ALBERT

Description: Flooding for 30 days induced several changes in Quercusmacrocarpa Michx. seedlings, with stomatal closure among the earliest responses. Stomata remained more closed in flooded than in unflooded plants during the entire experimental period. Leaf water potential was consistently higher in flooded than in unflooded plants. Other responses to flooding included acceleration of ethylene production by stems; formation of hypertrophied lenticels on submerged portions of stems; growth inhibition, with greatest reduction in roots; and formation of a few adventitious roots on submerged portions of the stem above the soil line. Some of the morphological responses to flooding, especially formation of hypertrophied lenticels, appeared to be associated with increased ethylene production. Quercusmacrocarpa seedlings adapted poorly to flooding as shown by failure of stomata to reopen after an early period of flooding and low capacity for production of adventitious roots. The much greater inhibition of root growth than shoot growth by flooding will reduce drought tolerance after floodwaters recede.

Description: Water stress of subalpine conifer species may be measured with the pressure chamber after several hours of tissue storage. Tissue samples stored in cool, humid vials exhibited very little change in xylem pressure potential over a 4-h period. However, xylem pressure potential declined steadily when a source of water vapor was not available. Xylem pressure potentials of current-year and 1-year-old needles of lodgepole pine (Pinuscontorta var. latifolia Engelm.) were slightly lower than those of older needles.

Description: Carbohydrate reserves and root growth potential (RGP) of 2 + 0 Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) seedlings were monitored through a lifting season and during dark, cold storage. Concentrations of total nonstructural carbohydrate and extractable sugars in root and stem tissues remained relatively constant through winter, while foliar sugars showed a sharp midwinter peak at about 195 mg•g−1 dry weight. RGP was lowest in November and March and peaked in January. During storage at +2 and −1 °C, carbohydrates were depleted in all tissues through respiratory consumption. In contrast, RGP increased during the first 6 months in storage and then fell rapidly. The results do not support the view that changes in RGP are driven by changes in carbohydrate concentrations. Storage may affect frost hardiness and drought resistance through its effect on sugar concentrations.

Description: A nonlinear analytical model is developed to describe the relationship between average plant size (weight or volume) and stand density in single-aged, monospecific plant populations. The model gives estimates of the slope and intercept of the −3/2 power rule asymptote, the nature of the size–density trajectory, and such features as relative density at crown closure and the effects of soil type or site index. The model is tested by growing red alder (Alnusrubra Bong.) seedlings under greenhouse and lath house conditions at three initial spacings (8 × 8, 4 × 4, and 2 × 2 cm) and two soil types (river loam and alder forest soil) for 525 growth days. There are seven harvests, starting at crown closure. All size–density trajectories tend consistently towards the same single asymptote irrespective of initial spacing, soil type, or age. The asymptote slope and intercept are 1.46 and ca. 94 kg tree−1•m−2. The crown closure line is parallel to the asymptote at a relative density of 4.6 × 10−3. The model also adequately describes the size–density trajectories for 20–50-year-old red pines (Pinusresinosa Ait.) growing at six initial spacings. The asymptote slope and intercept are 1.6 and ca. 87 × 103 m3•tree−1•ha−1, respectively.

Description: The pipe model theory presents the idea that a unit weight of tree foliage is serviced by a specific cross-sectional area of conducting sapwood in the crown. Below the crown, a large fraction of the tree bole may be nonconducting tissue, so the sapwood area would have to be known to estimate foliage. We applied the pipe model theory to the analysis of several western coniferous species to learn whether the distribution of canopy leaf area could be accurately estimated from knowledge of the sapwood cross-sectional area at various heights, including breast height (1.37 m). Results are excellent, but taper in the conducting area must be considered when sapwood area is measured below the crown.

Description: At 10 locations in Oregon and Washington, tree mortality resulted in dry-matter transfer of 1.5–4.5 Mg•ha−1•year−1 of boles and branches to the forest floor and 0.3–1.3 Mg•ha−1•year−1 of large-diameter roots directly to the mineral soil. The first value is about the same as that reported for leaf fall in similar stands; the second value generally is smaller than that reported for fine root turnover. Results are based on measurements by the U.S. Forest Service spanning 16–46 years and areas as large as 42 ha. Values based on intervals

Description: Reduced levels of root activity were associated with winter injury to shoots of 1-year-old black spruce (Piceamariana (Mill.) B.S.P.) container seedlings.

