Changes in hydrophobic-hydrophilic properties of chernozems under the influence of mineral fertilizers and their aftereffect

Soil samples and granulodensimetric fractions isolated from them ((silt particle size less than 1 µm, light fraction (LF) with a density of less than 2 g/cm3 and a fraction of the residues) of ordinary chernozem from experimental fields of the Kamennaya Steppe agricultural landscape of the Voronezh region were studied. The main differences between the variants of the experiment are introducing or stopping mineral fertilizers, and in the aftereffect of irrigation (13 years). There is an increase in the content of LF when using mineral fertilizers, as well as a change in the composition of sizedensity fractionations, expressed in different content of C and N and hydrophobic-hydrophilic components of humus substances (HS) of soils, silt and LF. The irrigation had practically no effect on the hydrophobichydrophilic composition of the initial soils, while the relative content of the hydrophilic components of the silt fraction of the soil increased, and the hydrophilic composition of HS LF decreased. The use of mineral fertilizers led to a significant variation in the degree of hydrophilicity of HS in silt and LF with a smaller change of this indicator for the HS of the soil as a whole. The abolition of fertilizers application, on the contrary, affected the hydrophobichydrophilic composition of the soil as a whole, and the composition of the soil silt and LF. The increase in the proportion of hydrophilic components in the composition of soil HS, as well as in the composition of HS silt and LF occurred simultaneously with an increase in the hydrophobicity of the surface of the solid phase of soil and with an increase in the carbon content in the soil, which indicates the stability of the system as a whole. Since the physical fractions of soils reacted more intensively to changes in the agrogenic load, compared with native soil samples, and changes in their qualitative composition were traced in two versions of the experiment, monitoring of hydrophobic-hydrophilic components of soil and soil granulodensimetric fractions is advisable to monitor and diagnose soil changes during agricultural use

Changes in the hydrophobic-hydrophilic properties of the organic matter of the chernozems of the Kamennaya Steppe

Soil samples and physical size-density fractions isolated from them (silt particle size less than 1 µm, light fraction (LF) with a density of less than 2 g/cm3 and a fraction of the residue) of ordinary chernozem were studied in three contrasting variants of the experimental fields of the Kamennaya Steppe agrolandscape of the Voronezh region: mowed steppe, long-term permanent bare fallow and permanent corn – the main differences of which are in tillage (cultivated and not cultivated lands) and in the supply/absence of plant residues and root secretions. The LF content changes in the series: “mowed steppe” > “permanent corn” > “permanent bare fallow”, which corresponds to the direction of changes in the total carbon content of the soil and a decrease in the value of the contact angle of wetting (CA) of the surface of the solid phase of the studied chernozems. The determination of the total C and N content revealed the change in the qualitative and quantitative composition of the size-density fractions for different land use cases. Chromatographic fractionation of alkaline extractions of humus substances (HS) of chernozem samples and size-density fractions revealed an increase in the degree of hydrophilicity of HS while simultaneously increasing the hydrophobicity of the solid phase surface and the carbon content in the soil. HS of LF of the “mowed steppe” turned out to be by 63% more hydrophilic than HS of LF of “permanent bare fallow” and by 47% more hydrophilic than HS of LF of “permanent corn”. While the hydrophilicity of the HS silt differed by 16 and 27%, respectively. The hydrophilicity of the HS of the original soil in the plot of the “mowed steppe” was by 41% higher than the hydrophilicity of the HS in the soil in the plot of “permanent bare fallow” and by 24% higher than in the soil of the plot of “permanent corn”. In addition, changes in the hydrophilicity of HS of size-density fractions are more intense than the HS of the soil, so the change in the degree of hydrophilicity of HS of size-density fractions is an indicator of soil degradation under different agrogenic pressue

The mass transfer of chemical elements and of their compounds in agrocenoses

The analysis of publications on the mass transfer of chemical elements in agrocenosis in the soil – plant system was carried out. Methods for estimating the content of mobile forms of chemical compounds coming from the soil into plants are considered. The phenomena of antagonism and synergism are characterized, and the necessity to consider them while planning fertilizer application is indicated. It is shown that the phenomena of synergism and antagonism of elements can be used in agriculture to regulate the flow of heavy metals or radionuclides into agricultural products. A balance model for mass transfer of chemical elements in agrocenosis is analyzed. It is shown that the introduction of organic fertilizers in soil mostly leads to a positive balance of microelements in the agrosystem. To characterize the efficiency of fertilizer use an assessment of the balance of nutrients in the agrosystem is required. The removal of trace elements by agricultural crops increases with the use of mineral fertilizers in doses that are optimal for the cultivation of crops in the region. In some cases, the input of heavy metals with technogenic fallout may exceed the removal of metals by plants from the soil. It may cause the accumulation of metals in the system. In uncontaminated background areas, the levels of microelement intake from fertilizers and atmospheric fallout in agrocenoses are comparable

