Showing papers in "Canadian Journal of Soil Science in 1984"

Effect of crop rotation and fertilization on some biological properties of a loam in southwestern Saskatchewan.

Abstract: Effects of rotation length, fallow-substitute crops, and N and P fertilizer on some physical and biological properties of a Brown Chernozemic loam in southwestern Saskatchewan were determined over ...

The measurement of soil water content using a portable tdr hand probe

Abstract: The time-domain reflectrometry (TDR) technique had previously been shown to measure the volumetric water content of soil accurately when applied to long-term installations of parallel transmission lines. In this study a hand probe was used with a portable TDR instrument to measure water content of soil down the wall of soils pits to a depth greater than 1 m. In a separate experiment the water content of the surface soil at two sites was measured repeatedly in increasing depth increments of 50 mm to 300 mm. The TDR measured values were compared with values obtained by a gravimetric determination on a sample of soil. The TDR gave values that were calculated at the time of measurement in the field. TDR measured values were as accurate and precise as those from gravimetric samples. Key words: Volumetric water content, soil, time domain reflectometry

Nitrous oxide emissions from soils during thawing

Abstract: We, as well as others, have observed that nitrous oxide (N2O) fluxes increased markedly during soil thaw in early spring. This phenomenon was examined further by determining nitrous oxide concentrations in the soil profile and N2O fluxes from the soil surface during the winter-spring period and evaluating physical release and microbial production of N2O on thawing of frozen soil cores in the laboratory. In mid-winter, soil profile N2O concentrations were close to ambient and surface N2O fluxes were low. At thawing, high N2O concentrations (ranging from 1082 to 2066 mg∙m−3) were found at 10–30 cm in the soil profiles of a coniferous forest, and in manure- and straw-treated plots. Concurrently, N2O flux increased markedly and reached some of the highest values observed during the entire season. When thawing was complete, soil profile N2O concentrations and N2O flux declined. Soil cores were taken from frozen soil, warmed in the laboratory, and N2O release measured. Nitrous oxide was released on warming, and...

Plant growth regulator activity of soluble humic complexes

Abstract: Auxin and cytokinin bioassays were performed to test the biological activity of soluble humic complexes (SHC). "Pea split stem curvature" (auxin test) and "cucumber" tests (cytokinin test) did not show any quantifiable biological activity of SHC. On the contrary, "cress test" and "senescence test" offered good evidence of a hormonal-like activity 100 times lower than that of IAA (10 mg IAA∙g−1 SHC) and 10 times lower than that of N6 BA (100 mg N6 BA∙g−1 SHC). At a high concentration of SHC, toxic effects were evident, indicating the presence of inhibitory substances which counteracted the hormone-like activity of humic complexes. Key words: Plant growth regulators, soluble humic complexes

Mineralization rate constants and their use for estimating nitrogen mineralization in some canadian prairie soils

Abstract: There is a need to provide quantitative relationships that will allow agronomists to estimate accurately the nitrogen-supplying power of soils while taking into account both temperature and soil moisture variations. The procedure for estimating net nitrogen mineralization proposed by Stanford and co-workers was used to determine Arrhenius relationships between the rate constants (k) and absolute temperature (°K) for 33 virgin and cultivated Western Canadian prairie surface (0–15 cm) soils. There was no significant difference in Arrhenius relationship between soils within each soil zone; thus, a single average Arrhenius equation was calculated per soil zone. Average Q10 for the Brown chernozemic soils was 2.75, for the Dark Brown, thin Black and thick Black chernozems, 2.18, and for the Gray luvisols, 2.0. These Q10 values are as high or higher than those reported in other parts of the world and may be related to the degree of degradation of the soil organic matter in these various soils. Culture had no ma...

Comparison of 1:1 and 1:2 suspensions and extracts with the saturation extract in estimating salinity in saskatchewan soils

Abstract: Electrical conductivity of saturation extracts was related to that of 1:1 and 1:2 (soil:H2O) suspensions and extracts for a wide range of Saskatchewan soils. The conductivity of 1:1 extracts was 1.75 times greater than for 1:1 suspensions and the conductivity of 1:2 extracts was 1.38 times greater than that of 1:1 suspensions. The conductivity of the saturation extract was closely related to all of 1:1 extract or suspension; 1:2 extract or suspension (r = 0.96–0.98). The regression coefficient relating the conductivity of 1:1 and 1:2 extracts and suspensions to that of the saturated paste extract decreased in going from coarse to medium to fine soil textures. The concentrations of Na+, Ca2+ + Mg2+ and Cl− in 1:1 and 1:2 (soil:H2O) extracts were highly correlated with the amounts in the saturation extract (r = 0.93 to 0.99). Key words: Soil salinity, 1:1 and 1:2 suspension and extract, saturated paste

