耕地土壤交换性钙镁比值的研究

对沈阳市郊区1994个耕地表土(0～20cm)样点和4个典型剖面中交换性Ca/Mg的比值进行了对比研究。结果表明:不同土属耕层土壤中Ca、Mg交换量有较大差别,交换性Ca/Mg的比值主要受母质等成土因素的影响;棕壤的各个土属的Ca/Mg在4左右,石灰性草甸土和草甸沼泽土的Ca/Mg则在8以上。棕壤和草甸土典型剖面不同层次中的Ca/Mg比值有着随深度加深而降低的趋势;由于Ca的植物返还率较Mg高,同一土壤类型中Ca/Mg比值的最大值出现在表土层,母质层中的Ca/Mg则相对稳定。对土壤Ca/Mg进行研究可以丰富土壤离子交换性能研究和土壤发生学特性研究的内容。     

The influence of acid soil factors on the growth of snapbeans in major appalachian soils

Abstract

Acid soil limitations to plant growth were assessed In 55 horizons of 14 major Appalachian hill land soils. Aluminum sensitive “Romano” and Al‐tolerant “Dade” snapbeans (Phaseolus vulgaris L.) were grown for 5 weeks in limed and unlimed treatments of the 55 horizons. Shoot and root growth was depressed >20% in unlimed relative to limed treatments in approximately 2/3 of the horizons. Dade snapbeans were generally more tolerant of the acid soil conditions and had higher Ca concentrations in the shoots than Romano snapbeans. However, the sensitive‐tolerant snapbean pair could not consistently be used to identify horizons with soil Al problems. Growth of both snapbeans was generally best in A horizons and worst in E horizons. The E horizons in this study were characterized by low Ca saturation (exchangeable Ca x 100/cation exchange capacity) and high Al saturation (exchangeable Al x 100/cation exchange capacity). Exchangeable Ca, soil Ca saturation and total soil solution Ca were positively correlated (p<0.01) with snapbean root and shoot growth. Soil Al saturation, total soil solution Al and soil solution Al reacting in 15 seconds with 8‐hydroxyquinoline were negatively correlated (p<0.01) with growth. The ratio of Ca/Al in soil solution was more closely related to snapbean growth than the soil solution concentration of any individual element. Soil and soil solution Mn were, in general, not significantly correlated with snapbean growth. Many of the horizons in this study had both Al toxicity and Ca deficiency problems and interaction between Ca and Al affected both snapbean growth and Ca uptake. These findings confirm the importance of considering Ca as well as Al when investigating Al phytotoxicity.     

Relationship between Norway Spruce Status and Soil Water Base Cations/Aluminum Ratios in the Czech Republic

There is a concern that soil acidification by acidic deposition, along with the resulting depletion of the labile pool of nutrient cations (e.g. Ca, Mg) and enhanced leaching of Al from soil may contribute to forest dieback. The molar ratios of Ca/Al or (Ca+Mg+K)/Al in the soil solution have been widely used as a criterion for risk of tree damage due to acidification. Intensity and quality of the crown and branch structure transformation due to formation of secondary shoots in successive series is a very sensitive indicator of long-term tree damage, and the subsequent regenerative processes. Soil water chemistry and crown structure transformation of Norway spruce were observed at 16 forest plots within the Czech Republic with the following results: parameters, expressing degradation processes in the crown (defoliation of primary structure), regeneration processes (percentage of secondary shoots) or synthetic stages of crown structure transformation showed high correlation with soil water (Ca+Mg+K)/Al ratio in organic horizons. No relationships were found for mineral horizons. The correlations between soil water and crown status parameters were considerably stronger when using the (Ca+Mg+K)/Al ratio rather than the Ca/Al ratio.     

A greenhouse study of northern red oak seedling growth on two forest soils at different stages of acidification

