Clause 16 of the Reforestation Rules states:
Promotion of natural reforestation through soil mineralization is carried out in areas where there are sources of seeds of valuable tree species of forest plantations (adjacent forest plantations, individual seed trees or their groups, clumps, strips, under the canopy of forest plantations entering felling with a density of no more than 0.6) .
Soil mineralization should be carried out in years of satisfactory and abundant harvest of forest seeds. The best time for mineralization of the soil surface is before the seeds of forest woody plants begin to fall.
Work is carried out by treating the soil with mechanical, chemical or fire means, depending on the mechanical composition and moisture of the soil, the density and height of the grass cover, the thickness of the forest floor, the degree of mineralization of the soil surface, the number of seed trees and other site conditions.
In clearings and plantings where soil mineralization is planned, permanent trial plots of 0.5-1.0 hectares are established to assess the effectiveness of these measures. Their number is established depending on the size of the plots, but not less: on areas up to 10 hectares - one; from 10 to 25 - two; over 25 hectares - three. The trial plots are divided into two parts: one is left for control, the other for carrying out such activities as throughout the entire site. On each part of the trial plot, undergrowth and self-seeding of all species are taken into account.
Counts of self-seeding and young trees aged two years and older are carried out on counting plots measuring 2x2 m, laid in rows at the same distance. The number of rows (passes) must be at least three in each trial plot. The total number of sites is at least 25.
Accounting data is entered into registration cards, which serve as the basis for filling out a list of areas designated to promote natural regeneration, and a notebook (book) for recording areas with measures taken to promote natural regeneration.
In addition to logging, natural regeneration can be promoted under the forest canopy. Soil mineralization to promote natural reforestation is carried out in forest stands with a crown density of no more than 0.6 and in places where there is no undergrowth. In spruce forests, soil mineralization occurs 7-10 years before felling, and in pine forests - 3-5 years. In pure coniferous forest stands, the soil is mineralized in late summer and autumn, in mixed forest stands with the participation of deciduous species in the composition of more than 0.1 - in late autumn after the leaves have fallen.
Tree stands in which soil mineralization has been carried out to promote regeneration are subject to felling in winter.
Soil mineralization is not carried out in clearings with relatively fertile or wet soils.
The size of the cultivated area under the forest canopy should be at least 15-20% of the area of the site, in clearings - 30%.
Methods and technical means for removing ground cover are selected depending on the types of trees, their growing conditions, the degree of turf, the type of soil, its moisture and density, etc.
In clearings with dry and fresh sandy, sandy loam soils in groups of forest types: lichen, heather and lingonberry pine forests, soil mineralization to promote the natural regeneration of pine is carried out in strips 20-30 cm wide to a depth of 5-7 cm. In non-turfed 1-3-year-old clearings with fresh and moist sandy loam and light loamy soils in groups of forest types: pine and spruce forests, complex and blueberry, soil mineralization is carried out in strips at least 1 m wide to a depth of 7‑9 cm. In clearings with loamy and heavy loamy damp and wet soils in forest types: long-moss pine forests and blueberry-small-grass and brook spruce forests, soil mineralization in clearings is carried out by plowing layers 10-20 cm thick. The distance between mineralized strips or layers should be 2-5 m.
To mineralize the soil in clearings and under the forest canopy, special cover strippers are used - seeders, cultivators and plows.
In fresh fellings in sorrel and similar forest types, shallow loosening is recommended with the removal of the soil layer and litter to the surface of the humus horizon, carried out using forest plows PKL-70, PLP-135, PL-1, etc. When processing with PKL-70 plows , forming a mineralized strip width of 1.4 m, furrows are laid every 2-4 m, and when processing with PLP-135 plows, creating a mineralized strip 2.7 m wide - after 5-6 m. On sites with wet and damp soils (with excessive moisture), soil mineralization is combined with drainage measures, laying a network of furrows through 10-30 m. For this purpose, they use PKLN-500 ditch plows, LKA-2M and LKN-600 ditch-diggers, and even TE-3M, E-304V, E-5015, etc. excavators. This equipment is recommended for use on long-lasting, sphagnum, meadowsweet, lancet-reed, etc. types of clearings with waterlogged soils.
In most cases, these plows are used for their main purpose - to prepare the soil in clearings and under the forest canopy, during artificial reforestation and reclamation work. They will be discussed in more detail below. More often, when mineralizing the soil in order to promote natural regeneration, various types of cover strippers, rippers, cultivators and cutters are used. These tools perform loosening with simultaneous mixing of the litter and the upper mineral horizon in strips 0.5-2.0 m wide to a depth of 5-10 cm. The distance between the loosened strips, depending on the success of natural regeneration, is 2-4 m in clearings, and under the canopy forests - 3‑6 m. Distance between loosened strips b can also be calculated using the formula:
Where B– working width of the unit;
k m– the mineralization coefficient adopted to ensure the receipt of a sufficient amount of undergrowth of main species (10-20 thousand pieces per 1 ha) equal to k m=0.25-0.30 area with unsatisfactory natural renewal;
k rho– coefficient that takes into account the degree of mineralization in the processed strip depending on the type of working parts of the implements and is taken equal to: 1.0 – for plow bodies; 0.5-0.6 – for machines with disk working bodies with a single pass and, respectively, 0.7-0.8 and 0.9-1.0 – with two- and three-track processing;
k doors– coefficient taking into account the nature of the movement of the implement, taken equal to 1.0 for strip processing, and 1.85 for cross processing.
