Lateral flow in loamy to sandy Kandiudults of the Upper Coastal Plain of Georgia (USA)

Interest in site-specific agronomic management in intensively cropped regions necessitates characterization of subsurface water movement for efficient water management (irrigation timing) and control of off-site agrichemical movement. Soils formed in fluvial sediments in portions of the Upper Coastal Plain of Georgia (USA) are extensively used for peanut, cotton, and corn production. Certain proximate soils in this region possess contrasting subsoil properties, and it was hypothesized that these differences would have major effects on water redistribution across the landscape. This could be important in irrigation management, where soils possessing increased impedance to vertical flow could require decreased irrigation as opposed to soils without vertical flow restrictions. At a site near Plains, GA. (USA), hydraulic properties of soils with differences in overlying sand thickness and contrasting argillic horizon textures (sandy vs. loamy) were evaluated. The soils were predominantly in loamy and sandy families of Typic, Arenic, and Grossarenic Kandiudults. Laboratory measurements, field monitoring of matric potentials under simulated and natural rainfall, and modeling (VS2DT) were utilized to evaluate soil hydraulic properties. Reduction in vertical K_s occurred in horizons containing higher clay (argillic horizon). Changes in tension and build ups in hydraulic gradients associated with infiltration and redistribution events existed above and within horizons with low K_s. Evidence suggested there was less groundwater recharge occurring in the loamy than in the sandy pedons, suggesting more pronounced lateral flow occurred in the loamier soils. Model simulations of water movement across a slightly sloping (1%) simulated landscape indicated lateral gradients of flow existed within the solum of these soils. Analyses of tracer (Br) movement suggested a very slight lateral redistribution occurred within a relatively short monitoring period within the sandy pedon's Bt1 horizon, and the Bt2 and Bt3 horizons of the loamy pedon. Evidence suggested both loamy and sandy argillic horizons slightly, but not overwhelmingly, induced lateral flow on these landscapes.     

Soil-geomorphology relations in mountains of Oregon,U.S.A.

The development and distribution of soils in the Coast Range and Klamath Mountains are related to geomorphic surfaces and slope gradients. Soils over basalt, studied in the Coast Range, were formed in transported materials and include examples of more than a half dozen great groups of the Alfisol, Inceptisol, Mollisol, and Ultisol orders. Distribution patterns of the soils can be related to active slopes, metastable slopes, pediments, ridge tops, flood plains, and alluvial fans. Variables among the factors of soil formation in the Coast Range are chiefly geomorphic surfaces and parent materials.Soils of a lithosequence of pyroclastics, granite and schist in the Klamath Mountains include examples of great groups in the Entisol, Inceptisol, and Mollisol orders. All soils from pyroclastics have argillic horizons, those from granite lack argillic horizons, and those from schist lack argillic horizons except on relatively stable surfaces. Average thicknesses of soils over saprolite range from 76 cm over granite and schist to 150 cm over pyroclastics.Lithologic discontinuities are common in both mountain areas. Field techniques for identification, described briefly, include stone lines, irregular distribution of rock fragments with depth, thicknesses of weathering rinds on rock fragments, and the lateral extensions of soil horizons.     

我国北亚热带白浆化土壤矿物学特性的研究

本文对北亚热带地区七个白浆化土壤的原生矿物和次生矿物的特性进行了研究。重，轻矿物含量表明土壤继承了母质的特性，粘淀层与漂白层的母质沉积是间断的，前者风化强度大于后者。石英颗粒表现特征显示漂白层物来来源于黄土物质再堆积，粘土矿物以水云母为主，其结晶度较差，氧化铁类型以针铁矿和赤铁矿为主，也有非晶质氧化铁和硅酸盐中的Ｆｅ＾２＋，其形成条件与现代化成土条件一致。     

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.     