Description: Three methods were compared for total sulphur analysis of tree foliage: magnesium nitrate ashing followed by turbidimetry, sodium hypobromite (NaOBr) oxidation followed by colorimetry, and an instrumental method using the Fisher S analyser, model 475. The latter method was found to be substantially better than the other methods with respect to accuracy and speed of analysis, and of satisfactory precision (average coefficient of variation (CV) was 2.5%). Dry ashing resulted in good precision (CV = 1.9%) but only recovered 76% of the reported total S in the United States National Bureau of Standards (NBS) orchard leaf standard. The NaOBr method recovered 88% of reported S from the NBS standard but showed poorer precision (CV = 4.5%). The Fisher analyser had the lowest operating cost per sample, largely owing to lower labour costs.

Description: Water chemistry profiles of an 18-year-old forest ecosystem are compared with those of a 70- to 90-year-old forest ecosystem for a 9-month period. The younger ecosystem was dominated by Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) and red alder (Alnusrubra Bong.) whereas western hemlock (Tsugaheterophylla (Raf.) Sarg.), Douglas-fir, and western red cedar (Thujaplicata Donn.) dominated the older ecosystem. Concentrations of nutrients and other chemicals were measured in throughfall, forest floor and mineral soil lecachates, saturated-zone water, and stream water. Concentrations of dissolved chemicals were much greater in the younger ecosystem than in the older ecosystem at intermediate stages in the profiles. However, stream water concentrations differed less between the two ecosystems for most of the chemicals investigated. Nitrate and silica were exceptional; stream water nitrate concentrations in the younger ecosystem averaged 16 times greater than those in the older ecosystem. This was probably a result of biological nitrogen fixation by red alder in the younger ecosystem, a process which would more than compensate for the higher nitrate losses. Silica concentrations in the younger ecosystem consistently exceeded levels in the older ecosystem by 40 to 100%. suggesting a possibility of a greater rate of mineral weathering in the younger ecosystem.Although nutrient concentrations were higher in the soil leachates of the younger ecosystem, these higher levels failed to persist through the saturated-zone water and stream water stages of the water chemistry profile. Consequently, the younger ecosystem appeared relatively more efficient at retaining dissolved nutrients than the older ecosystem. Stream water chemistry was relatively insensitive to the magnitudes of the differences in biogeochemical process rates of the two ecosystems.

Description: A data screening algorithm (SCREEN) identified stand age, average stand diameter, timber type, soil type, aspect, habitat type, and elevation as forest stand or site characteristics strongly associated with root-disease occurrence in northern Idaho forests. The logistic regression model was used to predict root disease center occurrence. A second algorithm (RISK) was used to compute the estimates for the coefficients and to test different prediction equations. On wet aspects, highest probability of root disease centers was found on soils with lowest year-round moisture availability. The reverse was true on dry aspects. Increased slope was associated with increased root disease. Root disease center frequency was inversely related to elevation and directly related to occurrence of Pseudotsugamenziesii (Mirb.) Franco and Abiesgrandis (Dougl.) Lindl. Expression of disease centers was maximum at 60–100 years of stand age on all habitat types. A habitat-type–age interaction was observed in oldest aged stands.

Description: The effects of defoliation by western spruce budworm (Choristoneuraoccidentalis (Freeman)), on Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) radial growth at breast height and tree mortality are given. Four hundred and twenty trees were marked in an 81-year-old stand, and their defoliation levels were recorded annually from 1970 to 1980 in an outbreak that lasted from 1970 to 1974, inclusive. Forty-one trees were felled and dissected in 1977, 3 years after recovery began. The number of stems per hectare was reduced by 39.3% and basal area by 11.6% through mortality, most occurring among the small diameter, suppressed, and intermediate trees. Relationships were established between mortality and defoliation. Radial increments were examined, and the presence of four outbreaks during the life of the stand was detected. The combined effect of these infestations amounted to a loss of about 12% of the estimated potential diameter had not the insects been active. The most recent outbreak (1970–1974) caused a total of 10 years of subnormal growth, including 5 years due to defoliation and 5 years of recovery. The relationship between radial increment losses and defoliation intensity and duration is studied and quantified.

Description: The vegetative phenology of Piceaglauca (Moench) Voss and P. mariana (Mill.) B.S.P. was determined in 1979 based on four ramets selected from each of 14 clones of each species located at a seed orchard in northern Ontario. The time of flushing of the leaders and four lateral branches was determined by a qualitative index of bud and shoot development; time of growth cessation was scored as the date at which 95% of shoot growth was complete. The flushing of the vegetative buds of white spruce lasted for a 10-day period compared with only 6 days for black spruce. Although the average date of flushing for white spruce clones was 9 days ahead of the average date for black spruce clones, the latest white spruce clone flushed only 3 days before the earliest black spruce clones. As well, degree-day requirements for flushing were significantly different for clones within each of the two species. These results suggest that the selection of late-flushing white spruce trees for seed orchard stock has the potential to decrease spring frost damage in this species in northern Ontario. Date of budbreak was not correlated with date of growth cessation for either white or black spruce; however, early-flushing clones of black spruce produced significantly greater leader extension than late-flushing clones.