The objective of this study was to determine whether or not Ca and P in soils from two forested sites at two different stages of acidification were limiting growth of red oak seedlings. The A and E horizons of a Berks soil from Watershed 4 at the Fernow Experimental Forest (cation exchange buffer range) and a Hazelton/Dekalb soil from Pea Vine Hill in Southwestern Pennsylvania (Al buffer range) were placed in pots and utilized as the growth medium for northern red oak seedlings in a greenhouse environment. Soil water NO₃-N, Ca, Mg, and K concentrations were significantly higher (α≤0.05) on the Berks soil. Soil exchangeable P and soil solution TP (total phosphorus) were significantly higher (α≤0.10) on the Hazelton/Dekalb soil. Both soils were amended with bone meal (CaPO₄) to determine the effects of Ca and P addition on the growth and nutrient uptake of the seedlings. Height growth of the control red oak seedlings was significantly (α≤0.05) greater on the Berks soil after 45 d, but amendment of Hazelton/Dekalb soil with bone meal eliminated this difference. Bone meal addition to the Hazelton/Dekalb soil resulted in significantly greater (α≤0.05) height growth of red oak seedlings when compared to red oak seedlings grown on unamended Hazelton/Dekalb soil, but did not have a similar effect for red oak seedlings grown on Berks soil. Bone meal addition to Hazelton/Dekalb soil resulted in greater (α≤0.05) concentrations of Ca and Mg in red oak leaves. Unfertilized Berks red oak seedling leaves had significantly higher (α≤0.05) concentrations of Ca and K than their Hazelton/Dekalb counterparts. Al/Ca molar ratios were significantly lower on the Berks soil. Red oak height growth was increased significantly by Ca addition to the Hazelton/Dekalb soil.     

Macronutrient variation in small grain forage as related to specie and variety

Abstract

Incidence of grass tetany on small grain pastures has been related to forage Mg content and K/Ca + Mg ratio. The objective of this study was to relate P, K, Ca, Mg, and the K/Ca + Mg ratio in winter forage to specie and variety. In one year on unlimed soil with low pH, rye forage tended to be higher in P than oats, barley, or wheat. P content increased the next year on higher pH soil with less specie differences. K differed little with specie, and was higher in November than later harvests. Rye tended to be higher in Ca both years, especially in the early harvest. Percent Mg was lower for wheat the first year on the low pH soil than the other species, and percent Mg increased in all species at all harvests the next year on higher pH soil with wheat having similar Mg levels to the other species. The K/Ca + Mg ratio of wheat was higher than rye, oats, and barley on the low pH soil. Liming reduced this ratio to near 2.2 on all species. Grass tetany has been reported more likely to occur when K/Ca + Mg is over 2.2, and this study suggests rye, followed closely by oats and barley, would maintain lower ratios than wheat under conditions of low Mg availability.     

Effect of Initial Soluble Salt Composition of Saline Soil on Salinity Tolerance of Barley Plant

A pot experiment was carried out on a marine saline soil to study the effect of initial soluble Na/Ca ratio of saline soil on the salinity tolerance of barley plant.The results showed that (1) the Na/Ca ratio affected significantly the dry weight of the plant at an earlier stage of growth,the critical values of initial Na/Ca ratio at which the plant could grow normally on soils containing salts of 2.5,3.5 and 4.5g kg^-1 were 30,20 and 15,respectively;(2)smaller Na/Ca ratio resulted in a considerable decrease in Na accumulation but a great increase in K accumulation in the barley plant;and (3) the plasmallema of barley leaf were badly injured when the Na/Ca ratio was more than 30 and the increase of Na content of plant caused an exudation of K from the leaf cells.Some critical indexes were suggested for the cultivation of barley plant on marine saline soils and could be used as reference in the biological reclamation of marine saline soils.     

Effect of Calcium/Magnesium Ratio in Soil on Magnesium Availability,Yield, and Yield Components of Maize

Abstract

The effect of calcium (Ca)/magnesium (Mg) ratio in the soil on Mg availability, yield, and yield components of maize (Zea mays L.) was investigated both in the greenhouse and the field at eight different Ca/Mg ratios ranging from 1∶1 and 8∶1. In the greenhouse, exchangeable Ca/Mg ratios of 2∶1 to 3∶1 gave optimum yield of maize without Mg‐deficiency symptoms. The Ca/Mg ratios in the soil were positively and significantly correlated with Ca content and negatively and significantly correlated with Mg content. The Ca/Mg ratio in the soil was also positively and significantly correlated with observed Ca/Mg ratio in the maize plant tissue. The Ca/Mg ratio in the soil could be a limiting factor for Mg nutrition of the maize plant. Under field conditions, exchangeable Ca/Mg ratios in the soil showed no significant effects on the Ca and Mg contents of the maize earleaf. However, optimum maize yield was obtained at an exchangeable Ca/Mg ratio of 6∶1.     

Growth and composition of corn,alfalfa, and orchardgrass grown on soils contaminated with airborne dust containing Ca and Mg

Abstract

A greenhouse experiment was conducted with soils allegedly contaminated with airbourne dust containing Mg and Ca oxides and carbonates to study the growth and composition of corn, orchardgrass, and alfalfa plants. Soils were obtained from sites varying in distance from the alleged source of airbourne dust.

