Showing papers in "Canadian Journal of Soil Science in 1987"

Soil organic matter characteristics after long-term cropping to various spring wheat rotations

Abstract: Soil from a long-term crop rotation study conducted at Lethbridge, Alberta was analyzed to determine the influence of various spring wheat rotations with and without perennial forages on total and mineralizable soil organic matter contents. Crop rotations considered included: continuous wheat (W), fallow-wheat (FW), fallow-wheat-wheat (FWW), and fallow-wheat-wheat-forage-forage-forage (FWWAAA) in which the forage was a mixture of alfalfa and crested wheat grass. The organic C and N contents of soil after 33 yr of cropping were highest in treatments W and FWWAAA, and decreased with increasing frequency of fallow in the rotation. The inclusion of the perennial forage in the rotation did not increase organic C and N levels above those observed in the continuous wheat treatment (W). Differences in levels of mineralizable organic matter among treatments, as measured in laboratory incubations, were much greater than differences in total organic matter content among treatments. In the surface soil layer (0–15 cm...

Comparison of morphology and porosity of a soil under conventional and zero tillage

Abstract: Effects of tillage on soil morphology and porosity were investigated in plots planted to corn (Zea mays L.) for seven consecutive years. Micromorphometric analyses indicated that Ap horizons of no-till plots had approximately half the macroporosity (pores ≥ 200 μm equivalent circular diameter) of those of conventionally tilled plots. Loss of macroporosity was characterized by a decrease in mean pore size and a tendency for pores to become elongated, less tortuous, and oriented parallel to the soil surface. Obvious zoological activity, which consisted mainly of burrowing earthworms, resulted in two to nine times more bioporosity in a no-till pedon than in a conventionally tilled pedon. Earthworm activity also contributed to the formation of 5-cm-thick B & A horizon and a more uniform distribution of organic carbon than in the conventionally tilled pedon. These differences in morphology are reflected in the classification under Soil Taxonomy but not under the Canadian System. We speculate that zoological ac...

Comparison of 13c cpmas nmr and chemical techniques for measuring the degree of decomposition in virgin and cultivated peat profiles

Abstract: Solid-state 13C CPMAS NMR was used to examine organic soils from virgin, 5-yr and 15-yr cultivated sites. In agreement with previous studies using other techniques, the chemical effects of cultivation were essentially confined to the plough layer. Cultivated sites had less carbohydrate, and increased lipid and methoxyl carbon; these changes were similar to those found with depth, due to natural decomposition. Changes in aromatic and phenolic carbon with depth or years of cultivation were small. When the NMR data were compared with other indicators of decomposition, there were no correlations between the pyrophosphate index and NMR parameters. Rubbed fiber correlated positively with carbohydrate, and negatively with lipid. This study supports the use of rubbed fiber as a routine indicator of the degree of decomposition, and the use of 13C CPMAS NMR for elucidating chemical changes in organic soils. It also illustrates the need to separate more clearly chemical changes occurring during decomposition or cult...

THE EFFECT OF NITROGEN, SULPHUR AND BORON ON YIELD AND QUALITY OF RAPESEED (Brassica napus L. and B. campestris L.)

Abstract: In northeastern Saskatchewan on Gray Luvisolic soils, rapeseed (Brassica napus L. and B. campestris L.) grown on many fields does not set seed, possibly because of deficiencies of S and B. Therefore, experiments were begun in 1979 to determine (1) the effect of N, S and B fertilizers on yield and quality of rapeseed; (2) if cultivars (B. napus and B. campestris L.) responded differently to these nutrients; and (3) nutrient and nutrient interaction effects of five rates of N, S and B in a composite rotatable design on yield and quality of the cultivar Regent (B. napus L.). Rates of up to 200 kg N ha−1, 50 kg S ha−1 and 2.8 kg B ha−1 were applied. The experiments were conducted on 13 sites. Nine were in N.E. Saskatchewan on Sylvania f1, Waitville 1 (Luvisolic) and Melfort sicl (Black Chernozemic) soils. Four were in N.W. Saskatchewan on Loon River 1 and Waitville 1, (Luvisolic) soils. In N.W. Saskatchewan there was a significant yield increase because of N (1.00 t ha−1) and S (1.06 t ha−1). In N.E. Saskatch...