The anchor peeler YAP-1 (Fig. 2.1) is intended for preparing the soil in ungrazed clearings and under the forest canopy by stripping the vegetation cover to the surface of the humus horizon. It consists of two dimensionless anchor-type sections connected by a chain. The first section is lighter and has the shape of an irregular hexagonal pyramid, to the base of which working bodies in the form of paws are welded. The second section is heavier and has an oblong shuttle-shaped shape, with ripping arms welded in the middle of the base. When the anchor peeler operates, the paws of the front section rip off the ground cover, and the paws of the rear section loosen the mineral soil to a depth of 4‑5 cm. The YAP-1 is mounted on tractors TDT-55, Onezhets-300, TLT-100, TDT-44 or LHT-55 , to which it is connected by a chain.
Rice. 2.1. Anchor skin peeler
On ungrown clearings with the number of stumps up to 800 pcs. for 1 hectare, littered with logging residues, dead wood, stones, as well as in wastelands and burnt areas, cover strippers-rippers are used (Fig. 2.2) RL-1.8 and PL-1.2, aggregated with tractors Onezhets-300, TLT-100, TDT-55, LHT-55, T-100M, etc. They are designed for stripping forest litter and moss cover while simultaneously loosening the soil in strips to promote natural regeneration. The RL-1.8 ripper consists of a frame with consoles and a trailer, a shaft with a double-sided bracket, working parts in the form of teeth, two wheels with stops, locking and locking mechanisms. At the rear of the frame there is an axle with brackets into which chisel-shaped teeth are inserted. At the ends of the axle there are wheels with stops and semicircular grooves. When transporting implements over long distances, plugs are inserted into the grooves, which give the wheels a normal round shape. When the unit moves, the teeth go deep into the soil and loosen it. When encountering an insurmountable obstacle or when the teeth are clogged with dead wood, the locking mechanism releases the wheels, and they begin to rotate the axle with teeth 180°, after which the second row of teeth takes up working position, and the locking mechanism locks the wheels again. Thus, the ripper teeth seem to “step over” obstacles. The forest cover peeler PL-1.2 has a similar device and operating principle.
Rice. 2.2. Forest cover peeler
Disc implements are widely used for soil mineralization in clearings: forest ripper RLD-2, disc cultivator DLKN-6/8, disc cover stripper PDN-1, furrow cultivator KLB-1.7 (the main purpose is to care for crops planted in the bottom of furrows ). The design and principle of the influence of the working bodies on the soil are largely similar. Disc guns use spherical solid or cut-edge (more often) discs mounted at an attack angle of up to 45°. The disks are assembled into batteries by placing them on a square axis and installing bearing coils between them, which ensure, in addition to a strictly maintained distance between the disks, rotation in the bearings (Fig. 2.3).
Rice. 2.3. Disc peeler
The RLD-2 ripper (Fig. 2.4) has a battery consisting of two disks. The batteries are placed along the tracks of the tractor tracks, which protects the disk batteries from impacts, because the tractor driver chooses a direction of movement that prevents the tracks from hitting stumps. In addition, the use of spring-loaded stands, which allow the discs to deflect when encountering stumps or roots, protects the batteries from damage. Safety springs are found on guns such as PDN-1 and KLB-1.7. The latest guns provide for adjustment of the angle of attack of the discs due to rotating devices consisting of movable and fixed plates, fixed with bolts in the adjustment holes. These guns also provide adjustment of the stroke depth up to 10-12 cm through the use of ballast boxes.
In the PDN-1 skin peeler, spherical disks are installed on balancers and arranged in a herringbone pattern, with the front and rear disks overlapping each other in the transverse plane. The balanced suspension allows the discs to follow the microrelief and ensures a high degree of soil mineralization. In the middle part of the implement frame, in front of the disks, a spring-loaded ripper arm is hinged, which deflects when it encounters an obstacle. Using a ballast box mounted on the rear of the frame, the working depth can be adjusted up to 12 cm.
Rice. 2.4. Forest disk ripper RLD-2:
1 – battery disk; 2 – stand; 3 – safety spring; 4 – frame; 5 – hitch; 6 – seed drum; 7 – shaft; 8 – friction drive; 9 – spring
In strip tillage, areas set aside to promote natural reforestation through soil mineralization are divided into paddocks. It is advisable to take the length of the rut at least 200 m, and the width - at least 100 m. With smaller plot sizes, a significant part of the time is spent on idle travel at the end of the rut.
In wild rosemary and sphagnum pine forests, bog cutters FBN-0.9 and FBN-1.5 are used for milling peat with simultaneous rolling for capillary rise of moisture. In fresh and underdeveloped felled areas with the number of stumps up to 600 stumps/ha, the FLU-0.8 forestry cutter is used to promote natural regeneration (Fig. 2.5). The design of these cutters is similar, while the FLU-0.8 cutter is unified with the FBN-1.5 cutter. The main components of the cutter are: a frame with an attachment, a cardan transmission, bevel and spur gearboxes, a milling drum, a rake grid, a mechanism for adjusting the processing depth and a protective casing.
Rice. 2.5. Diagram of the FLU-0.8 cutter:
1 – attachment; 2 – protective casing; 3, 4 – bevel and chain gearboxes; 5 – adjustment holes for the deepening mechanism; 6 – rake; 7 – milling drum; 8 – limit skid; 9 – hinge of the limit skid; 10 – frame; 11 – cardan transmission
The working part of the cutter is the milling drum. It contains driving and driven disks that interact with each other through friction pads. Eight L-shaped knives are attached to each driven disk: four right and four left. The driven discs with knives sit freely on the shaft, and the driving discs with friction linings are mounted on the shaft on splines. The driven and driving disks are pressed by their working surfaces against each other using springs. Transmitting rotation to the driven disks using friction clutches allows them to slip on the drum shaft when encountering insurmountable obstacles in the form of stumps, stones, large roots, logging residues, etc., and thereby protect the knives from breakage. The actuation moment of the clutches is adjusted by compressing the springs using two adjusting nuts located on the sides of the milling drum. The processing depth of the FBN-0.9 and FBN-1.5 cutters is up to 20 cm, and the FLU-0.8 cutter is up to 16 cm.