Description: Ocular and shoot-count defoliation estimation techniques were compared for accuracy and precision at the levels of branches and crown position within trees, whole trees, plots, and stands. A shoot-count estimate of defoliation for a midcrown branch had the best relative accuracy (±7%), while the best ocular estimate was for the whole tree by an experienced observer (accuracy ±12%). Ocular estimates were biased towards ovcrestimation at low defoliation levels (error 20–30% defoliation), and previous defoliation caused the ovcrestimation of current defoliation by 30–40% on trees that had been previously severely defoliated. Observers were found to be consistent in their rating, but biased by about ±10%; experienced observers were about 5–10% more accurate than inexperienced observers. Intertree variance in defoliation was greater than intratree variance or variance between plots in a stand. It was concluded that ocular estimation of defoliation is a viable technique that can give accuracy within the limits required for surveys and many research applications, if the influence of observer experience, observer bias, and previous defoliation arc recognized, and adjusted for when necessary.

Description: The effects of fertilization and thinning of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) on the distribution of area increment along the bole were assessed using radial growth measurements 6 and 9 years after treatment. Within treatments, the average area increment per tree was linearly related to diameter at breast height, and this relationship was used to evaluate the effects of treatment on growth rate. Fertilization had the greatest effect on average area increment, and for a particular fertilization regime, thinning increased the response. Thinning modified the distribution of growth over the bole of all trees and increased butt flare, especially in smaller trees. The effect declined from the 4- to 6-year measurement period to the 7-to 9-year measurement period. Fertilization had no consistent effect on growth distribution. The regression methods used in this study provided a more sensitive measure of form changes than previous methods, were independent of size distribution, and facilitated extrapolations and evaluation of temporal trend.

Description: Organic content of the forest floor decreases for several years after clear-cutting, and then slowly recovers. Thickness, bulk density, organic matter, and nitrogen content of forest floors were measured for 13 northern hardwood stands in the White Mountains of New Hampshire. Stands ranged from 1 to about 100 years in age. Forest-floor thickness varied significantly with stand age, but bulk density, organic fraction, and nitrogen fraction were independent of age. Total organic content of the forest floor agreed very well with data from Covington's (W. W. Covington 1981. Ecology, 62: 41–48) study of the same area. Both studies indicated that mature forest floors have about 80 Mg organic matter•ha−1 and 1.9 Mg nitrogen•ha−1. Within 10 or 15 years after cutting, the organic matter content of the floor decreases to 50 Mg•ha−1, and its nitrogen content to 1.1 Mg•ha−1. The question whether the decrease is rapid and the minimum broad and flat, or if the decrease is gradual and the minimum sharp, cannot be answered. The subsequent increase to levels reached in mature forest requires about 50 years. Some of the initial decrease in organic matter and nitrogen content of the forest floor may be caused by organic decomposition and nitrogen leaching, but mechanical and chemical mixing of floor into mineral soil, during and after the harvest operation, may also be important. The difference is vital with respect to maintenance of long-term productivity.

Description: Straw was added over snow to smother ground vegetation (straw experiment) in sample plots in a 45-year-old jack pine (Pinusbanksiana Lamb.) stand in Quebec. Sample plots in the same stand were fertilized six times with N, P, and K in a 10-year period to maintain four foliar N regimes (optimum nutrition experiment). Smothering of ground vegetation with straw improved N nutrition and produced a sustained increase in tree growth. Sustained growth increases were obtained by repeated applications of 56 kg N/ha associated with 1.4% N foliar concentrations in current foliage. Gross volume increments of about 3 m3 • ha−1 • year−1 were sustained with these low applications. Repeated heavy N applications killed trees and reduced growth. Repeated additions of P and K with N did not produce appreciable differences in response from additions of N alone. Increment cores showed the annual development in growth as increasing over most of the 10-year period for low repeated N additions, and as increased and stable over the same period for the straw addition.