Chemistry of pedogenesis in Indo-Gangetic alluvial plains

Five soil pedons–two aquic and two udic Haplustalfs and one petrocalcic Natrustalf–from the Indo-Gangetic alluvial plain of Western Uttar Pradesh were investigated to evaluate the pedogenetic processes. Sand/silt ratios indicate that parent material discontinuities are insignificant. Higher K content and lower SiO₂/R₂O₃ ratios of the non-clay fractions in Bt, rather than in the A, horizons suggest maximum weathering at or near the surface.
An almost linear relationship between decrease in molar SiO₂/R₂O₃ and % increase in clay to about 100cm depth in all the pedons, presence of clay argillans in Bt horizons (where % clay, fine/coarse clay ratio and bulk density values are greatest), all indicate that the development of argillic horizons in these soils was due, at least partly, to lessivage of clay. Fe in clay fractions decreases with depth whilst Al increases, but in the fine earth both increase steadily with depth. This, together with crystalline iron concretions in the lower Bt horizons, suggests that in Haplustalfs these horizons are gaining clay by neoformation/ reorganization of illuviated constituents, especially A1₂O₃.     

Influences of quaternary climatic changes on processes of soil development on desert loess deposits of the Cima volcanic field, California

Soils formed in loess are evidence of both relict and buried landscapes developed on Pliocene-to-latest Pleistocene basalt flows of the Cima volcanic field in the eastern Mojave Desert, California. The characteristics of these soils change systematically and as functions of the age and surface morphology of the lava flow. Four distinct phases of soil development are recognized: phase 1 - weakly developed soils on flows less than 0.18 M.y. old; phase 2 - strongly developed soils with thick argillic horizons on 0.18 – 0.7 M.y. old flows; phase 3 - strongly developed soils with truncated argillic horizons massively impregnated by carbonate on 0.7 to 1.1 M.y. old flows; and phase 4 - degraded soils with petrocalcic rubble on Pliocene flows. A critical aspect of the development of stage 1 soils is the evolution of a vesicular A horizon which profoundly affects the infiltration characteristics of the loess parent materials. Laboratory studies show that secondary gypsum and possibly other salt accumulation probably occurred during the period of phase 1 soil development. Slight reddening of the interiors of peds from vesicular-A horizons of phase 1 soils and presence of weakly developed B horizons indicates a slight degree of in situ chemical alteration. However, clay and Fe oxide contents of these soils show that these constituents, as well as carbonates and soluble salts, are incorporated as eolian dust. In contrast to phase 1 soils, chemical and mineralogical analysis of argillic horizons of phase 2 soils indicate proportionally greater degrees of in-situ chemical alteration. These data, the abundant clay films, and the strong reddening in the thick argillic horizons suggest that phase 2 and phase 3 soils formed during long periods of time and periodically were subjected to leaching regimes more intense than those that now exist. Flow-age data and soil-stratigraphic evidence also indicate that several major loess-deposition events occurred during the past 1.0 M.y. Loess events are attributed to past changes in climate, such as the Pleistocene-to-Holocene climatic change, that periodically caused regional desiccation of pluvial lakes, reduction of vegetational density, and exposure of loose, unconsolidated fine materials. During times of warmer interglacial climates, precipitation infiltrates to shallower depths than during glacial periods. Extensive, saline playas which developed in the Mojave Desert during the Holocene are a likely source of much of the carbonates and soluble salts that are accumulating at shallow depths both in phase 1 soils and in the formerly noncalcareous, nongypsiferous argillic horizons of phase 2 and 3 soils.     

成土作用及人为活动对水耕人为土钙镁行为的影响

The formation of Stagnic Anthrosols is closely related to rice planting and parent materials. Six representative pedons,two from each of three Stagnic Anthrosol subgroups, Vertic Haplic-, Vertic Gleyic-, and Sulfic Gleyic-Stagnic Anthrosols,from different parent materials and soil formation processes, from Liaoning Province, China, were selected and used along with additional supporting data to assess the potential impact in each soil subgroup combination of both pedogenic and anthropogenic factors on the migration and geochemical characteristics of calcium (Ca) and magnesium (Mg) and their relations to soil particle-size composition. Results revealed that exchangeable Mg was correlated positively with clay and silt content, but negatively with sand content, suggesting that clay and silt could retain more exchangeable Mg than sand. Also, in the six pedons exchangeable Ca/Mg ratios generally decreased with depth, which was most likely due to the preferential retention of Mg below the Apl horizon and the effects of bio-cycling in rice-soil systems. The pedons with high pH had smaller exchangeable Ca/Mg ratios than those with low pH. Thus, it was concluded that exchangeable Ca/Mg ratios could be helpful in classification of Stagnic Anthrosols.     