When the tractor moves with the power take-off shaft turned on, the milling drum rotates, and its L-shaped knives crush soil and roots with a diameter of up to 4 cm, throwing the crushed mass onto a rake grid, which additionally crushes large fractions of turf. Plant residues and large fractions are retained by the grate and remain in the lower part of the treated soil layer, and small fractions pass through the rake grate and fall asleep on top of the treated layer. In one hour of operation, the cutter can travel up to 3 km.
It should be noted that promoting natural regeneration can be successful when 15-25% of the cleared area is treated. Since soil mineralization is a labor-intensive process, it should be resorted to when there is a sufficient amount of seed deposits from the seed plants or the forest wall. If there are seeders with a yield not lower than average, the soil should be cultivated at a distance of no more than 100 m. In deciduous plantations, the soil is cultivated after the leaves have fallen. When prescribing soil tillage with implements to promote natural regeneration, one should take into account the percentage of mineralization obtained during timber harvesting (removal of litter by machines and moving trees and canes). After self-seeding appears on mineralized strips, it is necessary to systematically care for it. Given this, it may be that the cost of promoting natural regeneration may be close to the cost of establishing forest crops. In this case, it may be more appropriate in the absence of a deficiency labor resources switch to artificial reforestation.
It is known that even a large number of seeds that have fallen to the surface of the litter often cannot ensure regeneration under the canopy and in clearings. At the same time, it has long been noted that mixing the litter with underlying soil horizons or simply exposing the mineral layer leads to good germination of seeds, establishment of seedlings and their transformation into undergrowth. This phenomenon is the basis for a very common method of planned promotion of forest regeneration called soil mineralization. Mineralization, both under the forest canopy and in clearings where there are sources of contamination, is carried out in productive years.
With dry sandy soils in clearings, removing litter in small areas or strips 20-25 cm wide is sufficient. Here the living cover grows slowly and cannot quickly colonize the mineralized strip. On fresh loamy and sandy loam soils, it is necessary to make a strip up to 1 m wide or areas of 1 m2. On wet soils it is useful to create micro-rises. If the soil is wet or very fertile, then mineralization, as a rule, does not give positive results.
If the above activities are carried out under the forest canopy (if the canopy density is below 0.6, this is useful to do), then in spruce forests this should be done 7-10 years before felling, and in pine forests 3-5 years. The treated area in clearings should be 30%, and under the canopy 15-20%. Preparing the soil under the tree canopy provides an additional opportunity to obtain natural preliminary regeneration of the forest.
In connection with the allocation of cutting areas 2-3 years before felling in technological map forest exploitation provide for measures to promote natural regeneration under the canopy of spruce, fir, beech, oak and other tree stands: in oak, pine, larch and other mixed plantings, soil loosening 1-3 years before felling, in spruce-fir forest types 5-b years, in beech for 4-5 years.
Tillage is carried out from the second half of summer, and in a mixed forest with the participation of deciduous trees in the fall, after the leaves have completely fallen. Tillage is allowed under the canopy of a pine forest. in early spring, until the end of the mass emergence of seeds from the cones. The main task What is envisaged during tillage is the mineralization of the soil surface, especially where it is covered with herbaceous and mossy vegetation or a thick layer of dead cover. In conditions of damp, excessively moist soils, microelevations are created. If there is an admixture of aspen in highly productive pine and spruce stands, soil preparation is carried out after preliminary ringing of the aspen or its poisoning with chemicals. Ringing is practiced 5-6 years before logging.
Soil mineralization can be done mechanically, by fire or by chemical means. Thus, in fresh meadow and reed clearings, ground cover and litter are removed using cover strippers. Apiary and main trails, as well as places where logging residues are burned, are subject to loosening. High germination of seeds on fire pits was observed in cases where the layer of unburnt litter reached 0.5-2 cm, and with thicker litter or when it was completely burned, seed germination decreased.
In conditions of green moss clearings, soil mineralization by fire brings favorable results, especially where the moss layer is dense. Mineralized strips are created by cover peelers, disc cultivators, bulldozers, rippers and other mechanisms. The total area of treated soil should be 20-30%, taking into account damage to the soil cover during logging.
In clearings with heavily podzolic, loamy, moist and damp soils, micro-highs are created in the form of ridges and shafts using double-mouldboard forest and swamp-shrub plows. To promote natural regeneration in coniferous clearings, it is advisable to prepare the soil in late summer, autumn or early spring.
Long moss and sphagnum fellings are treated with chemical substances. In the second half of summer, microelevations are fertilized with chemicals in 500-600 places per 1 hectare in areas of 1 m2 with a consumption of magnesium chlorate at 15-20 kg/ha and 2.4-D at 0.7-0.8 g per 1 m2.
Reed grass and meadow grass, as well as other cereal plants, are cultivated in the spring, and in the northern subzone of the taiga in the second half of summer in areas of 2-3 m2 in size, 500-600 places per 1 hectare at a consumption of ammonium sulfate of 100 kg/ha.
Clearings overgrown with less valuable deciduous trees, sprayed with 2,4-D butyl ether emulsions in a dosage of 0.3-0.4 kg per 1000 m2 for aspen and 0.1-0.2 kg for birch, alder and hazel. Sodium salt 2,4-D is also used in a dosage of 0.3-0.4 kg per 1000 m2. Treatment is carried out in nests measuring 4-5 m2 (1000-1500 nests per 1 ha) or in strips of varying widths. Spraying of the root shoots of aspen or birch and other species is carried out in the first half of summer, when the apical bud is still forming in the plants.
The greatest difficulties in reforestation occur in clearings covered with meadowsweet, reed grass and meadow grass. Then, due to the difficulty of renewal, there are long-moss and sphagnum fellings. Timely preparation of the soil in cleared areas, before the growth of herbaceous vegetation, facilitates the process of reforestation. In cases where measures to promote natural regeneration do not produce positive results, sowing and planting of forests is carried out.