Soil pH values ranged from 6.2 to 8.7. Plant yields decreased only when the soil pH increased above 7.7. There was no apparent relationship between the observed yield decrease and the N, P, K, and B concentrations in the plants. Although the Mn and Zn concentrations generally decreased with increasing soil pH, the decrease was not great enough to account for the yield depressions. The obviously minor symptoms occurring on the plants growing on the most affected soils could not be associated with a deficiency or excess of any other element.

The Ca/Mg ratio in the alfalfa plants decreased as soil pH increased over the range from 6.2 to 8.7. However, the Ca/Mg ratios in the corn and orchardgrass plants decreased only when the soil pH values increased above 7.7. The apparent imbalance of Ca and Mg in the tissues may account for the yield depressions.     

The effect of Ca and K levels on the herbage yield and nutrient composition of barley plants grown in high Mg soils

Abstract

The effects of Ca and K levels on barley (cv. Johnston) yield were studied in soil media containing high levels of Mg. The dry matter yield of barley decreased with increasing concentrations of Mg in soils, but the decrease was small. Dry matter yield was positively related to concentration of K in the soil. However, additions of fertilizer Ca or K did not increase dry matter yield, indicating that depressed yield associated with high Mg levels was not due to reduced availability of Ca or K. In commercial agriculture, applications of either Ca or K to such soils are unlikely to prove beneficial in increasing crop yields.

Concentrations of Mg in soil solutions of unfertilized soils were lower than levels which were previously shown to reduce crop yield. Additions of N fertilizer increased Mg concentrations to levels which could reduce barley yield     

Soil properties and tree growth along an altitudinal transect in Ecuadorian tropical montane forest

In tropical montane forests, soil properties change with increasing altitude, and tree‐growth decreases. In a tropical montane forest in Ecuador, we determined soil and tree properties along an altitudinal transect between 1960 and 2450 m asl. In different vegetation units, all horizons of three replicate profiles at each of eight sites were sampled and height, basal area, and diameter growth of trees were recorded. We determined pH and total concentrations of Al, C, Ca, K, Mg, Mn, N, Na, P, S, Zn, polyphenols, and lignin in all soil horizons and in the mineral soil additionally the effective cation‐exchange capacity (CEC). The soils were Cambisols, Planosols, and Histosols. The concentrations of Mg, Mn, N, P, and S in the O horizons and of Al, C, and all nutrients except Ca in the A horizons correlated significantly negatively with altitude. The C : N, C : P, and C : S ratios increased, and the lignin concentrations decreased in O and A horizons with increasing altitude. Forest stature, tree basal area, and tree growth decreased with altitude. An ANOVA analysis indicated that macronutrients (e.g., N, P, Ca) and micronutrients (e.g., Mn) in the O layer and in the soil mineral A horizon were correlated with tree growth. Furthermore, lignin concentrations in the O layer and the C : N ratio in soil affected tree growth. These effects were consistent, even if the effect of altitude was accounted for in a hierarchical statistical model. This suggests a contribution of nutrient deficiencies to reduced tree growth possibly caused by reduced organic‐matter turnover at higher altitudes.     

Evaluation of the Impacts of Marine Salts and Asian Dust on the Forested Yakushima Island Ecosystem, a World Natural Heritage Site in Japan

To elucidate the influence of airborne materials on the ecosystem of Japan??s Yakushima Island, we determined the elemental compositions and Sr and Nd isotope ratios in streamwater, soils, vegetation, and rocks. Streamwater had high Na and Cl contents, low Ca and HCO₃ contents, and Na/Cl and Mg/Cl ratios close to those of seawater, but it had low pH (5.4 to 7.1), a higher Ca/Cl ratio than seawater, and distinct ⁸⁷Sr/⁸⁶Sr ratios that depended on the bedrock type. The proportions of rain-derived cations in streamwater, estimated by assuming that Cl was derived from sea salt aerosols, averaged 81?% for Na, 83?% for Mg, 36?% for K, 32?% for Ca, and 33?% for Sr. The Sr value was comparable to the 28?% estimated by comparing Sr isotope ratios between rain and granite bedrock. The soils are depleted in Ca, Na, P, and Sr compared with the parent materials. At Yotsuse in the northwestern side, plants and the soil pool have ⁸⁷Sr/⁸⁶Sr ratios similar to that of rainwater with a high sea salt component. In contrast, the Sr and Nd isotope ratios of soil minerals in the A and B horizons approach those of silicate minerals in northern China??s loess soils. The soil Ca and P depletion results largely from chemical weathering of plagioclase and of small amounts of apatite and calcite in granitic rocks. This suggests that Yakushima??s ecosystem is affected by large amounts of acidic precipitation with a high sea salt component, which leaches Ca and its proxy (Sr) from bedrock into streams, and by Asian dust-derived apatite, which is an important source of P in base cation-depleted soils.     

