Soil-genetic zoning: Principles, goals, structure, and applications

The soil-genetic zoning proposed, unlike the known scheme of soil-genetic zoning, is based on the analysis of soil properties and soil-forming processes. Its objective is to interpret the soil cover in the format of the substantive-genetic soil classification of Russia (2004). The units of the soil-genetic zoning are distinguished according to the manifestations of horizon-forming processes: the main processes determining the principal trend of pedogenesis and the soil profile composition at the first level and the additional processes (forming the associated soils) serving as criteria for distinguishing the units at the second level. The results obtained allow considering this investigation as an experience of a new interpretation of a small-scale soil map and its analysis from two positions: the geography of the soil-forming processes and the complexity of the soil cover. The soil-genetic zoning has been carried out on the basis of the State Soil Map sheets; it can be an instrument for the conversion of the map??s contents into the substantive-genetic soil classification of Russia (2004).     

DMPP硝化抑制效果受其浓度、施用方式及土壤基质势的影响

The efficacy of nitrification inhibitors depends on soil properties and environmental conditions. The nitrification inhibitor 3.4-dimethylpyrazole phosphate （DMPP） was investigated in a sandy loam and a loamy soil to study its effectiveness as influenced by inhibitor concentration, application form, and soil matric potential. DMPP was applied with concentrations up to 34.6 mg DMPP kg^-1 soil as solution or as ammonium-sulfate/ammonium-nitrate granules formulated with DMPP. DMPP inhibited the oxidation of ammonium in both soils, but this effect was more pronounced in the sandy loam than in the loamy soil. When applied as solution, increasing DMPP concentrations up to 7 mg DMPP kg^-1 soil had no influence on the inhibition. The effectiveness of DMPP formulated as fertilizer granules was superior to the liquid application of DMPP and NH4^＋, particularly in the loamy soil. Without DMPP, a decline in soil matric potential down to -600 kPa decreased nitrification in both soils, but this effect was more pronounced in the sandy loam than in the loamy soil. DMPP was most effective in the sandy loam particularly under conditions of higher soil moisture, i.e., under conditions favorable for nitrate leaching.     

Modelling of Cd, Cu, Ni, Pb and Zn uptake, by winter wheat and forage maize, from a sewage disposal farm

Abstract. A predictive model of metal concentrations in crops was developed to optimize soil liming and sludge application strategies at a dedicated sewage sludge disposal site. Predictions of metal concentrations in plant tissue were derived from measured values of soil metal concentration, humus content and soil pH. The plant and soil data used to parameterize the model were collected on site using quadrat sampling of mature crop and underlying topsoil. The uptake model was used to map predicted metal concentrations in wheat grain and forage maize based upon a database of soil characteristics (metal content, % humus and pH) measured as part of a routine geochemical survey of the site. The effect of a management strategy to modify uptake of Cd by wheat by changing soil pH was investigated. The effect of soil dust adhering to maize plants at harvest was also simulated to investigate the importance of this pathway for Cd transfer to animal feed such as silage.
The model gave satisfactory predictions for uptake of Cd and Zn but less useful simulations for Pb, Cu and Ni. The results for Cd uptake showed a greater dependence on soil pH in the case of wheat in comparison to maize. It is suggested that, for the study site, liming to pH 7.0 will reduce Cd concentrations in wheat grain to within EC legal standards. However the Cd content of maize may still exceed these guidelines, with a relatively minor contribution from contamination with soil dust.     

Arsenic Contamination in Rice, Wheat, Pulses, and Vegetables: A Study in an Arsenic Affected Area of West Bengal, India

Water retention and transport in soils is dependent upon the surface tension of the aqueous phase. Surfactants present in aqueous solution reduce the surface tension of aqueous phase. In soil–water systems, this can result in water drainage and reductions in field capacity and hydraulic conductivity. In this investigation, the surface tension of surfactant solutions mixed with soil—in a constant fixed ratio—was measured as a function of surfactant concentration. Two anionic surfactants were used: sodium dodecyl sulphate and sodium bis (2-ethylhexyl) sulfosuccinate. Two soils were also used—a clay soil and a sandy soil. The key observation made by this investigation was that the addition of soil to the surfactant solution provided a further component of surface tension reduction. Neither soil sample reduced the surface tension of water when surfactant was absent from the aqueous phase, though both soils released soil organic matter at low surfactant concentrations as shown by measurement of the chemical oxygen demand of the supernatant solutions. Furthermore, both surfactants were shown to be weakly adsorbed by soil as shown by the use of a methylene blue assay. It is therefore proposed that the additional reduction in surface tension arises from synergistic interactions between the surfactants and dissolved soil organic matter.     