Description: In 4 different years' experiments with loblolly (Pinustaeda L.), slash (Pinuselliottiielliottii Engelm.), and longleaf (Pinuspalustris Mill.) pine, timing of gibberellin A4/7 (GA4/7) treatments was critical for optimal promotion of pollen conebuds. Two or three biweekly treatments given at strategic times were equivalent to six given from May to August. July to August applications best promoted pollen conebuds. Using the cationic surfactant Aromox C/12, aqueous foliar sprays of 200 mg/L of GA4/7 were more effective than ethanolic topical bud treatments for pollen conebud induction in slash pine. Addition of naphthaleneacetic acid enhanced the GA4/7 effect in loblolly pine but diminished it in slash and longleaf pine.

Description: The relationships of root attributes and tree, stand, and site factors to root contact between second-growth Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) were studied in excavated root systems. Type 1 contacts (tenuous) were positively related to root length and inversely related to root volume. Type 2–3 contacts (with slight to severe root deformation) were positively related to number of roots. Type 4 contacts (apparent grafts) were positively related to root number and cross-sectional area. Differentiation among groups containing no contacts. Type 1 contacts only or all contact types showed that intertree distance, tree diameter, rooting depth, soil gravel content, and percent slope were significant in determining probability of root contact.

Description: Root and shoot biomass and mycorrhizal development were examined for white spruce (Piceaglauca (Moench) Voss) seedlings naturally regenerating in four floodplain communities in the boreal forest. Mean seedling biomass was highest in the open community and lowest in the spruce community. Seedlings growing in the open community had higher root:shoot ratios (0.50) compared with seedlings growing in the willow (0.34), alder (0.20), and spruce (0.24) communities. Essentially all short roots of spruce seedlings growing in all four communities were infected by mycorrhizal fungi throughout the growing season.

Description: Growth response of young, spaced balsam fir (Abiesbalsamea (L.) Mill.) to 3 successive years (1979–1981) of treatment with Bacillusthuringiensis Berliner for spruce budworm (Choristoneurafumiferana (Clem.)) control was examined in 20 plots on the Cape Breton Highlands, Nova Scotia. Defoliation commenced in 1976, 3 years before control operations began. Five plots were established both inside and outside the spray block, in areas that had been severely defoliated by budworm and in areas moderately defoliated. All plots in the severely defoliated area suffered heavy tree mortality, but mortality was significantly lower in the protected plots. In contrast, the moderately defoliated plots suffered virtually no tree mortality. The average volume increment of stem-analyzed trees from 1979 to 1981 was 0.63 dm3/tree for protected and 0.43 dm3/tree for unprotected trees in the severely defoliated area versus 4.15 dm3/tree for protected and 3.08 dm3/tree for unprotected trees in the moderately defoliated area. These volume increment values are equivalent to 8.8 m3/ha of growth between 1979 and 1981 for protected plots in the moderately defoliated area, compared with 6.1 m3/ha for unprotected plots. Therefore, a total gain of 2.7 m3/ha can be attributed to the 3 years of B. thuringiensis spraying. Long-term growth responses toB. thuringiensis spraying were not evaluated. Better results would be expected had protection started at the beginning of the budworm outbreak, instead of after 3 years of severe defoliation.

Description: Black alder, Alnusglutinosa (L.) Gaertn., seedlings were grown and kept well watered for 10 weeks, and then subjected to moisture stress conditioning for 5 subsequent weeks, where one-half of the seedlings were watered only when visibly wilted. The remaining seedlings (controls) were kept well watered. Moisture stress conditioning greatly reduced shoot, root, nodule, and total plant dry weight. The root–shoot ratio (grams/grams) of seedlings was significantly increased from 0.28 in the control seedlings to 0.33 in the water-stressed treatment. Acetylene reduction rates decreased only slightly in the range of water potentials between −0.50 and −1.29 MPa, then dropped rapidly below water potentials of −1.30 MPa. Moisture stress conditioning had no significant influence on this response. Although not significantly different, leaf and nodule osmotic potentials were consistently lower in the water-stressed plants.

Description: The relationships between foliage area and sapwood area between trees and within the crowns of 20 Piceasitchensis (Bong.) Carr., provenance Queen Charlotte Island, British Columbia (10 in a control plot and 10 in a plot fertilized with potassium and phosphorus 8 years before harvest) and 10 Pinuscontorta Dougl., provenance Ladysmith trees were examined using a physiological analysis based on Darcy's law. Foliage area index on the fertilized P. sitchensis plot was higher than on the control. The variation of foliage area density with depth in the canopies followed a normal distribution. Relationships between foliage area and sapwood basal area were linear but the slopes were different for the two species. There was no significant difference between the control and fertilized P. sitchensis trees. The relationship between foliage area and the product of sapwood area and permeability was linear and data from the three plots fell on the same line. Sapwood area, permeability, and their product decreased with depth through the crowns of the trees. Within the crowns, relationships between cumulative foliage area and sapwood area, and between cumulative foliage area and the product of sapwood area × permeability were different with species and treatment. A single linear relationship resulted when the product of cumulative foliage area above an internode × the internode length was plotted against sapwood area × permeability for the internode. This suggests that it is the drop in potential across a node and internode rather than the gradient of potential across the internode that is related to the flux of water through tree crowns. The data support the hypothesis that the relationship between foliage area and sapwood area depends on permeability of the sapwood and the local climate through its influence on transpiration rate, particularly via average water vapour pressure deficit of the air and stomatal conductance.

