High Humus Content Research Articles

БИОЛОГИЧЕСКАЯ АКТИВНОСТЬ ГОРНЫХ И РАВНИННЫХ ЧЕРНОЗЁМОВ ЦЕНТРАЛЬНОГО КАВКАЗА (В ГРАНИЦАХ КАБАРДИНО-БАЛКАРИИ)

A comparative analysis of biological properties of several subtypes of mountain and plain chernosems in the Central Caucasus (within Kabardino-Balkaria) was conducted. Statistically significant differences between the parameters of biological activity in the upper horizons (0 - 20 cm) of the soils under study were revealed. Mountain chernosems are characterized by the high humus content (by 38% on average), an increased activity of dehydrogenase (by 42%) and urease (by 35%), and all microbial parameters (by 12 - 53%). The invertase activity was higher in plain chernosems (by 47% on average). Dispersion analysis has shown that the influence of formation conditions (mountain or plain) is a more significant factor for a number of the studied parameters than features of the studied soils at the subtype level. The strength of the factor of genetic differences lies in the range of 1 - 5%, while the influence of formation conditions ranges from 15 to 33%. The total biological activity of the upper horizons in mountain and plain chernosems was evaluated by means of an integral index of ecologico-biological soil status (IIEBSS) which shows a higher biological activity of the upper horizons in mountain soils (IIEBSS differences are within 5 - 18%).

State of Organic Matter and Particularities of Physicochemical Properties of Soils in the Endogenous Hydrogen Seepage Zones

In the territory of the Voronezh region of Russia in ordinary middle loam chernozem the elevated concentration of endogenous hydrogen streams up to 0.65% at the depth of 100 - 120 cm was detected. This phenomenon is observed in the center of depressions. The soils differ in morphological, chemical and physical properties. The top humus horizon is markedly bleached comparing to the soil outside the depression: The lightness L readings increase for 16% - 30%. The soil acidity (up to pH 4.5 - 5.0) and organic carbon content are elevated comparing to the sample for reference. The proportion of fulvic acids increases on average thrice as compared with the soils outside the hydrogen fluids influence zone. Despite the high humus content the mechanical strength of aggregates decreases 3 - 4 times. Under conditions of hydrogen fluids, changes occur at the aggregate structural level in the direction of decreasing their mechanical strength. In the center of the depressions strength of aggregates is reduced by 2 - 3 times in comparison with the control. The opposite regularity was observed in the absence of hydrogen flows, where the strength of aggregates was 3 times higher than in comparison with the control.

Агроекологічна оцінка грунтів адміністративних районів Херсонської області

Intensive irrational use of land leads to deterioration of the agro-ecological state. The criterion for assessing the agro-ecological state of agricultural lands is the level of soil fertility, because fertility determines economic significance and cost. The territory of the Kherson region is one of the regions with the largest development in agricultural terms, where the area of agricultural lands is 71.4%. The soil fertility level is estimated by the content of organic matter, and the humus reserves determine the agrophysical properties of the soils. The more humus in the soil, the richer it is on the main elements of the nutrition, because of the contains a large amount of macro- and microelements. The acidic soil environment is one of the factors which restrict receipt of high-quality agricultural crops. One of the main indicators of the soil fertility is the content of a complex of specific organic substances - humus, nitrogen, phosphorus and potassium. In the eroded soils its fertility loses because their supply decreases. On the territory of the Kherson region there are soils with very low, low, medium, high, higher and highest humus content in it. In the regions soils in terms of the average content of humus vary from 2% in the Golopristansky area to 80,7 in Nizhnosigorozhsky. Unsolonated, weakly solonetous, strongly salted soils and saline soils are observed in the region. The non-sunny soils (53,84%) have the largest proportion. Low salinity, strongly saline soils and saline soils make up 46,16%, of which the weakly solotic soils make up 38,17%. The territory of the Kherson region was investigating on the content of heavy metals of gross and mobile forms. An excess of maximum allowable concentration was found on lead content. The maximum allowable concentration of the mobile form of lead 2 mg / kg. In the Kalanchatsky area the concentration of mobile lead forms is 2,43 mg / kg, while in Nizhnosigorogorsky it is 2,21 mg / kg. For the territory the disadvantage of the research is the absence of detail. The assessment of the state of the territory does not repeat the boundaries of administrative districts. But conducted studies show the best agro-ecological conditions are observed on the territory of the Velikolepetysky district, and the worst ones are in Kalanchatsky and Nizhnosigorozorsky, where the decisive role in the assessment has an excess of the maximum allowable concentration value for lead content.