Tillage effects on soil degradation, soil resilience, soil quality, and sustainability

Soil degradation, decrease in soil's actual and potential productivity owing to land misuse, is a major threat to agricultural sustainability and environmental quality. The problem is particularly severe in the tropics and sub-tropics as a result of high demographic pressure, shortage of prime agricultural land, harsh environments, and resource poor farmers who presumably cannot afford science based recommended inputs. Tillage methods and soil surface management affect sustainable use of soil resources through their influence on soil stability, soil resilience, and soil quality. Soil stability refers to the susceptibility of soil to change under natural or anthropogenic perturbations. In comparison, soil resilience refers to soil's ability to restore its life support processes after being stressed. The term soil quality refers to the soil's capacity to perform its three principal functions e.g. economic productivity, environment regulation, and aesthetic and cultural values. There is a need to develop precise objective and quantitative indices of assessing these attributes of the soil. These indices can only be developed from the data obtained from well designed and properly implemented long-term soil management experiments conducted on major soils in principal ecoregions.     

Soil microbial activity and free-living nematode community in the upper soil layer of the anticline erosional cirque,Makhtesh Ramon,Israel

The physical–chemical peculiarity of soil rock formations is one of the leading factors determining diversity and abundance of soil biota. The main aim of the present research was to study soil microbial and free-living nematode abundance and diversity on different soil rock formations (basalt, sandstone, limestone, granite and gypsum) of the Makhtesh Ramon erosional cirque. The obtained results showed the strong effect of soil features of different soil formations on microbial biomass and respiration as well as on the soil free-living nematode communities and its trophic and species composition. The Sorenson-Czenkanowski similarity index indicated significant differences between soil properties as well as between soil biota in observed soil formations. The qCO₂, which is known to increase according to the level of environmental stress, reached maximal values in the sandstone soil formation. The values of ecological indices such as Simpson's dominance index, maturity index and modification and species richness pointed to a specific ecological condition in the studied soil formations dependent on low content of an essential soil matter as soil moisture, organic matter and cations.     

Soil development along primary succession sequences on moraines of Hailuogou Glacier,Gongga Mountain,Sichuan, China

Soil properties related to soil development were measured in six profiles over approximately 180 years of soil development on recessional moraines of the Hailuogou Glacier, Sichuan of southwestern China. It is hypothesized that soil development is strictly time-dependent. Field and laboratory work indicate that as soil develops from initially coarse gravel outwash, the properties undergo a progressive physical and chemical change such that there is a considerable profile differentiation between the youngest and the oldest soils. The pH is also highly stratified; it decreases with time from 8.5 to 4.2 in the upper mineral soil and increases with depth in all profiles. Accumulation of soil organic C and N increases with time but the rates of accumulation become slower with time. Within the investigated timespan, soil C and N accumulated to a considerable level of 3.5 and 0.6 kg/m² respectively, with mean annual rates of 28 g/m² for carbon and 3.5 g/m² for nitrogen. The rapid accumulation of organic C and N accelerates the processes of soil formation, but the content of organic C and N did not reach a steady-state during the observed timespan. The accumulation of soil organic matter results in increased acid production and in the chemical weathering of minerals that promote formation and translocation of the clay fraction and leaching of carbonate; it is also directly responsible for development of soil properties such as cation exchange capacity (CEC), and bulk density.     

Diagnostic properties,horizons, soils and landscapes

For the classification of soil individuals such properties or horizons are used as diagnostic ones, which – as indicators for the weakest or strongest consequent transformation of the parent material and for the complementary translocation of transformation products – are assumed to reflect best the soil genesis. It is discussed how far the FAO-Unesco system satisfies this pretension. Like soil individuals as metamorphic figures of rock or sediment material soil landscapes can be considered as such of rock or sediment bodies (geomorphic units). Since both are coined by principally the same processes, the soils reflecting best the extent of consequent transformations and complementary translocations of/in the geomorphic units can be used as diagnostic ones in the classification of soil landscapes. Principles of such a taxonomy and its relation to that of soil individuals are discussed, especially in view of the ?intrazonal”? soils.     

