ALBERT

Beschreibung: Effects of short-term flooding on stomatal conductance, net photosynthesis, and water status of sweet gum (Liquidambarstyraciflua L.) seedlings were studied under controlled environment conditions. Flooding for 9 days induced partial stomatal closure, resulting in significant declines in transpiration and net photosynthesis. The response to flooding was rapid with an average daily stomatal conductance declining from a preflood level of 0.43 cm•s−1 to 0.26 cm•s−1 by 24 h after flooding began (40% reduction). The average preflooding daily net photosynthesis was reduced from 13.7 to 10.2 mg CO2•dm−2•h−1 (25% reduction) during the same period and the average daily stomatal conductance and net photosynthesis for the 9th day of flooding were reduced by 70 and 77%, respectively, compared with preflood levels. The leaf xylem pressure potential measurements, however, indicated that water deficits did not develop as a result of flooding. Partial stomatal reopening 3 days after termination of flooding was noted with an average daily stomatal conductance approaching 63% of the preflood levels and an average daily net photosynthesis reaching 46% of its preflood levels. Maintenance of positive net photosynthesis throughout flooding, and partial stomatal and photosynthetic recovery following drainage may account for the tolerance of sweet gum seedlings to short-term flooding.

Beschreibung: Previous reconstructions of the late Quaternary biogeographical history of lodgepole pine (Pinuscontorta Dougl.) have been based upon inferences from the modern geographical distribution of morphological and genetic variation. These studies have led to the widely accepted conclusion that relict populations of the Rocky Mountain subspecies of lodgepole pine (ssp. latifolia Engelm.) persisted in glacial refugia located in northwestern Canada. New fossil pollen evidence of the late Pleistocene and Holocene distribution of lodgepole pine in the western interior of Canada contradicts this view. Pinuscontorta ssp. latifolia migrated northward into Canada from refugia located south of the continental glacial limits and did not reach its northern range limits in the southern Yukon until the late Holocene.

Beschreibung: A procedure is presented for estimating the coefficients of allometric models for predicting tree component biomass. The resulting equations force the sum of the component estimates to be equal to the estimate of total biomass. An illustration of the procedure is given using published biomass data and the relationship of this procedure to previously published procedures is discussed.

Beschreibung: The most common method for determining tree profile models is by fitting an analytical function to a set of sample trees. In situations where the forester has relatively little a priori knowledge about the nature of profiles, choosing the analytical form of the parametric model is a critical problem without a satisfactory solution. An alternative is to use a nonparametric approach in which the model of the profile is explicitly specified by a tabulation of diameters at discrete heights. In this paper, it is shown how the model can be determined from the sample trees by means of a classical nonparametric probability density function estimation technique. Field tests and a measure of goodness of fit are used to express how well the models match the actual stem profiles. Using the Moroccan cedar (Cedrusatlantica Manetti) tree as an example, it is shown how the new nonparametric model can be compared with any classical parametric model. The results achieved demonstrate the advantages in using a nonparametric representation of stem profiles, which, moreover, is well suited to computer calculation constraints.

Beschreibung: Seventy-five eastern Cottonwood (Populusdeltoides Bartr.) clones, selected from tests representing the top one-third of clones tested throughout the Lower Mississippi River Valley, were analyzed for alpha cellulose content, specific gravity, and volume after three growing seasons. All traits were found to differ significantly among clones. Mean clonal alpha cellulose content ranged from 48.2 to 55.8% of oven-dry, extractive-free wood with an average of 51.1%. Specific gravity averaged 0.33, with clones ranging from 0.27 to 0.39. Specific gravity was highly inherited, while alpha cellulose content was found to be moderately heritable. Negative genetic correlations between volume and both wood properties indicate that using a selection index to simultaneously improve all three traits is currently not possible. Two other selection methods were discussed. These selections showed substantial gain differentials in volume, but either a small loss or improvement in specific gravity and alpha cellulose content. This indicates that at age 3 years only volume should be considered in a selection program.

Beschreibung: Forest soil respiration insitu was used as a comparative measure of the metabolic activity of substrate in eastern Ontario jack pine (Pinusbanksiana Lamb.) ecosystems that had been exposed to various burning treatments, including wildfire. The five burning treatments consisted of a 1920 wildfire, experimental understorey burning (nonlethal to the overstorey) of this age-class in 1962 and 1963, a 1964 wildfire, and experimental burning of this age-class in 1977. Seasonal respiration trends were similar on all treatments. Carbon dioxide evolution increased in the spring (4000 mg•m−2•d−1) in response to ambient warming (5000 mg•m−2•d−1 in August) and decreased in late fall as seasonal temperatures declined (4000 mg•m−2•d−1 in November). Precipitation and autumnal litter fall apparently acted as secondary modifiers of this general trend by affecting substrate moisture content and nutrient quality, respectively. Highest metabolic activities were measured on the 1963 understorey burning treatment followed in decreasing order by the 1920 wildfire, the 1964 wildfire, the 1962 experimental understorey burn, and the 1977 burn of the 1964 age-class. Multiple comparisons of overall seasonal respiration means revealed lower rates (P 

Beschreibung: Productivities of 5 black cottonwood clones from each of 10 source populations (50 clones in total) were compared at one plantation site in western Washington. The source populations are located west of the Cascade Mountains, between central Oregon and southern British Columbia. Most source stands represented populations in major river valleys. Individual clones were selected for superior form and growth rate. Spacing was 1.2 × 1.2 m (6944 stems•ha−1) and trees were harvested after 4 years. Considerable variation in mortality, height, and productivity were found among clones within individual stands and among stands. Southwestern clones were generally more productive. Heights of individual clones averaged between 8.5 and 11.8 m at 4 years. Average dry weight production of black cottonwood clones was 12.5 Mg•ha−1•year−1 and varied between 5.2 and 23.1 Mg•ha−1•year−1 for individual clones. Three new Populustrichocarpa × P. deltoides hybrids planted in the trial were generally more productive than black cottonwood or the 'Robusta' hybrid, with average heights varying from 11.5 to 12.2 m and dry weight production ranging from 15.6 to 27.8 Mg•ha−1•year−1 for an average of 23.6 Mg•ha−1•year−1. The high yields in this experiment are attributed to favorable climate (1940 degree-days•year−1)3, cultural treatments (irrigation, N fertilization) and genetic constitution of certain clones. The data promise substantial gains in short-rotation productivity from combining clonal selection with interspecific hybridization.

Beschreibung: One-year-old Pinussylvestris (L.) seedlings were wounded at the stem base by stripping off stem bark pieces of approximately 10 mm in length and covering about 50% of the stem circumference. The seedlings were thereafter planted out in the field or in a climate chamber. The field experiment was repeated on four different planting dates. Wounded and control seedlings were successively harvested for gas chromatographic determination of changes in resin acid concentrations of the bark surrounding the wounded area. Independent of planting date, wounded seedlings were found to have higher concentrations of total resin acids than corresponding controls. The most important quantitative changes in resin acids were observed for isopimaric, levopimaric + palustric, dehydroabietie, abietic, and neoabietic acid. In wounded seedlings the concentration of dehydroabietic acid showed the most significant increase, both in the field and in climate chamber experiments. This increase was rapid and appeared within 1 week in the field and within 3 days in the climate chamber. The other resin acids identified showed a somewhat similar variation pattern, but the differences were not as distinct as for dehydroabietic acid. These wound-induced rapid changes in resin acid concentrations could be important for resistance to pathogens.

Beschreibung: Measurements were made of the transfer of N,P,K, Ca, Mg, Mn, and B to the atmosphere during low-intensity (350–600 kWm−1) prescribed burns in three Australian subalpine eucalypt forests dominated by overstoreys of either Eucalyptuspauciflora (Sieb. ex Spreng), Eucalyptusdives (Schau.), or Eucalyptusdelegatensis (R. T. Baker). Elemental transfer was calculated as the difference between the quantity of an element in the fuel (litter plus understorey) before burning and that present in the postfire residues which were recovered quantitatively using small aluminium trays. Complete recovery of fine ash is essential for accurate budgeting for elements other than N. The mass ranges of elements transferred to the atmosphere (kilograms per hectare) were as follows: N, 74–109; P, 1.96–3.04; K, 12.1–21.0; Ca, 18.7–29.7; Mg, 4.5–9.7; Mn, 1.6–4.3; B, 0.08–0.12. These transfers represented, as a percentage of the element initially present in the fuel, the following: N, 54–75; P, 37–50, K, 43–66; Ca, 31–34; Mg, 25–49; Mn, 25–43; B, 35–54. The percentage loss of elements was positively linearly correlated with the percentage loss in fuel weight. High concentrations of P and cations occur in fine ash, especially grey (mineral) ash. In comparison with unburnt litter, concentrations of Ca, Mg, and P were increased by 10- to 50-fold, 10- to 35-fold, and 10-fold in fine (

Beschreibung: An alternative approach to goal programming is described. The approach incorporates both cardinal weighting and ordinal ranking of deviation variables, and does not require apriori specification of goal target levels. Ordinal rankings are used to describe feasible and optimal policy spaces. Cardinal weightings are then adjusted through an interactive procedure until the decision makers are satisfied with the weightings and with the resulting compromise solution. The procedure is demonstrated using a hypothetical reforestation budget allocation problem.

Beschreibung: The variability of wood specific gravity and yield of 23 white spruce provenances from the Great Lakes – St. Lawrence forest region was studied 20 years after planting at Harrington Forest Farm, Québec. The results indicate no relationship between wood specific gravity of provenances and their respective growth performance. The southwestern section of this region showed a small decrease in wood specific gravity, but it was compensated for by a strong increase in volume growth, resulting in an important gain in dry weight productivity. The variability of white spruce wood specific gravity was split into three sources: 11% was attributed to provenance differences, 8% to provenance and repetition interaction, and the remainder to differences among trees of the same provenance and to experimental error. In a breeding program, a first selection should be made at the provenance level on the basis of volume productivity and a second selection on the basis of wood specific gravity values within the selected provenances, to maximize the overall genetic and economic gain.

Beschreibung: A soda lime technique was used to measure CO2 evolution at the soil surface in four mature forest types (aspen (Populustremuloides Michx.), paper birch (Betulapapyrifera Marsh.), black spruce (Piceamariana (Mill.) B.S.P.), and white spruce (Piceaglauca (Moeneh) Voss)) in interior Alaska. Surface temperature, 15-cm depth temperature, and soil moisture were measured concurrently with CO2 evolution. Accumulated CO2 evolution ranged from 1315 to 1654 g CO2•m−2 for the period May 1 – September 30 in 1981 and 1982 in the four stands. Data were used to develop three-dimensional response surfaces and test mathematical models of respiration in relation to substrate temperature and moisture. GRESP, a biologically based model, provided a fairly accurate simulation of the seasonal course of respiration as a function of substrate temperature and moisture. In an attempt to better define the observed response surface trends, a best-fit equation model, BRESP, was formulated. BRESP includes the moisture portion of the GRESP equation, and an altered temperature equation which more adequately defines the upper and lower thresholds of respiration in relation to substrate temperature. GRESP and BRESP each produced similar r2 values; however, higher order polynomial equations gave a better-fit model. The weakest area of all models for simulating seasonal trends was during the periods of peak respiration in June.