Екологічні умови територій садів та парків колишніх залізних рудників (Криворізький басейн, Україна)

<p>The aim of this study was to analyse the ecological conditions for the location area of gardens and parks of the former iron mines at Kryvorizhzhya. <em>The object of this study</em> were seven existing parks (“Ternivskyi”, “Shakhtarskyi”, «Zatyshnyi», Suvorov sports park, park near the Palace of Culture of mine «Rodina», «Saksahanskyi», «Rudanivskyi»), one abandonment park in fall of ground zone (Park of mine «Hvardiiska»), one garden of hotel «Park House» (private property). The territory of the former iron gardens and parks began to form on the brink the XIX and XX centuries. However, this practice was not widespread and today these greenery’s objects are not preserved. System planting of these mines started in 30<sup>th</sup> years of the XX century, and became widespread in the 50-60<sup>th</sup> years of the XX century. The period of greatest prosperity for mine gardens and parks was in the 60-70<sup>th</sup> years of XX century. Further there was a gradual change in ownership and social status and reduce the cost of maintaining for these objects gardening. The territory of parks «Ternivskyi», «Shakhtarskyi», «Zatyshnyi», near the Palace of Culture of mine «Rodina», «Saksahanskyi», «Rudanivskyi» is located in upland areas of the valley-ravine and valley ‘s divide - ravine types of landscapes. In these areas common: eluvial geochemical landscapes, relatively rich of trophotopes and very dry-dry of hidrotopes. In these areas also common chernozems ordinary (Chernozems by World Reference Base for Soil Resources), which are characterized by: average powerful humus horizon (50-70 cm), medium humus content (4,5-4,7%), neutral reaction of soil solution (pH <sub>H2O</sub> - 7,0-7,2), good formed the soil absorbing complex (total exchange basics – 30-35 mg.-eq / 100 g soil). Therefore, the growth and development of trees and shrubs formed over there is very complicated natural ecological habitats.</p><p>The territory of Suvorov Sports Park and garden of hotel «Park House» are located in overflow land areas of the valley-valley terrace types of landscapes. In these areas common: superaquatic geochemical landscapes, rich trophotopes, cheese-fresh hidrotopes. In these areas also common meadow-chernozems soils (Mollic Calcic Fluvisols by World Reference Base for Soil Resources) which are characterized by: powerful and super powerful humus horizon (90-130 cm), high humus content (9.1-9.8%), slightly acidic soil solution (pH <sub>H2O</sub> 6.5-6.7) well formed soil absorbing complex (total exchange bases –37 mg.-eq / 100 g soil). Therefore, the growth and development of trees and shrubs occurs in a very favorable natural ecological condition. The territory of three objects of planting (Suvorov sports park, Park near the Palace of Culture of mine «Rodina», and garden of hotel «Park House») are subject to significant level of anthropogenic air pollution; the territory of Park «Saksahanskyi» is subject to middle level of anthropogenic air pollution; whereas the other objects of gardening are subject to an insignificant level of anthropogenic pollution. Ecological conditions of park «Saksahanskyi» were evaluated as the most favorable for the growth and development of trees and shrubs. The results can be used to justify measures gardening optimization of existing facilities in the industrial regions of the steppe zone and designing new ones.</p>

Unified understanding of physico-chemical properties of activated sludge and fouling propensity

A range of parameters affecting floc characteristics, sludge composition and filtration properties was investigated by analyzing 29 sludge samples from municipal and industrial conventional activated sludge systems and municipal membrane bioreactors (MBR). Samples were characterized by physico-chemical parameters, composition of ions and EPS, degree of flocculation, settling properties, dewatering properties, and filtration properties. By analyzing the interplay between various metrics instead of single parameters, a unified understanding of the influence of sludge composition and characteristics was developed. From this, a conceptual model was proposed to describe the interplay between sludge composition, characteristics, and filtration properties. The article shows three major results contributing to describe the interplay between sludge characteristics and fouling propensity: First, the degree of flocculation could be quantified by the ratio between floc size and residual turbidity and was a key parameter to assess fouling propensity. Second, extracted EPS to polyvalent cations ratio was used as an indicator of the flocculation. A high ratio combined with a high concentration of EPS resulted in large, loosely bound, and weak flocs that were easily deformed, hence giving compressible fouling layers. Finally, high amounts of carbohydrates in both total and extracted EPS resulted in more pronounced fouling, which may be explained by carbohydrates forming poorer flocs than humic substances and proteins. Accordingly, samples with high humic content showed lower specific resistance to filtration due to better floc structure. The amount of carbohydrates in EPS correlated positively to the influent COD/N ratio, which may explain why systems with high influent COD/N ratio demonstrated higher fouling propensity.