Description: Analysis of dead boles of Piceasitchensis (Bong.) Carr. and Tsugaheterophylla (Raf.) Sarg. in open- and closed-canopy forests of the Olympic Peninsula Washington, U.S.A., revealed that hemlock mortality in both forest types was due mainly to windthrow, whereas spruce typically died upright. The open forest contained 120 t/ha of dead bole wood; the closed forest contained 161 t/ha. Hemlock boles decayed more rapidly than the larger spruce boles, although both showed considerable variability. On a per-hectare basis, 146–223 kg of N, 147–197 kg of Ca. 39–61 kg of K, 18–29 kg of Mg, 6–14 kg of Na, and 17–29 kg of P were contained in dead boles of the open- and closed-canopy forests, respectively. Except for N and Mg, the nutrient concentrations of the wood were not significantly different after 33–68 years of bole decay. The N:P ratios increased with increasing decay for both species.

Description: The biomass of 76 jack pine (Pinusbanksiana Lamb.) trees (29 stands) and 72 red pine (P. resinosa Ait.) trees (28 stands) from throughout the northern Lake States was determined. All trees were from even-aged, unthinned plantations ranging from 20–61 years old; site indexes represented nearly the complete range for these species. Individual tree component weights (foliage, live branches, dead branches, stem wood, and stem bark) were regressed against dbh and tree height using the nonlinear form Bt = aDbHc. Stand biomass was also estimated with stand basal area and mean height of dominant and codominant trees using the equation form Bs = a + b(B) + c(Hs) or a + b(B)(Hs). The equations were tested in two additional stands of red pine and two of jack pine and by comparison with literature values. Individual tree equations were most accurate for estimating bole components and the total tree and less accurate for foliage and branches. The standard error of the estimate divided by mean weight ranged from 0.06 to 0.17 for bole components, from 0.21 to 0.28 for live crown components, and from 0.43 to 0.49 for dead branches. For all components, jack pine equations were slightly less precise than those for red pine. The individual tree equations appear to be applicable over a wide geographical area and usable for both natural stands and plantations. The equations appear to be valid for the majority of unthinned stands in the age range of 20–50 years. The stand equations, while less precise than individual tree estimates, should give reasonably accurate estimates of stand biomass components in most situations.

Description: This paper is a comprehensive review of operational research studies in forest fire management during the years 1961 through 1981. It includes a brief discussion of fire management decision making, summaries of and comments regarding the practical merits of the work that has been done, and suggestions concerning future efforts in this field.

Description: Retranslocation from leaves was investigated as a means of retaining nutrients in stands of Quercusprinus L. on two sites in southern Illinois, where wind rapidly moves litter downslope. Foliage samples were collected from late summer until leaf fall to describe the trends of leaf dry weight and nutrient concentration (N, K, P, Ca) changes. Free-falling rain and throughfall were collected to estimate foliar leaching. Foliar concentrations of N, K, and P decreased markedly during senescence while Ca concentrations increased. The pattern of concentration change was unique for each element, and the change in N concentration was closely correlated with change in leaf color. For the study sites as a whole, leaf dry weight decreased to 70% of the original value. Of 84.2 kg N/ha in green foliage, only 22.6% was returned to the site as litter. The canopy gained 0.3 kg N/ha (0.4%) from rainfall. The 78.5% N unaccounted for is attributed to retranslocation. Similarly, from 51.4 kg K/ha; 8.2, P; and 47.8, Ca in green foliage, 9.8, 1.3, and 3.3%, respectively, were removed by leaching; 27.4, 43.7, and 85.1% were returned to the site in litter. The remaining 63.0% K, 55.0% P, and 11.5% Ca unaccounted for is attributed to retranslocation. Retranslocation and leaching of nutrients was greater on the site of higher quality. But on both sites it appears that retranslocation is an important means of retaining and conserving N, K, and P countering the effect of annual litter removal.