Beschreibung: Canopy leaching or retention of all major ions was determined for three deciduous forests in eastern Tennessee that are currently receiving wet and dry acidic deposition. For all three canopies, the retention of atmospherically deposited cations (H+ and [Formula: see text]) exceeded retention of deposited anions [Formula: see text] on a charge-equivalent basis. Charge balance was maintained by ion exchange between the deposited cations and K+, Ca2+, and Mg2+ on the canopy surfaces. It was found that 40–60% of the leaching of K+, Ca2+, and Mg2+ from these canopies results from this exchange process, with the remainder attributable to coleaching with plant-derived anions. Because the cation exchange can be largely attributed to retention of deposited H+, we interpret it as a measure of the acidic deposition effect on foliar cation leaching. Dry deposition was found to be an important input for most of the major cations and anions. The data indicate that organic anions may be important counter ions to cation leaching, especially in the absence of acidic deposition, and that acid–base reactions in the canopy can obscure the true H+-exchange reactions between the deposition and the canopy.

Beschreibung: Studies on nonsymbiotic dinitrogen fixation (C2H2) in soil were conducted in 20 different forest stands in central Sweden. The stands were between 40 and 120 years old and included both coniferous and deciduous types. The relationships between nitrogenase activity and site productivity, stand composition, and soil properties were examined. Based on three samplings during the growing season, a considerable difference in activity was found to occur between the stands. The highest yearly mean activity for a stand was 200 times the lowest value. The activity was positively and significantly correlated to site productivity. The effect of stand composition on the activity in the forest floor was studied on five sites. The activity was similar under spruce (Piceaabies (L.) Karst.) and pine (Pinussylvestris L.), higher under spruce than beech (Fagussylvatica L.), and much higher under birch (Betulapendula Roth) than spruce when compared two by two on identical parent material. The activity under birch was mainly concentrated in the birch leaf litter. Evaluating the influence of soil properties by regression analysis revealed a strong positive correlation between activity and pH. The soil acidity alone explained 85% of the variation in yearly mean activity among the 15 coniferous stands. The conversion factor between C2H2 reduction and 15N2 fixation was determined for five soils and ranged from 1.6 to 5.6. The N2 fixation down to a depth of 6 cm during the growing season was estimated to 0.4–1.4 kg ha−1 in these soils.

Beschreibung: A number of nondestructive techniques for analyzing the timing, frequency, and magnitude of natural disturbances in forest stands are discussed in this paper. Intensive age determination of trees is desirable for reconstructing forest disturbance history, but age distribution alone is not always a sufficient basis for a disturbance chronology. Frequently all-aged forests have undergone severe past disturbance which cannot be readily identified from the distribution of trees among age-classes. Radial growth patterns provide more direct evidence of past canopy tree deaths. In cases where a large sample of tree ages and growth records is not feasible, structural attributes of forests can provide valuable supplementary evidence. Evidence of the effects of disturbance history and age structure on diameter distributions is examined, and principles for valid interpretation proposed. Crown area distributions and diameter distributions of nonsuppressed trees potentially appear to be more reliable structural indicators of past canopy disturbance than simple size distributions. For regional studies of disturbance frequency, random dispersal of medium to large plots across large landscape units is recommended as a sample design.

Beschreibung: Tree-ring analyses of hickory (Carya spp.) from the long-term ecological research site, Coweeta Hydrologic Research Laboratory, revealed that concentrations (micrograms per gram) of lead, aluminum, and zinc are increasing, that concentrations of copper, cadmium, nickel, and manganese have remained generally constant since the 1880's, and that hickory annual radial growth increments are declining. Lead, aluminum, and zinc burdens (microgram per growth interval), unlike their respective concentrations, have remained generally constant during the 1900's. The interpretation of growth and burden data indicates that hickory trees at Coweeta are in a mature phase of their life cycle and that annual growth does not seem to be reduced by pollutants.

Beschreibung: Four forest floor manipulation treatments were applied to an eastern Ontario jack pine (Pinusbanksiana Lamb.) ecosystem. These included a one-time complete removal of the forest floor to mineral soil; annual removal of the total forest floor to mineral soil; one-time removal of the forest floor, ashing of the material, and broadcast spreading of the ash onto exposed mineral soil; and an untreated control. Eight years after treatment radial tree growth on the treated plots showed a 30% reduction compared with the untreated plot. Annual removal of the forest floor caused most severe nitrogen depletion in jack pine foliage, forest floor, and mineral soil. Effects of one-time removal and burning treatments were less severe, but significant. Any interference with the normal buildup of the forest floor during stand development should be avoided if site quality is to be maintained for tree growth.

Beschreibung: Growth and development of native species of trees in response to long-term increases in atmospheric CO2 concentration were studied. Seedlings of two competing perennials, Pinustaeda L. and Liquidambarstyraciflua L., were obtained from germinated seeds and grown through one complete growing season at 350, 500, and 650 μL•L−1 CO2. The plants were grown in CO2 controlled greenhouses under natural photoperiods and light regimes, with temperature controlled to simulate mean local climate. Stem length and basal stem diameter increased with increasing CO2 in both species. Liquidambarstyraciflua maintained size dominance in all concentrations. The dry weights of stems, roots, and leaves increased in both species. In P. taeda, however, the seedlings reached maximum size at 500 μL•L−1 while L. styraciflua continued to increase up to 650 μL•L−1. Liquidambarstyraciflua produced significantly more branches and leaves at the higher CO2 concentrations than at 350 μL L−1. Differences in plant shape and responses in growth rate of these two naturally competing tree species suggest that continuing atmospheric CO2 enrichment could affect future interactions between the species and might produce changes in community composition.

Beschreibung: Using a large data base of permanent research plots in coastal Douglas-fir, a growth projection strategy is developed. The emphasis is on stratifying growth influences into potential and modifier functions for components of diameter and height growth within a stand table. Growth periods are defined as equal increments of top height through time. The model developed is an individual-tree, distance-independent, stand-projection model.

Beschreibung: Morphological and phenological variation among five black cottonwood (Populustrichocarpa Torr. & Gray) clones from each of 10 natural populations were studied at one plantation site in western Washington. Source populations are located in major river valleys, west of the Cascade Mountains, between central Oregon (latitude 44°44′ N) and southern British Columbia (latitude 49°05′ N). Populations and individual clones were selected for superior form and growth rate. Tested at a spacing of 1.2 × 1.2 m, the 50 clones displayed a large range of variation in 15 leaf, branch, and phenology characters studied. Clones and populations differed significantly in 14 and 10 characters, respectively. Population means for seven characters and a character association (principal component) varied clinally with source latitude, longitude, and (or) elevation. The most consistent genetic cline follows a geographic gradient from southwest to northeast: southwestern clones develop smaller leaves on more erect branches, and continue growth later in the fall. Variation patterns seem to reflect regional climatic gradients, annual disturbance in riparian environments, and the life history characteristics of the species. The results point to the great potential of clonal selection for black cottonwood improvement.

Beschreibung: The objective of this paper is to explain the distributions, assumptions, interpretations, and relationships of the two compatible, stochastic models of fire history: the negative exponential and the Weibull. For each model the "fire interval" and "time-sinee-fire" distributions are given. Both models apply to homogenous stationary stochastic processes. The negative exponential states that the instantaneous fire hazard rate is constant for all stand ages. The Weibull states that the instantaneous fire hazard rate increases with stand age when the shape parameter is 〉 1 (the negative exponential is a special ease of the Weibull when shape = 1). An empirical method is given for separating from an observed fire history distribution, the pre- and post-fire suppression distributions. Four relationships are derived from the models and defined per study region (per stand): (i) the fire cycle (average fire interval), (ii) the annual percent burned area (fire frequency), (iii) the average age of the vegetation (average prospective life-time), and (iv) the renewal rate.

Beschreibung: Published data and newly presented evidence demonstrate that the proportion of N or P lost from plant material during combustion under a wide range of conditions increases linearly with percentage loss of fuel weight during combustion. For N the correlation is strong, and the slope (β) of the regression line approaches unity for combustions under field or simulated-field conditions, but reduces to 0.78 for materials combusted in a muffle furnace. Almost all of the losses of N are due to volatilization. The relationship for P is less well defined, and β is lower (0.56 for field studies; about 0.2 for simulated-field or laboratory combustions). Calcium is not volatilized at the temperatures generated in most vegetation fires, thus increases in the ratio of Ca to other elements during combustion (i.e., higher ratios in burnt residue) indicate nonparticulate transfer of elements to the atmosphere. Increased ratios for Ca to N, P, K, Mg, Mn, and B were demonstrated for several components of eucalypt litter fuels, especially where the degree of combustion was high. The positive relationship between increase in Ca:element ratio and percentage element loss in nonparticulate form during combustion, is of Mitscherlich form so that initial increases in the ratio represent proportionally most element loss. Partitioning of the transfer of elements from the litter and understory to the atmosphere measured during low-intensity fires in three eucalypt forest communities demonstrated a low particulate contribution (and thus a high nonparticulate transfer) for N, K, P, and B. Particulate contributions to elemental transfers are less where combustion is more complete, resulting in formation and transport of fine grey ash which has a high Ca:element ratio. Of particular ecological importance is the significant transfer of P by nonparticulate mechanisms, because such P is likely to be permanently lost from burnt sites and natural rates of P replacement are usually very slow. Fine grey or white ash is highly nutrient enriched (e.g., up to 50-fold for P compared with concentrations in unburnt fuel), and hence its transport from the site in the smoke column, or subsequently by either wind or water, can result in substantial export of nutrients.

Beschreibung: The problem of determining the effects of forest fire on stand yields is often neglected in forest yield analyses. Using previous theoretical results, "fire-adjusted, volume–rotation curves" can be developed which provide a graphical technique for determining optimal rotation age and long-run yield when the risk of fire is present. For white spruce of the northern interior of British Columbia it is shown that even modest rates of fire can result in very large reductions in long-run yield. Similar results are established for the effects of fire on land expectation value, which is dissipated very quickly under the risk of fire.