Rate of podzolic soil formation near hudson bay, ontario

Abstract: Six soil profiles on a transect orthogonal to the Hudson Bay coast of Ontario are shown to be of increasing age from approximately 100 yr near the coast to > 5000 yr 70 km inland. The stages of Podzolic soil development from calcareous parent materials are documented. The Ah horizons required at least 750 yr to develop. The Ae-Bh horizon sequence required at least 1893 yr to form. The Ae-Bf horizon sequence required at least 2300 yr to develop. The depth of carbonate leaching and vermiculite formation in the A horizons are very closely correlated to soil age. Key words: Vermiculite, Podzolic B horizon, carbon dating, carbonate leaching

Effect of cropping, summerfallow and fertilizer nitrogen on nitrate-nitrogen lost by leaching on a brown chernozemic loam

Abstract: In 1982, six crop rotation treatments that were initiated in 1967 on a Orthic Brown Chernozemic loam were sampled for soil NO3-N and moisture to a depth of 240 cm. Soil samples were taken on 18 May and 10 June from all treatments, on 2 Sept. on fallow treatments only, and on 14 Oct. from cropped treatments. Precipitation during the sampling period was about 23% above the long-term average. It was estimated that at least 123 kg NO3-N∙ha−1 were leached from the top 240 cm of fallow soils. Leaching appeared to result from a portion of the precipitation moving through macro soil pores. There was evidence that water and NO3-N might also move upwards from below the 240-cm depth. Of the six rotations examined, the 2-yr and 3-yr spring wheat (Triticum aestivum L.) rotations lost the most NO3-N. The presence of fall rye (Secale cereale L.) in a fallow-rye-wheat rotation was very effective in reducing NO3-N losses. Spring wheat, when grown continuously, was also very effective in reducing NO3-N losses but even here...

Dispersion of kaolinite by dissolved organic matter from douglas-fir roots

Abstract: The organic constituents of water extracts from Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco var. menziesii) roots that cause kaolinite dispersion were investigated. The dissolved organic matter was fractionated according to molecular size and chemical characteristics into acids, neutrals, and bases of the hydrophilic and hydrophobic groups. The dominant fraction causing dispersion included the hydrophobic acids and organics with molecular sizes greater than 104 nominal molecular weight. Partial oxidation of the dissolved organic matter increased its carboxylic acid content and dispersion potential. Organic acids promoting kaolinite dispersion included aliphatic and aromatic carboxylic acids. The dispersing ability of a carboxylic acid was related to its charge and charge density. Kaolinite has a pH-dependent surface charge; specific adsorption of carboxyl groups makes the clay more negative and promotes dispersion. Polycarboxylic acids appear to play the major role in kaolinite dispersion by dissolv...

Monosaccharides in hydrolysates of water-stable aggregates after 67 years of cropping to spring wheat as determined by capillary gas chromatography

Abstract: Two non-replicated, unfertilized, dryland grain rotations—continuous wheat and wheat-fallow — were established in 1912 on a Dark Brown Chernozemic soil in southern Alberta. The effect of long-term cropping on the monosaccharide distribution in the hydrolysates of the water-stable aggregates was assessed. Although all the hydrolysates of the aggregates had the same suite of monosaccharides, the relative proportions changed with cultivation. The eight monosaccharides identified represented between 92 and 96% of the total GC detector response. The monosaccharide C of aggregate organic C for the native prairie varied from 6.9 to 7.6%, while for the continuous wheat and the wheat and fallow of the wheat-fallow rotation it varied from 3.6 to 5.5%, from 1.8 to 5.1%, and from 1.6 to 6.7%, respectively; the higher percentages were associated with the larger aggregate fractions. Except for galactose, the average relative proportions of the monosaccharides identified in the hydrolysates of the water-stable aggregate...