Methane and carbon dioxide evolution from subarctic fens

Abstract: Rates of net methane and carbon dioxide evolution from four subarctic fens over one summer ranged from 0 to 7 mmol CH4 m−2 d−1 and from 2 to 29 mmol CO2 m2 d−1. Average molar ratios of carbon dioxide to methane ranged from 3 to 10. Partially because of the high spatial variability in evolution rates, the temperature dependence of carbon dioxide was weak, but stronger for methane, with significant (P < 0.05) positive correlations at two sites, especially with peat temperatures. Annual flux of methane is estimated to be 0.1–0.6 g C m−2 which, although low compared to other wetlands, becomes a substantial atmospheric contribution when the large area occupied by subarctic peatlands is taken into account. Key words: Methane, carbon dioxide, peatlands, fens

Comparison of measured soil 137-cesium losses and erosion rates

Abstract: Atmospheric deposition rates of 90Sr and analysis of soil samples from non-eroded sites indicated base levels of total soil 137Cs were approximately 2700 Bq m−2 in southern Ontario in 1985. Measured 137Cs losses (1965–1976) from long-term runoff plots were significantly correlated to measured soil losses during the same period. Monitoring temporal changes in soil 137Cs should be an accurate method of estimating soil loss in southern Ontario. Key words: Soil loss, 137Cs, Ontario, runoff plots

Cation nutrition of barley as influenced by soil solution composition in a saline soil

Abstract: Identification of nutritional disorders in crops growing on saline soils may facilitate the development of breeding or agronomic practices that improve yields in saline areas. An investigation was conducted under controlled environment conditions to identify possible cation deficiencies in barley (Hordeum vulgare 'Gait') grown under sulfate-dominated salinity stress. Soil was artificially salinized to produce a factorial of five salinity levels (ranging from approximately 6.5 to 17.5 dS m−1) and five salt types containing various ratios of Na:Mg:Ca. A control treatment (3.1 dS m−1) was also included. Barley was grown for 75 d and harvested for analysis of dry matter yield and tissue composition. Yield response of barley to salinity stress was not differentially affected by the type of salt used in salinization. Concentrations of sodium and magnesium in the plant tissue were generally increased by salinity stress, but these accumulations did not restrict yield since no consistent relationship was found bet...

Influence of cropping treatments on the monosaccharide content of the hydrolysates of a soil and its aggregate fractions

Abstract: The influence of three cropping treatments on the quantitative and qualitative composition of the carbohydrate fraction of a silt loam soil and its water-stable aggregates was assessed. Three cropping treatments were considered: bromegrass (Bromus inermis Leyss.) grown continuously for 15 yr (B15), grain-corn (Zea mays L.) grown continuously using conventional tillage for 15 yr (C15), and grain-corn grown continuously for 13 yr followed by 2 yr of bromegrass (B13C2). Six water-stable aggregate size fractions ranging from 8.00–4.70 to 0.25–0.10 mm in diameter were separated from the soil by wet sieving. The carbohydrate fraction was extracted by acid hydrolysis, reduced, acetylated to alditol acetates and analyzed by temperature-programmed capillary gas chromatography. Total carbohydrate content was not significantly influenced by cropping treatment but was observed to increase as aggregate size decreased irrespective of cropping treatment. The carbohydrate content in the different aggregate size fractions...