Some Features of Forest Stands Growth and Development on Distributed Lands of Novyj Rozdil Sulphur Quarry Dumps

Intensive mining in the mid-twentieth century within Western Ukraine territory led to destruction of large areas of the ground, vegetation and soils. Such lands are marked by lack of fertile layer with dramatically altered topography and hydrological regime, worsening sanitary conditions of industrial areas and negatively affect on the ecological state of surrounding farmlands and other areas. Accelerating the process of natural regeneration of vegetation, giving it a certain direction, forming productive and sustainable biogeocenosis which are characterized by high aesthetics, conservation and economic value will allow solving current tasks. The authors have conducted the study of growth and development of forest stands on disturbed lands of dumps of Novyj Rozdil sulfur quarry. Firstly, we have revealed that the most productive are poplar stands that showed the highest averages height and diameter, lower reserve of timber. They are characterized by mixed stands featuring black alder, cherry, ash and aspen and the least productivity reaches oak stands with little admixture of black alder and aspen. We have noted that black alder in elm stand is characterized by the highest impedance and the lowest capacitance values of polarization. Significantly lower impedance is in the sample oak plantation, cherry and elm plantation. Growth and development of tree species in analyzed forest stands significantly affects the physical-chemical and chemical properties of the soil, contributes to the reproduction of sois, organic matter accumulation, and supersedes acidity. Secondly, high humus content at the top soil layer is defined in the section of stand composition 6E1O1Ch1Al1Ac and on the section of stands 6O2Al2Os + 1W. Increased humus content is also observed in the top layer of soil on the section of stand composition 10P + Ch and average degree of humus is observed on the sections of stand composition 6A3Ch1As + A. Based on the research we have made the following conclusions. The highest productivity in the dumps of Novyj Rozdil sulfur quarry is shown by poplar stands, a smaller timber stock has mixed stands featuring black alder, cherry, ash and aspen, and the least performance is characterized by oak stands with little admixture of black alder and aspen. Average degree of phosphorus provision is noted in the top (up to 0.10 cm) layer of the soil on section with ash-cherry-alder-oak stands. A very low level of availability of phosphorus in analyzed soil horizon is noted on section of poplar and elm stand.

Soil distribution and soil properties in the subalpine region of Kazbegi; Greater Caucasus; Georgia: Soil quality rating of agricultural soils

Abstract Soils of the alpine ecosystem of Kazbegi region were investigated according to the Muencheberg Soil Quality Rating (M-SQR). Most limiting factors are climate as well as steepness, while the low nutrient supply and soil acidity can be tackled by adequate fertilization and liming practice. Inorganic or organic pollution were not detected. Soils on sediment fans as well as glacial sediments, mostly Cambisols (Humic) , are characterized by a low to moderate yield potential while high-yield soils, mostly Cambic Umbrisols , can be found on volcanic plateaus. A common element of all soils is the high humus content. Actually, most of them are used only for pasture, due to poor accessibility. Soils on fluvial deposits, mostly Fluvisols , show a very high range of M-SQR-scores. Altogether, the soils of the study area have the actually untapped potential to optimize the basic supply of the local population as well as tourism also by cultivation of cereals. Nevertheless, variety trials on different soil forming substrates as well as erosion control are major preconditions for successful implementation of new cropping systems in the Kazbegi region. Furthermore, particularly rare soils, e.g. Cambisols on Tephra, should be protected.