The contact angle of wetting as an integral indicator of physical-chemical properties of Сhernozems of Kamennaya Steppe

The sessile drop method was used to measure the contact angle of wetting (CA) of ordinary Chernozem from the fields of the Kamennaya Steppe agrolandscape used in various ways. The treatments differ in the intensity of tillage operations (protected mowed steppe, arable land after moldboard plowing), the use of mineral fertilizers and their aftereffect, as well as changes in soil properties under the influence of irrigation. At the same time, the total organic carbon content, C/N ratio, specific surface area, and rheological parameters were determined for the physical and chemical characteristics of soils. The results of the study showed that the hydrophilic-hydrophobic properties of the surface of the solid phase of soils, which largely determine the main structure-forming properties of soils, can be characterized by the value of the wetting edge angle. The CA of the studied soil samples varies from 32 degrees (highest wettability) to 45 degrees (lowest wettability). The lowest wettability is due to the increased content of hydrophobic compounds in the organic matter of soils and is characterized by the highest CA and is typical for native, untreated soil of the mowed steppe, which differs from other studied variants of the experiment in all explored physical and chemical parameters. Moldboard plowing as well as fallowing lead to changes in the physical and chemical properties of the soil and the qualitative composition of organic matter in the direction of their deterioration and a decrease in the CA. The use of mineral fertilizers contributes to the increase in the studied indicator mainly due to changes in plant productivity, in particular, the differences in CA are due to the impact of root secretions and plant residues on the soil properties. For the studied soils, the CA changes in the following series: mowed steppe > arable land with the mineral fertilizers application > arable land undergone the aftereffect of fertilizers. Correlation analysis revealed the relationship of CA with organic carbon content, specific surface area, and rheological characteristics of Chernozems. Thus, CA can serve as an integral indicator of changes in the physical and chemical properties of soils, their degradation changes under the conditions of different agricultural load. The method used in this research for determining CA requires a smaller amount of sample compared to rheological methods and is generally more informative than determining the content of organic matter

Stocks and fraction composition of phosphorus in the Ili Alatau foothill soils and their change under long-term use

In soils of Ili Alatau (dark kastanozems, light kastanozems, mountain chernozems) both in continuous cropping system of sugar beet and in crop rotation with prolonged use of fertilizers the soil agrochemical indices, phosphorus reserves and group composition (total, organic and mineral) vary significantly. The total phosphorus content in the soils was 1720–2330 mg/kg and decreased in the series: virgin mountain chernozems > arable dark kastanozems > arable mountain chernozems > light kashtanozems > virgin dark kastanozems. It was observed, that in arable dark kastanozems, as compared to virgin soils, the content of available forms of phosphorus (loose-bound phosphates Ca-PI and miscellaneous calcium phosphates Ca-PII) increased, and the content of plant unavailable forms of phosphorus (poorly soluble Ca phosphates Ca-PIII, phosphates of aluminum Al-P and iron Fe-P) decreased. In arable mountain chernozems, in comparison with virgin mountain chernozems, the content of all fractions of phosphorus decreased. Arable light kastanozems contain the least amount of available phosphates and the highest of phosphates of aluminum and iron. When cultivating beets on light kastanozems, the content of all fractions of phosphorus, except iron phosphates, increased with increasing dose of fertilizers. The effectiveness of the application of the organic-mineral fertilizers was comparable to the introduction of NK + P1.5 and NK + P2, the yield of sugar beet in the crop rotation in these variants is the highest and amounts to 614 and 577 centner/ha; in the control value (obtained without fertilizers) – 197 centner/ha, and in the variant with application of only NK fertilizers – 277 centner/ha. In continuous cropping system these values were 576 and 561 centner/ha; 311 and 327 centner/ha respectively. Close values of crop yield were obtained in two variants: with the organo-mineral system and NK + P1.5, due to the additional use by the plants of sugar beet phosphorus of newly formed organic compounds