An Assessment of the Ca:Al Ratios of Selected Pennsylvania Forest Soils

The Ca:Al status of selected Pennsylvania forest soils was assessed based on data compiled from various soil chemistry evaluations done between 1991–94. A total of 116 horizons (76 mineral, 40 organic) from 39 different soil profiles representing 18 different soil series were evaluated. Ca and Al were determined by extraction with 0.01M SrCl₂. Non-linear regression analysis (logarithmic curve) showed a significant (p < 0.01) negative relationship between extractable Ca and Al across all horizons (R² = 0.64). An acid soil infertility and aluminum stress risk assessment was conducted using the method suggested by Cronan and Grigal (1995). None of the soil organic horizons were found to be at risk; however, nearly 42% of the AE/E horizons were classified at a 50% or greater risk of producing aluminum stress to trees. The B horizons had the highest risk levels, with 91.2% classified at a 50% or greater risk level. The Ca:Al ratios of most of the mineral soil horizons included in this evaluation were low enough to present considerable risk of aluminum stress to trees growing on the sites from which these soils were collected. The application of Ca:Al ratio as a diagnostic tool in declining and nondeclining sugar maple stands in northcentral Pennsylvania generally produced consistent results for soil and roots but not for organic soil horizons and foliage of declining sugar maples.     

Elemental and/or cation ratio efficiency of corn hybrids grown on an infertile soil inadequate in magnesium

Abstract

Magnesium deficiency in corn (Zea mays L.) is often attributed to the low levels of Mg in soils. This study was conducted to determine elemental and/or cation balance efficiency of corn hybrids grown on a soil low in available Mg, Among the 15 hybrids tested, no differential efficiency in ear leaf concentration of P was found at two planting dates. Leaf concentrations of Zn and Fe were influenced by planting date for all hybrids but interactions between hybrids and planting date were found only for K, Ca, Mg concentrations and the sum of the Meq Ca + Mg/100 g, the Meq K + Ca + Mg/100 g, and the K/Ca and K/Ca + Mg ratios. Planting dates did not Influence the K/Mg ratio among hybrids. Large differences in efficiency of K, Ca, and Mg were found but these cations were found to have large Interactions. Data show that Ca and Mg efficient hybrids are less efficient in K than Ca and Mg inefficient hybrids. It should be possible to breed corn hybrids for better cation balance efficiency for use on infertile soils low in avallable Mg.     

Calcium,magnesium, and potassium uptake by crested wheatgrass grown on calcareous soils

Abstract

Forage intake with potassium/(calcium + magnesium) [K/(Mg + Ca)] values in excess of 2.2 are associated with grass tetany and Mg deficiencies in ruminants. This study was conducted to determine the degree to which forage K and Mg concentrations and K/(Ca + Mg) ratios could be predicted from soil bicarbonate (HCO₃) extractable phosphate‐phosphorus (PO₄‐P), and saturation extract Ca, Mg, K, sodium (Na), and nitrate‐nitrogen (NO₃‐N) concentrations. Crested wheatgrass (Agropyron spp) strains and cultivars representing four ploidy levels were grown in the greenhouse on eight calcareous soils with different saturation extract Ca, Mg, K and K/Mg ratios. The plants were harvested three times. Soil solution K/(Ca + Mg) and K/Mg ratios were the only measured soil parameters that showed a consistent correlation with plant K/(Ca + Mg) ratios. Bicarbonate extractable soil P was positively related to plant P and K uptake in the first harvest, but was not related in the second and third harvests nor was soil P related to plant Ca or Mg content. There was a tendency for the higher ploidy level entries to have higher plant K/(Ca + Mg) ratios. It was concluded that soil K/(Ca + Mg) ratios can be used to predict relative forage K/(Ca + Mg) ratios for grasses grown under similar conditions.     

Macro- and micromorphological features of genetic horizons in a solonetzic soil complex at the Dzhanybek Research Station

The comparative analysis of macro- and microfabrics of soil horizons in a trench crossing a solonetzic soil complex on a virgin plot has shown incomplete correspondence between the macro- and micromorphological features. Solonetzic and solodic horizons and features are differently manifested in different types of soils. The soils of the complex are subjected to continuous transformation dictated by the general trend of the landscape evolution in the Caspian Lowland and by the local changes related to the activity of burrowing animals and fluctuations in the groundwater level. The current trends of evolutionary changes are reflected in the soil microfabrics and salt pedofeatures, whereas more ancient processes are recorded in the properties of the clayey plasma. In the soil of the microlow, the most complete correspondence between the macro- and micromorphological features is observed. At the microlevel, the horizons of this soil resemble the humus-accumulative and metamorphic horizons of dark-colored chernozem-like soils of vast mesodepressions. A variant of the soil evolution within the solonetzic complex is discussed.     