Dispersion of kaolinite by water extracts of douglas-fir ash

Abstract: The inorganic constituents of black and gray ash from Douglas-fir slash were analyzed to evaluate the mechanism by which ash extract disperses kaolinite. Chemical constituents promoting kaolinite dispersion were anions that increase alkalinity and are specifically adsorbed, namely orthophosphate, carbonate, hydroxyl, and me-tasilicate. Key words: Fire, specific adsorption, carbonate

The forest floor: lateral variability as revealed by systematic sampling

Abstract: The forest floor of a mature, naturally regenerated conifer stand on a well-drained podzolic soil in the Central Uplands of New Brunswick was sampled systematically. The forest-floor properties measured were: oven-dried mass per unit area, depth, moisture content, pH, potassium-chloride-extractable NH4-N and NO3-N, water-soluble phosphate, and ammonium-acetate-extractable K, Mg, and Ca. Total elemental C, N, P, K, Mg, Ca, Al, Fe concentrations were also determined. Coefficients of variation varied from 0.066 (total C) to 1.78 (2 N KCl-extractable NO3-N). Concentrations (measured in ppm or percent) were in each case less variable than absolute amounts (measured in kilograms per hectare). Frequency distributions were positively skewed (except for total C and N) and appeared to follow a gamma or Weibull distribution pattern. Key words: Ferro-Humic-Podzol, forest floor, lateral variability, spruce-fir forest, systematic sampling

Crop utilization of placed and broadcast 15N-urea fertilizer under zero and conventional tillage.

Abstract: Growth chamber and field studies were conducted to assess the relative utilization of placed and broadcast 15N-urea by spring wheat. The field studies were conducted on zero and conventional (shallow) tillage systems, of 4-yr duration, located on Chernozemic soils at two locations in Saskatchewan. Placement below the seeding depth in comparison to broadcast application, generally reduced fertilizer N immobilization and increased fertilizer N uptake, recovery, and efficiency. Under moisture stress, placed applications were effective in enhancing dry matter yield and total N uptake. It is concluded that fertilizer N placement for these two contrasting tillage systems should be identical, thus some soil disturbance under zero tillage may be necessary to achieve optimum crop use of applied fertilizer N. The dominant N transformation processes and possible tillage induced differences, in regard to methods of N application, are discussed. Key words: Placed and broadcast N application, N efficiency, N utilizatio...

Influence of subsoil acidity on root development and crop growth in soils of alberta and northeastern british columbia

Abstract: Experiments were conducted in the field and greenhouse with soils of Alberta and northeastern British Columbia to determine the influence of subsoil acidity on acid-sensitive crops. Experiments involved liming of only the topsoil, liming of both topsoil and subsoil, and measuring the aboveground crop yield and the yield of roots in the topsoil and subsoil. In both field and greenhouse, subsoil acidity reduced the yields of top growth and subsoil root pernetration for both barley and alfalfa. The reductions in yield of top growth and roots in the subsoils were correlated closely with the amount of Al (extractable in 0.02 M CaCl2) in the unlimed subsoil. Lowering the soil temperature did not reduce root growth more in acid soils than in limed soil. There were five field experiments, and in the three of these which had subsoils high in extractable Al, the limed subsoils had less moisture at the time of harvest than the unlimed subsoils. The damage to crops caused by subsoil acidity was eliminated by deep lim...

Soil mesofaunal studies under different vegetative regimes in north central alberta

Abstract: Research on soil mesofauna distribution and diversity was conducted on a cultivated Gray Luvisol near Breton, Alberta. Particular reference was made to the soil Collembola (springtails) and the Acarina (mites). Seven different vegetative regimes (grass litter, balsam leaves, aspen leaves, straw litter, fescue grass, alfalfa, check) were established on 14 (2 m × 2 m) microplots. Microarthropod distribution and diversity were found to be dependent on a number of soil parameters such as temperature, moisture, depth, nutrient status, microhabitat availability and vegetative cover. Seasonal changes were also monitored. Examination of soil thin-sections revealed that a wide variety of fauna contribute to the reorganization of fabrics, especially in the upper 7 cm of soil. These fauna varied in their significance throughout the microplots. Fecal pellets of 280–350 μm size were encountered, commonly comprising mull-like material. Insect larvae are thought to be responsible but their type is unknown. The authors s...

Effect of different inoculant adhesive agents on rhizobial survival, nodulation, and nitrogenase (acetylene-reducing) activity of soybeans (Glycine max (L.) Merrill).