In oak stands on fresh and moist soils with a completeness of the upper canopy of 0.4-0.6, the soil is cultivated after the acorns have fallen, simultaneously embedding them into the soil. If the soil is heavily turfed, the grass cover is removed in strips 0.8-1 m wide, or in areas of 1×2 or 2×2 m.
In the forest-steppe zone in dry oak groves, the soil is loosened to a depth of 15 cm. In elevated areas, microdepressions are created by removing turf or cultivating mineralized areas. Very often, 1-3 years before felling, acorns are “stuffed” in oak forests. Dense undergrowth is thinned by 40-60%.
In beech stands, before the seeds fall, the litter is loosened and surface layer soil to a depth of 1-2 cm. On gentle slopes, the soil is cultivated only horizontally, and on steep slopes - in areas of 400-600 pcs/ha.
Fencing cleared areas from being eaten by livestock is possible in small areas. There is a particular need to fence off clearings in floodplains and near pastures during regrowth, as they are more sensitive to damage by livestock. In all areas where assistance measures have been taken, grazing, haymaking and litter collection are prohibited.
In the future, one should keep in mind the promotion of forest regeneration by fertilizing it. Other activities that contribute to the resumption of logging include temporary agricultural use.
Plantings that arose as a result of assistance (including from preserved undergrowth) are taken into account in a special book and transferred to a forested area as natural young growth.
The mineral part of the soil arose as a result of the weathering of rocks and minerals in the upper layers of the lithosphere and their transformations during the process of soil formation. This is confirmed by the similarity of the chemical composition of the lithosphere and soils. Under the combined influence on the mineral nature of physical and chemical factors, especially living organisms (plants and microorganisms), profound changes occurred, which led to the formation of soil cover on the surface of the earth's crust.
Thus, the “builders” of the soil are plants and microorganisms, as well as micro- and macrofauna living in the soil, the building material is rocks (parent) rocks and the surrounding atmosphere and hydrosphere, and the energy source of soil formation is solar energy.
Soils inherit the geochemical characteristics of soil-forming rocks. For example, the richness of a rock in silicon oxide also determines its increased content in the soil, and an excess of clay minerals is reflected in their predominance in the genetic horizons of the soil. On carbonate rocks, soils enriched with alkaline earth elements develop, and on saline rocks, saline soils are formed, etc. However, the biological factor plays a decisive role in soil formation.
Under the influence of living organisms in the soil, compared to the earth’s crust, the amount of carbon increased by 20 times, and nitrogen by 10 times. This indicates that plants contribute to the accumulation of biologically important elements in the soil. Soil formation in natural conditions proceeds quite slowly. With the help of fertilizers and proper agricultural technology, the intensity of soil processes can be significantly accelerated. For example, when using fertilizers, the vital activity of not only plants, but also soil microflora is enhanced, which sharply accelerates the processes
savings organic matter and biologically important elements, i.e. soil fertility increases.
b o
s/h “F” [ZD]6"
Rice. 3.1. Groups of compounds of 8O4 tetrahedrons
In the predominant part of soils, the mineral basis of its solid phase is made up of silicon-oxygen compounds. The most common mineral in soil is quartz (silicon oxide). Aluminum and iron for the most part are part of aluminosilicate and ferrosilicate minerals. Silicon atoms combine with oxygen to form tightly bound 8104 groups, in which silicon is surrounded in tetrahedral coordination by four oxygen atoms. Since silicon is tetravalent and oxygen is divalent, the SiO4 tetrahedron has unsaturated oxygen valences and can be considered as a four-charged anion. The ability of SiO4 tetrahedra to connect with each other to form groups of a certain number of silicon and oxygen atoms is very significant (Fig. 3.1).
In the structure of minerals of finely dispersed soil fractions, silicon-oxygen tetrahedra are connected into layers, chains or isolated groups of SiO4 tetrahedra, which are complex anionic complexes, since the oxygen atom that does not participate in the connection between two SiO4 tetrahedra remains with a free valence or one negative charge. IN
In complex combinations of silicon-oxygen tetrahedra, some of the silicon atoms can be replaced by aluminum atoms, which increases the unsaturation of the anionic radical.
In the quartz crystal lattice, the 8104 tetrahedron is connected through shared oxygen atoms to four other 8104 tetrahedra according to the diagram
The general formula of such a compound is (SiO2)i. In feldspars, part of the silicon atoms in a similar structure is replaced by aluminum, as a result of which such a silicon-aluminum-oxygen framework develops a negative charge, which is compensated by the corresponding amount of sodium, calcium and other cations located inside the framework, in the “cavities” of the lattice. For example, feldspar albite, which has the general formula Na^AlOv], is built from interconnected silicon-oxygen and aluminum-oxygen tetrahedra, and for every three silicon atoms there is one aluminum atom and one sodium ion, which neutralizes the negative charge of the framework.
Aluminum in tetrahedral coordination with oxygen or hydroxyl ions forms octahedral groups in which the aluminum ion is surrounded by six oxygen or hydroxyl ions. The general formula of such a compound (layer) [A1(0H)3]l corresponds to the composition of the mineral gibbsite (hydrargillite) found in the soil. The structure of such minerals can be written as follows:
...[(OH)zA12(OH)z] l...[(OH)zA12(OH)z] ¦ and...[(OH)3A12(OH)3] l.
The formula shows the chemical composition of the layer (package), and the points are the interpacket spaces.