Influence of cropping history and chemical treatments on the water-stable aggregation of a silt loam soil

Abstract: Changes in cropping practices can alter soil structural characteristics. The purpose of this study was to assess the extent and rate at which bromegrass (Bromus inermis Leyss) and continuous grain-corn (Zea mays L.) influence soil aggregation and various soil binding agents. Five cropping treatments ranging from 15 yr of continuous grain-corn to 15 yr of continuous bromegrass production were investigated. Soil aggregation and the nature of soil binding agents were determined by measuring the water-stable aggregate size distribution subsequent to the application of six chemical pretreatments — control, distilled water, 0.08 M sodium azide, 0.08 M sodium chloride, 0.08 M sodium periodate, and 0.02 M sodium pyrophosphate. A simple power function was used to describe the relationship between the cumulative percentage by weight of water-stable aggregates and aggregate diameter. The exponent in the power function provided a measure of the influence of cropping treatment and chemical pretreatment across the whol...

Influence of texture and management practices on the forms and distribution of soil phosphorus

Abstract: Changes in soil phosphorus (P) forms, as determined by a sequential fractionation procedure, were used to assess the influence of soil texture and management practices on the forms and distribution of soil P in a Brown Chernozemic loam soil at Swift Current, Saskatchewan. Significant proportions of the variability of all P fractions except residual-P could be attributed to changes in sand content. Changes in the forms and distribution of soil P with decreasing sand content followed patterns similar to those associated with a weathering sequence. The proportion of total soil P in inorganic and organic extractable forms that were extractable sequentially with anion exchange resin (resin-Pi), sodium bicarbonate (bicarb-Pi and -Po), and sodium hydroxide (NaOH-Pi and -Po) increased with decreasing sand content. Acid-extractable inorganic P (HCl-Pi) was the only P fraction positively correlated with sand content. The presence of a crop increased the proportion of soil P present as the more labile organic-P frac...

Soil incubations in polyethylene bags: effect of bag thickness and temperature on nitrogen transformations and co2 permeability

Abstract: Ground, sieved forest floor material, collected from an interior Alaskan white spruce (Picea glauca (Moench.) Voss) stand was incubated in polyethylene bags of three thicknesses (0.015, 0.020 and 0.032 mm) at three temperatures (5, 15 and 25 °C) for periods of up to 28 d. Temperature and length of incubation proved to be more important factors affecting nitrogen mineralization than thickness of bag over the range of thicknesses tested. Regardless of temperature and time of incubation, all thicknesses of bags remained permeable to CO2. All bag thicknesses remained impermeable to H2O loss, thus ensuring constant moisture content over the duration of the experiment. An additional experiment which utilized a urea-amendment to stimulate CO2 production indicated that, even under circumstances of high CO2 evolution, the bags remained well oxygenated. Key words: Spruce (white), soil incubation, polyethylene bags, nitrogen mineralization

Effect of fertilizer on soil productivity in long-term spring wheat rotations

Abstract: Surface soil samples taken from two long-term crop rotations at Lethbridge, Alberta were used to assess the influence of fertilizer N and P on total and mineralizable concentrations of organic C an

Sulphate relationships in some central Ontario forest soils.

Abstract: The status of sandy, podzolic soils from central Ontario was examined. Water-soluble was positively correlated with soil organic C concentrations but not with Fe and Al oxides (citrate-dithionite-bicarbonate minus pyrophosphate extractable Fe and Al). For adsorbed the reverse was true. Surface horizons were high in soluble and low in adsorbed whereas B horizons containing high levels of Fe and Al oxides contained large amounts of adsorbed and little soluble . Successive distilled water extractions of some samples indicated the removal of almost all soluble from surface horizons in one or two extractions. Sulphate, however, remained present in the B horizons after five extractions. The amount of soluble extracted was dependent on horizon type and amount of water used for extraction. This makes evident the importance of moisture status, residence time and hydrologic pathways in determining release from the soil, and demonstrates the need for in situ studies. Plastic Lake B horizons adsorbed added in the lab...