A sterile environment for growing,and monitoring,micro-organisms under a range of soil matric potentials

The energy status of soil water, as defined by the soil matric potential, plays an important role in regulating the dynamics of all soil organisms. In particular the relations between soil matric potential and soil microbes have been well documented. We have built a simple, reproducible, and inexpensive tension table designed to equilibrate soil samples in a sterile environment, or in an environment that ensures specific populations of soil micro-organisms are protected from competing populations.     

Toxicity interaction of metals (Ag, Cu, Hg, Zn) to urease and dehydrogenase activities in soils

A study of the individual and mixture toxicities of the trace metals Ag, Cu, Hg, Zn to the soil enzymes dehydrogenase and urease was undertaken. An agricultural soil and a sandy forest soil were spiked with metal salts, individually and in combinations. The anion additions to the various treatments and controls were normalized for added anions using Ca salts. The soils were then left to equilibrate and leached to reduce the excess metals and anions. Total and dissolved metal concentrations were measured concurrently in order to consider the effect of soil chemistry on the enzyme activities. Dose-response relationships for total soil metals and soil solution metals were estimated for each metal separately following a log-logistic curve fitting. Ag and Hg were the most efficient metals to reduce soil enzyme activities. The Bliss independence model was used to predict the toxicity of metal combinations. The enzyme responses in relation to the total soil metal combinations were synergistic for the agricultural soil and antagonistic for the forest soil; possibly as a result of a higher organic matter content and higher pH in the latter soil. Enzyme activities expressed in relation to the dissolved metal concentrations were more variable than against the total metal contents and consequently we observed both synergistic and antagonistic interactions.     

Soil physical quality: Part I. Theory, effects of soil texture, density, and organic matter, and effects on root growth

A soil physical parameter, S, is defined. It is equal to the slope of the soil water retention curve at its inflection point. This curve must be plotted as the logarithm (to base e) of the water potential against the gravimetric water content (kg kg⁻¹). The value of S is indicative of the extent to which the soil porosity is concentrated into a narrow range of pore sizes. In most soils, larger values of S are consistent with the presence of a better-defined microstructure. Much previous work has shown that this microstructure is responsible for most of the soil physical properties that are necessary for the proper functioning of soil in agriculture and the environment. The use of S is illustrated with examples of soils with different texture, density (or degree of compaction), and organic matter (OM) content. The effects of S on root growth in soil are investigated, and S is shown to be a better indicator of soil rootability than bulk density. It is suggested that S can be used as an index of soil physical quality that enables different soils and the effects of different management treatments and conditions to be compared directly.     

Water, Salt and Heat Influences on Carbon and Nitrogen Dynamics in Seasonally Frozen Soils in Hetao Irrigation District, Inner Mongolia, China

To investigate carbon (C) and nitrogen (N) dynamics in seasonally frozen soils under saline and shallow groundwater supply conditions, in-situ lysimeter experiments with different groundwater table depths (WTD=1.8 and 2.2 m) were conducted in Inner Mongolia, China during the wintertime of 2012-2013. Changes in soil organic C and total N in multiple layers during various periods, as well as their relationships with soil water, salt, and heat dynamics were analyzed. Accumulation of soil organic C and total N during freezing periods was strongly related to water and salt accumulation under temperature and water potential gradients. Water and salt showed direct influences on soil C and N dynamics by transporting them to upper layer and changing soil microbial activity. Salt accumulation in the upper layer during freezing and thawing of soil affected microbial activity by lowering osmotic potential, resulting in lower C/N ratio. Nitrogen in soil tended to be more mobile with water during freezing and thawing than organic C, and the groundwater table also served as a water source for consecutive upward transport of dissolved N and C. The changes in C and N in the upper 10 cm soil layer served as a good sign for identification of water and salt influences on soil microbial activity during freezing/thawing.     