Beschreibung: Xylem sap extraction of branches as a new field problem-solving technique in forestry, environmental pollution, and botany is described. The influence of extraction pressure, crown aspect, height into the crown, tree age, time of year and day, and soil chemistry on the ion concentrations in xylem sap are discussed. Xylem sap extraction with a pressure chamber provides a good indication of the nutrient status of a species if the trees are of similar age, and if they are sampled at the same aspect, crown height, time of day, time of year, and on the same soils. Pseudotsugamenziesii (Mirb.) Franco (Douglas-fir), growing on nutrient-poor acid soils and moderately fertile alkaline soils showed significant differences in growth rate and ion concentrations in the xylem sap and soil. Trees on the faster growth site (

Beschreibung: A survey of the DTPA-extractable Cu levels of approximately 1000 fields representing a large number of soil types in Saskatchewan suggested that, under current cropping systems, Cu deficiencies appear to be concentrated in the Grey Soil Zone. They are especially probable in seven soil associations, which include light Transition of Grey and Brownish-Grey Podzolic soils. Soil criteria for detecting Cu deficiencies in cereal crops cannot be fully documented using conventional calibration tests and techniques. However, data from 21 field trials and a growth chamber study indicated that the critical level of DTPA-extractable Cu in these soils is approximately 0.4 mg∙kg−1 for cereals. Large spatial variability of DTPA-extractable Cu levels has been found to occur in a level field, thus suggesting that the Cu status of a field may not be adequately described by assessing the Cu levels of composite field samples. Key words: DTPA-extractable Cu, soil survey, critical level, spatial variability

Beschreibung: The thermal stability and acidic characteristics of Al interlayered montmorillonite were affected by citric acid which was present during its formation. Perturbation to the formation of Al interlayers by citric acid resulted in more gradual loss of their structural water in the 430 °C to 520 °C region at initial citric acid/Al molar ratios of 0.1 and 0.5. The data clearly reveal that, besides hydroxy-Al polymers, hydroxy-Al-citrate complexes adsorbed on the surfaces of montmorillonite very substantially contribute to the total and third buffer range titratable acidity of the clay. Key words: Hydroxy-Al-citrate interlayers, smectite, organic acid, DTA, third buffer range, organic carbon

Beschreibung: To investigate the content of amorphous forms of Fe, Al and Si in podzolic soils, the B horizons from 54 Humo-Ferric Podzols and 24 Eluviated Dystric Brunisols were sampled in northern Ontario. Dithionite-citrate-bicarbonate (DCB) Fed and Ald, acid NH4-oxalate Feo, Alo and Sio, Na-pyrophosphate Fep, Alp and Cp and NaOH-tetraborate Fet and Alt were determined on all samples. Feo/Fed ratios averaged 0.87 and suggested that most of the extractable Fe was amorphous. Inorganically bound Fe and Al in pyrophosphate extracts were estimated by addition of NH4OH to the extracts. The amount of inorganically bound Fe, expressed as a percentage of that extracted by DCB, was calculated at 79 ± 23%, whereas the corresponding value for Al was 61 ± 20%. (Alo-Alp)/Sio atomic ratios, plus linear correlation analysis of (Alo-Alp) against Sio, suggested the presence of amorphous aluminosilicates with Al/Si ratios approaching 3. (Feorg + Alorg)/Cp ratios averaged 0.10, a figure near the value suggested by other authors for the maximum amount of Fe and Al bound to organic matter. (Cp/(Fep + Alp) atomic ratios did not appear to be useful in differentiating Podzolic from Brunisolic soils. Key words: Podzolic soils, chemical criteria, extractants

Beschreibung: Subsoil moisture accumulation due to cultivation and particularly summerfallowing is considered as an important causative agent of dryland salinity. However, few studies have been conducted to quantify the magnitude of this accumulation. The amount of additional moisture that had accumulated under cultivated land as compared to adjacent native prairie was determined at two sites in Southern Alberta. In comparison to noncultivated sites, a total of 74.0 cm of additional moisture was found under the cultivated area of a Dark Brown Chernozem and 36.2 cm under a Brown Chernozem to a depth of 6 m. Only relatively insignificant changes in salt content were found. Key words: Dryland salinity, soil moisture, soluble salts

Beschreibung: Response of spring wheat (Triticum aestivum) to varied amounts of broadcast and band-applied phosphorus (P) was examined at soil temperatures of 10, 15, 20 and 25 °C. The research emphasized the response of shoot yields with time and the root proliferation in the band-applied P. A non-destructive technique to measure growth with time was developed. This method allowed interpretation of plant responses even though the temperature treatments markedly changed the rate of physiological development. The relative plant-shoot response to P application did not change with time or developmental stage in this experiment. There was a marked effect of temperature on plant response to band-applied P. Band application was more efficient than broadcast P at 10 °C soil temperature, but less efficient at 25 °C soil temperature. Root proliferation in the fertilizer band was significantly different from the control soil-zone only at 10 °C and was not diminished by concurrent application of broadcast P. The efficiency of band application was confirmed with 32P labelling of the banded P. Banded P accounted for more of the total plant P at lower soil temperatures than at higher soil temperatures, regardless of concurrent application of broadcast P. Temperature had little effect on yield response to broadcast P at the final sampling or throughout the growth period. Tissue P concentrations decreased with increases in temperature and with time. Key words: Temperature, root proliferation, band, broadcast, phosphorus

Beschreibung: Mean and dominant tree heights were determined on 28 sample plots within 18 jack pine (Pinusbanksiana Lamb.) plantations varying in age from 6 to 16 years. An average dominant tree was removed from each plot for stem analysis. The height versus age data were used to determine 2-, 3- and 4-year growth intercepts in each sample tree. Growth intercepts were positively correlated with foliar concentrations of nitrogen, phosphorus, and potassium, total nitrogen concentration in the main rooting layer of the mineral soil, as well as soil physical parameters associated with good drainage. Depth of forest floor and Ae horizon, clay content, bulk density, and drainage class were negatively correlated with growth. Close correlations were also revealed for site occupancy by ericaceous ground cover species and growth intercepts. The numerous site variables included in this study were reduced to five factors with significance to jack pine growth: (i) ericaceous cover – forest floor, (ii) drainage, (iii) extractable P, (iv) exchangeable K, and (v) Ae horizon development.

Beschreibung: Logging residue decomposition rates were determined in four conifer forest ecosystems in the State of Washington, U.S.A. (coastal western hemlock, Puget lowland Douglas-fir, high-elevation Pacific silver fir, and eastern Cascade ponderosa pine), by examining wood density changes in a series of south-facing harvest areas with residues of different ages. Decomposition rates were determined for two diameter classes (1–2 and 8–12 cm) and two vertical locations (on and 〉20 cm above the soil surface). Pacific silver fir and ponderosa pine ecosystems had the lowest k values (0.005 and 0.010 year−1, respectively) followed by Douglas-fir (range, 0.004–0.037 year−1) and western hemlock (range, 0.010–0.030 year−1). Small-diameter residues decomposed at rates significantly slower than large-diameter residues in Douglas-fir and western hemlock ecosystems; this relationship was also implied in the other ecosystems. In all four ecosystems, dry season moisture contents were lower in smaller-diameter residues. Moisture levels associated with small-diameter residues were too low for significant decomposition to occur during the dry summer period and probably contributed to the slow annual decay rates. Residues located above the soil surface decomposed significantly slower than residues on the soil surface only in the Douglas-fir ecosystem. Dry season residue moisture, rather than initial lignin concentration, appeared to be the dominant factor determining residue decomposition rates on exposed harvested areas.

Beschreibung: The importance of microrelief in relation to mass loss was studied in a Minnesota ombrotrophic forested peatland. Litter and paper strips placed in hummocks for 1 yr lost significantly more mass (two and three times, respectively) than similar material placed in hollows. Less favorable environmental conditions for decomposition, especially lower temperature, reduced decomposition in the hollows. Key words: Peatlands, ombrotrophic, decomposition, Histosols

Beschreibung: The objective of this study was to evaluate different available P extracting methods in relation with soil properties, oat yield and plant P uptake. Six chemical extractants (Bray-1, Bray-2, new Mehlich, North Carolina DA-4, DA-10, and Olsen) and two anion exchange resins (F− and HCO3−) were compared on 42 acid soils. The DA-4, DA-10, new Mehlich, and HCO3− resin methods showed the best correlation with oat yield and plant P uptake. The Bray-1, Bray-2 methods were significantly less correlated than the other methods. The HCO3− resin was better than F− resin to predict plant P uptake and yield. Available P levels as determined by these eight methods were classified poor, medium and rich by the Cate and Nelson procedure. Oxalate extractable Al, pH (NaF), pH (H2O), exchangeable (Ca + Mg), forms of P, maximum P fixation capacity and soil texture have great influence on the plant P uptake. Soil organic matter content and oxalate-extractable Fe had significantly less important an effect. The Bray-1 and Bray-2 methods were the most affected by soil properties especially oxalate-extractable Al. The P-HCl/P-DAF ratio proposed by Mehlich to identify forms of soil P indicated that seven soils contain predominantly Ca-P and 21 soils with predominantly Al-P and Fe-P. This ratio was related with oxalate extractable Al (r = − 0.32*), pH NaF (r = − 0.59**), pH H2O (r = 0.52**) and exchangeable Ca + Mg (r = 0.55**). The maximum P fixation capacity (M) ranged from 150 to 4200 μg P/g soil and was closely related with oxalate-extractable Al (r = 0.81**), pH NaF (r = 0.74**), pH H2O (r = − 0.36*) and Mehlich ratio (r = − 0.33*). The maximum P buffering capacity (Mb) of soils was also measured and showed the best correlation with oxalate-extractable Al (r = 0.84**) and pH NaF (r = 0.53**). Key words: Soil testing, available P, anion exchange resins, P fixation, oxalate-Al, forms of P

Beschreibung: A micropenetrometer with a diameter similar in magnitude to that of a root is capable of measuring variations in tip resistance over distances as small as 0.1 mm. Measurements at this scale offer the potential of characterizing zones of high resistance to penetration and the frequency of occurrence of zones of low resistance which could be exploited by a growing root. Spectral analysis provides a new approach to characterizing soil structure and has been applied to the micropenetrometer tip resistance profiles obtained from beds of aggregates. Nine different aggregate size ranges were considered; the aggregate diameters varied from less than 0.36 mm to 6.4–12.8 mm. The analyses indicate that larger aggregates are more resistant to penetration. In addition, comparison of variance spectra among several of the aggregate sizes reveals information on the structural make up of soil aggregates, namely that larger aggregates are made up of smaller "component" aggregates which offer higher resistance when they occur in large aggregates than when they occur individually in loose packing. The use of spectral analysis also appears to provide information on the spatial separation of zones of low resistance which correlate with aggregate size if the aggregate diameters are larger than 1.6 mm. Key words: Soil strength, soil resistance to penetration, micropenetrometer, aggregate size

Beschreibung: The rapid increase in anhydrous ammonia use in Western Canada has created concerns about possible detrimental soil effects, particularly solubilization of organic matter. Anhydrous ammonia was injected at rates of 0.206, 0.416 and 0.834 g NH3-N into undisturbed soils taken in 20-cm-diameter cylinders. Both field capacity (FC) and permanent wilting point (PWP) moisture contents were used. Samples were taken at 0–2.5, 2.5–5.0, 5.0–7.5 and 7.5–10.0 cm from the injection point, 1 day after injection. For the 0.416 g NH3-N rate samples were also obtained 35 days after injection. Soluble organic carbon (SOC) was measured in a 1:15 soil:water extract. The SOC was closely related to the NH4+-N concentration (r2 = 0.79 to 0.99; P 

Beschreibung: A kinetic process was investigated by which H+ ions interact with soil surfaces giving rise to a positive electric charge distribution. A two-step process took place in the range of time examined. A first rapid step was always followed by a relatively slower step, and a first-order kinetic equation was applied to describe this second step of the process. The values of specific rate, calculated at different initial H+ ion activities and two different amounts of soil, indicated that a diffusion-controlled mechanism was governing the rate of the slower step and consequently the overall rate of the process. Protonation and deprotonation specific rates were also calculated in the presence of varying concentrations of supporting electrolytes. It was found that the specific rate was dependent on either the structure of the electric double layer formed on soil surfaces in the presence of electrolyte, or on the particular surface electric charge distribution of the examined soil. Key words: Protonation kinetics, specific rate, diffusion phenomena, permanent charge, pH-dependent charge, diffuse double layer