Primary and secondary minerals are found in soils. Primary minerals include minerals that have passed from the earth's crust into the soil unchanged or almost unchanged. These include minerals of the soil skeleton: quartz and its varieties, feldspars, including plagioclases, micas, hornblende, augite, tourmaline, magnetite, calcite, dolomite, etc. Primary minerals are part of the parent soil-forming rocks that arose as a result weathering and destruction of rocks, of which
composes the shell of the earth's crust. In soils, these minerals are present mainly in the form of sand-sized particles (from
- 05 to 1.0 mm) and dust particles (from 0.001 to 0.05 mm). In small quantities, some of them are present in the form of silty (lt;0.001 mm) and colloidal (lt;0.25 µm) particles.
The crystal lattice of aluminosilicate minerals of the fine soil fraction is based on combinations of silicon-oxygen tetrahedral and aluminohydroxyl octahedral layers.
In kaolinite, the crystal lattice is formed by packages of two layers interconnected by common oxygen atoms: tetrahedral silicon-oxygen and octahedral aluminum-hydroxyl type
... p... ¦ p.
In montmorillonite, hydromica, the crystal lattice package is formed by one aluminum-hydroxyl layer and two silicon-oxygen layers attached to it
...p...p...
In minerals of the kaolinite group, the bond between the packets is stronger, the spaces between the packets are small. The interaction of microcrystalline particles with the solution in this case occurs only on the outer surface.
In minerals of the montmorillonite group, the interpacket spaces are larger, the connection between the packets is weak, and when moistened, water enters the interpacket spaces. Therefore, cations located both on the surface of the particles and those located in the interstitial spaces take part in the exchange for cations in the soil solution. This explains the higher exchange absorption capacity of minerals of the montmorillonite group, as well as the presence of non-exchange absorption of cations in them.
Soil clay minerals are divided into four groups: montmorillonite (montmorillonite, beidellite, nontronite, etc.), kaolinite (kaolinite and halloysite), hydromicas and sesquioxide minerals (hematite, boehmite, hydrargillite, goethite, etc.). Of the secondary minerals, montmorillonite has the highest absorption capacity, and kaolinite has the least. For example, the absorption capacity of kaolinite is 8-15 times less than the absorption capacity of montmorillonite. This feature of minerals is essential in the absorption of fertilizers and should be taken into account when using them. Secondary aluminosilicate minerals in the soil are in the form of crystals, are highly dispersed, and have a high absorption capacity.
The mineral part of the soil also includes amorphous substances. These are hydrates of aluminum oxides Al20s*lH20 and iron oxides Fe20s*lH20, as well as hydrates of silica SiO2*uH20. They may crystallize. Minerals of oxides and hydroxyls of aluminum and iron are found in significant quantities in red soils and yellow soils.
Based on their chemical composition, minerals are divided into silicates and aluminosilicates. The most common silicate is quartz. Typically, its content in soils is more than 60%, and in sandy soils it is above 90%. It is a chemically inert, stable and durable mineral.
Aluminosilicates are represented by primary and secondary minerals. Of the primary ones, the most abundant are feldspars: potassium (orthoclase KA^sOv) and sodium-calcium (plagioclase). There is less micas in the soil compared to feldspars. They contain potassium. Muscovite contains a lot of aluminum, and biotite is an iron-magnesian mica. Feldspars and micas gradually break down, releasing potassium, calcium, magnesium, iron and other plant nutrients.
By their chemical nature, secondary aluminosilicates belong to hydroaluminosilicates and are divided into three groups.
- Montmorillonites (montmorillonite - А128140у(0Н)2 ^Н20, beidellite - А1381з09(0Н)злН20, etc.). This group of clays is characterized by high dispersion, swelling, stickiness and viscosity.
- Kaolinites (kaolinite - А1281205(0Н)4 and halloysite А1281205(0Н)4-2Н20). This group of clays is less dispersed, has slight swelling and stickiness. In soddy-podzolic soils and chernozems formed on cover loams, the composition of highly dispersed minerals is dominated by montmorillonite and hydromicas. Red soils, yellow soils and soddy-podzolic soils formed on the products of ancient humid weathering of granite contain significant quantities of minerals of the kaolinite group.
- Hydromicas (hydromuscovite, hydrobiotite, vermiculite) are formed from micas, have a variable chemical composition, and in physical properties occupy an intermediate position between montmorillonite and kaolinite. Mica determines agrochemical and physical properties soil. They are a source of potassium nutrition for plants. The energy of potassium absorption by colloids is high, as a result of which the absorption complex of many soils contains 0.5-10 mmol/100 g of soil. Some soils have a deficiency of potassium, for example, red soils and laterites, which is explained by the low content of mica and hydromicas and the richness of the soil in minerals of the kaolinite group, which contains almost no potassium.
In addition to macroelements, the soil contains a certain amount of microelements: some (iodine, boron) more than in the lithosphere, others (copper, cobalt) less, and some about the same amount (Table 3.1). The main source of microelements in the soil are soil-forming rocks. For example, soils formed on weathering products of acidic rocks (granites, liparites, porphyry granites, etc.) are poor in nickel, cobalt, copper, and soils formed on weathering products of basic rocks (basalts, gabbro, etc.), on the contrary, enriched with these elements. Some microelements (I, B, B, Fe, Az) can enter the soil with gases from the atmosphere, from volcanic eruptions and meteorite precipitation, and for microelements such as iodine and fluorine, these are the main sources.
3.1. Content of microelements in soil (A) and lithosphere (B), mass. %
| Element | A | IN | Element | A | IN |
| MP | 8.5 ¦ 10"2 | 9 10"2 | Si | 2 10"3 | 1 10"2 |
| AND | 2 10"2 | 2,7 10’2 | bп | 5 10"3 | 5 10"3 |
| \?A | 1 10"2 | 1,5 10"2 | Co | ABOUT OO | 3 1(G3 |
| IN | 1 10"3 | 3 KG4 | Mo | 3 kg4 | 3 10" |
| N1 | 4 10"3 | OO ABOUT | I | 5 10-4 | 3 10‘5 |
Fractions of the mineral part of the soil with different granulometric compositions differ sharply in the content of various minerals. Sand and coarse dust are dominated by quartz and feldspars. And finely dispersed (<0.001 mm) silty and colloidal fractions consist mainly of secondary aluminosilicate minerals. In this regard, different mechanical fractions of soil differ significantly in chemical composition.