Description: Mathematical growth analysis techniques were used to assess the effects of atmospheric carbon dioxide enrichment on growth and biomass partitioning of Liquidambarstyraciflua L. (sweetgum) and Pinustaeda L. (loblolly pine) seedlings. Plants were grown from seed under high (1000 μmol•m−2•s−1) and low (250 μmol•m−2•s−1) photosynthetic photon flux density at CO2 concentrations of 350, 675, and 1000 μL•L−1 for 84 or 112–113 days. Elevated atmospheric CO2 concentration significantly increased height, leaf area, basal stem diameter, and total dry weight of sweetgum seedlings grown under high irradiance and to a lesser extent under low irradiance. Increases in dry matter accumulation were associated with early CO2 enhancement of net assimilation rate, but increases in amount of leaf surface area contributed more towards maintenance of larger size as seedlings aged. For sweetgum seedlings in particular, reduction of growth by low irradiance under normal atmospheric CO2 was compensated for by growing plants with elevated CO2. In contrast, elevated CO2 concentration produced no significant increase in growth of loblolly pine seedlings.

Description: Stomatal conductance was measured with porometers in two plots of Pinussylvestris L. with markedly different tree spacings (plot 1, 608 stems ha−1; plot 2, 3281 stems ha−1), and hourly rates of transpiration were calculated using the Penman–Monteith equation at intervals throughout one growing season. Stomatal conductance varied little in relation to height or age of foliage. There was a linear decrease in canopy conductance with increasing water vapour pressure deficit of the air. Transpiration rates on both plots increased during the summer (maximum 0.3 mm h−1); rates on plot 1 were always lower (ca. 0.7 times) than on plot 2. Needle water potentials were similar throughout the season and only slightly lower on plot 1 than on plot 2. The mean hydraulic resistance of the trees on plot 1 was 2.4 times that on plot 2. The results support a hypothesis that considers the changes in transpiration rate, conducting cross-sectional area, canopy leaf area, water potential, and hydraulic resistance following thinning as a set of homeostatic relationships.

Description: There is a need to provide quantitative relationships that will allow agronomists to estimate accurately the nitrogen-supplying power of soils while taking into account both temperature and soil moisture variations. The procedure for estimating net nitrogen mineralization proposed by Stanford and co-workers was used to determine Arrhenius relationships between the rate constants (k) and absolute temperature (°K) for 33 virgin and cultivated Western Canadian prairie surface (0–15 cm) soils. There was no significant difference in Arrhenius relationship between soils within each soil zone; thus, a single average Arrhenius equation was calculated per soil zone. Average Q10 for the Brown chernozemic soils was 2.75, for the Dark Brown, thin Black and thick Black chernozems, 2.18, and for the Gray luvisols, 2.0. These Q10 values are as high or higher than those reported in other parts of the world and may be related to the degree of degradation of the soil organic matter in these various soils. Culture had no marked effect on Q10 but sandy soils had higher Q10 than loams and clays. An equation for estimating net nitrogen mineralization for the Wood Mountain loam (a Brown chernozem) was tested using data from a previous study. The results were quite satisfactory, especially when the test data were derived under laboratory conditions where moisture was well controlled. The temperature functions presented herein can be used together with moisture functions and potentially mineralizable nitrogen results published earlier to make first estimates of net nitrogen mineralized during the growing season in the soils tested. Key words: Q10, Arrhenius relationship, potentially mineralizable nitrogen

Description: The use of commercially available porous cup soil water samplers for soil solution extraction was evaluated. Ortho-P, (NO3 + NO2)-N and potassium (K) were adsorbed by the porous cup during extraction of soil water samples, but the retention of (NO3 + NO2)-N was minimal. The screening of NO3− by the cup was not obvious. The retention of ortho-P and K was a function of solution concentration and the time of contact between soil solution and the cup. A rest period between extractions, during which samplers remained in contact with solution at zero tension, appeared to enhance phosphorus sorption capacity of the ceramic cup. Furthermore, phosphorus sorption was reversible in nature. The porous cup subjected to high solution concentration initially, released phosphorus when flushed with soilsolution of low concentration. It is recommended that several consecutive soil water extractions be carried out at high (0.6 bar) tension, using high flow rate porous cups. The sample collected in the last extraction should be used to determine true soil water quality.