Soil development processes in an Aqualf-Ochrept sequence from loess with admixtures of tephra, New Zealand

The properties of contrasting soils occurring under a 1050–1600 mm rainfall gradient are described. The soils range, with increasing rainfall, from Typic Fragiaqualfs to Andic Dystrochrepts. Sand mineralogy of these soils indicates that they have formed in essentially similar parent materials consisting largely of quartzo-feldspathic loess with admixtures of rhyolitic and andesitic tephra. The Fragiaqualfs have high bulk density, impeded drainage in winter, degraded chlorite, argillic horizons, halloysite and vermiculite. The Dystrochrepts have lower bulk density, free drainage, ferrihydrite, allophane, humus-(Al, Fe) complexes and no argillic horizons. An hypothesis to explain differences between these soil groups proposes that the dense horizons in the Fragiaqualfs arise largely from hydraulic suctions exerted by roots during periods of high summer water deficits. The consequent loss of porosity leads to impeded drainage in winter causing gleying and enhanced clay formation. In the Dystrochrepts the summer deficits are lower, consequently the soils have lower bulk densities and remain free draining.     

Light Gray Surface-Gleyed Loamy Sandy Soils of the Northern Part of Tambov Plain: Agroecology,Properties, and Diagnostics

Light gray soils of Tambov oblast mainly develop from sandy and loamy sandy parent materials; these are the least studied soils in this region. Despite their coarse texture, these soils are subjected to surface waterlogging. They are stronger affected by the agrogenic degradation in comparison with chernozems and dark gray soils. Morphology, major elements of water regime, physical properties, and productivity of loamy sandy light gray soils with different degrees of gleyzation have been studied in the northern part of Tambov Plain in order to substantiate the appropriate methods of their management. The texture of these soils changes at the depth of 70–100 cm. The upper part is enriched in silt particles (16–30%); in the lower part, the sand content reaches 80–85%. In the nongleyed variants, middle-profile horizons contain thin iron-cemented lamellae (pseudofibers); in surface-gleyed variants, iron nodules are present in the humus horizon. The removal of clay from the humus horizon and its accumulation at the lithological contact and in pseudofibers promote surface subsidence and formation of microlows in the years with moderate and intense winter precipitation. The low range of active moisture favors desiccation of the upper horizons to the wilting point in dry years. The yield of cereal crops reaches 3.5–4.5 t/ha in the years with high and moderate summer precipitation on nongleyed and slightly gleyed light gray soils and decreases by 20–50% on strongly gleyed light gray soils. On light gray soils without irrigation, crop yields are unstable, and productivity of pastures is low. High yields of cereals and vegetables can be obtained on irrigated soils. In this case, local drainage measures should be applied to microlows; liming can be recommended to improve soil productivity.     

黄土地区非代换性钾与土壤发育的关系

黄土地区土壤类型和发育程度与土壤非代换性钾有关。本文初步研究了黄土地区主要土壤类型非代换性钾的变化。影响土壤非代换性钾含量和释放累积量的主要因素是土壤质地和有机质。粉砂粒、粘粒和有机质与非代换性钾呈正相关,而砂粒与非代换性钾呈负相关。土壤非代换性钾含量由北向南从66.71-84.62增到117.09-129.95mg/100g土;释放累积量由北向南从147.03-173.00增到251.18-346.08mg/100g土。说明黄土地区土壤非代换性钾的含量和释放累积量均从北向南逐渐增加。砂绵土和黄绵土,砂黑垆土和轻黑垆土的非代换性钾含量和释放累积量其剖面分布较均一;而粘黑垆土和黑(土娄)土的粘化层的非代换性钾含量和释放累积量高于耕作层和母质层,但因地形部位不同又存有一定差异。     