A soil chronosequence on beach sands, vancouver island, british columbia

Abstract: A soil chronosequence near Cox Bay, on the west coast of Vancouver Island, British Columbia was investigated. Soils in the sequence have developed on sandy beach deposits, which are advancing toward the ocean at a rate of 0.26 m per year. Dendrochronology and geomorphology established surface ages ranging from 127 to 550 yr for seven selected pedons across these deposits. With soil age, there was progressive deepening and differentiation of genetic horizons, resulting in soil classification that ranged from an Orthic Dystric Brunisol at the youngest site (site 1) to an Orthic Humo Ferric Podzol at the oldest site (site 7). Organic matter increased from a maximum value for mineral horizons of 1.1% in the Bm of site 1 to 4.7% in the Ae of site 7. Oxalate-extractable Al in the uppermost B horizons of the soils increased from 0.12% at site 1 to 0.30% at site 6. Available Mg and K from the lowermost horizons sampled decreased from 35 and 25 mg kg−1 to 4 and 5 mg kg−1, respectively, when moving from sites 1 to ...

Soil erosion and corn yield in ontario. i. field evaluation

Abstract: Yield of corn (Zea mays L.) was measured at eight sites in 1982 and nine sites in 1983 on areas in farm fields exhibiting differing degrees of past erosion. Yield was also measured on depositional areas in some fields. Yield on depositional areas was, on average, marginally greater than on noneroded areas. Yield on severely eroded areas (all or most of original solum lost) ranged from 16 to 80% of that on noneroded areas with an average of 59%. There was little or no reduction in yield until the depth to Ck had been reduced to almost 50% of that on the noneroded profile. With further reductions in depth to Ck, yields declined rapidly on most sites. The primary cause of yield reduction varied from site to site and included reduced stand and seedling vigor due to a poor seedbed condition, nutrient deficiency and reduced available water holding capacity (AWHC). The impact of erosion on yield at a field and regional level was estimated based on the extent of erosion determined from aerial photographs and the ...

Biological properties of some prince edward island soils: relationship between microbial biomass nitrogen and mineralizable nitrogen

Abstract: The mineral N flush, a measure of microbial biomass N, and the N mineralization potential (No) were determined in eight representative agricultural soils (Humo-Ferric Podzols and Gray Luvisols) of Prince Edward Island. The acidic (pH 5.0–5.8) soils, varying in texture from loam to loamy sand had an organic C range of 0.75–2.74%. Both mineral N flush (4–38 μg N g−1 soil) and the percentage soil organic N in the mineral N flush (0.4–2.0%) were relatively low compared to other studies. This observation was related to the generally low pH range of these soils. Potentially mineralizable soil N (No) ranged from 44 to 247 μg N g−1 and accounted for 4.5–13.3% of the total soil organic N. The No was closely related to the mineral N flush (r2 = 0.94) but poorly related to percent organic matter (r2 = 0.26) or organic N (r2 = 0.38). The results indicate that for these soils of similar properties, with low levels of residual mineral N, the mineral N flush could be utilized as an indirect measure of the soil N mineral...

Oxidation of elemental sulfur under field conditions in central saskatchewan

Abstract: A field study was conducted at 4 sites in central Saskatchewan to examine the oxidation rate of elemental S and its influence on soil pH. Finely divided S (approximately 7-μm diameter) was applied at a rate of 200 kg ha−1 to soil cores in aluminum cylinders. Three entire cores from each site were removed and analyzed for sulfate content and soil pH four times during a 16-mo period. All four soils exhibited significant oxidative activity. Twenty-three to forty-five percent of applied S was recovered as sulfate 10 wk after application. Sulfate concentrations recovered in the soil profiles declined after approximately 1 yr, partly due to leaching losses. Fertilizer-derived sulfate was most persistent in soils of finer texture. In the coarse-textured soils, most of the fertilizer-derived sulfate was apparently leached from the soil profile by the end of the 16-mo period. Soil pH was marginally reduced by oxidation following the application of elemental S but differences were no longer statistically significan...

