Category: Specialist consultations
Andrey Kalinin, Doctor of Technical Sciences
From magazine No. 4 2015
We hope that for each of us, when choosing a particular product, there is always a comparison of its Form and Content. Of course, the ideal option is when high-quality content is designed accordingly. If we talk about modern mechanical engineering, design developments make it possible to aesthetically design a high-quality product. In this case, form and content go together, hand in hand.
When cultivating potatoes at the time of ridge formation, Form and Content come into conflict between external gloss and qualitative indicators of soil condition throughout the entire growing season. Let's consider the internal component of Form and Content to make a rational decision when choosing the configuration of machines for cultivating potatoes.
Every potato grower knows that the formation of ridges using modern European technologies is carried out as an independent operation 1-2 weeks after planting (Fig. 1) or simultaneously with planting when installing the appropriate ridge-forming module on a potato planting machine (Fig. 2). In both cases, potato growers want to obtain high-volume ridges with a cross-sectional perimeter exceeding 90 cm (Fig. 3). Such ridges have a height of 27...30 cm from the bottom of the furrow to their top, regardless of the row spacing. The correct shape of the ridges is obtained through the use of ridge-forming plates installed on row-crop cultivators of the milling type GF or with passive working bodies GH, as well as on trailed/mounted potato planters. Compacted ridges with a smooth surface, according to plant protection experts, provide the formation of a screen of soil herbicides to reliably protect potato plantings from weeds. There is no doubt that such smooth and even ridges, pressed with a plate on all sides, are pleasing to the eye and give hope for a high yield.
The formation of ridges can be performed by other working bodies, also installed on row-crop cultivators or potato planters, but so far little known and little in demand by Russian potato growers. We are talking about a combination of hilling bodies and a profile bar roller installed instead of a ridge-forming plate on a passive cultivator GH (Fig. 4), as well as on potato planters (Fig. 5) of a mounted or trailed type.
The ridges formed in this way do not look as impressive as after the passage of the ridge-forming plate, they have a relief surface along the entire perimeter, their height does not exceed 23 cm (Fig. 6), there is no need to talk about the perimeter of the cross section, and the ridge itself looks loose and not as durable as its ironed counterpart. In a word, the result of such ridge formation is not pleasing to the eyes and there is a desire to perform a second operation to correct the improper appearance. In addition, crop protection specialists will express their doubts about the reliable action of soil herbicides due to the difficulty of forming a film screen on an uneven surface.
When comparing different methods of ridge formation, the conclusion suggests itself in favor of the use of ridge-forming slabs as part of row-crop cultivators or potato planting machines. However, it is not without reason that they say that all that glitters is not gold, and in order to make informed decisions when choosing a method for forming ridges, it will be a mistake to rely only on their appearance.
Previously, we described in detail the dynamics of changes in the state of the soil inside the ridge during the entire potato growing season when using ridge-forming slabs (magazine “Potato System” No. 2, 2015). From this description it follows that in order to obtain a stable ridge, the soil is subjected to three-way compression from the side of the ridge-forming plate. This impact leads to some compaction of the soil inside the ridge, which only increases over time as it shrinks. However, the aftereffect of using ridge-forming slabs is the covering of the surface of the ridges (especially in their lower part) and the compaction of the bottom of the furrow with the divider shares. It is this effect that leads to the destruction of pores inside the soil and water-conducting capillaries on the surface of the ridges, which contribute to the absorption of water that falls in the form of precipitation and the penetration of air into the ridges.
The result of applying the generally accepted scheme for the formation of ridges is colossal losses of the fertile layer, which occur during heavy rainfall or artificial irrigation. This is due to the fact that water, falling on the ridges with a surface crust, flows from them to the bottom of the furrow. Since the compacted bottom of the furrow also has weak absorption capacity, water begins to flow to lower places along the ridges. If a depression is present inside the field, then a depression forms in this place (Fig. 7), which leads not only to the death of potatoes, but also to a decrease in traffic in the fields and difficulty in harvesting in the autumn. If the field is located on slopes, then the flow of water, flowing along the ridges, carries with it the most valuable soil particles into ditches/ravines or forest belts (Fig. 8).
In the summer, when there is heavy rainfall before the tops close, deep gullies are formed on a field with slopes as a result of the use of ridge-forming slabs, and tens of thousands of tons of fertile soil are irretrievably lost every year. Approximately the same picture is observed on irrigated lands for potatoes located on slopes. In this case, with a sufficient level of seasonal precipitation in the upper part of the field, plants may experience a lack of moisture, and in the lowlands where water flows, there may be an excess of it. All of the above examples indicate that the formation of smooth and compacted ridges does not allow the fallen moisture to be evenly distributed over the field area and the full potential of natural or artificial sprinkling to be used, and also reduces the level of soil fertility due to the removal of the most valuable soil particles by water flows along the bottom of the furrows size 1...3 mm.
A slightly different picture of the moisture supply regime is observed when forming ridges using a combination of loosening paws, hilling bodies and profile bar rollers, which can be installed on passive row-crop cultivators or on potato planting machines. The bottom of the furrow after passing such a combination remains loose to a depth of 15...18 cm due to the passage of the central loosening paw and partial shedding of the ridge after it is compacted with a roller. The surface of the ridges also remains loose, and the ridges themselves do not crumble under the influence of wind and precipitation, since they are subjected to some volumetric compression by a profile roller, which helps to strengthen them. Water that falls in the form of precipitation or during irrigation does not flow as intensively from the ridges, being evenly absorbed along their entire outer perimeter. The same water that falls on the bottom of the furrow is immediately absorbed into the loose soil, thereby preventing the drift of soil elements into the lowlands. Measurements of soil moisture in the fields after the use of bar rollers showed that its values in the upper part of the field and at the bottom of the slope are small from each other. This indicates the uniform distribution of precipitation over the entire field area, regardless of the difference in elevation. The soil at the bottom of the furrow remains loose and permeable until the very moment of harvesting (Fig. 9), and the harvesting itself can be done 1,5...2 hours after the end of rain of sufficiently high intensity (on plantings using ridge-forming slabs in the same weather conditions from -due to waterlogging of the furrow bottom, the resumption of harvesting had to be postponed for 1..2 days). When using artificial irrigation to achieve the required soil moisture inside the ridges, up to 30% less water is required in potato plantings using a combination of ripper arm, hilling body and profile bar roller.
However, using the combination mentioned above to form ridges requires correction of the planting depth. Due to the fact that the height of the ridge after passing such a combination is 5..7 cm less than after using a ridge-forming plate, it is necessary to increase the planting depth by the same amount. Ignoring this rule leads to the appearance of green tubers (Fig. 10) on the soil surface, which significantly reduces the commercial properties of the resulting products.
At the end of this review, it should be noted that Grimme machines for planting potatoes and for inter-row tillage can be equipped with various ridge formation systems upon customer request. Therefore, before making a choice of one or another method of forming ridges, you need to find out for yourself whether their correct shape will always correspond to the required content according to the moisture supply regime and help protect fields from water erosion. This is especially true for those farms that irrigate potatoes or whose fields have slopes in accordance with the topography of the earth's surface.