喀斯特山区不同母质(岩)发育的土壤主要理化性质差异性分析

在贵阳市乌当区采集了白云岩、石灰岩、钙质紫色砂页岩等9种母质(岩)上发育的土壤样品763个,分别进行了土壤主要理化性质的测定和差异性分析。结果表明不同母质(岩)发育的土壤理化性质具有很大的差异:红色粘土、老风化壳和页岩上发育的土壤pH值均为酸性至强酸性,有机质和CEC含量中等,土壤质地较粘重;石灰岩、白云岩和钙质紫色砂页岩上发育的土壤pH值为中性至微碱性,有机质和CEC含量较高,质地较为适中;砂页岩和河流冲积物上发育的土壤pH值为酸性至中性,其余理化性质为中等水平;砂岩发育的土壤pH值为强酸性,其余理化性质均较差。     

贵阳市乌当区不同母质发育的土壤理化性质和重金属含量差异研究

在贵阳市乌当区采集了9种母质（岩）上发育的土壤样品763个，分别测定了土壤的主要理化性质和主要重金属元素含量，通过对比分析表明不同母质（岩）发育的土壤理化性质和重金属含量都具有很大的差异。土壤理化性质的差异性主要表现为：石灰岩、红色粘土、老风化壳和页岩发育的土壤质地粘重。砂岩发育的土壤质地较轻，钙质紫色砂页岩、白云岩、砂页岩和河流冲积物发育的土壤质地适中；石灰岩、白云岩和钙质紫色砂页岩发育的土壤pH值为中性至微碱性。河流冲积物发育的土壤pH值为中性，其余5种母质（岩）发育的土壤pH值为酸性至强酸性；白云岩、钙质紫色砂页岩和河流冲积物发育的土壤有机质含量较高，而砂岩发育的土壤有机质含量较低，其余5种母质（岩）发育的土壤有机质含量介于二者之间；河流冲积物、石灰岩、白云岩和钙质紫色砂页岩等发育的土壤CEC较高，而砂岩发育的土壤CEC较低，其余4种母质（岩）发育的土壤CEC介于它们之间。土壤重金属含量差异性表现为：钙质紫色砂页岩、石灰岩、河流冲积物等发育的土壤中锅、铬、汞的含量较高。而红色粘土、河流冲积物和石灰岩等发育的土壤中铅和砷含量较高，砂岩发育的土壤中5种重金属元素的含量均为最低，其余母质（岩）发育的土壤中5种重金属元素的含量均介于上述之间。通过相关性分析结果表明：研究区域内土壤重金属镉、铬、汞、铅、砷的含量差异主要是由于成土母质（岩）的差异性所致，土壤理化性质的变化则是影响土壤重金属含量的次要因素。     

Potassium Dynamics in US Coastal Plain Soils

ABSTRACT

Potassium (K) deficiency in crops in southern US Coastal Plain soils has been documented since the l880s. Long-term soil fertility studies such as Alabama’s “Cullars Rotation” experiment (circa 1911) have been conducted with K since 1911. Other Alabama long-term experiments on several Coastal Plain and related Hapludults, Paleudults, and Kandiudults also contain K variable treatments which have been monitored since 1929. Soil test data from these long-term experiments have allowed us to answer some practical questions regarding K dynamics in Coastal Plain soils. Potassium movement through the soil profile is dependent on the soil’s cation exchange capacity (CEC) but relative accumulation is greater in the plow layer regardless of soil CEC. While subsoil K testing may be useful for identifying situations where subsoil K has been depleted, this extra effort and expense is not necessary for most cropping situations. A crop will remove most of its K from the plow layer if it is present in sufficient quantity based on soil test. Crop depletion of plow-layer K to the point where yield may be reduced is gradual and may take 10–15 years or more depending upon soil CEC and initial soil K concentration. Depletion is most rapid in low CEC soils as would be expected. However, soil test K can vary considerably during the course of a crop season with the lowest soil test K concentrations occurring immediately after harvest.     