A new hand tool for cutting soil monoliths

Abstract: A portable tool for cutting undisturbed soil monoliths has been developed and field tested. A soil column suitable for mounting or subsampling can be obtained in less than 5 min from all soils that are not excessively stony. Key words: Profile cutter, undisturbed samples

Accumulation of native arsenic in acid sulphate soils in alberta

Abstract: Acid sulphate soils belonging to the Boundary and Josephine soil series were analyzed for As to determine mineral partitioning, form, and redistribution of the element. Samples of soil, natrojarosite, and zones enriched in iron oxides were collected from upper and lower slope positions. Levels in bulk samples were 10 times higher and levels in some Fe oxides were 100 times higher than normal background abundances. Arsenic was partitioned into silt and clay fractions and appeared related to the distribution of iron oxides in the size separates. Most of the translocated As accumulated in the vein-like network of segregated iron oxide in fractures extending downward from B horizons. These vein samples contained as much as 450 mg As kg−1, primarily as adsorbed As associated with both crystalline and amorphous forms of iron. Microbiologically mediated losses of As had depleted surface horizons of the element. The weathering of pyrite is believed to account for the accumulations of As in acid sulphate soils. Ke...

Estimating soil net nitrogen mineralization as affected by tillage and soil drainage due to topographic position

Abstract: The influence of tillage on net nitrogen mineralization out of sod for two toposequences was estimated by several different methods. A field procedure utilizing small rain shelters to prevent leaching was employed to measure N mineralized in no-tillage (NT) and plowed (CT) treatments for six soils. Potentially mineralizable N and autoclavable N were also determined. An intact soil core procedure was developed to measure N mineralization. With the field procedure, mineralized N was generally greater in the well-drained soils but decreased with decreasing drainage. There was a highly significant interaction between soil type and tillage with greater amounts of N mineralized in the plowed well-drained soils but less in the poorly drained soils when compared to the corresponding no-tillage treatment. The standard laboratory estimates were able to predict differences between soils but did not predict the tillage effect. The development of a laboratory intact core procedure allowed for simulation of tillage eff...

Physical properties of some Prince Edward Island soils in relation to their tillage requirement and suitability for direct drilling

Abstract: Successful reduced tillage systems depend on suitable soil types and the maintenance of optimum soil structure. Studies were conducted to assess the tillage requirement of some well-drained Podzolic and Luvisolic soils in Prince Edward Island and their suitability for direct drilling. Relatively high amounts of silt and fine sand indicated that the soils were structurally unstable with a propensity for compaction. Compactability was inversely related (r2 = 0.90) to concentrations of soil organic carbon over a range of 0.2–2.0%. In the Ap horizons, where organic carbon exceeded 1.6%, the level of macroporosity (equivalent pore diam. > 50 μm) was generally greater than 10%. The B horizon and lower level of the Ap horizon, generally, had low porosity and organic matter, although pore continuity was adequate. Macroporosity was closely related to soil bulk density (r2 = 0.81). Penetrometer resistance down the soil profile indicated a relatively shallow rooting depth potential of 25–40 cm. A 3-yr direct drillin...

The dynamics of inorganic nitrogen in a fraser valley soil with and without spring or fall ammonium nitrate applications

Abstract: Nitrogen in fallow soil in four field trials was monitored at Agassiz to examine the response of N processes under humid weather conditions of south coastal British Columbia. Inorganic N in the soil profile of control and ammonium-nitrate-treated plots were compared at various time intervals. In two trials (Spring-78 and Spring-81) treatments were applied in late May and in two (Fall-79 and Fall-82) in early November. Leaching of spring-applied N was quite limited during the spring and summer. In the Spring-78 trial, there was negligible nitrate movement until September whereas in the Spring-81 trial there was some movement in June. In the Spring-81 trial, upward movement of nitrate was detected in late August. Nitrate leaching in the summer of 1981 was associated with an unusually high amount of precipitation during June. Leaching of nitrate was significant in late October to December. Nitrogen applied in early November showed extensive leaching by late December. The ammonium appeared to have been nitrif...