Beschreibung: An undisturbed site under forest cover near Breton, Alberta, was chosen to study the dynamics of a Gray Luvisol. Soil moisture and temperature were monitored at selected depths over a 2-yr study period. Canopy drip collectors and gravity lysimeters were used to study soil solution transport and the process of lessivage. The order of cation concentration for canopy drip, LFH and Ae lysimeter samples was K+ 〉 Ca++ 〉 Na+ 〉 Mg++. The lysimeter samples from the Bt showed Na+ 〉 Ca++ 〉 K+ 〉 Mg++. Lysimeter studies further indicated that micaceous clays were being illuviated into the upper Bt horizon. Water movement into the Ae horizon was found to be regulated by the LFH horizon; ice lensing in winter appeared to enhance the formation of the platy structure. The major processes in this soil are the translocation of Fe, Al and organic constituents both in solution and in colloidal form; the concentration of these elements was a function of the rate of water movement. The concentration of other cations was independent of the rate of water movement. Key words: Genesis, pedogenesis, Gray Luvisol, dynamic pedology, clay migration, lessivage, illuviation

Beschreibung: Horizontal Ksat was estimated as one of eight classes according to guidelines based on soil morphology and then measured by a piezometer method in soils of the Ottawa area that differed widely in texture and structure. The Ksat class estimated by two observers was either the same as, or one class different from the measured class for 14 and 16 of 18 layers tested (average 83%). Measured horizontal Ksat exceeded vertical Ksat by a factor of 9 in some sandy layers with strata of relatively coarse material. Measured vertical Ksat exceeded horizontal Ksat by a factor of more than 3 in some layers having numerous more-or-less vertical earthworm channels. Horizontal Ksat of the layers measured ranged from 0.3 to 14 m∙day−1 and vertical Ksat values for those layers ranged from 0.1 to 27 m∙day−1. Guidelines for estimating horizontal Ksat were revised on the basis of results from this study to give more emphasis to stratification. The results support the view that adequate estimates of vertical and horizontal Ksat can be made rapidly from the observation of soil morphology if specific guidelines are followed. The guidelines are based on relationships between soil morphology and measured Ksat values. Key words: Horizontal Ksat, vertical Ksat, soil morphology

Beschreibung: Molybdenum, Co and B concentrations in, and uptake by, corn and bromegrass were measured over a period of several years from three field experiments in which sewage sludge was applied and compared with ammonium nitrate as a source of N. There was little effect of sludge on B and Co concentrations in the crops grown. Slight increases in uptake were apparently due to yield increases due to sludge. A lime-treated sludge increased Mo concentration in plant tissues after several years of sludge application. The increase in plant Mo concentration was highest in the eighth and last year of the experiments, although lime-sludge application had ceased 1–3 yr previously. The soil-sludge interactions contributing to increased Mo uptake are discussed. Key words: Molybdenum, cobalt, boron, sewage sludge, corn (Zea mays L.), bromegrass (Bromus inermiss Leyss).

Beschreibung: In a field experiment in which heavy applications of liquid dairy manure were added annually for 6 yr to a vermiculite-containing corn-cropped sandy clay loam soil (Mountain series), fixation potential and X-ray diffraction analyses were done to determine if fixation of added K+ and NH4+ had occurred and clay mineralogical changes could be detected. Of the 850 kg K+ and the 460 kg NH4+ added per hectare each year, approximately 28% of the K+ and 24% of the NH4+ remained fixed. This caused a marked increase in the 1.0-nm peak at the expense of the 1.4-nm peak due to collapse of vermiculite layers to form pedogenic mica. Thus, changes in soil management, specifically in fertilizer practices, can result in significant changes in clay mineralogy within a short period of time. Such changes are agronomically important and should be taken into account in the interpretation of clay mineralogical data. Key words: Potassium and ammonium fixation, vermiculite to pedogenic mica transformation, liquid manure application

Beschreibung: Distilled water leaching of new alundum/ceramic plate lysimeters removed considerable amounts of Ca, Mg, Na, K, SO4, Cl and Zn. After washing with 3 L of distilled water, levels were still of sufficient magnitude to interfere with the analysis of solutions with low solute concentration. Washing the plates with 2 L of 1 N HCl extracted considerable amounts of Ca, Mg, Na and K, and higher amounts of Fe, Zn, Al and Mn, but further distilled water washing resulted in rapid equilibration with a spike solution. Rinsing new lysimeters with progressively more acidic solutions indicated residual zinc contamination when the solution pH was below 6.0. There was virtually no iron or manganese contamination from the lysimeters at a solution pH between 3.0 and 5.0. Aluminum was leached from the plates at solution pH of between 3.5 and 4.0; however, the high Al concentration in the soil solution at these pHs may mask this interference. Although Al poses a considerable contamination problem at solution pHs of 3.0, soil solutions at this pH level are unlikely except in unusual situations (e.g. soils developed on acid mine tailings). The pumping of 2 L of 1 N HCl followed by large volumes of distilled water through the lysimeters is recommended for most field studies. Prior testing of the plates is required if low solute concentrations are expected or if elements other than those mentioned here are of interest. Key words: Lysimeters, ceramic samplers, soil water collection, alundum lysimeters, soil solution

Beschreibung: Field studies were conducted to evaluate the effect of the rate and timing of N application and the amount of seed-placed P on grain yield and protein content of winter wheat grown on zero-tilled and conventionally tilled land in Manitoba. Yield increased with increasing amounts of fall-applied N and P. Yield, as affected by time of N application, decreased in the order: spring, freezeup, seeding, and applied on snow in winter. Split application of N resulted in yields comparable to that obtained with N applied at seeding. Protein concentration in grain decreased when small amounts of N led to large increases in dry matter but increased when sufficient quantities of N fertilizer were added to meet the requirements for both yield and protein. The amount of fertilizer N recovered in the grain did not differ with time of application in 1979–1980. However, in 1980–1981, N recovery was consistently higher with spring applications of N than with applications at any other time. Differences between the two seasons reflected the higher moisture availability for crop growth in 1980–1981 as compared to 1979–1980. Key words: Winter wheat, zero tillage, nitrogen, phosphorus, protein

Beschreibung: At the first level of detail of description of a thin section, qualitative information about the occurrence of the fabric zones (regions of distinct morphology) and their basic morphologic units (the various components) were recorded with symbols in a fabric description symbol. At a second level of detail of description, Level II, additional quantitative and qualitative micromorphological information can be included with coding into the fabric description symbol according to the following. general format:[Formula: see text]At Level II description, quantitative information on the areal proportions of the fabric zones and basic morphologic units are recorded with indices in the fabric unit; qualitative data on the kind of boundary relationships between adjacent fabric zones, and quantitative data on the areal occurrence of the fabric zones are recorded with the modifier expression; and both quantitative and qualitative information on the occurrence, morphology, and arrangement of specific features observed in the fabric zones are recorded with the fabric unit descriptor. Depending on the requirements of a study, more than one fabric unit descriptor can be written for each fabric zone that is delineated in a thin section. The procedure for writing fabric description symbols at a Level II detail of description of a thin section is presented and applied to the characterization of the micromorphology of an organic layer from a Typic Mesisol. Key words: Micromorphology, descriptive method, organic soils, characterization

Beschreibung: The effect of soil temperature on the availability of manganese to wheat (Triticum aestivum ’Neepawa’) and barley (Hordeum vulgare ’Conquest’) from an organic soil was studied in a controlled environment growth chamber. Wheat and barley plants were grown in cylindrical pots placed in temperature-controlled water baths with soil (root) temperatures maintained at 10, 15, 20 and 25 °C. Air temperatures were maintained at 20/13 °C for the day/night intervals, respectively. Aerial plant parts were harvested at the three- to four-leaf stage and at the boot stage. Dry matter yields of wheat and barley tended to be greatest at soil temperatures of 20 or 25 °C when harvested at the three- to four-leaf stage. In contrast, yields obtained at the boot stage were usually greatest at a soil temperature of 15 °C. Concentrations of manganese in shoots of wheat and barley at both stages of growth increased significantly when soil temperatures were increased from 10 to 25 °C.In a second study, MnSO4∙H2O was supplied to barley plants grown at the four different soil temperatures. The MnSO4 increased Mn concentrations in shoots harvested at the three- to four-leaf stage at all soil temperatures. In contrast, MnSO4 was ineffective in increasing Mn concentration in shoots harvested at the boot stage. In addition to the plant growth studies, soil samples were extracted with 0.005 M DTPA or 1.0 M ammonium acetate (NH4OAc) at the different temperatures. Extractable Mn increased with increasing soil temperature and amounts extracted closely reflected the increases in amounts of Mn utilized by the plants in the growth chamber studies. Key words: Soil temperature, manganese, organic soil, availability

Beschreibung: The stratigraphy and hydrology of saline soils were investigated at 15 sites in Saskatchewan, Canada. At five sites (Series A) nests of piezometers were installed and at 10 sites (Series B) a single piezometer was installed in or near an aquifer. Piezometric surface data from the nests showed the potential for upward movement in all Series A sites. The electrical conductivity (EC) of water from Series A piezometers increased from the deepest to shallowest and there was a general increase in soil EC towards the soil surface. Hydraulic conductivity of strata was measured at three sites and varied from 1.6 × 10−7 to 3.2 × 10−4 cm∙sec−1. It was calculated that observed salt loads for the three sites could accumulate by upward movement from the aquifer in from 500 to 5300 yr. For Series B sites the approximate sodium percentage (ASP) of the soil (Y) was related to the ASP of the aquifer (X) by the equation:[Formula: see text]For Series A and Series B sites combined the EC (dS∙m−1) of the 1:1 suspension of the stratum immediately above the aquifer (Y) was related to the EC of the aquifer (X) by the equation:[Formula: see text]Key words: Soil salinity, aquifers, stratigraphy, salt profiles

Beschreibung: A method is proposed for determining elemental S (S°) in organic horizons of forest soils. Elemental sulfur is extracted from the soil with acetone and assayed by a colorimetric method. The procedure is a modification of several existing methods and allows for the extraction of all forms of S°. It also reduces the interference of colored extracts from forest litter. The detection limit is 100 mg∙kg−1 (1 mg S°∙mL−1 of solution) and S° concentrations in excess of 50 000 mg∙kg−1 have been measured. The recovery of S° is approximately 90%. The method is suitable for determining S° in organic forest soils with a wide range of S° concentrations and where a high degree of accuracy and precision is not required. It is rapid and suitable for routine analysis in laboratories without specialized equipment. Key words: Elemental sulfur, forest soil analysis, organic horizon

Beschreibung: Three hundred and fifty-three B horizons from acidic, well- to imperfectly drained soils from northern Ontario were sampled in an effort to test and possibly refine the current color and pyrophosphate-extractable Fe and Al criteria as presently used in the Canadian System of Soil Classification. Each of the soils sampled displayed podzolic morphology in the form of reddish brown to brown B horizons that became yellower and/or paler with depth and underlay LFH and Ae horizons. The soils belonged to the Podzolic (171 sites) and Brunisolic (182 sites) Orders. It was found that as the hues became redder and the values darker there were increases in the means of pyrophosphate-extractable Fe (Fep), and Al (Alp) and of C (Cp). Soils with sand textures (sands and loamy sands) required less Fep plus Alp to give the same colors as finer textured soils. Using two schemes for attributing color codes to the Munsell Colour Chips, Cp was found to be the soil property most highly correlated with soil color. By revising the current color and Fep and Alp criteria it was found that the soils could be correctly classified using color 78% of the time, compared with only 52% using the present criteria. Key words: Soil color, soil classification, pyrophosphate-extractable Fe, Al, C

