Biological activity as an indicator of chernozem fertility in different biocenoses

Meadow chernozemic soil was studied in an idle land-shelterbelt-cropland system. It was found that the long-term agricultural use of chernozems leads to a decrease in the total nitrogen content and to changes in the soil microbial community. The portion of phytopathogenic Fusarium, Aspergillus ustus, Penicillium daleae, and Penicillium rubrum microorganisms in the complex of soil fungi increases, and the phytosanitary state of the soil worsens. The use of biotests made it possible to estimate the role of particular microorganisms in the soil phytotoxicity.     

Biological activity in the profiles of chernozems as dependent on the character of their agricultural use and microtopography

The biological activity of soil samples taken from genetic horizons of plowed and virgin chernozems in the Kamennaya Steppe Reserve was determined as the amount evolved from the soil upon its incubation in laboratory conditions. In the top humus horizons, the biological activity of virgin chernozem was two to three times higher as compared with that in the plowed chernozem. The intensity of biological processes and the microbial biomass in the soil profile was mainly controlled by the quantity and quality of soil organic matter. Long-term agricultural use exerted a weaker effect on the biological properties of chernozems developed on microelevations (blocks) of the paleocryogenic microtopography in comparison with chernozems developed in the microdepressions between the blocks. The factor analysis showed that soil characteristics related to the biological processes comprise more than 50% of the total variance of factor loads and are distinctly differentiated in the soil profile.     

Biological activity of a leached chernozem contaminated with the products of combustion of petroleum gas and its restoration upon phytoremediation

It is shown that contamination of leached chernozems by combustion products of petroleum gas favors changes in the biological activity of the soil: the number of hydrocarbon-oxidizing bacteria and micromycetes has increased, as well as the activity of catalase and lipase and phytotoxicity. Bromopsis inermis Leys used as a phytoameliorant has accelerated the destruction of hydrocarbons in the rhizosphere. The benzpyrene concentration in plants on contaminated soils considerably exceeds its background concentration.     

Biological activity of humic substances extracted from soils under different vegetation cover

Abstract

Comparisons were made between the chemical compositions of humic substances extracted from three soils covered by different vegetation and their biological activities assayed using 15‐ and 30‐day‐old seedlings of Pinus sylvestris and Picea abies. The growth, “α‐amylase and invertase activity were affected by humic fractions and by gibberellic acid (GA), indicating that humic matter had a gibberellin‐like activity. The isoenzymatic polymorphism in the electrophoretic patterns of esterase was influenced in a similar way by all humic fractions and by indoleacetic acid (IAA), which also suggested that the humic fractions exhibited an auxin‐like activity. The humic fractions extracted from the grassland, exhibiting higher amounts of phenolic and a considerable amount of carboxyl carbon, showed the best metabolic effect. The forest humic fractions, characterized by lower phenolic carbon content, appeared less effective in influencing plant metabolism, whereas the grassland‐forest humic substances proved to be even more less effective. The auxin‐ and the gibberellin‐like activities were related to a high content of phenolic and carboxylic groups. These results presented evidence that the biological activity of the humic substances was attributed to their chemical structure and to their functional groups, which could interact with hormone‐binding proteins in the membrane systems, evoking a hormone‐like response.     

Effect of sprinkling on the macrostructure of a typical chernozem

The alteration of the typical chernozem structure under long fallow, black fallow, and perennial grasses under the impact of sprinkling were studied. The changes in the macrostructural status of the soil were objectively estimated from the results of two coupled analysis methods. It was found that the most important changes in the aggregate-structural status occurred in the soil under black fallow and perennial grasses; long-fallow lands were the most stable and resistant to external impacts. Soil classes characterizing the quality of the soil structure in terms of the aggregation and water stability were proposed. As a result of the sprinkling, the soil structure quality of the long-fallow land changed from good (classes IVa–IVb) to medium (IIIb–IIIc), that of the black fallow changed from good and medium (classes IVa–IIIb) to poor (classes IIa, IIb, and IIc), and the structure quality of the soil under perennial grasses changed from medium and poor (IIIb–IIb) to poor and even unsatisfactory (classes IIb–Ic).     