Effect of crop rotations and fertilizers on moisture conserved and moisture use by spring wheat in southwestern saskatchewan

Abstract: The effects of crop rotation and fertilization on moisture conserved and moisture use efficiency (MUE) were assessed on a loam soil in the Brown soil zone of southwestern Saskatchewan over the period 1967–1984. Six spring wheat rotations were examined that were either fertilized at soil test recommended rates of N and P, or N or P was withheld according to rotation specifications. MUE in this study was calculated as grain yield divided by sum of 1 May to 31 Aug. precipitation plus soil moisture used between seeding and harvest. In the first fall after harvest 8–11 % of the precipitation received was stored in soil in all rotations. During the first winter 3–5 times as much moisture was stored as was stored in the fall; compared to continuous wheat receiving only P, continuous wheat fertilized with N and P increased moisture storage by 12 mm due to a larger amount of crop residues left in the field. In the first 9 mo of summer-fallow, 33% of the precipitation was stored, but over the entire 21-mo fallow pe...

In situ nutrient extraction by resin from forested, clear-cut and site-prepared soil

Abstract: Anion and cation resins were tested as sinks for nutrient ions under variable forest soil conditions. The resins, contained in nylon bags, were placed for periods of 4 wk below the forest floor of a softwood stand, and at approximately 7.5 cm depth on an adjacent clearcut with two different types of site preparation for tree planting. The soil was an Orthic Humo-ferric Podzol. Ion sorption below the forest floor, especially the sorption of ammonium, nitrate and phosphate, was strongly increased after clear-cutting of the forest. Sorption rates were generally lower in the mineral soil than immediately below the forest floor, except for nitrate and sulphate. Mixing of forest floor materials and fine logging debris into the mineral surface horizons generally increased resin sorption if compared to sorption in soil from which the forest floor had been removed. Resin sorption also revealed strong seasonal effects which may have been caused by changes in soil temperature and moisture. Key words: Ion exchange re...

Effects of cropping system on structure of brookston clay loam in long-term experimental plots at woodslee, ontario

Abstract: Macro- and microstructure were described and water desorption characteristics were measured for a Brookston clay loam soil under different cropping systems. The Ap horizon of the long-term corn (Zea mays L.) plots differed markedly from those of a bluegrass (Poa pratensis L.) plot and a never-cultivated plot as follows: massive as opposed to strongly structured, macroporosity (pore width > 60 μm) ≤ 6% as opposed to more than 10%, isolated pores as opposed to interconnected pores, bulk density 1.4–1.5 Mg m−3 as opposed to 1.0–1.3 Mg m−3. The Ap horizon of the rotation plots, oats (Avena sativa L.), alfalfa (Medicago sativa L.), alfalfa, corn, differed from those of the continuous corn plots in having many more biopores larger than 0.5 mm in diameter (≥ 0.2% relative to ≤ 0.02%). Below a depth of 30 cm comparable horizons of soils from all plots were similar in structure, bulk density and water characteristic curves. Key words: Porosity, biopores, compaction, macromorphology, image analysis

Retention of boron by agricultural soils from Ontario

Abstract: The retention of B by 20 agricultural soils from Ontario was investigated by equilibration of the soils with various concentrations of boric acid. The retention of B conformed to both Langmuir and Freundlich adsorption isotherms for all but one soil. Adsorption maxima were calculated for both isotherms and from simple linear regression analysis only pH was found to be significantly correlated with the calculated adsorption maxima. For soils with pH above 6.8, the Langmuir adsorption maxima were significantly correlated with organic C and water-soluble carbohydrate contents. Application of phase diagrams indicated that, under the experimental conditions employed, the solutions of some of the acidic soils were supersaturated with respect to the Ca-containing borate minerals inyoite, colemanite and nobleite and, given a number of reasonable assumptions, that at rates of B application of 3 kg ha−1, acidic soils could be supersaturated with respect to the mineral nobleite. The extent of complexation of B with ...