Geomorphological and paleoclimatic implications of soil development from siliceous materials on the coral-reef terraces of Liuchiu Island in southern Taiwan

Liuchiu Island is an uplifted coral-reef island located off southwestern Taiwan. A total of four soil pedons, labeled as LC-1 and LC-2 from the Holocene terraces and LC-3 and LC-4 from the Pleistocene terraces, were sampled on the island for this work. These soils were siliceous, and were characterized by enrichment of clay and free iron (Fe_d). According to Soil Taxonomy, pedons LC-3 and LC-4 were classified as Paleudults and pedons LC-1 and LC-2 were Dystrudepts. The soil properties showed progressive changes from pedon LC-1 to pedon LC-4 in morphology, physical and chemical properties, and clay mineralogy. The contents of total Fe and dithionite-citrate-bicarbonate extractable Fe were significantly higher in pedons LC-3 and LC-4 with high weathering degree than in pedons of LC-1 and LC-2 with less weathering degree. Enrichment of kaolinite and gibbsite in pedons LC-3 and LC-4 also suggested high chemical weathering degree of the soils. The estimated soil ages for all studied pedons were consistent with their degrees in pedogenesis, where pedons LC-3 and LC-4 were located at older terraces and pedons LC-1 and LC-2 were located at younger terraces. Namely, it complied with the geologic interpretation of the continuous and simultaneous uplift and tilt of the island over time. Instead of the in situ weathering from the underlying coral reef limestone, all soils developed from siliceous parent materials deposited onto the surfaces. The SiO₂/Al₂O₃ ratios of soils indicated a component of loess may have been incorporated from continental China as part of the parent material, which confirmed a climate change of strong monsoons or severe dust storms occurred before the Holocene. However, soil development increased by the subsequent warm and humid climates of the interglacial stage over time.     

Factors affecting the formation of dark, thick epipedons beneath forest vegetation, Michigan, USA

Extremely gravelly, coarse-textured soils (frigid Udorthents and Rendolls) with different thicknesses of Oa+A horizon sequences were studied to identify factors that have influenced their genesis. These well-drained, forested soils occur on geomorphic surfaces that range in age from 3200 to 6000 years BP. The soils all have more than 500 g kg^?1 coarse fragments by mass; most contain less than 300 g kg^?1 fine earth. In the lower solum of most pedons, content of cobbles increases and amount of fine earth decreases. Most coarse fragments are dolomite and chert. Thick, gravelly Oa and A horizons are weakly correlated with parent material characteristics such as high pH and carbonate contents. Organic matter concentrations in, and thicknesses of, upper horizons are enhanced by an abundance of coarse clasts, as soils with the most gravel exhibited the thickest and darkest epipedons. Relatively high amounts of crystalline clasts in the fine gravel fraction, as well as feldspathic minerals in the fine sands, also appear to promote the development of mollic epipedons.     

Effect of sulfur rate,application method,and source on yield and mineral content of corn

Abstract

Corn (Zea mays L.) grown on sandy Coastal Plain soils may be subject to sulfur (S) deficiency due to the low levels of available S in the soil. The diagnosis of S deficiency in the field is sometimes ambiguous since mineralization of soil organic matter or root growth into the subsoil may supply adequate S to the crop. Yield response to S fertilizers has been more frequent since incidental additions of S to the soil by air pollution and fertilizer applications have been reduced. This study was conducted to identify S deficiency in corn grown on sandy Coastal Plain soils and to determine the effects of S source, rate and method of application on grain yield. Irrigated corn was grown on Norfolk loamy sand and Tifton loamy sand near Leesburg and Moultrie, Georgia, respectively in 1987. Grain yields were increased with addition of 11 kg S ha^‐1 compared to the check treatment. Increased rates of S up to 88 kg ha^‐1 did not increase grain yields above the 11 kg ha^‐1 rate. There was no difference between banded or broadcast application of (NH₄)₂SO₄ or between elemental S and (NH₄)₂SO₄ as S sources. Earleaf S concentrations of 1.6 g kg^‐1 and extractable soil S concentrations of 4.0 to 8.7 mg kg^‐1 were associated with S deficiency. Visual symtoms of S deficiency were observed in the check treatments throughout the growing season at both experimental sites. The results indicate that visual symptoms and tissue analysis can be used to identify S deficiency. Extractable soil S may be useful in determining the possible response to S fertilizer especially if the subsoil is sampled.     