Description: A study designed to assess gaseous losses of N as N2O and N2 from soils of conventional till fields seeded to wheat in the Chernozemic soil region of Saskatchewan, together with limited supporting laboratory investigations, has confirmed that for the May-November period losses were in the vicinity of 3 kg N∙ha−1 or less. In contrast, total losses from a summer-fallowed field were approximately 300% higher. Comparisons at one site were made of N losses from a conventionally tilled and zero-tilled Dark Brown Chernozemic soil seeded to wheat; the total losses of N were twice as high for the zero till as the conventional till treatments. The N2O fluxes were shown to be the result of both reductive (denitrification) and oxidative (nitrification) processes and generally, under the conditions of these field experiments, both occurred simultaneously. This experiment also confirmed that C2H2 inhibited nitrification in a manner very similar to N-serve, a well-known nitrification inhibitor.

Description: Two separate field experiments were conducted on several crops to determine the effect of selenium (Se) applied to soils with pH levels between 5.7 and 6.6. Tissue Se levels after a single application of Se and lime, were monitored for up to six cropping years or until the tissue Se fell below 0.1 ppm, the level considered to be necessary for animal nutrition. For applications of 1.12 and 2.24 kg Se/ha, the minimal tissue Se concentration (〉 0.1 ppm) was maintained in barley (Hordeum vulgare L.) for two cropping years, but with a very sharp decrease for the first 3 yr. In the case of timothy (Phleum pratense L.), tissue levels greater than 0.1 ppm were maintained for 3 yr at the higher rate of Se without lime and up to 5 yr at high soil pH levels. At the applied rates of 0.28 and 0.56 kg Se/ha, the tissue Se levels above 0.1 ppm in timothy, red clover (Trifolium pratense L.), and alfalfa (Medicago sativa L.) were maintained for one and two cropping years, respectively. In spite of the sharp decrease in plant tissue Se levels, little decrease in total soil Se was noted at rates of 1.12 and 2.24 kg Se/ha after successive croppings of barley and timothy. Although not always significant, liming, in general, increased the plant Se concentration. The Se concentration (log ppm) for tissues (or depletion of Se availability) in the Se-applied plots decreased linearly for at least the first three cropping seasons.

Description: Potassium deficiency in grapes, as well as in other fruit crops grown on soils in the Niagara peninsula, is a common and often serious problem. Ap horizon samples from 12 of these soils and grape petiole samples from nine of the soil locations were analyzed to elucidate the behavior of the soil K and its availability to grapes. The soils ranged in texture from sandy loam to silty clay and their clay mineralogy was relatively uniform with mica as the main layer silicate. Vermiculite was quantified by potential K fixation methods and was concentrated in the clay. Up to 5.8% vermiculite was present in the soils which seemed to be sufficient to reduce K availability by K fixation. Amounts of exchangeable K extracted with NaCl or NH4Cl were relatively high (0.46–2.09 meq/100 g) but were not correlated with K uptake by grapes. Energies of K exchange obtained from immiscibly displaced soil solutions were closely related to vermiculite contents and amounts of K fixed after air drying. Energies of K exchange and ratios of exchangeable K over exchangeable Ca + Mg were highly correlated with K uptake by grapes. Soils with energies of K exchange less than or equal to −2800 cal/equiv. or K exch./(Ca + Mg) exch. equal to or more than 7% appeared to have adequate amounts of available K for grapes. These two analyses therefore show promise for predicting K availability to grapes. Key words: Exchangeability of K, energy of K exchange, fixation of K, soil mineralogy, availability of K to grapes

Description: The objectives of this study were to evaluate if zero tillage had significantly altered the distribution of certain soil properties formally developed under the shallow cultivation (conventional tillage) soil management systems used on the Canadian prairies. To this end, concentration gradients of available plant nutrients, microbial biomass and mineralizable C and N, were determined in the Ap soil horizon from four locations representing zero and conventional (shallow) tillage systems of 2-, 4-, 12- and 16-yr duration. No significant change coud be detected in total soil organic C and N between tillages systems. Concentrations of plant-available P and K were slightly increased in the surface 0- to 2-cm depth after 16 yr of zero tillage. Except for the 2-yr tillage site, concentration gradients of potential microbial biomass C and N, and potential net mineralizable C and N were significantly greater in the surface soil under zero tillage in comparison to conventional tillage. The reverse situation was observed at the lower depth. The percentage of soil organic C and N that was in the microbial biomass also reflected the above trends. Accumulation of mineral N and calculated N mineralization potentials were closely correlated to both the initial microbial biomass N and the decrease in size of the latter during mineralization. The possible relationships of tillage induced change and redistribution in potential biological activity to N availability were discussed.