Utilization of cattle manure containing wood shavings: effect on soil and crop

Abstract: A 7-yr study was conducted to determine the effects of repeated annual applications of manure containing softwood shavings (M + S) at 50 t ha−1 on the soil and its productivity, relative to manure without shavings (M) at 50 t ha−1 and nitrogen fertilizer (F) at 67 kg ha−1. The EC, OM, total N and C:N ratio of the soil of the M + S and M + S + F plots to 60-cm depth were not significantly greater than those from the M plots, and in some instances they were significantly less. The NO3-N and total N and available P contents of the soil from the M + S treatment were significantly lower than those from the M treatment. Immobilization of N in the M + S and M + S + F treatments was indicated. Barley (Hordeum vulgare L. 'Gait') straw and grain yields and protein content of the grain were generally greater under the M than under the M + S treatment. When N fertilizer was included in the M + S treatment (M + S + F) the yields were similar to those of M, and the protein content increased. If manure with shavings is ...

Effect of wheat straw incorporation on denitrification of n under anaerobic and aerobic conditions

Abstract: The effects of wheat straw incorporation on denitrification, immobilization of N, and C mineralization were investigated at H2O contents of 60, 90 and 120% saturation. Incorporation of increasing levels of straw consistently increased the rate of denitrification for the first 4–8 d, followed by negligible N losses thereafter. In a total period of 96 d, the addition of 1.0% straw increased N losses from 2.5 to 10.1, and from 61.6 to 83.9 μg g−1 in the 60 and 120% water saturation treatments, respectively. The pattern of CO2-C evolved was practically identical to that of the denitrification rate for the initial period when sufficient was present. This study has confirmed that in flooded soils, high rates of denitrification will persist only when C is supplied by native or applied organic C sources, provided adequate is present. When was low, denitrification rates rapidly decreased, even with a sufficient supply of C. Immobilization of fertilizer N (50 μg N g−1 as K15NO3) was very rapid. Around 90% of the to...

Persistence of changes in selected soil chemical and physical properties after pipeline installation in solonetzic native rangeland

Abstract: A study was conducted in Solonetzic mixed prairie of southern Alberta to evaluate and determine the longevity of selected ecosystem responses to pipeline installation. Five adjacent natural gas pipelines on a series of rights-of-way (ROW) were studied at three sites. The lines, which were installed in 1957, 1963, 1968, 1972 and 1981, had diameters of 86, 86, 91, 107 and 107 cm, respectively. Soils were analyzed for particle size distribution, bulk density, pH, electrical conductivity, ion composition, and organic matter content. It was concluded that pipeline construction in Solonetzic mixed prairie range-land initially tended to improve surface soil chemical and physical properties compared to blowouts, but reduced soil quality in vegetated native prairie. Surface bulk density increased to 1.3–1.6 Mg m−3 from an undisturbed density of 0.9–1.0 Mg m−3. Increased densities were evident to 55 cm in all 1981 transects except the trench where subsurface densities were reduced. Chemical changes were associated ...

The catalytic role of birnessite in the transformation of iron

Abstract: The influence of birnessite (δ-MnO2) on the precipitation products of iron was studied, in the FeCl2-NH4OH system at different Mn/Fe molar ratios (0, 0.01, 0.1 and 1.0) and in the acidic pH (4.0, 5.0 and 6.0) range, by X-ray, TEM, IR and chemical analyses. The precipitation products formed at pH 5.0 and 6.0 were found to be lepidocrocite (γ-FeOOH) in the absence of birnessite. Birnessite promoted increased precipitation of Fe oxide; the oxidation of Fe(II) by MnO2 was thermodynamically feasible and was confirmed by the presence of Mn(II) in the solution by ESR data. Birnessite also influenced the crystallization processes of hydrolytic products of Fe which range from lepidocrocite through goethite (α-FeOOH), akaganeite (β-FeOOH), to X-ray noncrystalline Fe oxides. The noncrystalline Fe oxides formed at a Mn/Fe molar ratio of 1.0 were characterized by infrared absorption maxima at 1400 and 750 cm−1. Key words: Birnessite, Fe(II) oxidation, ESR, lepidocrocite, akaganeite, noncrystalline oxide