Assessing the humus status and CO2 production in soils of anthropogenic and agrogenic landscapes in southern regions of the Russian Far East

The humus status and CO2 production have been assessed in soils of natural and anthropogenic landscapes in southern regions of the Far East with different types of redox conditions. A higher production of CO2 is typical of burozems and soddy-eluvial-metamorphic soils with oxidative and contrast redox conditions. These are soils with medium or high humus content, high potential humification capacity, and medium enrichment with catalase. A decrease in the content of humus in the plow horizons of soils in agrogenic landscapes is revealed compared to their natural analogues. The studied soils mainly have humus of the fulvate–humate type. The fractions strongly bound to the mineral soil component prevail in humic acids. In waterlogged mucky-humus gley soils, the anaerobic conditions hamper the biological activity and transformation of organic matter, which favors its accumulation. A low production of CO2 is observed in soils with reducing conditions. To determine the differences between the CO2 emission parameters in soils of agrogenic and natural landscapes, monitoring studies should be extended.

Spatial distribution of exchangeable bases in chernozem of Kamennaya Steppe

The high degree of base saturation and high cation exchange capacity with an appreciable dominance of calcium are related to the high carbonate content in parent rocks, high content of humus in chernozems, and abundant fine material in their profiles. These are characteristic features of prevalent soils in the Kamennaya Steppe. Almost all soils of monitoring and experimental plots have an appreciable spatial variation in exchangeable bases. The obtained data indicate that the content of adsorbed calcium in the exchangeable complex of the soil decreases with increasing shares of adsorbed magnesium and partially sodium.

Soil organic matter in the Moscow State University botanical garden on the Vorob’evy Hills

Humification conditions and humus status parameters in arboretum soils of the Moscow State University botanical garden on the Vorob’evy Hills have been studied. Although microbiological activity is reduced, the warm and mild climate in the city, the eutrophication of soils (due to atmospheric fallouts and dissolution of construction waste inclusions), the retention of plant waste on the soil surface, and the presence of abundant primary destructors (mesofauna) have resulted in the formation of organic matter with specific characteristics. During the 60 years that have elapsed since the arboretum establishment, soils with a high content (up to 10–14%) of humate humus (CHA/CFA > 1) characterized by a higher degree of humification than in the control soils under herbaceous vegetation have been developed in the area. Large reserves of organic carbon have been noted not only in the upper 30-cm-thick soil layer, but also in the 1-m-thick layer due to organic matter of buried and technogenic horizons.

MICROBIOLOGICAL RESEARCH OF CHESTNUT SOILS IN SOUTH-WEST TRANSBAIKAL

The microbiological researches in chestnut soil of South-West Transbaikalia occurring under peculiar natural-climatic conditions have been studied. Seasonal study of various ecological trophic groups of bacteria (saprophytes, proteolytics, cellulolytics), actinomycetes and fungi in chestnut soil has been carried out which showed a rather broad distribution and fixation of microorganisms through the whole soil profile. These groups (to 106C/g) were mostly observed in the top horizons of soils due to the high content of humus (2,91-4,94%), roots, and also regular condensation of atmospheric moisture. Down the profile the number of bacteria and fungi was generally decreasing by 1-3 orders. Feature of the studied soils was the broad distribution of actinomycetes through the whole soil profile and also increased of their number by1-2 orders in the mineral horizons (3 and 4 sites). The higher density of microorganisms was observed in summer (in its second half) and early autumn periods, which are more favorable because of hydrothermal indicators for vital activities of microorganisms in all researched ecosystems. The number of various ecological trophic groups of bacteria, actinomycetes and fungi indirect evidence of their large enough role in mineralization processes.