Beschreibung: not available

Beschreibung: Relationships between soil water retention and soil properties were developed for subsoil materials from Colchester County, Nova Scotia. The significant variables in the regression equation for soil water content at a suction of 33 kPa were the sand content and the product of silt content and bulk density of the soil. The variables for water retention at 1500 kPa suction were the clay content and the product of organic matter content and bulk density. The multiple correlation coefficients were 0.87 and 0.92 for suctions of 33 and 1500 kPa, respectively. The developed equations were comparable to ones derived elsewhere. Key words: Water retention, texture, organic matter, bulk density

Beschreibung: The gaseous losses of N (N2O + N2) measured for 130 days (May-September 1983) from conventional fallow at Yorkton, Oxbow and Weyburn soil sites ranged from 9 to 11, 15 to 31 and 60 to 87 kgN∙ha−1 for upper, middle and lower slope positions, respectively. The corresponding values for chemical fallow were 18–28, 24–51, and 69–98 kgN∙ha−1. In both tillage systems, gaseous N losses increased in the order of upper 

Beschreibung: The general and spatial variation of several soil profile chracteristics, and properties of agronomic and ameliorative importance, were determined on a regional and local area of Solonetzic soil in north central Alberta. Differences in general variation as characterized by the mean, median, coefficient of variation (CV), and range allowed grouping of soil properties according to high (e.g. EC in the Ap horizon), medium and low (e.g. pH of the Ap horizon) variation. Such grouping, along with specific differences in soil variation between the regional and local area was associated with the saline-sodic characteristics of these Solonetzic soils. Spatial variability was studied using a geostatistical method (variograms) on soil samples obtained from a 5-m grid. The variograms for most of the various soil properties did not reveal strong spatial dependence. Large nugget variances accounted for 60–90% of the total variance. The semivariance approximated the overall variance usually within 10 m. Variograms suggested periodic variation for the pH and EC of the Ap horizon. Extractable Ca in the Bnt horizon and the depth of the Ap and Bnt horizons were anisotropic showing significant spatial dependence with direction of sampling. The implication of soil variability in regard to soil sampling is discussed. Key words: Spatial variability, Solonetzic soil, saline-sodic soil, soil sampling, variogram

Beschreibung: Based on soil water modelling results of 19 stations, averaged long-term soil water reserves on the Canadian Prairies were compared for two soils having available water-holding capacities of 280 and 250 mm. The soil water reserves of the 250-mm capacity soil were 6.5%, 8.7% and 6.2% less than those of the 280-mm capacity soil on 1 May after a fallow year, 30 June heading time and 1 May after a crop year, respectively. The aridity indices for wheat at the soft dough stage for the 250-mm capacity soil ranged from 4% less in the drier part of the Prairies to 7–9% more in the wetter regions as compared to the 280-mm capacity soil. Water deficits for a perennial crop grown on a 280-mm capacity soil could not be used to infer the deficits on a 250-mm capacity soil because of the model’s sensitivity to rainfall distribution with time. Key words: Soil water, modelling, available water-holding capacity

Beschreibung: The variability in DTPA-extractable micronutrients was studied for the A and B horizons of a cultivated site and its native prairie counterpart. The results showed that there was a high degree of variability in samples taken every meter on a 46-m long transect. There were large differences among the cultivated and native prairie soils, the two soil horizons and the four micronutrients studied. In cultivated fields, larger numbers of samples were required for Cu and Mn than for Zn and Fe to obtain a precise estimate of the mean. The number of samples becomes critical as deficiency levels are approached. Key words: Soil sampling, sample size, soil variability

Beschreibung: A detailed soil salinity survey was carried out in three of the 13 irrigation districts in southern Alberta. About 30 quarter-sections in each district were randomly selected for soil sampling. The location, distance from water supply ditches, slope of the land, and depth to till and water table at each site were recorded. Soil texture and electrical conductivity of extracts of soil samples were determined in the laboratory. The extent of the area with a soil salinity level of 4 dS/m or more is 5% of the total surveyed land in the Western Block of the St. Mary River Irrigation District (WSMRID), 6% in the Lethbridge Northern Irrigation District (LNID) and 9% in the Taber Irrigation District (TID). These values are not as high as others have previously estimated. The salinity level of the soil at each site was found to vary with its location and distance from water supply ditches in the WSMRID and LNID, clay content in the 0- to 120-cm depth in the WSMRID and TID, and water table level in the TID. Key words: Soil texture, EC, SAR, pH

Beschreibung: During a period of 5 yr, the influence of different forms of N, P, combinations of K and levels of fertilizers on cigarette tobacco production were studied. Potassium nitrate was found to be significantly inferior compared with the other sources of nitrogen. No significant difference was detected between the different sources of phosphorus. The greatest yield but the poorest quality of tobacco was obtained with the highest level of fertilization. Key words: Flue-cured tobacco, nitrogen, phosphorus, potassium

Beschreibung: Crop response to deep plowing was determined at five locations in east-central Alberta. Yield and growth characteristics of barley, wheat and oats were evaluated as they relate to units of soil classification. Crops grown on Solonetzic landscapes responded more favorably to deep plowing than crops grown on landscapes with significant amounts [Formula: see text] of Chernozemic soils. Where Solonetzic and Chernozemic soils were present in the same landscape, the relative yield increase of wheat and barley resulting from deep plowing followed the sequence BL.SS and BL.SO 〉 SZ.BL 〉 O.BL. Deep plowing of landscapes containing [Formula: see text] Chernozemic soils does not appear beneficial because of limited crop response. Yield response of wheat was greater during the drier year. Yield responses on deep plowed soils resulted from increased tillering and increased grain yield per single stem, both of which were associated with reduced moisture stress. Crop emergence was generally unrelated to soil physical conditions. Key words: Deep plowing, crop response, Solonetzic soil

Beschreibung: Micromorphological, chemical, mineralogical and physical properties of deep plowed and conventionally tilled soils were evaluated at five sites in east-central Alberta. Soil properties, as they relate to soil classification and seedbed tilth, were determined. Deep plowing resulted in the development of a unique soil fabric in Ap horizons which, relative to conventionally tilled soils, had characteristics tending towards higher salinity, sodicity, pH, clay, smectite and strength and lower exchange acidity, total C, total N, available moisture, stability and plasticity. Landscapes dominated by Solonetzic soils responded differently to deep plowing than landscapes where significant areas of Chernozemic soils were present [Formula: see text]. Solonetzic landscapes tended towards significantly higher salinity, sodicity and strength in Ap horizons than Chernozemic landscapes. Key words: Tilth, deep plowing, soil classification, reclamation

Beschreibung: Cotton cloth was buried in contrasting soils for various lengths of time until close to physical disintegration. Cellulose degradation was assessed by comparing the tensile strength of cloth after recovery with that before burial. A curve was derived for loss of tensile strength of cloth, when rotting under constant conditions. The curve was linearized by a mathematical technique analogous to taking logarithms when there is exponential decay. By means of the linearization, rates of degradation were compared between widely differing sites, using both our own data and reworked data from the literature. The time to 50% loss of tensile strength ranged from 3.2 days in an incubator at 29 °C to 1.2 yr in an arctic tundra. A mathematical model of the decay process suggests that the rate of degradation depends mainly on the physico-chemical environment of the cotton in the soil, and is insensitive to the size of microbial inoculum. Key words: Decomposition, cotton strips, site comparison, cellulose degradation, soil burial test

Beschreibung: Thirteen pedons in an arctic environment were classified according to the Canadian and American systems of soil classification. Major differences in groupings result from the contrasting approaches. Although the definition used in Canada to define Cryosols is sometimes difficult to apply in the field, the underlying concept is valid, since soils with permafrost at a shallow depth should be separated at the highest level of classification. The American system virtually ignores the influence of permafrost on pedogenesis. Its reliance on soil temperature regimes at both the great group and subgroup levels is redundant. It is suggested that the definition of Cryosols, in the Canadian system, be changed to include strongly cryoturbated soils with very cold or colder soil temperature regimes. The American system should be altered to provide for pergelic great groups; in addition permafrost and strong cryoturbation should be used to create new subgroups. The requirement that a cambic horizon have a texture finer than loamy fine sand should be waived in soils having cryic or pergelic soil temperature regimes. Key words: Cryosols, cryoturbated soils, permafrost, pergelic soils

Beschreibung: In an effort to minimize the effect of wind on the placement of herbicide granules during simultaneous application-incorporation while seeding with a discer, a pneumatic conveying and dispersion system was designed, fabricated and tested. Nozzles designed for the system produced a uniform granule distribution pattern over a width of 300 mm. The system was mounted on a 2.8-m-wide discer for field evaluation. Field tests were conducted to determine the uniformity of incorporation at different soil depths under windy conditions. Bio-assay field trials were conducted over a period of 2 yr to evaluate crop injury and weed control with the pneumatic system. It was compared with other currently used methods of granular and liquid triallate application. The pneumatic system provided good weed control, no apparent crop injury and no reduction in crop yield. Key words: Pneumatic application, discer, herbicide granules

Beschreibung: Soil temperature profiles and the aerial growth of wheat were characterized over portions of the growing season in 1980 and 1981 under zero and conventional tillage systems in a semi-arid region of Saskatchewan. Differences in maximum and minimum soil temperature, accumulative heat sums and thermal diffusivity over the 2.5-cm to 20-cm soil depth were related to variations in surface crop residues, soil moisture and crop canopy. Generally, maximum soil temperatures were 1–5 °C lower under zero tillage compared to conventional tillage during the first 30 days of crop growth for spring wheat. Similar soil temperature differences were evident between winter wheat zero tilled on stubble or chemical fallow during the period of early spring growth. Subsequent differences in crop canopy (shoot height), between tillage systems, tended to modify the soil temperature profile. Soil temperature differences were not associated with differences in yields of spring or winter wheat. Key words: Soil temperature, soil thermal properties, zero tillage systems, wheat,semi-arid climate

Beschreibung: The natural 15N abundance of nodules of soybeans (Glycine max (L.) Merrill) which are actively fixing N2 is considerably higher than other tissues. To investigate the question of whether isotopic fractionation associated with denitrification by bacteroids causes this 15N enrichment, we inoculated soybeans with two strains of Rhizobium japonicum. Free-living cultures of one of these (strain USDA 33) were unable to denitrify or respire NO−3, while free-living cultures of the second (strain USDA 138) were capable of denitrification. USDA 138 formed nodules which fixed N2 very efficiently. The N of these nodules was enriched in 15N and the nodules reduced a substantial amount of NO−3 to NO−2 and N2O. Nodules infected with USDA 33 fixed about half as much N2 as those infected with USDA 138. The former nodules were enriched in 15N (although less so than nodules infected with USDA 138), despite the fact that the nodules formed by USDA 33 did not reduce NO−3. Clearly denitrification could not have been the cause of 15N enrichment of nodules infected with strain USDA 33. Alternative causes of 15N enrichment of soybean nodules and their possible metabolic significance are discussed. Key words: δ15N, nitrogen fixation

Beschreibung: To determine the capacity of the Lethbridge soil to inactivate paraquat, applications equivalent to a maximum of 3000 kg/ha of paraquat were made in growth chamber and field experiments. In the growth chamber and field, more than 600 and 1000 kg/ha, respectively, of paraquat in one application were required to reduce wheat growth by 10%. Paraquat residue levels in the field soil did not decrease after the first summer. Paraquat residue was not found in wheat grain growing in soil with 1650 kg/ha of paraquat in the 0–15 cm layer, but it was detected in plant leaves. The paraquat associated with plant leaves could have resulted from contamination of the leaves by soil rather than from translocation from roots to leaves. The 500 kg/ha rate of paraquat reduced the cation exchange capacity by 5%; however, further paraquat additions did not cause additional reductions. Paraquat could likely be applied for several hundred years at currently recommended rates for weed control on chemical fallow and not exceed the ability of Canadian Prairie soils to inactivate it. Key words: Paraquat, persistence, availability, inactivation, wheat, soil

