The preliminary surveys conducted with the use of a field density meter allowed for the identification of a compacted soil layer in the fields tilled with the use of the No-till technology. The depth of this layer varies across fields within the range of 8-23 cm with the average value of about 15 cm.
Fig 2 shows photographs of soil profiles laid out for morphological studies of the soil cover and soil sampling to determine the bulk density of soils in laboratory conditions.
The morphological studies of the soil cover allowed us to make up morphological descriptions of soil profiles.
a) Soil profile (a) is laid in sunflower crops on the experimental field with the use of direct seeding technology. The thickness of horizon A
plough is 22 cm. The color is black, homogeneous. The soil is moist, loose, granular, heavy loamy. Horizon AB with a thickness of 17 cm stands out. The color is black, homogeneous. The horizon is moist, dense, merged, heavy loamy. The transition to horizon B is gradual. The depth of horizon B is 27 cm. The color of the horizon varies from dark chestnut to light chestnut. The color heterogeneity is due to numerous inclusions of loess with lime nodules and humus streaks. The horizon is damp, dense, the structure is coarse-cloddy, heavy loamy. The transition to horizon C is gradual. Horizon C extends to a depth of 66 cm. The color of the horizon is homogeneous. Single inclusions of loess with lime nodules are observed. The horizon is dense, moist, structureless, heavy loamy.
b) Soil profile (b) is laid in sunflower crops on the experimental field with the use of the traditional technology. The thickness of horizon A
plough is 28 cm. The color is black, homogeneous. The soil is moist, dense, granular, heavy loamy. The 16 cm thick AB horizon is weakly manifested. The transition is gradual. Transitional 25 cm thick horizon B is distinguished. The color of the horizon changes from dark chestnut to light chestnut. The color heterogeneity is due to numerous inclusions of loess with lime nodules and humus streaks. The soil is moist, dense, the structure is coarse-cloddy, heavy loamy. The transition is gradual. Horizon C extends to a depth of 69 cm. The color of the horizon is chestnut. The horizon is evenly colored. Inclusions of loess with lime nodules are observed. The horizon is dense, moist, structureless, heavy loamy.
c) Soil profile (c) is laid in the land plot with natural vegetation. Horizon A
0 represents grassy litter of grass-forb vegetation mold 4 cm thick. The thickness of horizon A is 23 cm. The color is black, homogeneous. The soil is fresh, loose, fine-grained, medium loamy with abundant inclusions of small roots. The transition is sharp. Horizon B is 47 cm thick. The color is light chestnut, heterogeneous due to numerous inclusions of loess with lime nodules and humus streaks. The soil is moist, dense, the structure is coarse-cloddy, medium loamy. There are molehills. Horizon C extends to a depth of 60 cm. The horizon is chestnut, evenly colored. There are no inclusions of loess with lime nodules. The soil is compacted, moist, structureless, medium loamy.
The conducted morphological studies of the structure of the studied profiles made it possible to establish the upper boundary of the compacted layer of soils tilled with the use of the No-till technology as well as the thickness of this layer. For the soil of the experimental field, this indicator is 20 cm-horizon AB of the soil profile (a).
Table 1 shows the data of laboratory studies of the bulk density of the surveyed soils. Analysis of the data presented in Table 1 allowed us obtain the following information.
1. In general, if we evaluate the arithmetic mean values of the index of soil bulk density, then all the studied variants correspond to an equal value of 1.1 g cm
3-1.
2. The maximum values of the soil bulk density index are as follows: 1.4 g cm
3-1 - for a 80-90 cm layer of the soil profile (a); 1.31 g cm
3 1 - for a 60-70 cm layer and a 70-80 cm layer of the soil profile (b); 1.43 g cm
3-1 - for a 50-60 cm layer of the soil profile (c). These values correlate with the morphological description of the soil cover and refer to the soil horizons with the maximum content of loess with lime nodules. The carbonate soil layer is an important distinguishing feature of steppe soils.
3. The minimum values of the index of soil bulk density are as follows: 0.86 g cm
3-1 - for a 0-10 cm layer of the profile (a); 0.81 g cm
3-1 - for a 10-20 cm layer of the profile (b); 0.94 g cm
3-1 - for a 0-10 cm layer of the profile (c). These values refer to the surface layers of the soil. The lowest soil density refers to the variant of the soil tilled according to the traditional technology.