There is more silicon in sandy and silty soils. As the particle size decreases, its content decreases, and the amount of aluminum, iron, potassium, magnesium and phosphorus increases (Table 3.2). The highly dispersed part of the soil also contains humus, an indicator of its potential fertility. Therefore, silt and colloidal fractions are of the greatest value for plant nutrition. These fractions also determine the absorption capacity of the soil. The processes of physical and physicochemical adsorption occur most actively in them.
3.2. Approximate chemical composition of different mechanical fractions of soil,
wt. %
| Factions mm | 81 | A1 | Re | Sa | | TO | R |
| 1,0-0,2 | 43,4 | 0,8 | 0,8 | 0,3 | 0,3 | 0,7 | 0,02 |
| 0,2-0,04 | 43,8 | 1,1 | 0,8 | 0,4 | 0,1 | 1,2 | 0,04 |
| 0,04-0,01 | 41,6 | 2,7 | 1,0 | 0,6 | 0,2 | 1,9 | 0,09 |
| 0,01-0,002 | 34,6 | 7,0 | 3,6 | 1,1 | 0,2 | 3,5 | - |
| lt; 0.002 | 24,8 | 11,6 | 9,2 | 1,1 | 0,6 | 4,1 | 0,18 |
Soils of different granulometric compositions differ significantly in physical, physicochemical and chemical properties. Their mineralogical composition is also different.
Sandy and sandy loam soils consist of quartz and feldspars, loamy soils are composed of a mixture of primary and secondary minerals, and clayey soils are predominantly composed of secondary clay minerals with an admixture of quartz.
The content of the main ash nutrients - calcium, potassium, magnesium, iron, etc. - is also determined by the degree of soil dispersion, since they are contained in the mineral part of the soil, phosphorus and sulfur are found in both the mineral and organic parts, and the amount of nitrogen is determined soil humus level. Consequently, soils of different granulometric compositions differ significantly in the content of nutrients in them. Heavier clay and loamy soils are richer in nutrients than sandy and sandy loam soils.
Greetings to all lovers of metal detecting. Now we will talk about an important concept, which is soil mineralization. Probably beginners have already encountered this concept and someone could not answer the question “What is the degree of mineralization?”, “What is mineralization?”, “What does it affect?”, “how to deal with it?” etc. Now we will try to answer these enough simple questions and give advice that will help you when choosing a metal detector and in the future when working with them. And so, mineralization is the presence in the soil of electrically conductive impurities or magnetic impurities or magnetic impurities. The degree of mineralization can be different, for example, in one place the degree of mineralization will be minimal, that is, the presence of those elements that I mentioned will be minimal. Elsewhere, on the contrary, the amount of such impurities will be large. What awaits the search engine in this or that case, where the degree of mineralization is minimal will be easiest to search for. Many metal detectors do not have the ability to balance the detector on the ground in their settings. Balancing of metal detectors is necessary to overcome existing mineralization and create conditions for the deepest search. Where the degree of mineralization is low you will search at maximum depth, where the degree of mineralization is high you will lose in detection depth. But those metal detectors that have ground balancing, manual or automatic, will have an advantage over those metal detectors that do not have such a setting. The degree of mineralization may vary regionally, that is, let’s say in the Moscow region there is a predominantly low and close to medium degree of mineralization. But if you go to another place, you may encounter that the degree of mineralization is quite high. Therefore, when choosing yours, pay attention to whether it has the ability to balance on the ground and, if possible, clarify the information about the degree of mineralization in your region. This will greatly help you in future problems. Accordingly, when you go out searching with a metal detector, you must tune in to the ground, that is, rebuild the metal detector. If the metal detector does not have ground balancing, then you will have to sacrifice its sensitivity. You will reduce the sensitivity level and, accordingly, you will lose several centimeters in the detection depth. If the metal detector can adjust to the ground in automatic or manual mode, then you balance it on the current ground and get the maximum possible results. this soil detection depth values. This is what mineralization is and the methods that can be used to combat it. I wish you good luck. When choosing a metal detector, be sure to pay attention to whether it has the ability to ground balance or not. And get, if possible, information about the degree of mineralization in the places and regions where you are going to look. Good luck. Let's meet.
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Cultural indicators |
Optimal values |
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Overmoistening of the arable layer during the growing season, days. |
Absent or for perennial grasses - no more than 20, grains - no more than 3 |
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Topsoil thickness | |
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Surface evenness |
Closed microdepressions and microhighs on a segment of 5m - no more than 5cm. |
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Density of topsoil layer, g/cm 3 |
For spring grains – 1.1–1.3; annual grasses – 1.0–1.3; beets and potatoes – 1.0–1.2; |
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perennial grasses –1.1–1.25 |
Soil moisture in the 0–50 cm layer, % of PV |
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50–70 – for grains, 55–75 – for perennial grasses, 55–70 – for root crops and industrial crops | |
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Structurality coefficient | |
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Nitrogen (NO 3 + NH 4) mg/kg soil. | |
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Mobile phosphorus according to Kirsanov, mg/kg soil | |
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Exchangeable potassium, mg/kg soil |
Exchangeable base, mEq/kg soil |
At least 150–200, no mobile aluminum
These indicators are dynamic in nature, which is associated with weather conditions, the degree of moisture and soil cover, and the way the land is used. Thickness of the topsoil layer.