Abstract: Inoculation of soybeans is essential to the establishment of a successful N2-fixing symbiosis in western Canadian soils that lack indigenous soil Rhizobium japonicum. A comparison was thus made between commercial and non-commercial adhesive agents used to optimize inoculation of King Grain line X005 soybeans (Glycine max (L.) Merrill) with seed-applied powdered peat-based inoculant. Gum arabic (40%, wt/vol) and carboxymethyl cellulose (4% wt/vol), available only from chemical supply houses, were excellent adhesive agents, binding over 800 mg of the inoculant per seed and protecting bacteria from desiccation. Wallpaper glue (10%, wt/vol), readily available in the market place and in common use by some farmers, bound 894 mg of inoculant per seed. The two most readily available commercial adhesive agents, Nutrigum and Nitracoat, bound similar amounts of inoculant. The use of water as an adhesive agent did not nourish the bacteria or protect them from desiccation and can not be recommended. All 12 adhesive ag...

Effects of soil temperature on phosphorus extractability. i. extractions and plant uptake of soil and fertilizer phosphorus

Abstract: The effect of 10, 15, 20 and 25 °C soil temperatures on the extractability of soil and fertilizer phosphorus (P) was examined in two soils, one containing free carbonate (pH 7.8) and the other non-carbonated (pH 6.9). The time course of fixation and desorption reactions were monitored. The extractability of P was also assessed using sodium bicarbonate (NaHCO3) extractions, desorption curves, and short-term uptake by wheat seedlings. Phosphorus-32 was used throughout. Opposing effects of temperature were found. An increase in incubation temperature from 10 to 25 °C decreased the amount of applied P extracted probably due to accelerated fixation reactions. This effect was established 1 day after the P was applied and persisted for 57 days. An increase in extraction temperature over the corresponding incubation temperature increased the extractability of P, indicating endothermic desorption reactions. This effect was established 1 h after the extraction began and persisted for 48 h. Hence, the net effect of ...

Soil acidity in relation to soil properties and lime requirement

Abstract: The nature and components of acidity in a group of 20 Saskatchewan soils (pH 5.0–5.8) were investigated. KCl-exchangeable acidity was very low (0.3–2.2 mmol(+)∙kg−1) in all soils. Titratable acidity, determined as the difference between effective CEC and buffered (at pH 8.1) CEC, ranged from 9 to 191 mmol(+)∙kg−1 and constituted about 99% of the total acidity in the soils examined. Titratable acidity was highly correlated with organic carbon (r = 0.83) and with Al extracted using citrate-dithionite-bicarbonate (r = 0.95), potassium pyrophosphate (r = 0.92) and pH 4.8 ammonium acetate (r = 0.79). The combination of organic carbon and citrate-dithionite-bicarbonate-extractable Al accounted for 96% of the variation in titratable acidity. Although lime requirement determined by the Shoemaker-Mc-Lean-Pratt procedure was very highly correlated with titratable acidity (r = 0.98), the data show that the estimated amount of lime to raise soil pH to 6.8 actually exceeded the total (titratable plus exchangeable) aci...

Influence of tree windthrow on the properties and classification of selected forested soils from nova scotia

Abstract: Soils affected by tree-throw (arbroturbation) at three sites in Nova Scotia varied in development and microrelief characteristics. Soil horizonation was strongly developed and continuous through the mound-and-pit sequence at one site but was intermittent and irregular at the other two sites. Analytical data, particularly those for oxalate- and pyrophosphate-extractable Fe and Al reflected the morphological variations observed in the pedons. Classification of the arbroturbated soils according to the Canadian system is not a problem though it is necessary to indicate turbation by appending a phase to the soil class name at levels above the series. Mapping areas of such soils involves no change from regular procedures except in the description of the soil units. Hummocky microrelief due to arbroturbation presents some limitations in the use of land. Key words: Physical disturbance, classification, mapping, land use

Availability of subsoil sulphates to barley and rapeseed

Abstract: Increased use of sulphur (S) fertilizers in southern Alberta led to a series of field and phytotron experiments to investigate the importance of S fertilizers and the role of subsoil reserves of sulphate sulphur (SO4-S) for barley (Hordeum vulgare) and rapeseed (Brassica napus). Two types of experiments were conducted. In the field-plot studies, barley was grown on dryland soils low in surface SO4-S but underlain by subsoil high in SO4-S. Neither elemental nor SO4 forms of S significantly increased barley yields in a series of 10 experiments on those soils. The comparisons were made at three levels of N fertilizers. In a series of lysimeter studies, three successive crops were grown in soil low in inorganic S (2.0 μg SO4-S∙g−1), or soil supplemented with 25 μg 35SO4-S∙g−1 soil at specified depths in the lysimeters. Barley was adequately supplied with S from SO4-S at a depth of 54–72 cm. It obtained 55% of its S from a high SO4-S (25 μg∙g−1) layer of soil at that depth, although 40 days growth were require...