Soils of the southwestern part of the Dzhulukul Depression in the Altai Republic

Soils of the southwestern part of the Dzhulukul Depression in Ulagan district of the Altai Republic have been studied. They belong to two soil divisions: Al-Fe-humus soils (with various types of podburs) and iron-metamorphic soils (rzhavozems). The soils within the eluvial part of the studied catena—iron-illuvial soddy podburs—are developed from the residuum of magmatic and metamorphic rocks with high (up to 80 vol %) content of gravels and coarse rock fragments. Their high porosity favors downward migration and precipitation of humus-iron compounds on the surface of gravels and mineral grains in the illuvial horizon. The soils of the accumulative part of the catena—permafrost-affected raw-humus pod-burs and gleyic podburs)—are developed from moraine deposits of loamy-sandy texture with up to 30 vol % of gravels. In these soils, the features of the Al-Fe-humus migration are weakly pronounced; the soils are underlain by the waterproof frozen horizon (permafrost), have high humus content, and have thixotropic properties in the lower horizons. Their reaction is slightly acid to neutral, and their base saturation is up to 80%. These characteristics do not meet the criteria of podburs as defined in the new Russian soil classification system. Their origin may be related to the local mixing of weathering products of different bedrock materials, including magmatic, metamorphic, and sedimentary rocks during the deposition of moraine sediments. Iron-metamorphic soils (rzhavozems) are formed on convex parts of slopes from the residuum and colluvial derivatives of magmatic and metamorphic rocks (granite, metamorphic slates, red-colored sandstone, etc.). A distinctive feature of these soils is their ocherous-brown color and a considerable content of gravels in the entire profile. The chemical properties of rzhavozems resemble those of the Al-Fe-humus soils of automorphic positions: acid and slightly acid reaction, low base saturation, and a relatively high content of organic carbon in the organic and mineral horizons.

ESTIMATE OF CHERNOZEM ERODIBILITY LEVEL ACCORDING TO THE HUMIFICATION DEGREE

A short review of literature sources is presented to characterize the eroded soils according to their humus content. Traditional diagnostic indicators of the soil erodibility level based upon the humus status are the following: (1) decrease in the thickness of humus horizons in eroded soils in percentage of that in uneroded soil (standard); (2) decline in the humus storage in the eroded soil profile in percentage of that in uneroded soil (standard). It is worth emphasizing that the choice of the uneroded soil standard is a rather labor-consuming study in field and assumes an expert (subjective) character that is highly dependent on the soil scientist’s skill. It is shown that the main shortcomings of the available gradation for eroded soils consist in the absence of approaches to give their objective estimate and recommendations for permissible levels of soil erodibility taking into complete account the humus content in these soils. In the Russian Federation there is a gradation of arable soils (including chernozems) according to the humus content in the plough horizon. It contains four classes (less than the humus minimum, low, moderate and high humus content). In this paper it is recommended to give the gradation of eroded soils with the minimal humus content. The level of chernozem erodibility should be estimated as based upon the minimal and critical humus content. The minimal humus content is interpreted by Kërshens, whereas the critical humus content - by Kiryushin and Ganzhara. A gradation scale of soil erodibility is presented to estimate its permissible, non-permissible and critical levels. It is exemplified by the gradation of chernozem soils in Russia and Germany.

The evolution of podzolized and regraded chernozems in Eastern Upland Wooded Steppe of Ukraine and the ways of their development

It is indicated that podzolized and regarded chernozems in moderately humid and arid zones of Left-bank Wooded steppe with HTC 1,2–1,0 (within the valleys of the Sula and Oskil rivers) occur in high watersheds along right bedrock banks of the valleys, adjoining or being included into wooded refugiums. Being formed by the grove biogeocenosis, they have high rates of fertility. The morphological research of natural podzolized chernozems profiles showed, that the upper humus slightly-eluviated horizon, densely interweaved by roots, has coarse agronomically valuable structure, loose composition, dark-grey colour, that indicates high content of humus. It is mostly favoured by the biologically active, rich in calcium ground litter and the pristinity of soil texture. The general capacity of the humus profile is not less than 100 cm. While brining natural soils into tillage some changes of soil development conditions arise. They are: hydrothermic conditions, secondary carbonate enrichment (regradation), loosening of illuvial horizon. Under mechanical tillage the granular structure changes into a pulverescent and cloddy one, the topsoil becomes lighter because of humus loss, though the humus profile becomes 10–20 cm deeper. The analytical results indicate the sufficient differences in physicochemical and agrochemical characteristics between forest podzolized chernozems and their regradated analogs in tillage. Natural soils contain 5,7–6,5 % of humus in upper 0–35 cm layer, and up to 10,0 % in 0–15 cm layer. They also have considerable resources of hydrolyzable nitrogen. In agrogenic soils the humus content is up to 3,6 %. The humus is of a humate type both in podzolized and regarded soils. The smallest proportion of Сh.a./Сf.a is in the lower layer of humus eluviated horizon of forest soils. The level of humus loss by agrogenic soils in humus slightly-eluviated layer fluctuates from 37 % to 44 %. Dark-grey and grey forest soils lose more than half of humus content, typical chernozems – nearly 30 %, ordinary chernozems – 20 %. Regraded analogs are inferior according to the hydrolyzable nitrogen content. Positive evolutional changes in tillage, such as acidity reduction, bases saturation growth, illuvium destruction, didn’t yield expected results – resistance to degradation processes. For the development of agrogenic soils it is necessary to implement flexible complex systems of husbandry with minimal intensity of tillage, adapted to the landscape, bringing the culture of husbandry closer to natural conditions. Promising is the implementation of soil protection technologies with the maximum use of freak produce of plant growing. The integrity of soil composition and biologically active layer of mulch create the conditions, close to virgin ones, that lead to the transition of soil to natural non-degradation conditions without losing its productive functions.