Effect of bentonite on the fertility of an ordinary chernozem

The effect of bentonite clay on the main fertility parameters of an ordinary chernozem has been revealed. The maximum contents of nutrients in the soil have been obtained after the application of bentonite at rates of 7.5 t/ha for nitrate nitrogen and mobile potassium and 10.0 t/ha for available phosphorus. At the application of bentonite at rates of 10.0–15.0 t/ha, the content of agronomically valuable soil aggregates resistant to mechanical impact has increased by 2.7%, while that of water-stable aggregates has increased by 6.8%. The portion of water-stable microaggregates has increased, which has decreased the degree of dispersion. Because of the increased content of fine-silt and clay particles, the portion of physical clay in the soil has increased by 3.13%, and the portion of physical sand has decreased. The optimum application rate of bentonite (7.5 t/ha) has been found, which ensures an increase in the yield of sorghum by 16.3%. Its effect was insignificantly lower than that of mineral fertilizers.     

不同保藏年代的大豆根瘤菌冻干菌种的生物学活性研究

对实验室保藏的4～25年的冷冻干燥管大豆根瘤菌菌种进行了生物学活性测定。结果表明,供试4种大豆根瘤菌都有结瘤能力和固氮能力,它们之间的单株结瘤数和固氮酶活没有显著差异。同时证明冷冻干燥法是保藏根瘤菌的良好方法。     

畦面微地形时空变异分布状况试验研究

畦面微地形时空变异分布状况对畦灌性能的影响较为显著,该文依据从典型试验畦块获得的畦面相对高程实测数据,借助统计学方法分析评价田间耕作措施和地面灌溉对畦面微地形时空变异分布状况的影响。结果表明：农田机耕、围畦打埂等田间耕作措施对畦面微地形整体分布状态和畦面相对高程空间分布状况的影响显著;而地面灌溉虽对畦面相对高程空间分布状况有一定影响,但对畦面微地形整体分布状态的影响却较小;田间耕作和地面灌溉等人为生产活动对较小规格畦块的畦面微地形时空变异分布状况的影响明显一些,围畦打埂和入畦单宽流量是影响土地精平后畦面微地形分布状况发生变化的主要影响因素;对较大规格的畦块,除上述影响因素外,还应关注机耕作业留下的车轮压痕对畦面平整状况产生的负面作用。     

稀土农用的核酸生物学效应

稀土农用给中国农业带来巨大的经济效益,同时稀土环境安全问题也引发中外科学家的关注.核酸是储存和传递遗传信息的聚合物,本文从遗传学角度论述了稀土对核酸的影响及其机制.稀土可与核酸分子结合,或断裂核酸;阐述了稀土离子的核酸结合部位及作用方式,总结了断裂机理,并提出今后研究的方向.     

Amino acid pool of a typical chernozem of Moldova

New data on the content and composition of the amino acids in a typical chernozem of Moldova were obtained. Eighteen amino acids were identified. Among the usually found amino acids, tryptophan was not identified. It was found that the total content of free and bonded amino acids in the studied chernozem varies from 197 to 317 mg of N/kg of soil, which constitutes 8–11% of the total pool of nitrogen. The predomination of alanine (13.88–17.26%), glycine (10.66–14.51%), aspartic (9.15–13.29%), glutamine (7.26–11.30%), and arginine (8.12–11.99%) is typical of the chernozem. The size and composition of the amino acid pool in this chernozem correlated well with the soil’s organic matter content.     