Estimated soil water reserves applicable to a wheat-fallow rotation for generalized soil areas mapped in southern saskatchewan

Abstract: Long-term mean soil water reserves for a spring wheat-fallow rotation in the southern half of Saskatchewan were calculated using the Versatile Soil Moisture Budget. Four different available water-holding capacity classes and climatic data from 53 stations were used as input to the model. Soil water reserve data for the following times, seeding on 1 May in the crop year, at heading on 30 June, and on 1 May in the fallow year, were mapped. These were then combined with an available water-holding capacity map to portray in a single map the combined droughtiness due to climatic and soil attributes. Estimated soil water reserves compared well with measured data from one location in the Brown soil zone. The temporal and spatial changes in water reserves are discussed and related to summerfallowing. The maps provide information for use in making potential grain yield estimates. Key words: Soil water, wheat-fallow rotation, generalized soil areas, Saskatchewan, Versatile soil moisture budget

FORMATION OF HYDROXY-Al-MONTMORILLONITE COMPLEXES AS INFLUENCED BY CITRIC ACID

Abstract: Montmorillonite from Upton, Wyoming (< 2 μn) was aged 30 days in the presence of Al-citrate solutions both in the absence of NaOH and at an initial NaOH/Al molar ratio of 2.5. The effect of citric acid on the formation of hydroxy-Al-montmorillonite complexes depended greatly on the initial citrate/Al molar ratio. A low citrate/Al ratio of 0.1 did not significantly affect the CEC and X-ray diffraction patterns of hydroxy-Al-montmorillonite complexes. An intermediate citrate/Al ratio of 0.5 reduced the amount of Al depleted from solution and increased the proportion of 1 M KCl-exchangeable Al and 0.2 M HCl-extractable Al and the CEC of the samples; the structural perturbation in the interlamellar hydroxide sheet as revealed by XRD is attributed to the fixation of hydroxy-Al-citrate in the interlamellar spaces. At a high citrate/Al ratio of 1.0, most of the Al remained in solution and was prevented from being adsorbed by montmorillonite. The complexation between Al and citrate is a competitive reaction for t...

Integral land evaluation and its application to policy

Abstract: An approach to integral land evaluation is described and its application to land use policy issues is demonstrated. The approach provides a link between bio-physical land-related information bases and the information requirements of land use planning. It is based upon the premise that the importance of a land unit for a particular use can be determined by assessing the available land units and their productivities relative to the societal requirements for products and services from the land. A mathematical model specifies land use constraints, representing limitations on resource availability and goals for production, and identifies land use options that are feasible under the specified conditions. This modelling approach provides quantitative information on land use flexibility and on the critical importance of certain land areas for specified uses, given both the bio-physical and socio-economic conditions. For demonstration, a prototype model for the agri-food sector is applied to Ontario under three sc...

Potassium status of some quebec soils: k released by nitric acid and sodium tetraphenylboron as related to particle size and mineralogy

Abstract: The K release characteristics of surface samples from five Quebec soils were investigated. Each soil was fractionated by size into six separates. Each separate was extracted with 1 M ammonium acetate (NH4OAc), with 1 M nitric acid (HNO3) and with sodium tetraphenylboron (NaTPB) and the K extracted was determined. The clay separates contained most of the HNO3 and NaTPB-extractable K. The average amounts of K removed by 1 M HNO3 and NaTPB from the clay was up to 16 times more than that released from silt or sand fractions. The strong relationship between extractable K and clay content was probably due to the similarity in mineralogical composition and degree of weathering of these soils. Clay-sized chlorite and vermiculite were destroyed by the HNO3 extraction but not by the NaTPB extraction. Crop response to K fertilizer was generally reduced as clay content and extractable K increased. Key words: Extractable K, NaTPB-K, HNO3-K

Classification of podzolic soils as affected by cultivation

Abstract: The effects on soil properties of long-term potato cultivation and of erosion were studied by sampling soils along three transects in virgin forest sites and seven transects in potato fields with landforms and parent materials similar to those of the forest sites. The average thickness of solum was reduced from 35 cm in virgin forest to 27 cm in cultivated fields. More than 90% (28 of 30) of forested pedons were classified as Podzolic soils but only 27% (19 of 70) of the cultivated pedons met all of the criteria of Podzolic soils. The others were mainly Regosols and Brunisols. The main criterion that excluded the soils from the Podzolic order was one of the morphological criteria which states "… hue of 10 YR near the upper boundary (of B horizon) and becomes yellower with depth." Most of the Ap horizons (70%) still meet all the chemical criteria for the Podzolic order. By waiving the morphological criterion stated above for the cultivated sites, nearly 70% (48 of 70) of the soils observed remained as Podz...