The content of manganese in soddy brown soils of the Transcarpathian Mountain Valleys

The soil covering of Transcarpathia, which is used for cultivation of crops, is rather heterogeneous as to genetic features of soils. This is mostly caused by the climatic conditions of corresponding natural zones. Brown mountain soils, soddy brown soils, meadow brown soils and mountain meadow soils have originated in mountainous areas on mountain ranges and slopes of different altitude, which are different in terms of mechanical makeup and are well drained. They are characterized by high content of inaccessible humus (in which fulvic acids predominate), acid reaction of soil solution and evident diversity in provision of mobile forms of nourishing chemicals. On the average, the reaction of soil solution is 4,60 pH of a salt solution, in the case of hydrolytic acidity – 4, 28 me/100g of soil, which characterizes them as semi-acidic. The aim of our thesis is to research the level of manganese, which is one of essential and toxic elements for plants, depending on its concentration in soil, in soddy brown soils of the mountainous zone of Thranscarpathia, and also its distribution in profile of soil horizons. To carry out this aim, samples of soil were chosen by random selection. Total manganese in the soil was determined by the method of mass spectrometery. The samples were extracted by hydrogen peroxide, chlorohydric and azotic acids (ext. p.). Dissolution of the samples was carried out using microwave sample preparation system. Active forms of manganese were extracted by generally accepted extragents: water-soluble extragent – deionized water; free forms of manganese – ammonium acetate buffer solution рН 4.8 according to M. K. Krupskyi and H. М. Alexandrova. Afterwards, the samples of soil were analysed using the method of mass spectrometery. According to the results of the research, the max. total of the manganese is observed in the mineral upper humus-accumulative horizon, but if you make a transition to the parent rock, it decreases. According to the quantitative research on determining free forms of manganese, it can be observed that soddy brown soils of the researched region are provided with the mobile forms of manganese both in the upper humus horizon and in lower transitional humus horizon. Moreover, the humus horizon of the observed region has a high content of mobile forms of manganese, which constitutes >20,1, and in the transitional horizon to the parent rock the provision index is high. A considerable increase in the water-soluble manganese in the upper humus horizon was also observed. Its concentration is considerably decreased with a transition to the lower humus horizon. The research data confirms that soddy brown soils of the observed region are contaminated with manganese compounds.

The impact of high-intensity no-till agriculture on groundwater quality in the subtropical Capiibary catchment, SE Paraguay

The Capiibary catchment, SE Paraguay, forms part of the Guarani Aquifer System and is intensively used for cashcrop agriculture (soy bean, wheat, maize), with two or more harvests per year. The aim of this study was to investigate the effects of no-till agriculture with frequent herbicide and fertilizer applications on groundwater quality under subtropical climate. Water samples taken from 81 wells showed rather low nutrient (e.g. nitrate) concentrations, probably due to the high humus content of the no-till soils and the prevalent climatic conditions which allow constant microbial recycling of nutrients. The denitrificaton potential of the aquifer is, however, small. Further analysis in seven wells showed no indication of pesticides in groundwater. This is probably attributable to a combination of the effects of no-till agriculture and the subtropical climate.

Assessment of the agrochernozem status in trans-Ural steppe under application of No-Till management system

It was shown that the agrochernozems of trans-Ural steppe (Bashkortostan) used under conditions of the No-Till system (NT) from 4 to 19 years are marked by favorable hydrophysical properties for the growth and development of plants and medium and high humus content, but, on the other hand, by the lack of nitrogen and, especially, phosphorus. Slightly eroded agrochernozems occupied by eastern galega for 19 years are similar in their properties to noneroded ones; noneroded chernozems treated with the use of NT technique are similar to the virgin analogues.