Effects of land use on soil erosion in a tropical dry forest ecosystem,Chamela watershed,Mexico

During the past few decades, Mexico has been converting tropical dry forest (TDF) into cropland and pasture, with land degradation expressed as soil erosion being the main environmental consequence. The factors and processes influencing soil erosion are related to scale. At a microscale, the stability of soil aggregates has a significant impact on soil erodibility and strongly influences other soil properties. However, at plot and watershed scales, these relationships are less well known. The relationships between the distribution of soil aggregate size, soil properties and soil erosion were examined for two soil geomorphological units (hillslopes over granite and hillslopes over tuffs) and three land uses (TDF, unburned pasture and burned pasture) within the Chamela watershed of west–central Mexico. To evaluate soil aggregation as a parameter for upscaling soil erosion, the researchers measured microtopographic features at plot scales and interpreted 1:35,000 panchromatic aerial photographs at a watershed scale. Analysis of variance indicated significant differences in soil organic carbon (P < 0.05) and soil moisture (P < 0.01) contents between the two soil geomorphological units, and field tests showed differences in soil texture and structure.     

Fractional composition of nickel,copper, zinc,and lead compounds in soils polluted by oxides and soluble metal salts

The transformation of technogenic compounds of nickel, copper, zinc, and lead entering the soil as nitrates and oxides has been studied in a model experiment. It has been shown that the results of the determination of the fractional composition of the heavy metals strongly depend on the fractionating method used. The fractional composition of heavy metals that entered the soil as the readily soluble compounds mainly depends on the affinity of ions with the reaction centers of the soil components. When soils are polluted by such weakly soluble compounds of heavy metals as oxides, their transformation and, consequently, the fractional composition formed are determined, in the first place, by the solubility of these compounds and only afterwards by the interaction of the products of the dissolution with the soil. The transformation of the technogenictechnogenic zinc and lead oxides in the soils is more complete than that of copper and nickel oxides. This leads to a strong increase in the portion of the residual fraction of these elements under fractionating. The 1 N nitric acid almost does not extract copper and nickel oxides from the soil. This can be a reason for the erroneous estimation of the extent of soil pollution.     

长期三熟制下谷物产量和土壤氮磷钾及有机质性状的演化

自1973年10月起在麦稻稻三熟制下连续进行了26年定位试验。结果表明,长期配施N肥和猪厩肥可以实现谷物的持续增产,保持土壤有机质的持续增长,并培肥土壤,有机质达到60g/kg的高水平。稻田土壤的有机质数量演化可以幂指数方程表示。土壤N素平衡有余,全N大幅度增加,而有效N的增长差距巨大。全K和速效K显著下降,缓效K变化不大。全P在平衡或盈余时有效P大幅提高。     

The first conference of Istro,at Uppsala,Sweden, 1955

The main part of the paper is an English translation of a Swedish review (Johansson, 1955), which may be regarded as the Proceedings of the very first international soil tillage conference which was held in 1955 at Uppsala, Sweden. Later on, this conference was recognized as the 1st Conference of the International Soil Tillage Research Organization (ISTRO).The review deals with tillage problems as presented by the diverse terrain and climate of the British Isles, field trials with ploughing and shallow cultivation in the Federal Republic of Germany, soil cultivation and soil conservation in the U.S.A., and some aspects of different systems of ploughing in Sweden. In the discussion following the lectures, the advantages of the then newly introduced one-way plough are stressed.     

Aluminum diffusion in Oxisols as influenced by soil water matric potential,ph, lime,gypsum, potassium chloride,and calcium phosphate

Abstract

Plant root exposure to soil aluminum (Al) depends on the soil solution Al concentration and transport to the root by diffusion. Changes in Al diffusive flux for two Oxisols was measured under laboratory conditions as a function of pH, water matric potential, and applications of gypsum, potassium chloride, and calcium phosphate. Double‐faced cation exchange resin sheets served as sinks for Al transported during 10‐day incubations through chambers containing 314 cm³ of soil. Across a range of soil pH values from 4.5 to 5.5, maximum diffusive flux of Al occurred at pH values of 4.7–4.8 in both soils and corresponded to increases of 2.2–3.0% relative to the unlimed treatment. Between pH values of 4.7–4.8 and 5.4, diffusive flux of Al decreased by 38 and 46% in the two Oxisols. Diffusive flux of Al decreased by 16–20% for the two Oxisols as soil water potentials decreased from ‐10 to ‐200 kPa. Magnitude of the reductions in diffusive flux of Al with decreasing soil water potential were less than those reported for diffusive flux of phosphorus (P) in prior investigations. Diffusive flux of Al increased by as much as 4‐fold with additions of CaSO₄ and KCl, which increased the soil solution Al concentration. Additions of 400 mg P dm^‐3 of soil had no effect on Al diffusion in either Oxisol.     