Field techniques using the acetylene blockage of nitrous oxide reduction to measure denitrification

Abstract: Four techniques for the measurement of denitrification rates in the field were compared. All involved the use of acetylene (C2H2) to block nitrous oxide (N2O reduction and subsequent measurement of accumulated N2O. Two extracted core techniques were compared with two in situ cylinder techniques. The single-wall cylinder technique involved partial insertion of a PVC tube into the soil, sealing the head-space, injection of C2H2 into the headspace and, after suitable time periods, assaying N2O concentration in the headspace. A double-wall cylinder technique was devised to allow more rapid C2H2 introduction into the soil core from an interwall space in situ. A comparison of the four techniques on a 1-m2 area in the field showed large spatial variability. Estimates of denitrification rates decreased in the order double-wall cylinder, single-wall cylinder, extracted encased core and extracted loose core. Variation among replicates varied between sampling occasions but, on aveage, decreased in the order single-w...

Soluble aluminum in acidified organic horizons of forest soils

Abstract: Concentrations of labile and total Al in soil extracts were measured as a function of equilibrium solution pH in six forest soil organic horizons acidified with HNO3 (0–20 cmol H+∙kg−1) under controlled conditions of ionic strength (0.05 M NaNO3), temperature (23 °C), and solution:soil ratio (25:1). Decreases of 0.1–0.2 in solution pH in the range of pH 2.4–4.5 resulted in increases and decreases in concentrations of labile and total Al. Organic acids and soluble C were the dominant Al-complexing ligands in solution, and acidification of each horizon decreased their concentration. Silicon and F concentrations in the equilibrium solutions were lower than that of C, but levels were similar to those of nonlabile Al. Nonlabile complexes were the dominant forms of soluble Al in horizons above pH 4, and labile Al comprised an increasing percentage of total Al as pH decreased, especially below pH 3. The results showed pH alone to be a poor predictor of log nonlabile (r2 = 0.06) or total Al (r2 = 0.33) concentrat...

The casagrande method versus the drop-cone penetrometer method for the determination of liquid limit

Abstract: A comparison of the drop-cone penetrometer and Casagrande methods for determining the liquid limit of soils showed that the former method is simpler, faster and provides more precise results. Key words: Casagrande, drop-cone penetrometer, liquid limit, soil survey

Authigenic mineral formation by solodization

Abstract: Mineralogical and micromorphological examination of Solodized Solonetz pedons show the presence of both crystalline and non-crystalline authigenic minerals in the Ae horizons and the solodized zones of the columnar Bnt horizons. A zeolite mineral with the characteristics of clinoptilolite was detected in the coarse clay (1.0–2.0 μm) separates and was the mineral species dominant in the < 2.35 specific gravity separates of the fine (2.0–5.0 μm) and medium (5.0–20.0 μm) silt fractions. Measurement of pH (1.0 M NaF) of whole soil samples from the solodized zone of these pedons indicated the presence of high levels of active aluminum. Treatment with acid ammonium oxalate and hot 0.5 M KOH indicated that the poorly crystalline material was composed predominantly of silicon, aluminum and iron. Differential FT-IR analyses of these clay fractions before and after the chemical extractions indicated that components of this phase have characteristics reported for both opaline silica and allophane. Key words: Authige...

Effects of applied and residual boron on the nutrition of cabbage and field beans

Abstract: Field experiments were conducted at four locations in Prince Edward Island to determine the effect of applied B on leaf tissue B and yields of beans (Phaseolus vulgaris L.) and cabbage (Brassica oleracea var. capitata L.) in the year of application of B and again the following year. Application rates of 8.8 kg B∙ha−1 reduced bean seed yields at all locations and the 4.4-kg B∙ha−1 rate reduced yields at two locations in the first year. Leaf tissue B levels > 109 μg∙g−1 are clearly toxic for beans and seriously reduced bean yields. Furthermore, the yield and visual symptom data strongly suggest that tissue B levels even as low as 60 μg∙g−1 are toxic for this crop. No significant reductions in bean yields were noted in the second year crop, even at the 8.8 kg B∙ha−1 rate. Rates of up to 8.8 kg B∙ha−1 did not cause any reduction in cabbage yield even during the year of application. Leaf tissue B concentrations as high as 71–132 μg∙g−1 were not related to any B toxicity in cabbge. Added B did not increase yiel...