悬着水位对铝硅酸盐的稳定性及土壤发生的影响

The mineral stability and solute activities of soil solution extracted from selected horizons of seven studied pedons of Alfisols in Kentucky, USA, and the relationship between distribution of iron-manganese concretions and the restrictive layers were investigated. The results showed that the genesis and development of these soils and mineral weathering trends were strongly influenced by the depth of bedrock and the presence of perched water tables at lithic (limestone) interfaces due to the dissolution and buffering effect of limestone bedrock. The extractable Mg/Ca ratio as depth function and soil depth above bedrock could be used as indices of weathering and degree of soil development. Maximum iron-manganese concretion accumulation was found to occur in the horizon overlying clay horizon (>40% clay) with a sharp increase in clay content (>10%), which suggested that zones of Fe-Mn concretion accumulation in soils of the Inner Bluegrass Region appeared to be a sensitive genetic indicator of argillic horizons with restrictive permeability.     

磷钾肥施用对日光温室土壤溶液离子组成的影响

采用土培模拟试验研究了施用磷、钾肥对大田和温室土壤溶液电导率（EC）、离子含量及其比例的影响。结果表明,温室栽培土壤溶液EC、K+、Na+、Ca2+、Mg2+、NO3-含量以及K+ / Ca2+、K+ / Mg2+摩尔比分别为大田土壤的2.5、95.0、16.6、1.9、3.2、4.0、31.0和39.0倍,说明日光温室土壤离子累积及养分比例失调问题突出。施用磷、钾肥对土壤溶液中不同离子含量的影响不同,增加磷肥施用量,显著降低了大田和温室土壤溶液EC和Ca2+、Mg2+离子含量,而对土壤溶液K+、NO3--N和NH4+-N离子浓度均无显著影响;随施钾量增加,大田及温室土壤溶液EC、K+、Na+、Ca2+、Mg2+和K+/Ca2+、K+/Mg2+摩尔比均呈显著增加趋势。温室栽培实践中因过量施用磷、钾肥而造成的阳离子养分比例失调而带来的营养及生态环境问题值得关注。     

日光温室栽培对土壤养分累积及交换性养分含量和比例的影响

研究了日光温室栽培下陕西关中地区不同土壤养分累积及交换性养分含量及比例的变化,结果表明：日光温室栽培下土壤有机质、硝态氮、有效磷和速效钾等养分显著累积,土壤阳离子交换量明显增加,而土壤pH却出现下降趋势。日光温室土壤交换性K^＋含量显著增加;日光温室和大田土壤交换性Ca^2＋含量相比无明显差异,而日光温室土壤交换性Mg^2＋的含量及其离子饱和度有所提高。日光温室土壤钙饱和度、Ca/K和M g/K均明显低于大田土壤。认为日光温室栽培下大量施用钾肥,是土壤钙离子饱和度及Ca/K和M g/K比例降低的主要原因,建议在评价日光温室土壤养分有效性时,应综合考虑交换性养分的含量、饱和度及离子间的比例关系。     

Estimation of the areas of salt-affected soils in the European part of Russia on the basis of a digital map of soil salinization on a scale of 1 : 2.5 M

A digital version of the map of salt-affected soils on a scale of 1 : 2.5 M has been used to calculate the areas of these soils in the four federal okrugs (the Southern, Central, Volga, and Northwestern) of European Russia. The total area of soils with soluble salts in the upper meter reaches 23.3 million ha. More than half of them are solonchakous soils (with soluble salts in the layer deeper than 30 cm), and about 25% are saline from the surface. Soils of sulfate and chloride-sulfate salinization predominate (>50% of the area of salt-affected soils). Alkaline soda-saline soils and soils with the participation of soda comprise about 6%. We consider this value to be underestimated and requiring refinement, because soils of solonetzic complexes with neutral salts in the upper horizons may also contain soda in the solonetzic and subsolonetzic horizons, which was not always taken into consideration upon assessing the chemical composition of the salts. Solonetzes proper and solonetzic soils predominate among the salt-affected soils in the European part of Russia. The area of solonetzes is up to 9.4 million ha. The area of solonetzic soils (including solonetzic soils with salts in the layers of 0–100 and/or 100–200 cm) is 15.5 million ha. The highest percentage (32.2%) of salt-affected soils is in the Southern federal okrug.