Beschreibung: Twenty-four organic soil materials were selected in order to study pyrophosphatase activity and pyrophosphate retention and hydrolysis. The activation energy of pyrophosphate hydrolysis was 22 kJ∙mol−1 for virgin fibric soil materials and 33 kJ∙mol−1 for cultivated humic soil materials. Phosphatase and pyrophosphatase activities were highly correlated (r = 0.947**) and were promoted apparently by non-specific enzymes. Enzymatic activities varied from 11.6 to 148.1 mmol∙kg−1∙(2 h)−1, and were higher in virgin than in cultivated soil materials. Soil retention increased with an increase in ash content (r = 0.876**) and was apparently weak, as noted by complete pyrophosphate hydrolysis after 4–8 days of incubation. Half-life values of pyrophosphate incubated at room temperture varied from 0.1 to 3.7 days, and were highly correlated with enzymatic activities and levels of nonretained pyrophosphate. A regression model, involving an interaction between pyrophosphatase activity and level of nonretained pyrophosphate, accounted for 77% of the variation in log of half-life values of pyrophosphate in organic soil materials. Key words: Pyrophosphatase, phosphatase, pyrophosphate, half-life values, pyrophosphate retention

Beschreibung: The catalysis of atrazine hydrolysis at 25.0 °C by the types of acidic functional groups found in humic materials has been investigated. No evidence of catalysis by carboxylate ions was observed. From a knowledge of the types and numbers of acid functional groups in a quantitatively characterized fulvic acid, and the distributions of their KA values it was found that hydrogen ions and undissociated carboxyl groups were the only catalytic agents. The carboxyl groups have a second-order kAH of 7.88 days −1∙M−1. Weakly acidic functional groups having [Formula: see text]showed no catalysis. A predictive equation has been produced for the half-life of atrazine in fulvic acid solutions at 25.0 °C. It represents a general class of equations which should permit the practical prediction of atrazine persistence in soil solutions and other natural waters. Key words: Atrazine hydrolysis, atrazine persistence, fulvic acid, fulvic acid carboxyls, acid catalysis, carboxyl catalysis

Beschreibung: Under southwestern Ontario climatic conditions ethalfluralin (1.0 kg/ha) (N-ethyl-N-(2-methyl-2-propenyl)-2,6-dinitro-4-trifluoromethylbenzenamine) and dinitramine (0.55 kg/ha) (N4,N4-diethyl-a,a,a-trifluoro-3,5-dinitro-toluene-2,4 diamine) applied preplant incorporated to Brookston clay loam dissipated to less than 20% of the original rate within 70 days after application. Trifluralin (1.0 kg/ha, preplant incorporated) (a,a,a-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) was more presistent with about 40% remaining in an extractable form after 110 days. In Fox sandy loam trifluralin (2.0 kg/ha, preplant incorporated) and oryzalin (2.0 kg/ha, preemergence) (3,5-dinitro-N4,N4-dipropylsulfanilamide) appeared to have similar persistence with about 30% residue remaining after 80 days. Key words: Trifluralin, dinitramine, ethalfluralin, oryzalin, field persistence

Beschreibung: Sensitivity to paraquat as function of growth varied considerably among 15 rhizobia from seven cross-inoculation groups and 13 agrobacteria from five different species. No relationship was evident between the sensitivity and the "fast-growing" or the "slow-growing" characteristics among the rhizobia. The agrobacteria were uniformly less sensitive. Maximum stabilized paraquat resistance induced by the adptations ranged from 200 μg paraquat∙mL−1 in Rhizobium lupini 112, to 20 000 μg paraquat∙mL−1 in Agrobacterium radiobacter R-590 and A. tumefaciens A6-K1. No relationship was found between the sensitivity and the adaptability. Identical lytic patterns with six bacteriophages confirmed the relationship between the adapted and parent cultures suggesting no genetic effect of paraquat on susceptibility to lysis. The bacteria-plant symbiont interaction, including nodulation, plant weight, vigor and color, was unaffected by the adaptations to paraquat resistance. Similarly, the adaptations exerted no effect on tumorigenicity of A. tumefaciens A6-K1. Key words: Rhizobia, agrobacteria, adaptation, herbicides, paraquat, N2-fixation

Beschreibung: Glycerol/ethanol solutions with various glycerol concentrations were used for the solvation of smectite on glass slides. The effects of concentration and standing time before X-ray analysis were considered. A 14% glycerol solution in ethanol applied to the clay with a glycerol/clay weight ratio of 31% produced after 10 min standing time high intensity and maximum expansion of the basal spacing of smectite from 1.4 to 1.78 nm. The procedure described may be especially useful for the identification of smectite when present in small percentages. Key words: Glycerol solvation, basal spacing expansion, smectite characterization

Beschreibung: Slope is an important factor in terrain mapping and can be determined from contour maps or aerial photographs. Previously methods have been proposed to reduce the time element using contour maps. This paper describes and demonstrates a technique whereby aerial photographs can be used effectively when photogrammetric equipment and reliable contour maps are not available. Accuracy with the method is illustrated by comparison to slope determined from a contour map and a single computation sheet is provided for inclusion in a handbook or field guide. Key words: Slope measurement, terrain analysis, pedotechnical interpretations, aerial photos, photo interpretation, photogrammetry

Beschreibung: The distribution of organic and inorganic S forms was examined in peats formed under the influence of fresh and brackish water on the Fraser River Delta. Six peat facies classified as sphagnum, ericaceous sphagnum, freshwater sedge, brackish sedge, freshwater clay or brackish clay were found to contain variable levels of sulphur. Brackish systems contained much more S than freshwater-derived materials. Highest S contents (mean 3.0%) were found in brackish sedge peat samples, and the lowest in sphagnum-derived peat (mean 0.19%). For all facies examined, organic S was dominant and accounted for 90–97% of Total S. Carbon-bonded S was the dominant organic form and was much more abundant than organic sulphate S. Inorganic sulphate, elemental S, pyritic S and H2S made minor contributions to the total S. Increasing degree of decomposition of peat is associated with increasing S content. Key words: Sulphur forms, organic sulphur, peat sulphur, degree of decomposition

Beschreibung: Total fluorine was measured in a variety of Canadian soils using the lithium metaborate-nitric acid solution technique in conjunction with the fluoride electrode. Total fluorine ranged from 90 to 1000 mg∙kg−1. Key words: Soil fluorine analysis, fluoride electrode, CSSC reference soil samples

Beschreibung: Unrooted hybrid poplar cuttings were grown in a greenhouse at varying soil pH. The soil was a loamy fine sand (pH 5.7) collected from an Ap horizon of a forest tree nursery. The pH was adjusted over a wide range by incorporating different rates of powdered lime or elemental sulfur. Lime additions failed to improve growth significantly over a 20-wk period, and excessive liming to pH 7.6 reduced shoot dry weight by 33%, probably because of decreased availability of micronutrients. Sulfur, acidifying the soil to pH 4.1, depressed growth as much as 76%. This growth inhibition was closely associated with increased Al in both foliage and soil as well as reduced foliar uptake of the other essential nutrients. Maximum height growth of clone DTAC-32 occurred between pH 6.0 and 7.0, which falls within the general guidelines for producing hardwood nursery stock. Key words: Populus, soil pH, aluminum toxicity, micronutrient deficiency

Beschreibung: Vane shear (VS) strength in the upper 2 m of a relatively uniform clay soil varied both vertically and laterally. Obtaining VS values which are reliable at the 80% confidence level for the transect tested required measurements at three sites for a depth increment within the upper meter, but a single site would be adequate for depth increments between 1 and 2 m. A preferred procedure to that of characterizing a modal pedon is outlined for estimating VS strength in soil survey. Key words: Vane shear, variability

Beschreibung: Five Okanagan Valley soil series that had been in orchard for from 12 to 40 yr were studied to determine the effect of orchard practices on chemical and mineralogical soil properties. The soils were coarse-textured with relatively low organic C contents. Acidification produced by fertilization, irrigation and herbicide use had lowered soil pH values from between 5.0 and 6.0 in the alleys between the trees to about 3.0–3.5 near the trees and had greatly decreased permanent-charge cation exchange capacities, base saturation percentages, and ratios of exchangeable Ca/Mg, Ca/K, Mg/K. The pH-dependent or variable charge increased with organic C content and thus originated mainly from the organic matter of these coarse-textured soils. The proportional losses of exchangeable bases during acidification followed the order Ca 〉 Mg 〉 〉 K. Acidification had also released large quantities of plant-available Al and Mn. The soil clays from both the higher and lower pH sites were relatively poorly crystalline with X-ray amorphous constituents and mica as major components. Acidification appeared to have decreased mineral crystallinity as well, as indicated by consistently higher levels of extractable oxides of Si, Al and Fe in the clays from the acidified soils. These effects of orchard practices on chemical and mineralogical properties developed rapidly and were evident in one soil within 12 yr. Practical implications of these results for improving the management and fertility of orchard soils are discussed. Key words: Acidification, chemical and mineralogical changes, Okanagan soils, apple orchards

Beschreibung: Alfalfa (Medicago sativa L. ’Saranac’) was grown on Ste. Rosalie clay, Greensboro loam and St. Jude sand adjusted to about pH 5.0, 6.5 and 7.5 in a greenhouse experiment, to determine the changes in response of alfalfa to aluminum and manganese resulting from variations in soil pH and soil moisture. Rates of Mn were equivalent to 0 and 200 kg∙ha−1 and rates of Al were 0, and 100 kg∙ha−1. Three soil moisture regimes were used: (1) Optimum with soil moisture between field capacity (FC) and 70% of this value. (2) Wet: with soil moisture between saturation point (SP) and FC. (3) Very wet: with soil moisture between saturation point and a value half way between SP and FC. Manganese applied on acid soils (pH 5.2) under optimum soil moisture regimes decreased alfalfa yields by 3% only, compared to a 62% decrease in alfalfa yields by Mn applied on acid soils of the two high soil moisture regimes. This was due to a high level of Mn in alfalfa on the wet acid soils. A large quantity of aluminum was also found in alfalfa grown in acid soils along with a high concentration of "extractable" aluminum. This resulted in a 54% reduction of alfalfa yields. Content of Al and Mn in alfalfa top and in soils was decreased sharply by liming soils at pH of 6.5 or 7.5. On soils limed to a pH of about 7.0 alfalfa survived at high levels of Mn and Al such as frequently encountered in some acid and very wet soils. Key words: Soil Mn, soil Al, soil pH, soil moisture, alfalfa

Beschreibung: Southern Alberta growers often burn fields of seed alfalfa (Medicago sp.) prior to initiation of growth in the spring as apart of an Integrated Pest Management Program. The present study examined the effect of a single burn of the standing dead growth and debris of a 4-yr-old alfalfa crop in early spring, late spring, or autumn on various chemical properties of the upper 50 mm of soil. Burning led to small but significant increases in organic matter, NO3-N, NH4-N, available P, extractable K, EC, and pH levels immediately after the fire. The only measurable impact 1 year later was slightly higher (P 