Effects of trace elements on urease activity in soils

Disposal of sewage sludges and effluents on agricultural land is becoming a widespread practice. Most sludge samples disposed on soils contain large quantities of various trace elements. Studies of 20 trace elements commonly found in sludge samples showed that they inhibit the activity of urease in soils and that their order of effectiveness as inhibitors of urease depends on the soil. When the trace elements were compared by using 5 μmiol·g^?1 soil, however, some of them showed the same order of effectiveness as urease inhibitors in the six soils studied i.e., for the monovalent and divalent ions, Ag⁺ ≥ Hg²⁺ >Cu²⁺ >Cd²⁺ >Zn²⁺ >Sn²⁺ >Mn²⁺, and generally, Fe²⁺ >Fe²⁺andCu²⁺ >Cu⁺. Other trace element ions that inhibited urease were Ni²⁺, Co²⁺, Pb²⁺, Ba²⁺, As³⁺ B³⁺, Cr³⁺, Al³⁺. V⁴⁺ Se⁴⁺ and Mo⁶⁺. Of the trace element ions studied, only As⁵⁺ and W⁶⁺ did not inhibit urease activity in soils.Studies on the distribution of urease activity showed that it is concentrated in surface soils and decreases with depth. Urease activity was proportional to organic C distribution in each soil profile and was significantly correlated with organic C in the surface soils studied.     

Fluorescent properties of low-molecular-weight fractions from chernozem humic acids

The polyacrylamide gel electrophoresis of chernozem humic acids (HAs) followed by ultraviolet detection (λ = 312 nm) has revealed a new highly fluorescent fraction that has the highest electrophoretic mobility and the lowest nominal molecular weight (NMW). The preparative isolation of the fraction has been performed using the multiple microfiltration of the same HA sample in a 7 M carbamide solution on a membrane with a nominal pore size of 5 kDa. Thirty ultrafiltrates with NMW < 5 kDa and different fluorescence maximums in the region of 475–505 nm have been prepared, as well as a nonfluorescent concentrate with NMW > 5 kDa. Fluorescence maximums at and below 490 nm have been noted only in the first four ultrafiltrates. All the ultrafiltrates have been combined into the fraction with NMW < 5 kDa, which has been successively passed through membranes of 3 and 1 kDa. Solutions of subfractions F 3–5 kDa, F 1–3 kDa, and F < 1 kDa with fluorescence maximums at 505, 488, and 465 nm, respectively, have been prepared. The F < 1 kDa subfraction with the lowest NMW had the highest fluorescence intensity. The distribution of the fluorescence maximums in the ultrafiltrates has indicated the presence of at least two groups of fluorophores and has confirmed the supramolecular organization of the extracted soil HAs.     

地表微地形测量及定量化方法研究综述

地表微地形测量是地表粗糙度定量化的基础,对地表形态动态监测、水文过程模拟以及土壤侵蚀过程模型的构建具有重要意义。目前,微地形测量方法主要分为接触式和非接触式2大类,前者包括测针法、链条法、差分GPS法等,后者包括超声波测距法、红外线传感器法、结构光激光扫描法、激光测距扫描法、三维激光扫描仪法、近景摄影测量法等。在全面回顾各方法原理、优缺点及其应用的基础上,分析地表粗糙度定量化常用方法：统计方法指数、地统计学指数和分形及多重分形模型。认为：1）差分GPS法、结构光激光扫描法、三维激光扫描仪法和近景摄影测量法将在亚毫米一,厘米级地表微地形测量及地表粗糙度多尺度特征研究中发挥重要作用,同时简单、方便的测针法可能在野外测量中依然占据主导地位;2）以地表微地形测量技术为基础,在土壤侵蚀过程模型中亟需形成一套完整的“测量一定量化一模型应用”范式,同时应加强对地表微地形空间异质性和各向异性的研究,发展新的统一的地表粗糙度定量化方法。     

Biological activity of acetylated phenolic compounds

In recent years an effort has been made to isolate and identify biologically active compounds that are included in the Mediterranean diet. The existence of naturally occurring acetylated phenolics, as well as studies with synthetic ones, provide evidence that acetyl groups could be correlated with their biological activity. Platelet activating factor (PAF) is implicated in atherosclerosis, whereas its inhibitors seem to play a protective role against cardiovascular disease. The aim of this study was to examine the biological activity of resveratrol and tyrosol and their acetylated derivatives as inhibitors of PAF-induced washed rabbit platelet aggregation. Acetylation of resveratrol and tyrosol was performed, and separation was achieved by HPLC. Acetylated derivatives were identified by negative mass spectrometry. The data showed that tyrosol and its monoacetylated derivatives act as PAF inhibitors, whereas diacetylated derivatives induce platelet aggregation. Resveratrol and its mono- and triacetylated derivatives exert similar inhibitory activity, whereas the diacetylated ones are more potent inhibitors. In conclusion, acetylated phenolics exert the same or even higher antithrombotic activity compared to the biological activity of the initial one.     