红壤性水稻土可溶态稀土分布特征及与酸度调控的关系

测定了具有代表性的4种母质发育、3种水育型的红壤性水稻土及起源土壤的可溶性稀土(REEs)和稀土总丰度(∑REE),分析了REEs的分布特征及与∑REE的相关,研究了经酸碱调节后土壤REEs与pH值的关系,结果表明:(1)不同母质发育的供试土壤REEs平均值依石英闪长岩母质土壤系列、凝灰岩母质土壤系列、黑云母花岗岩母质土壤系列、玄武岩母质土壤系列顺序递减。(2)供试土壤REEs与∑REE的相关不显著。(3)起源土壤剖面中REEs具有明显自上而下增大的趋势,而不同水育型水稻土剖面的REEs分布各有特征,但总的趋势是自上而下减少。(4)经酸度调节后供试土壤的REEs随着土壤pH值的提高而下降,呈显著的幂函数相关。     

Response of soil exchangeable and crop potassium concentrations to variable fertilizer and cropping regimes in long-term field experiments on different soil types

Annual potassium (K) balances have been calculated over a 40‐year period for five field experiments located on varying parent materials (from loamy sand to clay) in south and central Sweden. Each experiment consisted of a number of K fertilizer regimes and was divided into two crop rotations, mixed arable/livestock (I) and arable only (II). Annual calculations were based on data for K inputs through manure and fertilizer, and outputs in crop removal. Plots receiving no K fertilizer showed negative K balances which ranged from 30 to 65 kg ha^?1 year^?1 in rotation I, compared with 10–26 kg ha^?1 year^?1 for rotation II. On sandy loam and clay soils, the K yield of nil K plots (rotation I) increased significantly with time during the experimental period indicating increasing release of K from soil minerals, uptake from deeper soil horizons and/or depletion of exchangeable soil K (K_ex). Significant depletion of K_ex in the topsoil was only found in the loamy sand indicating a K supply from internal sources in the sandy loam and clay soils. On silty clay and clay soils, a grass/clover ley K concentration of ～2% (dry weight) was maintained during the 40‐year study period on the nil K plots, but on the sandy loam, loam and loamy sand, herbage concentrations were generally less than 2% K.     

ABSTRACT of the Articles Printed in Journal of the Science of Soil and Manure,Japan

A contrasting occurrence of clay minerals was found within a soil profile which was derived from volcanic materials in the suburbs of Fukuoka-city, Northern Kyushu. The soil profile is located on an isolated terrace, and the morphological characteristics of the soil correspond exactly to Andosols, so-called Kuroboku soils or Humic Allophane soils.

The clay fraction of upper horizons of the soil consists largely of alumina-rich gel-like materials, gibbsite, and layer silicates such as chlorite and chloritevermiculite intergrades, while that of lower horizons is composed of allophane and gibbsite or halloysite. There was no positive indication of allophane in the upper horizons. Corresponding with the clay mineralogical composition, quartz is abundant in the fine sand fraction of the upper horizons, while the mineral is very scarce or none in the lower horizons, suggesting a close relation between the petrological nature of parent volcanic materials and the mineralogical composition of weathering products. The dominant clay mineral in the volcanic 1.10il might be dependent on the petrological nature of parent materials, and allophane is mostly formed from andesitic materials, and alumina-rich gel-like materials and layer silicates have come from quartz andesitic materials. Allophane would transform to gibbsite or halloysite according to weathering conditions, and aluminarich gel-like materials change to gibbsite under a well-drained condition.

The soil materials have been so greatly weathered that some horizons contain gibbsite of even more than 40 per cent or halloysite over 70 per cent. The morphology and mineralogy are quite similar to so-cailed “non-volcanic Kuroboku soils.”