Hard soil with a lot of stones Farmers sometimes use the phrase that stones "grow in the fields." For those unfamiliar with the topic, this may sound amusing, but it is not. It is estimated that in Poland, 10-15% of the arable land consists of soil in which the stone content exceeds the conventional threshold of 10 tons per hectare, with 40% of the stones in the arable layer measuring 10 to 60 cm in diameter. This value is not constant, as the processes of soil freezing and thawing, along with drying and wetting, lead to the emergence of an increasing number of boulders each year. This presents a serious problem. Stones in the field damage tubers and reduce crop yields. They also diminish machine efficiency and cause failures, leading to the rapid wear of working elements due to friction. Rolmako addresses these challenges by offering non-stop machines equipped with protective mechanisms such as shaped springs (pressure, tension, wound into screws, torsion, etc.), rubber elastomers, and hydro-pneumatic accumulators. Each cultivation machine is developed with tailored protection for its working elements, adapted to the specific conditions in which it operates. Various protection options against stones enable obstacle bypassing and uninterrupted work without downtime or replacement of screws or damaged working components.

Densities within the soil profile
Soil compaction deep within the profile is typically caused by the pressure exerted by various agricultural equipment. Throughout the year, a farmer traverses several dozen kilometers in the field, often repeating the same route. In traditional grain cultivation, wheel tracks cover approximately 54.5% to 61.4% of the field area. In Poland, it is estimated that 15% of the total soil area is exposed to high-level compaction, and 22% to medium-level compaction. Such compaction results in denser soil, which is less rich in water and nutrients, adversely affecting plant development. A common example is poorly developed, short beet roots. Consequently, crop yields can drop by up to 30%, and their quality deteriorates. Furthermore, increased soil compaction damages all elements operating within the soil, leading to greater resistance and loads on various machine components. To mitigate these negative effects, Rolmako introduces several cultivation simplifications using the tractor's front three-point linkage, allowing two machines to be connected into a set via various couplings. This approach reduces the number of work passes in the field and saves money.

MORE ABOUT CULTIVATION SIMPLIFICATIONS

Surface densification due to drought
Surface soil compaction is a physical manifestation of soil drought. Due to lack of rainfall, high temperatures, and strong winds, soil deprived of water changes its structure. Particularly in dense soils, this leads to characteristic cracking. This phenomenon is highly dangerous because the destruction of humus and deep cracks deprive deeper soil layers of water and damage plant roots. This negatively impacts both current and future crops. The occurrence of soil compaction in the surface layer can decrease yield by an average of 10-20%. Moreover, failure to take appropriate measures in time exacerbates this problem.

Selection of appropriate machines
The recommended solution for cultivation in stony soil is to purchase a descaling machine. However, the cost is substantial. Additionally, ordering such a service is expensive, as descaling the field is a time-consuming and energy-intensive process.

A simpler and more economical option is to invest in "massive structures" of cultivation machines made of high-quality, durable steel. The most popular structural steel is S235, but this is insufficient for agricultural machines that must cope with drought conditions and a large accumulation of stones. This commonly used type is characterized by inadequate resistance to high impact loads and is only suitable for small cultivation runs. At Rolmako, we use much more durable and resistant fine-grained steel, S500 and S700, to build cultivation machines.

The type of steel or alloy is also of significant importance. The hardest building materials include boron steel, carbon steel, HARDOX, and cemented carbide. The hardness of steel and its resistance are measured in HCR units. Generally, higher values indicate better performance. The same applies to the thickness of steel: thicker profiles are more durable. It is essential to use the best possible steel not only for working elements but also for the frame, the three-point hitch tower, all perforated elements, bushings, roller rings, etc. These elements are highly susceptible to loads when working on a stony field. At Rolmako, there is no room for compromise; the steels used and the processing techniques meet the highest quality standards and are chosen for high mileage and the most challenging cultivation conditions.

The production method is crucial. Modern technologies enable precise millimeter fitting of structural elements, akin to assembling puzzles, followed by perfect welds at the joints. The technology for processing pipes and profiles allows for chamfering connected elements, significantly enhancing the strength of welds. Hole elements, as well as those with pins and screw connections, are created with the same precision. Laser techniques significantly increase the strength and lifespan of the machine.

It is also worth mentioning shock absorbers, which are designed to protect working elements when encountering a stone or other obstacle. Typically, screw protection is common. However, in fields with many stones, this becomes problematic. Maintenance-free rubber shock absorbers (in disc harrows), spring protection (in cultivators), or hydraulic protection (in subsoilers) are more effective. Their operation principle is similar: when the working element encounters an obstacle, the shock absorber causes a quick deflection up and down, allowing work at a set depth for each element separately.

Compaction deeper into the soil profile
"Robust" Rolmako machines, due to their durability, effectively address deep soil compaction. Utilizing modular units or transitioning to simplified cultivation, if feasible, can reduce the number of field passes. Equipment such as a heavy disc harrow, a no-plough cultivator, and a chisel plough are suitable for this purpose. Although assembling such heavy machinery increases ground pressure, on compacted and stony soils, the greater weight enhances ground pressure and field loosening force, permitting effective operation where lighter machines may fail.

In cases of stagnant water, subsoiling is recommended, involving soil loosening up to 60 cm. A pass with a subsoiler or chisel plough, such as those from Rolmako, will reduce soil bulk density and increase its permeability and porosity. This procedure only needs to be performed once every few years.

Surface compaction
In the case of surface soil compaction, subsoiling, ploughing, or any deeper loosening of the soil is not recommended, as it would exacerbate the situation. It is advisable to perform shallow plowing promptly or employ another method to mix the chopped straw with the top layer of soil. This will create mulch and prevent seepage and evaporation of water from deeper layers.

Before sowing, loosen the soil to the depth of sowing and place the seeds on a moist substrate to facilitate water absorption. ComboTill cultivators and SpeedCutter ultra-shallow harrows manufactured by Rolmako are highly effective for this purpose. Integrating additional cultivation and seeding devices can reduce the number of field passes, thereby minimizing compaction and enhancing soil quality.

Terminology
Soil freezing and thawing - this term refers to the process by which soil changes state depending on temperature. During periods of low temperatures, water contained in the soil freezes, causing its volume to expand and increase pressure on the surrounding materials.