residue mixing. For proper leveling, they come factory-equipped with a working section and pressing rollers (typically tubular or ring rollers with V, U, and T profiles), behind which rakes with thick, flexible fingers can be placed. The simplest stubble cultivators feature springy tines 70x12 or 90x13 with double-sided goose feet, similar to the four-bar universal pre-sowing and stubble cultivator Rolmako U 497. Another option includes heart coulters or divided coulters with side cutting wings, as seen in the Rolmako U 453 model. The three-bar multifunctional unit U 436 is designed for no-till cultivation and can handle shallow, medium, and deep cultivation up to 35 cm. This tiller's design features teeth that can be fitted with chisels and removable side shares for deeper cultivation. It can process stubble to a depth of 3 to 7 cm to stimulate weed germination. Additionally, the U 436 grubbers can mix crop residues with the soil at a depth of 7 to 15 cm and deeply loosen the soil up to 35 cm. Common equipment includes a front cutter roller or drag drag mounted at the front and a scraper at the rear to spread harvest residues across the working width. Various types of shafts, either single or double, are also available on these tools.

Two-beam cultivator

As a rule, the two-beam cultivator was created to replace and eliminate the stubble plow from cultivation. However, it is important to note that it remains a component of plowing technology. After using such a machine, deep plowing will be necessary. The two-beam cultivator, as shown by infrared analysis, leaves clear traces of post-harvest residues behind the tines in the field. These residues will not be uniformly mixed with the upper layer of soil in such cultivation.

Three-beam cultivator

The primary difference in the three-beam machine is the use of a greater number of working elements compared to the two-beam version. In theory, the same number of cultivator tines could be mounted on two beams; however, the spacing between the working elements would then be so small that when working with a large amount of crop residues, the flow of material would be difficult, which could often result in the machine clogging. The three-beam cultivator is recommended for farms that wish to adopt no plough farming. Currently, there is a trend towards creating four-beam machines, which perform their tasks even better. From the perspective of most farms, however, the three-beam machine is definitely sufficient.

Multifunctional discs

Specialized devices for shallow soil cultivation include disc harrows. These implements mix the soil effectively and resist clogging, even with substantial post-harvest residues. Compared to cultivators, disc harrows are more efficient, durable, and less susceptible to contamination by straw and stones. They are equipped with knife rollers, drag, rear comb beam and rollers. The purpose of these features is to level the unevenness created by the discs' operation. The most popular type of disc harrows are compact tools known as disc aggregates. In design, the discs are mounted in two parallel rows along the tool's length, each independently suspended from the supporting frame.

The uniformity of crop residues in the field is paramount

As previously mentioned, the primary objective of stubble cultivation is to minimize water loss. Special attention must be given to the distribution of crop residues, particularly when straw is not harvested. Used combine harvesters equipped with straw choppers and spreaders often fail to disperse the remains evenly over the entire working width of the header. This issue becomes more pronounced in high stubble fields and with larger working widths. Consequently, strips with accumulated straw and scattered seeds form directly in the tracks of the walkers, while wide strips with significantly fewer remains are found between them. This phenomenon is often underestimated, but its consequences are significant. Post-harvest cultivation with a stubble cultivator following the track of the combine harvester results in a notable reduction in future harvests. In areas with accumulated straw and fallen seeds, directly under the combine straw walkers, plant development is significantly hindered compared to nearby strips. The weakened crop development is due to the presence of many self-seeding plants competing with the actual crops for water and nutrients. With a header width of 6.0 meters, the area affected by the straw walker strips is approximately 20%. Improper stubble cultivation direction can lead to considerable water loss and a yield reduction of 0.5 tons per hectare.

Objective: To minimize evaporation and cover the stubble

Stubble cultivation aims primarily to reduce water loss. By disturbing surface-level soil, capillary pores are disrupted, limiting water evaporation. Consequently, water is retained beneath the dried surface layer, facilitating subsequent agricultural operations. Shallow stubble cultivation prevents the deep layers of soil from drying out and stimulates the germination of weeds and self-seeding plants. Adequately covering crop residues promotes decomposition under anaerobic conditions and proper moisture, thereby enhancing soil fertility. Uncovered remnants on the soil surface provide a breeding ground for fungi and pests. Stubble cultivation helps eliminate weeds by deeply burying seeds or runners. Leaving a field uncultivated for an extended period, especially post-cereal harvest, can result in overgrowth of self-seeding crops and stubble, complicating future cultivation efforts.

The Key to Success

Post-harvest soil cultivation involves harrowing, cultivating, tilling, or plowing. These activities should align with the current soil conditions, which are influenced by factors such as weed infestation, clodding state, type and class, water infiltration and retention, and soil nutrient levels. The timing and intervals of post-harvest operations are also crucial. Accurate assessment of these factors and proper timing of operations are essential to ensure favorable conditions for the next planting season. Ensuring satisfactory yield in terms of both quantity and quality is equally important.

Summary

Stubble cultivation is an important agrotechnical procedure. Its primary tasks are to limit unproductive water evaporation and to mix post-harvest residues with remaining mineral fertilizers, organic matter, or lime. It is commonly accepted that stubble cultivation must be carried out quickly. However, this does not mean that it can be done carelessly, as it is a significant procedure that greatly impacts future yields. It can be stated that stubble cultivation fully deserves to be considered a necessary farming procedure. It reduces water loss, helps control weed growth by stimulating the germination of fallen seeds from crops and weeds, and enables some level of production ecologization by eliminating glyphosate. At the same time, it is a procedure that must be performed by following a few principles described above. When managing cultivation aggregates equipped with straw rakes, it is essential to remember to do it diagonally to the direction of the combine harvester, and the procedure itself should be done as shallow as possible.