The main task when creating a deep, uniform arable layer is to improve its physical properties and increase the effective fertility of the soil. Research and the experience of farms in creating and cultivating mineral soils of various granulometric compositions confirm that the deeper the arable layer, the higher and more stable the yields. An arable layer of 30–40 cm can absorb and retain 30–50% of melt water and completely rainfall – 50–60 mm without waterlogging. With an increase in the thickness of the arable layer by only one centimeter, the mass increases by 120–130 t/ha with an increase in organic matter up to three tons. During deep processing, moisture penetrates faster and more into the underlying layers, the temperature of the loosened layer increases, and gas exchange occurs better. On heavy soddy-podzolic gleyic soils with deep cultivation, the optimal air content in the spring was established 20–22 days earlier compared to conventional plowing, which is especially important for winter crops. Loosening the subsoil layer promotes greater release of carbon dioxide. With an increase in the thickness of the arable layer by one centimeter, the volume of total porosity increases by 50–55 m 3 /ha.
A thick cultivated arable layer has great irrigation and drainage value. With an increase in the filtration coefficient and moisture capacity of the soil, the volume of runoff is reduced and thereby increases the effect of drainage systems and reduces the removal of nutrients. Increasing the thickness of the arable layer from 15–20 to 25–30 cm, the filtration coefficient on loamy soils increases from 1.0–1.5 to 2.0–3.0, and on clay soils – from 0.5 to 2–3 meters per day. In a thick arable layer, more favorable conditions are created for the development of microorganisms and the root system of field crops. Weed seeds planted at great depths germinate slowly, and a significant part of them die. When the roots of weeds are deeply pruned, they die off faster. Deep incorporation of crop residues with good formation coverage eliminates the possibility of pests and diseases appearing on the subsequent crop.
Plants react differently to the depth of the arable layer and the depth of the main cultivation. Beets, corn, potatoes, alfalfa and clover, vetch, broad beans, and vegetable crops respond well to deep basic tillage. Winter grains, peas, barley, oats, buckwheat are crops that are moderately responsive to deep processing. Those that respond poorly or do not respond at all to non-deep processing include flax, spring wheat, and lupine.
Due to special significance For deep cultivation of the arable layer, methods for deepening and cultivating the arable layer have been developed. Reclamation plowing with intensive cultivation of podzolic soils can create a homogeneous arable layer with a depth of about 30 cm. At the same time, this technique, and especially plantation plowing, requires a lot of time and expense. The illuvial horizon raised to the surface is water-resistant only when wet. After repeated drying and wetting by precipitation, its structure is destroyed, structureless floating clay is formed and, when dried, becomes covered with a crust, which worsens soil conditions.
The use of two- or three-tier plowing, as a method of radically altering the profile, makes it impossible to create an arable layer of uniform fertility. Due to the high costs of longline plowing, it is unlikely that this technique can be applied on a large scale.
The deepening of the arable horizon by gradually plowing the lower layer towards the arable layer is noticeably manifested against the background of the application of sufficiently high doses of fertilizers and lime. It is better to deepen the topsoil during autumn plowing for crops that are responsive to deepening. The plowed podzolized part of the horizon should be mixed with the arable one in the spring, plowing up to 16 cm with the addition of organic matter.
Improvement of the soil profile of shallow peatlands is carried out using standard plowing combined with the formation of loosened strips under the plowed horizon. This ensures decompaction of the plow sole, the water-retaining layer and creates temporary cracks and wormholes.
The technology for creating a powerful arable layer of heavy soils that is uniform in terms of fertility consists of a system of layer-by-layer plowing with the elimination of the podzolic horizon. It involves the use of plant residues that serve bioreclamation a layer to regulate the water regime, using reclamation and conventional plowing, loosening, disking, and surface leveling.
Each of the above methods has both positive and negative sides. When designing intake systems to create a thick topsoil, it depends entirely on the type of soil.
General physical properties of soil.Soil solid density(specific gravity) – the ratio of the mass of its solid phase to the mass of water in the same volume at +4 0 C. The value is constant. Its value varies depending on the amount of humus and the composition of the mineral part of the soil. For soddy-podzolic soils of the republic, this indicator ranges from 2.40 to 2.65 g/cm 3 for peat-bog soils - from 0.5 to 1.4 g/cm 3 .
Density soil (volumetric mass) - the mass of a unit volume of absolutely dry soil taken in its natural composition, expressed in g/cm 3 . Density affects soil regimes and is a variable value, both in the process of soil cultivation and over the seasonal period. After loosening, the density of the soil decreases, then under the influence of precipitation and its weight it increases and reaches an equilibrium density. Best conditions for crops by density they are added when the values of the optimal and equilibrium densities coincide.
Increased density negatively affects the water regime, gas exchange and biological activity of the soil. Excessive density reduces the field germination of seeds, reduces the depth of root penetration and their shape. The growth of the root system at a soil density of 1.4–1.55 g/cm 3 is difficult; more than 1.60 g/cm 3 is impossible. A very loose build is also unfavorable.
The topsoil layer is considered loose at a density of 1.15, dense at 1.15–1.35, and very dense at a density above 1.35 g/cm3. Field crops respond differently to soil compaction. Potatoes, fodder root crops, sugar and table beets grow well and produce high yields only on loose soils. The ratio of perennial grasses to soil density depends on the age of the plants. Young plants of legumes and cereal grasses, especially red clover, do not tolerate compaction of the topsoil very well. In the second and subsequent years of life, they can grow on relatively compacted soil. The density of the subsoil horizon also affects plant growth.
The optimal values of volumetric mass on light loamy soils for crop rotation crops are 1.15–1.25 for barley, 1.20–1.30 for winter rye, 1.15–1.25 for oats, 1.02–1.30 for broad beans , potatoes 1.00–1.20, corn 1.10–1.40 g/cm 3 .