The data of laboratory analyses confirm the data of preliminary studies conducted with the use of a field density meter that let reveal the compaction of the root layer of soil in the fields tilled according to the new technology. The bulk density of the soil cultivated with the use of the No-till technology is equal to 1.33 g cm
3-1 for a layer of 10-20 cm.
In recent decades, No-till technology has been widely introduced into farming practice
(Pittelkow et al., 2015; Kiryushin, 2013;
Ovchinnikov et al., 2011; Duboc et al., 2011). The development of ideas on minimizing tillage has also been promoted by the current climate agenda to achieve carbon neutrality
(Chen, 2021;
Liu et al., 2022; Huovila et al., 2022; Reijnders, 2023) in all spheres of human activity, including agriculture.
According to FAO, No-till technology refers to conservation agriculture, which is based on three principles
(Mandal and Mani, 2020;
Choudhary et al., 2016): 1 - minimal mechanical impact on soil; 2 - permanent soil organic cover; 3 - plant species diversification. The practice of conservation agriculture is aimed at preserving and increasing soil fertility, improving soil moisture availability and increasing soil biological resources, which are the most urgent issues under anthropogenic pressures and climate change
(Gupta, 2019;
Kust et al., 2020; Derpsch et al., 2010; Belyakov and Koshelev, 2023;
Zhang et al., 2022; Tufa et al., 2023; Francaviglia et al., 2023).
A number of authors
(Kiryushin, 2013;
Konischev, 2020;
Tupitsin and Valiaiki, 2001;
Cherkasov et al., 2011) argue that the “primitive” minimization of tillage established in Russia leads to increased erosion processes, weediness of crops and, in the eastern steppe regions of the country, to the growth of dust storms, which has been happening recently
(Belyakov and Koshelev, 2023;
Belyakov, 2021;
Kulik and Dubenok, 2016;
Shinkarenko et al., 2020).
As a result of our research it was established that on the studied fields of the farm with No-till technology the problem of erosion processes development differs significantly. Thus, the territory of Agro-1 (Novokievka farm) belongs to Medveditsky Yars territory with an average manifestation of gully erosion 1-2 km km
2-1; the territory of Agro-3 (Bocharovsky farm) belongs to Khopersko-Buzulukskaya plain, territory with a weak manifestation of gully erosion at 0.2-0.5 km km
2-1.
These specific indicators are eloquent evidence of the fact that the problem of erosion processes development is more relevant for the farm Agro-1. Closely related to the development of gully erosion is the problem of soil cover condition of hollows located on arable land. To assess the state of the processes in Agro-1 (Novokievka village), ground reconnaissance reconnaissance traversals of some hollows were made (Fig 3). Traversals of the hollow valleys showed active, progressive state of erosion processes. As one moves from the top to the mouth of the hollows, one can observe traces of water erosion everywhere-transit outflow and accumulation of fine-grained soil. Soil washout processes are very strongly developed in the hollows-one can observe outcrops of bedrock (clay) in the hollows’ thalweg. Water channels are concentrated and form a single channel. The mouths of scour holes are interlocked with the existing hydrographic network (gullies) - the stage of transition of scour holes into gullies or the “hanging gully” stage.
The results of our research indicate a higher soil density of fields cultivated with No-till technology in comparison with conventional tillage. They are consistent with the research data obtained for chernozems of the Voronezh region
(Struchkova et al., 2019; Artemyeva et al., 2019).
According to Selezneva,
Dedova (2019) the density of erosion network for different territories of Volgograd region varies 40 times from 0.1 to 4 km km
2-1. An increase in soil density in the 20-30 cm layer especially in rugged terrain can contribute to the development of erosion processes, because during spring snowmelt due to over-compacted soil layer, surface runoff may not pass into in-soil runoff
(Barabanov, 2020;
Barabanov et al., 2018; Yasinsky and Kashutina, 2007;
Dagesse, 2010;
Cerda et al., 2021; Kumar et al., 2022; Hieke and Schmidt, 2013), this is also true for storm precipitation in the rest of the seasons of the year.
Thus, in conjunction with other aspects of the impact of the application of the technology under consideration
(Struchkova et al., 2019; Nikitin et al., 2020; Voloshenkova et al., 2021; Singh et al., 2010; etc.), it is important to note the need to develop a set of measures aimed at compensating for the impact of factors that reduce crop yields, weediness of crops, development of erosion processes and further improvement of this technology in the zonal aspect for the territory of Russia.