有机无机肥配施对碳酸盐黑钙土的退化修复研究

针对碳酸盐黑钙土有机质含量逐年减少,保水、保肥、蓄水保墒能力下降等问题,开展了以增施牛粪、翻压绿肥和配方施肥等方法的碳酸盐黑钙土修复技术研究。结果表明,采用增施牛粪、绿肥等有机肥和配方施肥技术可明显改善碳酸盐黑钙土的理化性质,与当地常规施肥相比,增施有机肥和配方施肥处理的田间持水量增加6.9%~17.4%,土壤孔隙度增加7.4%~11.8%,土壤容重降低0.09~0.1 g/cm3,玉米产量增加10.3%~16%,翻压绿肥对碳酸盐黑钙土保墒蓄水能力提升效果好,连续施用有机肥对退化碳酸盐黑钙土修复效果明显。     

Biological activity of the coprolites of earthworms

The most important indicators of biological activity (respiration, methane genesis, nitrogen fixation, denitrification, and size and structure of the microbial population) were determined in coprolites of two types of earthworms (Lumbricus rubellus considered as the “litter” type and Aporrectodea rosea as the “soil” type) in the model experiment, in which the earthworms were kept separately and together, as in soddy-podzolic loamy soil. The biological activity of coprolites was significantly higher than in the soil and varied between worm species.     

黑土区农地侵蚀性降雨标准研究

侵蚀性降雨,是指能够引起土壤侵蚀的降雨。确定侵蚀性降雨的标准,是土壤侵蚀预报研究的一项基本内容。本文采用频率分析的方法,通过对黑土侵蚀区克山水保试验站径流小区4年24次天然侵蚀性降雨资料的统计分析,确定了黑土区农地侵蚀性降雨的基本雨量标准、一般雨量标准、瞬时雨率标准和暴雨基本雨量标准。     

Effect of water on the rheological properties of typical chernozem in Kursk oblast

The rheological properties of typical chernozem were investigated by the amplitude sweep test on an MCR-302 rheometer (Anton Paar, Austria) for three water contents: maximum swelling, the liquid limit, and capillary rupture. A method is proposed for determining the water content of capillary rupture on an analyzer by using the curves for soil drying at constant temperature, determined simultaneously with the water content. Comparison of rheological soil characteristics at different soil humidity has shown that variations in the forms of soil water cause changes in the rheological soil behavior from viscous to elastic–brittle.     

微地形分布差异对畦灌过程及性能的影响模拟

微地形空间变异对畦灌性能影响显著,同一微地形起伏幅度下微地形起伏位置空间分布差异对畦灌过程及性能影响方面的研究甚少。该文基于随机生成的畦面相对高程的最小样本容量值,将微地形随机模拟方法与灌溉模型相结合,模拟分析同一微地形起伏幅度下微地形起伏位置空间分布差异对畦灌过程和畦灌性能的影响,讨论其影响程度随微地形起伏幅度的变化趋势。结果表明,同一微地形起伏幅度下起伏位置空间分布差异对畦灌过程和性能影响明显,且不同微地形起伏幅度下相应起伏位置空间分布差异对畦灌系统的影响随着起伏幅度的增加而增加。微地形标准偏差小于3cm时微地形起伏位置空间分布差异所引起的畦灌性能的变异属弱变异性,而微地形标准偏差大于3cm后其变异性增强,此时,在畦灌系统的田间评价、设计和管理中忽略其影响易产生较大误差。