Changes in aggregate stability,nutrient status,indigenous microbial populations,and seedling emergence,following inoculation of soil withNostoc muscorum

The potential of the N₂-fixing cyanophyteNostoc muscorum for improving the aggregate stability of a poorly structured silt loam soil was studied in a greenhouse experiment. Inoculum rates were 1.61×10⁵ cells g^-1 soil dry weight (low rate) and 4.04×10⁵ cell g^-1 soil dry weight (high rate), approximately equivalent to a field application of 2 and 5 kg ha^-1 cells dry weight, respectively.N. muscorum numbers had increased 8-fold (low rate) and 10-fold (high rate) by 300 days after inoculation, indicating not only survival but proliferation. Increases in soil polysaccharides, determined as soil carbohydrate C, were 2.96–3.49 time the values in the non-inoculated soils and aggregate stability had incrased by an average of 18% on day 300. Inoculation withN. muscorum also had a pronounced effect on soil chemical and biological properties, with total C increasing by 50–63% and total N increasing by 111–120%. Increases in the soil indigenous microbial population were recorded, with numbers of bacteria 500, fungi 16, and actinomycetes 48 times the non-inoculated values on day 300 in the high-rate soil. The emergence of lettuce seedlings (Lactuca sativa var. Saladin) in undisturbed inoculated 300-day soils was 56% (low rate) and 52% (high rate) higher than in non-inoculated soils. However, homogenising soils and irrigating (to smulate ploughing and surface crusting) significantly reduced this increase in both treatments, although emergence in inoculated soils was still greater by 45% (low) and 24% (high). It is recommended that inoculated soils be left undisturbed prior to planting. The effects ofN. muscorum on soil physical, chemical, and biological properties indicate the possible benefits of cyanobacteria as soil inoculants, not only for the improvement of soil aggregate stability but also as a means of improving seedling emergence.     

氮、磷、钾肥与酚对漂洗水稻土硅、铝、铁的活化效应

本研究以四川盆地西缘茶区漂洗水稻土为供试土壤,采用浸提试验探讨尿素（N）、磷酸二氢钙（P）、硫酸钾（K）和邻苯二酚（Phy）对其硅、铝、铁的活化效应（以浸提液硅、铝、铁的浓度表征）,结果表明: 1）各种处理浸提液均以硅的浓度最大,铝次之,铁最小,即活化效应为硅＞铝＞铁; 2）浸提液硅的浓度为NPK+Phy＞NPK P＞Phy＞K CK N处理,说明磷肥通过磷酸根的配位吸附对其活化产生最重要的影响,同时酚类物质也通过弱酸作用促进其活化; 3）浸提液铝的浓度为NPK+Phy＞Phy＞P NPK K N CK处理,说明酚类物质通过与游离铝形成可溶性络合物而对其活化起突出作用,同时磷肥中的钙离子和钾肥中的钾离子也能将强酸性供试土壤中大量交换性铝离子交换而活化; 4）浸提液铁的浓度为NPK+Phy＞Phy＞K P NPK CK N处理,说明酚类物质通过络合溶铁、还原溶铁等作用对其活化做出重大贡献,同时钾肥中的钾离子和磷肥中的钙离子也将土壤胶体吸附的亚铁离子交换而活化; 5）尿素对漂洗水稻土硅、铝、铁均无显著活化效应。综上所述,磷、钾肥和酚类物质是漂洗水稻土中硅、铝、铁活化的重要影响因素。     

Survival of Escherichia coli donor,recipient, and transconjugant cells in soil

Survival of Escherichia coli donor, recipient and transconjugant cells was studied in sterile soil incubated under a variety of conditions. In soil not amended with additional nutrients, the absence of transconjugants indicated that R-plasmid transfer had not occurred. In soil supplemented with a low level of nutrient broth, both donor and recipient cells survived over a 48 hr period. In addition, transconjugant cells were detected in soil as early as two hr after the soil was inoculated with donor and recipient strains.