Biological Activity of Soils in Mountain Tundra Ecosystems under Postpyrogenic Restoration

The dynamics of the content and microbiological transformation of carbon and nitrogen compounds in the surface horizons of mountain tundra soils are considered in the postpyrogenic succession. The contents of total and labile carbon and nitrogen increase in the course of postpyrogenic soil evolution. At the same time, in the surface organic horizons, the carbon reserves, as compared to the nitrogen ones, are restored faster. The aerobic transformation of carbon compounds prevails at all the stages of the succession. The tolerance of soil organic matter toward mineralization increases as the ecosystem recovers after fire. However, this parameter reaches the values characteristic of the control soils no earlier than 60 years after the fire. The microbial communities of the podburs (Folic Podzols, Haplic Podzols) restore their functional activity fast enough after the fire (about three years). In the remote future, the effect of fire leads to an increase in the availability of soil nitrogen and in the soil ability to fix atmospheric nitrogen. Despite the temporary increase in the availability of mineral nitrogen (including nitrates) at early stages of the postpyrogenic restoration of soil systems, denitrification does not play a significant role in the biogeochemical cycle of nitrogen.     

Studying the kinetics of <Superscript>137</Superscript>Cs selective sorption by the dynamic method with the measurement of radioactivity in the sorbent solid phase

The dynamic method was proposed for studying the kinetics of ¹³⁷Cs selective sorption by the measurement of the ¹³⁷Cs activity directly in the sorbent solid phase. A thin layer of the sorbent in a disposable syringe membrane filter (MF) was eluted with a ¹³⁷Cs solution containing K⁺ and Ca²⁺ ions with a gradual decrease in the solution flow rate from 6 to 0.2 cm³/min. The activity of the sorbed ¹³⁷Cs was determined periodically by placing the same MF in the detector well of a Wizard 1480 gamma counter. It was shown that the masses of the sorbent and water in the MF had no effect on the efficiency of the ¹³⁷Cs measurement. A linear relationship between the RIP(K) value and the square root of the time for the period between 4 and 30 days was revealed using this method. The relative increase in the RIP(K) with time changed by 6 times (from 0.034 to 0.208 days^−0.5) for the soils and by 20 times (from 0.008 to 0.153 days^−0.5) for the mineral sorbents. The RIP(K) values measured for the interaction of soddy-podzolic soils with ¹³⁷Cs during 24 hours using the standard limited volume method were lower than the values determined by the proposed dynamic method for the interaction period of 30 days by 50–100%.     

Effect of periodic wetting and drying on selective sorption of 137Cs by mixtures of soil and organomineral sorbent

The incubation of sandy soddy-podzolic soil with a three-component organomineral sorbent (OMS) on the basis of sapropel, neutralized hydrolysis lignin, and clay-salt slime under alternating wetting-drying (W-D) conditions for two years has increased the selective sorption of ¹³⁷Cs by 2.5–5 times. The addition of 5% OMS increases the effect of periodic W-D cycles on the selective sorption of ¹³⁷Cs compared to the addition of 10% OMS. The relationship between the ¹³⁷Cs interception potential and the number of W-D cycles has been predicted on the basis of the additivity rule and under the assumption that this potential linearly depends on the number of W-D cycles. The predicted values of the ¹³⁷Cs interception potential almost coincide with the experimental data for the mixtures of sandy soddy-podzolic soil with 10% OMS and are lower than the experimental values by 60% for the mixtures of soil with 10% OMS.     

Breeding of winter wheat for resistance to biotic and abiotic factors under conditions of the Middle Povolzhye

As a result of many-year research, the methods of wheat breeding for resistance to pests and diseases have been developed. They are based on interspecific and remote crossings by the use of various types of step hybridization and multiple individual selection with account for determination of specifically assigned tasks. On that basis, the immune conception for breeding the grain crops for productivity, plasticity in yield, and quality of grain and complex resistance to pests and diseases most propagated in the region has been created.     

The role of soil microorganisms in environmental and food security

The review considers some problems of soil microbial system management, as well as the possibilities, constraints, and risks caused by environmental and food security problems. A natural microbial system, which obeys its own dynamic laws, is considered a required condition for the existence of a biosphere. Ignorance and disregard of these laws can lead to catastrophic consequences for the higher hierarchical system in which humanity acts.     

Changes in the Pools of Total and Labile Soil Organic Carbon during Post-Fire Succession in the Khibiny Mountain Tundra Ecosystems

Eurasian Soil Science - The changes in the total soil carbon storage and the pools of labile and potentially mineralizable organic matter in Entic Folic Podzols of the Khibiny Mountains (Murmansk...     

Nitrification in Eutrophic Peat Soils under Different Land-Use Management Practices

Eurasian Soil Science - We have analyzed the distribution of soil properties and the intensity of net nitrification in the profiles of eutrophic peatlands on the Yakhroma River floodplain (Moscow...     

The potassium status of sandy gleyic soddy-podzolic soils under forest, cropland, and fallow

The contents and distribution of water-soluble, exchangeable, and nonexchangeable forms of potassium have been studied in the profiles of sandy gleyic soddy-podzolic soils under forest, intensively used cropland, extensively used cropland, and a 20-year-old fallow. It is shown that soil cultivation leads to a rise in the concentration of mobile potassium compounds. The ratio between nonexchangeable and exchangeable forms of potassium also changes in the cultivated soil. Under the fallow, the restoration of this ratio to the values typical of the soil under natural forest cenoses takes place. Data on the mineralogical composition of the clay and colloidal fractions in the virgin and cultivated soils are presented.