ТЕНДЕНЦИИ СПОСОБОВ КОМПЛЕКСИРОВАНИЯ В СИСТЕМАХ НАВИГАЦИИ И ПОСАДКИ

Advantages and disadvantages of various navigation methods are considered. The main advantage of an inertial method of navigation consisting in a high noise stability is given. The drawback of this navigation method consisting in accumulating mistakes by the time is given. The benefit of satellite navigation systems from the point of view of their globality and high precision of measurement is proved. Disadvantages and advantages of a rho-rho navigation in comparison with satellite navigation systems are considered. The main activities of a complex using of satellite and radar navigation aids, and also satellite and inertial navigation aids are given. Various systems of complex use of a rho-rho navigation and satellite navigation systems are considered. The common important faults inherent in methods and systems according to patents are in detail considered. Methods of a complex using of inertial and satellite navigation systems in the form of inertial system use are given in a complex with the satellite receiver in contours of phase and frequency autocontrol of a satellite signal to increase accuracy and continuity of a signal from the receiver, and also in the form of a satellite method use with the differential mode to increase accuracy of an inertial method with correcting the inertial system signal are given. The analysis of various patents for complex methods of navigation is carried out.Рассмотрены достоинства и недостатки различных способов навигации. Приведено основное достоинство инерциального способа навигации, заключающееся в высокой помехоустойчивости. Приведен недостаток этого способа навигации, заключающийся в накоплении ошибок с течением времени. Обосновано преимущество спутниковых систем навигации с точки зрения их глобальности и высокой точности измерения. Рассмотрены недостатки и достоинства дальномерного способа навигации по сравнению со спутниковыми системами навигации. Приведены основные направления комплексирования спутниковых и радиолокационных средств навигации, а также спутниковых и инерциальных средств навигации. Предложены различные системы комплексного использования дальномерного способа навигации и спутниковых систем навигации. Подробно рассмотрены общие важные недостатки, присущие способам и системам по патентам. Приведены способы комплексирования инерциальной и спутниковой систем навигации в виде использования инерциальной системы в комплексе со спутниковым приемником в контурах авторегулирования фазы и частоты спутникового сигнала для повышения точности и непрерывности сигнала на выходе приемника, а также в виде использования спутникового способа с дифференциальным режимом для повышения точности инерциального способа путем коррекции сигнала на выходе инерциальной системы. Проведен анализ различных патентов на комплексные способы навигации

The Biogeochemistry of Lantanides in Soils

The lithogenous minerals containing lantanides (Ln) are unsustainable within the zone of hypergenesis. Their dilution impoverish soils in terms of lantanides content, especially in humid regions. In conditions of neutral environmental pH in dry steppe zone, the lantanides loose their mobility, and, hence, become unavailable for plants. The lantanides are characterized by the high biochemical and biological activity. The physiologic impact of lantanides on plants is set. The separate parts of vascular plants accumulate lantanides in different degree. The difference may reach 100-fold level. For many plants the accumulation of lantanides occurs at the reverse order: roots > leaves > stalks > grain/fruits. Lantanides accumulators (such as brackens), promote their accumulation within the humus layer of soils. Fertilizers with lantanides are widely implemented in China. They powder seeds and implement top dressing in soils with lantanides deficit, i.e., with low bulk content and/or with low availability for plants. Although at moderate increasing of Ln concentration in solution, there is often observed the increasing of the crop yield in laboratory conditions. However, the implementation of lantanides in the soil does not always give the positive effect. The main share of Ln in the soils with high sorption capacity is sorbed, and the increasing of doses leads to the decrease of the yield. The light lantanides are characterized by physical and chemical properties equal to Cа2+. And the mass replacement of Cа2+ by lantanides harms the development of plants. The high doses of lantanides have a negative impact on the biochemical processes in plants. The competition with iron and phosphorus is stipulated by the close solubility of iron and lanthanum phosphates: the accumulation of La in plants tissues affects the content of P and Fe within them

THE METHOD OF PREPARING SOIL SAMPLES FOR SOIL – WATER CONTACT ANGLE MEASUREMENT USING SESSILE-DROP TECHNIQUE

The method of soil samples preparation for measuring the (wetting) contact angle (CA) of the soil solid phase surface using membrane filters is proposed. The samples of kaolinite, a standard sample of chernozem and samples of agro-chestnut soil were taken for the experiment. The results of the CA measurements using two types of sample preparation for the analysis were compared. The first method of sample preparation was to apply a sample to a double-sided adhesive tape; the second method involved the deposition of suspensions of the studied samples of certain concentrations on membrane filters. The advantages and disadvantages of each sample preparation method are described. The significant difference in the obtained CA values depending on the sample preparation for measurement was revealed. The method of sample preparation with the use of membrane filters developed by the authors made it possible to reduce the CA measurement error by more than 2 times. Reducing the variation of the CA value of a single sample will allow comparing similar soil samples, including soils of the same type, but involved in different land use systems

The Geochemical specificities of distribution of macroelements within the soils of undisturbed landscapes of middle ural (on the example of “Basegi” preserve)

The geochemical specificities of mountainous soils of Middle Ural on the example of Basegi Ridge were considered in this work. We calculated and analyzed geochemical coefficients of accumulation, subsurface weathering, eluviation and oxidation. It is shown that soil forming processes on Severniy Baseg Mountain don’t lead to the clear differentiation of the profile according to the content of one or another microelements. The level of concentrations of elements in landscapes was increased from elluvial to transaccumulative. This was determined by the increasing role of lateral distribution of concentration of chemical elements in mountainous ecosystems. This is confirmed by the calculated accumulation coeffecients and also by the results of cluster analysis. It shows that there are higher concentrations of Al, Fe, K, Ca, Mg, Mn in the soils of forest-mountainous belt, comparing to soils of goltsy altitudinal belt and subgoltsy altitudinal belt, and comparing to alpine belt. The analysis of the original data and literature sources confirmed that the climate change in the end of late Holocene affected dramatically on the climate change of mountainous part of western macroslope of Middle Ural