半干旱黄土丘陵区纯林土壤腐殖质异化特征及与其他性质的关系

纯林长期生长或多代连栽必然会导致土壤腐殖质含量和构成发生异化,探究这种异化特征及其与土壤其他性质的关系可以为纯林管理或混交改造提供科学依据。通过对半干旱黄土丘陵区南泥湾林场8种典型纯林土壤腐殖质及其他性质进行系统检测,结果表明:(1)侧柏林土壤腐殖质含量最高(34.61 g/kg),腐殖化程度和稳定性一般;白榆和白桦林土壤的腐殖质含量中等(19.69-23.58 g/kg)、腐殖化程度和稳定性最佳;茶条槭和小叶杨林土壤的腐殖质含量(20.59-22.53 g/kg)和构成均为中等水平;油松、沙棘和刺槐林土壤的腐殖质质量较低(11.77-13.81 g/kg),且腐殖化程度较低,稳定性相对最差;(2)与胡敏酸含量存在显著相互促进作用(P < 0.05)的土壤性质为CEC、N、微生物量和蛋白酶活性(相关系数0.769-0.926,下同),存在显著相互抑制作用的为有效Cu(-0.793);与富啡酸存在显著相互促进作用的为N、CEC、微生物量、蔗糖酶和磷酸酶活性(0.836-0.955),存在显著相互抑制作用的为有效Cu(-0.822);与胡敏素存在显著相互促进作用的为N、CEC、微生物量、磷酸酶活性和有效Zn(0.766-0.951),存在显著相互抑制作用的为脱氢酶活性(-0.784)。(3)腐殖质构成与其他性质的相关性均不显著(P > 0.05),其中相对有利于提高胡敏酸/腐殖酸含量之比的土壤性质为蛋白酶、蔗糖酶和过氧化氢酶活性,而不利的是脱氢酶活性;相对有利于提高胡敏酸/富啡酸含量之比的为速效K、CEC和脲酶活性,而不利的是脱氢酶活性。(4)总体而言土壤腐殖质含量较之腐殖质构成与其他性质之间具有更大的相关性;向土壤增施N肥可以促进腐殖质的形成,增加K肥则有利于腐殖质构成的改善,而通过混交改造或增加林下植被是促进纯林土壤腐殖质化过程和解决土壤退化的根本措施。

Paleosols and climate of the steppe zone in early iron age: Identifying short term warming of climate on slightly-sensors soils

Studies on paleosols under an archaeological landmark of a rare type (a complex of kurgans with “whiskers”) dating from the Early Iron Age (the fourth century AD) have been performed in the steppe zone of the Transural Plateau. The size and shape of third-order soil polygons under stony ridges (“whiskers”) between the kurgans have been described in detail. The results have shown that the paleosol under the kurgans erected at the turn of the Late Sarmatian and Hun times (1600 years ago) is characterized by a higher humus content and deeper location of the carbonate horizon, compared to the recent soil. This indicates that an increase in atmospheric humidity took place in the fourth century AD.

Dissimilation of soil humus in forest with pure stands and its relationship with other bio-chemical properties in the semi-arid windy region of the Loess Plateau, China

Abstract Dissimilation of soil humus in 7 typical forests with pure stands in the semiarid windy region of the Loess Plateau in China was investigated. In addition, its relationships with other bio-chemical characteristics were assessed by canonical correlation analysis. The results was as follows: (1) Pinus tabuliformis Carrière forest had the lowest humus content and the worst stability among 7 forests with pure stands; Populus simonii Carrière forest had low humus content and worse stability; Robinia pseudoacacia L. forest had moderate humus content but the best stability; Salix matsudana Koidz. forest had moderate humus content and bad stability; Hippophae rhamnoides L. forest had high humus content and the best stability; Caragana microphylla Lam. forest had high humus content and moderate stability; Amorpha fruticosa L. forest had the highest humus content and benign stability; (2) Large microbial biomass and sufficient available P would accelerate the formation of humic acid and fulvic acid, respectively. High available N, P and Fe contents and high urease and protease activity were conducive to increase the humus stability. The particularity of community environment and litter properties of pure stands were identified as the key reasons for the humus dissimilation, thus mixed-reformation or establishing ground vegetation would be feasible ways to improve humus properties in forest with pure stands.