Beschreibung: A pipeline trench across the Glacial Lake Regina basin provided an opportunity to examine the nature of soil development in heavy textured swelling clays in Saskatchewan. Radiocarbon dates showed a steep age versus depth gradient within the upper 1 m of these soils, and an abrupt change of gradient at this depth. Granular surface structure, deep and wide cracking, slickensides, weak horizon development, and gradual changes in organic matter content were the major characteristics of these soils. The dark-colored subsurface layer in the depressional position appeared to represent a former surface which was buried by accretion of materials from upper slopes. The characteristic morphological features signify the need to re-examine the classification of these soils in the Canadian System of Soil Classification. Key words: Organic 14C dates, soil age, paleosols, swelling clay soils, Holocene soils

Beschreibung: Organic carbon content and color value of A horizons are used as differentiating characteristics in separating Humic Gleysols from other Gleysolic soils in the Canadian System of Soil Classification. Many Gleysolic soils meet the organic carbon criterion but fail to meet the color value criterion of Humic Gleysol. It is concluded that the color value criterion is not an effective differentiating characteristic even though color is a useful indicator of organic carbon when laboratory data are not available. Key words: Principles of soil classification, differentiating characteristics

Beschreibung: Bisbee Delicious apple trees (Malus domestica Borkh.) on Mailing 26 rootstock, planted in 1979 on an Osoyoos loamy sand were subjected, commencing in 1981, to five different orchard soil management treatments including full ground cover, early season vegetation control, total vegetation control, black plastic mulching and shallow tillage. All ground cover suppression treatments decreased leaf K and increased leaf Mg, leaf N and yield. With the exception of early season vegetation control, all ground cover suppression treatments decreased leaf P although P was adequate for initial growth. Declines in soil solution Ca, Mg, and K concentration, 1980–1983, were observed regardless of soil management method. Key words: Apples, M.26 rootstock, leaf N, P, K, Ca, Mg, fruit yield

Beschreibung: Soil surface distribution patterns of herbicide granules from a Gandy dribble type applicator were determined under different wind velocities in the laboratory and verified in the field. Results indicted that a combined operation of application and incorporation during seeding with a discer would not provide satisfactory placement of granules assuming wind velocities that occur normally in Saskatchewan during the seeding period. Key words: Wind, discer, herbicide granules, incorporation

Beschreibung: Estimates of monthly soil temperatures under short-grass cover across Canada using a macroclimatic model (Ouellet 1973a) were compared to monthly averages of soil temperatures monitored over winter at Ottawa between November 1959 and April 1981. Although the fit between monthly estimates and Ottawa observations was generally good (R for all months and depths 0.10, 0.20, 0.50, 1.00 and 1.50 m was 0.90), it was noted that midwinter estimates were generally below observed temperatures at all soil depths. Data sets used in the development of the original Ouellet (1973a) multiple regression equations were collected from stations across Canada, many of which have reduced snow cover. It was found that the buffering capability of the snow cover accumulated at Ottawa during the winter months was underestimated by the pertinent partial regression coefficients in these equations. The coefficients were therefore modified for the Ottawa station during the winter months. The resultant regression models were used to estimate soil temperature during the winters of 1981–1982 and 1982–1983. Although the Ottawa-based models included fewer variables because of the smaller data base available from a single site, comparisons of model estimates and observations were good (R = 0.84 and 0.91) and midwinter estimates were not consistently underestimated as they were using the original Ouellet (1973a) model. Reliable monthly estimates of soil temperatures are important since they are a necessary input to more detailed predictive models of daily soil temperatures. Key words: Regression model, snowcover, stepwise regression, variable selection

Beschreibung: An undisturbed site under forest cover near Breton, Alberta was chosen to study the characteristics of a typical Gray Luvisol. Smectite and to a lesser extent mica were dominant in the clay fraction of the Bt. This horizon contained higher levels of organic C, pyrophosphate-extractable Fe and Al and dithionite-citrate-bicarbonate-extractable Al than adjacent horizons. Lime carbonate was not found to a depth of 2.25 m. Argillans occupied more than 1% of the area of thin sections from Bt and BC horizons but were better developed and more numerous at depths of 1.5–2.25 m. Pedoturbation appears to have caused the disruption and incorporation of argillans into the soil matrix. Argillans in the upper Bt horizon were optically similar to mica and contained more K than argillans from the BC horizons. Silt grains imbedded in argillans were common throughout the solum. Key words: Genesis, Gray Luvisol, pedogenesis, static pedology, clay migration, lessivage

Beschreibung: A growth chamber experiment with six organic soils was conducted to assess the Cu and Mn nutrition of spring wheat grown on organic soils. Three rates of Cu (0, 5, and 10 μg∙g−1 of equivalent volume of a fsl) and three rates on Mn (0, 25, and 50 μg∙g−1 of equivalent volume of a fsl) were applied in all combinations to spring wheat grown on six organic soils. Normal growth of wheat plants was achieved only in soils and treatments where a proper balance on Mn and Cu was achieved. Dry matter yield responses at 45, and 60 days and grain yields reflected the significance of this balance. The major conclusion from this study is that normal wheat growth was achieved on organic soils only when the DTPA-extractable soil (soil: extractant ratio of 1:5) Mn/Cu ratio was between 1–15. At Mn/Cu ratio below 1 and above 15, yield reducion and death of plants occurred due to Mn and Cu deficiency, respectively. Key words: Organic soils, spring wheat, available soil Mn and Cu, Mn/Cu interaction, Mn/Cu ratio

Beschreibung: This study was an evaluation of soil survey methods, particularly soil survey intensity (survey order), based on information from 53 recent surveys in Canada. The data were gathered by questionnaire and indicate that revisions to the specifications outlined by the Expert Committee on Soil Survey are required.(1) An index calculated from the density (number of inspections per unit area) and distribution (percent of delineations with at least one inspection) of soil inspections allocates a survey unambiguously to one survey intensity level (SIL).(2) For each SIL, ranging from 1 (very detailed) to 5 (exploratory), the proportion of delineations with at least one inspection is reduced, and a smaller proportion of the total length of soil boundaries is checked in the field. A closer spacing of traverses at each SIL is recommended.Other information shows that SIL 5 surveys are more appropriately published at a scale of 1:250 000 than the usual 1:100 000; a smaller proportion of time is spent in the field in surveys of lower intensity; soil surveyors concentrate more on describing areas than verifying boundaries; and rates of progress at a given intensity level vary among different physiographic regions, with slowest progress in the Canadian Shield. Key words: Soil survey, intensity, order, index, Canada

Beschreibung: Oxidation of organic matter with H2O2 produced substantial amounts of NH3 which was then fixed by vermiculite, causing partial or complete collapse and converting the mineral to a mica-like product. The collapse of the mineral was indicated by shifts in the 001 spacing from 1.476 to 1.030 nm and the appearance of a well-defined band at 1430 cm−1 in the IR spectrum, indicative of the presence of NH4+ in the interlayer positions of the clay. Our data suggest that: (a) the transformation of vermiculite to mica during H2O2 oxidation may result in underestimation of the vermiculite content of soils by XRD, and (b) the wide occurrence of mixed-layer minerals in soils may in part have resulted from the fixation of NH3 liberated from the microbial mineralization of organically bound N. Key words: Ammonia, X-ray diffraction, IR spectrophotometry, mixed-layer minerals, H2O2 pretreatment

Beschreibung: Soil erosion potential maps and summary statistics can be produced from existing information with relative ease with the aid of computers. Soil maps are digitized and survey information is stored as attributes for each soil. Algorithms are then prepared which evaluate the appropriate data base attributes (e.g. texture, slope) for each interpretation. Forty surface soil erosion potential maps were produced for the Lower Fraser Valley which identify the most erosion-prone areas and indicate average potential soil losses to be expected under assumed conditions. The algorithm developed follows the universal soil loss equation. Differences across the landscape in the R, K, and S factors are taken into account whereas the L factor is considered as a constant equal to 1.0. Worst conditions of bare soil (no crop cover, i.e. C = 1.0) and no erosion control practices (i.e. P = 1.0) are assumed. The five surface soil erosion potential classes are determined by a weighted average annual soil loss value based both on the upper 20 cm of mineral soil and on the proportion of the various soils in the polygon. A unique polygon number shown on the erosion potential map provides a link to computer tables which give additional information for each individual soil within that polygon. Key words: Erosion, computer mapping, USLE

Beschreibung: Copper deficiencies have been reported in cattle in the Fort Fraser-Vanderhoof region of British Columbia and a subsequent forage Cu survey showed widespread low-Cu forages. A series of greenhouse pot studies was conducted to assess the effectiveness of Cu fertilization in increasing yields and Cu concentrations in crops grown on two soils, a Vanderhoof silty clay loam and Welch sandy loam. Copper concentrations in whole-plant barley, bromegrass and alsike clover were increased by Cu fertilization at rates of 2.5 and 10 μg∙g−1. However, yields were not affected. Copper application at 2.5 μg∙g−1 was sufficient to increase Cu concentrations in whole-plant barley and bromegrass above the 4 μg∙g−1 critical value for beef cattle. Alsike clover contained adequate Cu without Cu addition. DTPA Cu concentrations over 1.8 μg∙g−1 were required to produce bromegrass and whole-plant barley Cu concentrations in excess of 4 μg∙g−1. The Vanderhoof silty clay loam provided more available Cu at the 0 and 2.5 μg∙g−1 Cu application rates, but Cu fertilization at both rates increased Cu uptake over the 0 Cu treatments to a greater extent in the Welch sandy loam. Phosphorus fertilization at 25 μg∙g−1 increased whole-plant barley Cu concentrations slightly. Fertilization with Cu or increased use of legumes are possible approaches to the problem of Cu deficiencies in forage-based beef cattle production in this region. Key words: Bromegrass, alsike, whole-plant barley, DTPA Cu, Cu × P fertilization, beef forage system

Beschreibung: Adaptations of eight strains of rhizobia from seven cross-inoculation groups and of two agrobacteria from two species to paraquat, in concentrations up to 20 000 μg∙mL−1, affected 11 of the 40 properties studied, including carbohydrate, nitrogen, sulfur, and other metabolism. The number of characteristics altered varied among the bacteria without species or group affiliation. Of the total of 18 changes, 13 occurred in Rhizobium meliloti 22 and R. trifolii 7 and 42, while R. leguminosarum 56, R. lupini 112, R. japonicum 80, cowpea strain 131, and Agrobacterium tumefaciens A6-K1 had only one. Rhizobium phaseoli 95 and A. radiobacter R-590 remained unaffected. Generally, the adapted organisms produced lower nephelometric growth and manometric respiration rates at 0 and 200 μg of paraquat∙mL−1, relative to the herbicide-free parent controls. Tolerance of R. trifolii 7 to NaCl increased from 1% to 5% (wt/vol). The findings suggest that paraquat may have affected cell permeability, adaptive and/or constitutive enzymes in these bacteria. Key words: Rhizobia, agrobacteria, adaptations, physiology, paraquat and herbicides