Soil porosity (porosity). The spaces between the soil lumps that make up the solid phase of the soil are called pores. The total pore volume as a percentage of the total soil volume is called porosity or duty cycle soil. Distinguish non-capillary and capillary porosity. Due to non-capillary pores, water permeability and air exchange occur. Capillary pores determine the supply of moisture available to plants. If the non-capillary porosity is less than 50%, then air exchange sharply decreases; if it is above 65%, the water-holding capacity of the soil decreases.
The ratio of the volumes occupied by the solid phase of soil and various types it's called structure of the arable layer soil. The optimal ratio of the volume of the solid phase of the soil and the total porosity for soils with a heavy granulometric composition is 40–35 and 60–65%, and for soils with a light granulometric composition, the solid phase of the soil is 50–55% and 45–50% of the total porosity.
The structure of the soil is regulated by improving the structure and tillage. Treatment methods increase overall porosity, increasing the volume of non-capillary pores, which improves the water-air regime of the soil. However, excessive soil looseness leads to loss of moisture and rapid mineralization of organic matter. It becomes difficult to plant small-seeded crops that require shallow planting of seeds - flax, clover, vegetables, millet, perennial grasses, so I compact the soil with rollers.
Soil structure. The main factor determining the composition of soils of medium and heavy granulometric composition and its stability over time is a mechanically strong and water-resistant structure.
The ability of soil to break down into aggregates is called structure. A set of aggregates of various sizes, shapes and qualitative composition is called soil structure. Depending on the diameter of the particles, a blocky structure is distinguished - lumps more than 10 mm, macrostructure - from 0.25 to 10 mm, microstructure - less than 0.25 mm. The most common forms of aggregates are granular, lumpy, blocky, and dusty structures. In agronomic terms, the most valuable for arable land is granular and lumpy with an aggregate diameter of 0.25 to 10 mm.
Structural soils have developed capillary pores that absorb moisture, and the spaces between them are filled with air. This enhances the development of plant roots and the work of microorganisms to decompose organic matter into nitrogen and ash nutrition. Structural soils do not float, have low surface runoff, and do not require much effort to cultivate. Evaporation from structural soil occurs slowly due to the wide spaces between the lumps, and hence the water reserve.
In structureless soil, moisture is absorbed slowly, and a significant part of it is lost due to surface runoff. The surface of structureless soil floats when moistened, and when it dries, it becomes compacted, forming a crust; gas exchange between the soil and atmospheric air is disrupted.
An agronomically valuable structure is characterized by such indicators as particle size, water resistance and aggregate quality.
Water resistance structure is called its ability to resist the erosive action of water. Soils with a high water stability of the structure for a long time retain the favorable composition achieved by the first treatment. Experiments have shown that the arable layer has a stable composition if it contains at least 40–45% of water-resistant aggregates larger than 0.25 mm. With a lower content of water-resistant aggregates, the soil quickly becomes compacted under the influence of precipitation. Structural soil has a loose composition, lower density and high porosity, more than 45%, the size of aggregates is 0.25–10 mm, capillary spaces predominate inside the lumps, and large non-capillary spaces between the lumps. Even with abundant moisture in structural soil, air is retained in the pores between the units; plant roots and aerobic microorganisms do not feel its lack.
The soil structure is destroyed mainly under the influence of mechanical, physicochemical and biological factors. Mechanical destruction of the structure occurs in the uppermost layers and is caused mainly by tillage machines; physical and chemical destruction can be caused by monovalent cations entering the soil with precipitation and fertilizers; biological reasons for the destruction of the structure are associated with microbiological processes in which humus decomposes in aggregates and their destruction.
To create an agronomically valuable structure and maintain it in a water-resistant state, various agrotechnical techniques are used - sowing many summer grasses, applying organic fertilizers and liming, draining waterlogged soils, and methods of soil cultivation.
Cultivated crops also have a certain effect on the structure of the soil; for example, in the third year of barley monoculture, the coefficient of structure of the arable layer was 1.57, timothy – 1.54 and fodder beet – 1.10. The higher the total mass of roots per unit volume, the more strongly it influences the division of a continuous soil into macrostructural units, the actions of which can be compared to the function of wedges. Thus, perennial grasses significantly affect the soil only when the hay yield is 40–50 c/ha and higher, since the mass of the roots left is proportional to (or equal to) the mass of the above-ground part. On the nature of root mass accumulation big influence depends on the depth of application of fertilizers and methods of tillage. Humic substances, especially freshly formed ones, having a gluing ability, have a great influence on the formation of an agronomically valuable cohesive, water-resistant and porous soil structure.
Physico-mechanical properties of soil.Plastic– the ability of soil to maintain its shape under the influence of external forces. It appears when there is heavy moisture, especially on clay soils.
Connectivity– the ability of the soil to withstand forces directed at it. Sandy and structural soils have low cohesion. Humus in heavy loamy and clayey soils reduces their cohesion, while in light sandy soils it slightly increases it.
Swelling– an increase in soil volume when moistened, and shrinkage– reduction in soil volume upon drying. Sandy soils do not swell, clayey and loamy soils to a large extent. When these volumes change, the soil surface cracks, moisture is lost, and the root system of plants may rupture.
Ripeness. The condition of the soil is suitable for cultivation, i.e. when the cohesion is low and the soil does not stick to the implements, it crumbles well.
Hardness- this is the resistance of the soil to penetration into it to a certain depth solid. High hardness is a sign of poor physical, chemical and agrophysical properties.
Resistivity- this is the effort spent on cutting the formation, turnover and friction against work surface guns, kg/cm 2 . Based on the soil resistivity, they are divided into:
– light with a resistivity of 0.2–0.35 kg/cm 2 these are sandy, sandy loam and some peat;
– loamy with a resistivity of 0.35–0.55 kg/cm2;
– heavy soils(clayey) have a resistivity of 0.55–0.80 kg/cm2.
Table 2.2. Influence of soil mechanical composition on resistivity
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