Stagnant water in spring is the initial indication of a plough sole. During the growing season, this results in improper crop root development. The final, markedly noticeable sign is the high sensitivity of plants to water shortages. By excavating an open pit in this area, the issue becomes apparent. It is advisable to perform this several times during the growing season to assess root development.

The plow sole, also known as the tillage pan, is a soil layer compacted due to consistent plowing at the same depth over many years. This results in a harder soil layer just below the plowed depth, which acts as a barrier to plant roots, water flow, and air exchange. The plow pan negatively impacts plant growth by limiting root access to deeper soil layers, which contain essential nutrients and water. It can also cause drainage issues, leading to water stagnation in the soil's surface layers. The solution to the plow sole problem is subsoiling, which involves mechanically breaking up this compacted layer to improve soil structure.

The plough sole, which impedes root growth and rainwater infiltration, typically forms beneath the humus layer at a depth of approximately 30-40 cm. To accurately determine its location, a sharpened rod can be used. After creating an open pit, the rod is driven into the ground. Detectable resistance signifies the presence of the sole. This test should be conducted when the soil is adequately moistened; in very dry conditions, the rod will encounter significant resistance. The test will help assess the plough sole's depth and thickness, allowing for proper adjustment of the subsoiler's working depth. Subsoiling to a depth of 50-60 cm is not always necessary. Note that subsoiling is energy-intensive, with each additional centimeter of depth typically consuming about 1 liter of diesel per hectare.

The purpose of subsoiling is to loosen the plough sole. When loosened, the roots reach deeper, which is the main purpose of this procedure. In our country, lessive soils dominate. This means that beneath the humus layer there is a leaching level, and below that, an enriched level. Due to rainwater from the upper soil layers, the clay components have been washed to lower levels. Small soil fractions accumulate water better, so without the plough sole, plants can utilize it.

The purpose of subsoiling:
- breaking the compacted layer of soil below the topsoil to enhance water infiltration and plant root growth
- improving air exchange within the soil
- increasing the soil's water storage capacity
- enhancing nutrient availability for plants

The subsoiling procedure should be performed when the soil is dry. The working elements underground must lift the soil; when the soil is dry, it cracks easily over the entire width of the crop. Therefore, the time after harvest and early autumn is the optimal period for deep soil loosening. By working deeply, we reach the ground level with a fraction that stores water well. If subsoiling is performed in overly humid conditions, the effect may be contrary to the intended one, as the wet soil will smear.

Subsoiling benefits:
- enhanced root access to water and nutrients in deeper soil layers
- improved soil health through better aeration
- reduced risk of surface water accumulation
- increased fertilization efficiency.

The range of machines for deep loosening and eliminating the plough sole is extensive. Rolmako manufactures, among others, the U602 universal subsoiler with straight tines and subsoilers with tines deflected to the side, known as the Michel tine, models U608, U614, and U619. The Rolmako U624 chisel plough with the Ripper tine is also effective for this purpose. The wider the subsoiler legs are spaced, and the wider the working elements are, the deeper the soil can be loosened. A chisel plough, with its working elements arranged much more densely, is designed for shallower operation, e.g., 40 - 50 cm. Rolmako also produces the DeepTiller chisel plough, which can work at a depth of 65 cm.

Conditions and timing for the procedure:
- perform subsoiling during a dry period to prevent soil compaction by heavy equipment
- when compaction of the topsoil layer is identified (e.g. based on plant growth observations or soil tests)
- frequent subsoiling is not recommended; only perform as necessary to avoid degradation of soil structure
- the procedure is best conducted in early autumn, but can also be done in early spring before the growing season.

The plough sole is typically formed when plowing occurs under excessively wet conditions. The tractor wheel operating in the furrow compacts the soil several dozen centimeters deeper. Cultivating overly wet soil results in compaction, even under simplified systems. Errors leading to soil compaction necessitate corrective measures requiring significant energy.

Crop rotation is crucial. Cultivating deep-rooted species naturally subsoils the land, such as rapeseed, sunflowers, or sugar beets. However, excessively compacted soil hinders proper root system development.

Summary
The benefits of subsoiling include: breaking up the plough sole, improving water infiltration, enhancing soil aeration, increasing root access to nutrients and water, improving fertilization efficiency, increasing soil water storage capacity, reducing surface ponding, increasing microbiological activity, reducing erosion risk, and optimizing soil temperature for plant growth.