Beschreibung: N2O emissions from soils under aerobic conditions were severalfold higher in the presence of azide (1 mM) than in its absence. Nitrogen, added either as NH4+ or NO3−, had no effect on the azide’s induced N2O production. Although the physiological basis by which azide induces the very high evolution of N2O remains unknown, it cannot be attributed to nitrification as a source of N2O emission in the presence of azide, the inhibitory effect of azide on the reduction of N2O to N2, or to the extensive destruction of azide by nitrite under the conditions of the present study. A possible explanation may lie in the stimulation of denitrification processes due to the azide’s role in the synthesis of denitrifying enzymes. This study has reconfirmed that, like N-serve and C2H2, azide (1 mM) is a very effective inhibitor of nitrification. However, azide had no effect on the oxidation of NO2− to NO3−, and was also shown not to be a general inhibitor of microbial activity. Key words: Denitrification, nitrification, dissimilatory nitrase reductase, denitrifying enzymes

Beschreibung: Ateshian’s (1974) equation, used by Wall et al. (1983) to calculate the USLE rainfall erosion index (R) for Canada, appears to considerably overestimate the actual R value for Saskatchewan. An alternative equation derived using a generalized distribution curve for prairie rainstorms given by McKay (1970) predicted an R value of 350 for Saskatoon which was close to the 12-yr average (R = 340) for Saskatoon calculated from tipping bucket rain data. More R values need to be calculated from existing climatological data to determine which (if any) estimation equation is satisfactory. Key words: Rainfall factor, prediction, USLE

Beschreibung: Soils supporting even-aged spruce-fir stands in eastern Maine are highly acid with soil pH often found to be a useful indicator of potential tree growth. This investigation examined the chemical characteristics of these soils at 22 spruce-fir sites and the relationship between soil chemical properties and site productivity. Each major soil horizon exhibited a distinctly different chemical environment. Spruce-fir site productivity was found to be significantly correlated with B horizon organic-P, O horizon pH, and the total organic matter content of the mineral soil horizons. Soil pH increased with depth in the profile ranging from a mean value of 3.13 in the O horizon (i.e. F + H) to 4.91 in the C horizon. Significant correlations were exhibited between pH and exchangeable Ca, exchangeable Al, and extractable Al throughout the profile. Fractionation of P in the B horizons demonstrated that occluded-P was the most concentrated of the fractions measured, with the order of relative abundance for the P fractions being occluded-P 〉 Al-P 〉 organic-P 〉 Fe-P 〉 Ca-P 〉 extractable-P. Sampling of soils for evaluating the potential for forest growth in this region must be carried out by horizons, as these differ remarkably with respect to those variables that have been shown to have an influence on tree growth. Key words: pH, site quality, organic matter, phosphorus, aluminum, spruce-fir

Beschreibung: A study was conducted to determine the content and distribution of total 1.0 M NH4OAc-, 0.1 M HCl-, 1 M MgCl2-, and 0.005 M DTPA-extractable Zn in the genetic horizons of 16 soil profiles from major cacao-growing areas in Southwestern Nigeria. The content of total Zn for all the soils varied from 12 to 92 μg/g with soils derived from igneous and metamorphic rocks containing more than those of sedimentary origin. Most of the soils had the highest concentration of total Zn in the surface horizons. There was a strong association between total Zn and organic matter, total Zn and silt/clay content. The 1 M NH4OAc-, 0.1 M NCl-, 1 M MgCl2- and 0.005 M DTPA-extractable Zn in all the soils and horizons varied from 0.17 to 5.6, from 0.06 to 2.37, from 0.20 to 1.20 and from 0.022 to 1.14 μg Zn/g, respectively. The NH4OAc generally removed more Zn than the other three extractants. The amount of Zn extracted showed a general decrease with depth. A significant amount of MgCl2-extractable Zn appeared to be associated with silt content while soil pH influenced the quantity of Zn extracted by the NH4OAc method. Key words: Total Zn, NH4OAc-extractable N, HCl-extractable N, MgCl2-extractable N, DTPA-extractable Zn, soil profile

Beschreibung: Postfire recovery of biomass and soil organic pools was measured in a sequence of 10 subarctic lichen woodlands aged from 0 to 140 years. Less than one-tenth of total live biomass combusted at the time of burning. Aboveground biomass combustion of species ranged from nil to over 90% depending on plant stature. Although no trees or lichen survived, shrub mortality (6%) was minor. Developmental phases similar to those in northern hardwood forest were apparent. Reorganization was dominated by shrubs over the first three decades. Aggradation resulted in a fourfold increase in total biomass; it was then followed by a 14% decrease occurring at transition (110–140 years postfire). Breakdown of the burnt lichen mat was rapid (1500 kg•ha−1•year−1) compared with the disintegration of dead wood. Of an initial 40 000 kg•ha−1 in dead boles and branches, 15 000 kg•ha−1 remained 110 years later. Little change in soil humus mass occurred during fire and postfire. Total live and dead organic mass remained relatively constant over the 140 years of recovery. However, the live/dead ratio of organic mass showed a gradual but consistent increase.

Beschreibung: Concentrations of N, P, K, Ca, Mg, S, Fe, Mn, Zn, Cu, and Na were examined in whole leaves collected in August 1981 from specified positions within the crowns of 15 Acersaccharum Marsh, and 10 Betulaalleghaniensis Britton trees growing in closed forest on a Precambrian-derived till soil in northern Ontario. Concentrations of K, Ca, Mg, Fe, Zn, and Na were significantly higher in lower crown leaves of A. saccharum, and Ca was significantly higher in lower crown leaves of B. alleghaniensis, but in other elements there were no significant differences attributable to crown position. There was a tendency for element concentrations to be higher at all crown positions in intermediate as opposed to codominant trees; however, differences were not significant or were weakly significant at best. Tree-to-tree variation was less in mid- and lower-crown, as opposed to upper-crown, foliage. Generally, for both species, to bring standard errors to within ± 10% of the group mean, about 30 trees per stand should be sampled if analyses are restricted to N, P, K, Ca, Mg, and 40–70 trees per stand should be sampled if trace elements such as Mn are to be included.

Beschreibung: Many researchers set up an experiment, make measurements, do an analysis of variance, calculate the mean response for each treatment, and then try to decide if the treatment means are significantly different and why. Duncan's multiple-range test is frequently used to test the difference among treatment means. It is, however, only one of a number of techniques that can be used to examine treatment means. Some researchers are unaware of the different techniques and that the interpretation of the results of an experiment can be strongly influenced by the technique used. In fact, using an inappropriate technique can lead to making incorrect recommendations and to completely missing major treatment effects. Selection of the appropriate technique to use for a particular experiment depends upon the nature of the treatments and the objectives of the research. This paper discusses four techniques (ranking treatment means, multiple comparison procedures, fitting response models, and using contrasts to make planned comparisons) that can be used to examine treatment means and presents examples of each one.

Beschreibung: Aboveground biomass and leaf area, net primary production, and nutrient cycling through vegetation were studied for 3 years after clear-cutting (stems only) of a 10.24-ha watershed in the Oregon Cascade Mountains. The riparian zone and four main habitats were analyzed separately. In 3 years, aboveground net primary production increased from 5 to 112 g•m−2•year−1 in the ridgetop habitat; midsummer aboveground biomass increased from 8 to 196 g/m2 in the riparian zone and from 198 to 327 g/m2 on the ridgetop. Other values were intermediate to these. Litter fall of species with perennial aboveground parts averaged 20–27% of standing biomass. Native annuals, especially Araliacalifornica Wats., dominated the riparian zone. Seneciosylvaticus L., an introduced species, dominated most of the rest of the watershed, except for the ridgetop habitat, which was dominated by residual woody shrubs. Uptake of N exceeded losses in streamflow the 1st year and was six times greater in the 2nd; uptake of P and K in that year was 2.5 and 3 times greater than losses. In the 3rd year, total uptake of K (2.5 g•m−2•year−1) equaled the preclear-cutting level, and uptake of N (1.3 g•m−2•year−1) and P (0.3 g•m−2•year−1) was about half that level. No correlation was found between plant uptake and nutrient loss in streamflow. Uptake of all elements exceeded return through leaching and litter fall by 16%, except that of Mg, which exceeded return by 44%. Because of early dominance by species with annuals, the proportion of elements redistributed internally by vegetation was generally low. The amount of nutrients in flux through vegetation, atmosphere, and stream was small in comparison to the amount lost in the removal of tree stems.

Beschreibung: Sulfate was the dominant anion in throughfall and soil solutions from a chestnut oak (Quercuspinus L.) and a yellow poplar (Liriodendrontulipifera L.) forest in eastern Tennessee. Assuming much of this [Formula: see text] was of anthropogenic origin, cation-leaching rates from foliage and in soils of these forests would have to have been accelerated by acid deposition by two- to three-fold. This acclerated leaching could, in turn, cause changes in the rates of K+, Ca2+, or Mg2+ cycling according to any of a number of possible scenarios explored in this paper. Subsoils beneath the chestnut oak stand adsorbed [Formula: see text] from atmospheric deposition, which reduced [Formula: see text]-mediated cation leaching to some extent. In contrast, subsoils from the yellow poplar stand showed a current net output of [Formula: see text] (perhaps desorbing sulfate adsorbed during previous periods of higher input) and much higher rates of cation leaching. The yellow poplar site showed net annual exports of Ca2+, Mg2+, K+, and Na+, but the chestnut oak site showed a net accumulation of Ca2+ and lower net annual exports of Mg2+ and K+ than the yellow poplar site. Both sites had inexplicably large net exports of Na+.

Beschreibung: Most Douglas-fir stands respond to nitrogen fertilization by increasing stem growth for less than 8 years, but one plantation at the United States Forest Service Wind River Experimental Forest has responded for over 15 years. The nitrogen concentration of foliage and fresh litter were higher in the fertilized (applied at 470 kg N/ha) plots 18 years after fertilization. Retranslocation of N from senescent needles was not affected and stem growth per unit N in the canopy was similar between unfertilized and fertilized plots. An index of soil N availability in the fertilized plots was twice that of unfertilized plots. The higher stem growth, leaf area, and stem growth per unit leaf area appeared related to a sustained increase in soil N availability rather than increased N-use efficiency. Soil N transformation processes need to be examined to complete the explanation of the unusually prolonged fertilizer response in these plots.

Beschreibung: Relatively little work has been done to evaluate the effects of chronically high levels of carbon dioxide on growth and physiology of woody plants. In this study, seedlings of lodgepole pine (Pinuscontorta Dougl. var. latifoliaEngelm.) were grown for 5-month periods at 330, 1000, or 2000 μL CO2•L−1. Height growth; leaf area production; biomass of leaves, stems, and roots; and photosynthetic responses to changing light, moisture, and CO2 concentration were measured. Significant differences between treatments were found in mean seedling height on all measurement dates. Seedlings grown at 1000 μL CO2•L−1 were tallest, with seedlings grown in 2000 μL•L−1 intermediate between the control (330 μL•L−1) and 1000 μL•L−1 treatments. The same relationship was found in production of total leaf surface area. Increased leaf surface area yields a productive advantage to seedlings grown at concentrations of CO2 up to 2000 μL•L−1 even if no increase in net photosynthesis is assumed. Biomass of stems, roots, and secondary leaves was increased in both elevated CO2 conditions, with root biomass approximately 15 times greater in seedlings grown at 1000 μL•L−1 than in those grown at 330 μL•CO2•L−1. Stomatal resistances were essentially the same for all treatments, indicating no CO2-induced stomatal closure to at least 2000 μL•L−1. Photosynthetic Vmax (milligrams per square decimetre per hour) for light response curves varied with CO2 concentration. If results are extrapolated beyond a 5-month period and into field conditions, it appears that size of trees, interactions with competitors, and ecological role of the species might be altered.