Description: In 1982, six crop rotation treatments that were initiated in 1967 on a Orthic Brown Chernozemic loam were sampled for soil NO3-N and moisture to a depth of 240 cm. Soil samples were taken on 18 May and 10 June from all treatments, on 2 Sept. on fallow treatments only, and on 14 Oct. from cropped treatments. Precipitation during the sampling period was about 23% above the long-term average. It was estimated that at least 123 kg NO3-N∙ha−1 were leached from the top 240 cm of fallow soils. Leaching appeared to result from a portion of the precipitation moving through macro soil pores. There was evidence that water and NO3-N might also move upwards from below the 240-cm depth. Of the six rotations examined, the 2-yr and 3-yr spring wheat (Triticum aestivum L.) rotations lost the most NO3-N. The presence of fall rye (Secale cereale L.) in a fallow-rye-wheat rotation was very effective in reducing NO3-N losses. Spring wheat, when grown continuously, was also very effective in reducing NO3-N losses but even here there was some evidence of leaching beyond the root zone. Application of fertilizer N and P at amounts based on soil test recommendations reduced NO3-N leached. It was estimated from long-term precipitation data, that over the past 100 yr about 20% of the soil organic N that was present at the time of breaking the land has been lost from the soil via leaching. It was concluded that leaching losses of N from the soils on the Canadian prairies had been greatly underestimated and were partly responsible for losses attributed to the more visible wind erosion. Key words: Nitrate movement, crop rotations, fertilizer and leaching, summerfallow and leaching, bimodal leaching

Description: Experiments were done to characterize the hydrolyzed solutions of aluminum nitrate, aluminum chloride and aluminum sulfate. The hydrolysis of the dilute solutions (10−3M) was accomplished under reflux process at 92 °C. The results showed that anions associated with Al have an effect on hydrolysis of aluminum and the order of ease of hydrolysis for similar concentrations of Al was NO3 〉 Cl 〉 SO4. The average composition of the hydroxyaluminum cation (Aln(OH)m) was calculated as [Formula: see text] and [Formula: see text] for hydrolyzed solutions of Al(NO3)3, AlCl3, and Al2(SO4)3, respectively. The infrared spectra of the hydrolyzed species of aluminum were obtained by a subtraction technique and infrared peaks at 1410 cm−1 and 1085 cm−1 in the AlCl3 system and at 1435 cm−1 and 1070 cm−1 in the Al2(SO4)3 system were assigned to polynuclear hydroxyaluminum species having been formed due to reflux process.

Description: Current irrigation water criteria for boron (B) are based upon the B concentration of either the irrigation water or the soil saturation extract. The effects of the leaching fraction (LF) and the boron adsorption capacity (BAC) of the soil upon the soil solution concentration have not been considered. The objectives of this paper were (i) to develop a predictive model relating soil solution B concentration at equilibrium to the B concentration in irrigation water and the LF, and (ii) to show how the relationship between the B concentration of the soil solution under field conditions and the B concentration of the soil saturation extract can be modelled. The predictive model, derived from the mass balance concept, indicated that at equilibrium the value of the soil solution B in well-drained soil would be close to that of irrigation water, at the soil surface and will increase with depth with the highest value being near the bottom of the root zone where its magnitude is determined primarily on the degree of leaching. For irrigation water concentrations between 0.5 and 10 mg B/L, the weighted average B concentration of the soil solution in the profile of an alfalfa field would be about 1.9–2.7 times the irrigation water concentration at a LF of 0.1; it would be 1.4–1.9 times for a LF of 0.25; and 1.3–1.5 times for a LF of 0.4. The model of the relationship between soil solution B at field capacity and saturation extract B indicates the importance of the BAC of the soil. Without considering BAC, the ratio between the two would be 2. However, the model indicates that the ratio ranges from 1.0 to 1.8 depending upon the B concentration in the solution and the BAC of the soil. This suggests that the B concentration of the soil saturation extract does not provide a true representation of the soil solution B. In assessing B toxicity, the saturation extract concentration should be converted to the soil solution concentration at the actual water content of the soil.

Description: A preliminary field study was conducted to investigate the influence of fall applications of nitrogen and phosphorus on winter survival of winter wheat on zero-tilled and conventionally tilled land. Nitrogen fertilization tended to decrease winter survival while phosphorus fertilization tended to increase survival. A N-P interaction was observed, with the decrease in survival in response to added N being more evident in the absense of applied P. Balanced N-P fertilization may therefore result in highest winter survival in both conventionally tilled and zero-tilled winter wheat. Key words: Zero-tillage, winter survival, nitrogen, phosphorus, winter wheat

Description: Increased use of sulphur (S) fertilizers in southern Alberta led to a series of field and phytotron experiments to investigate the importance of S fertilizers and the role of subsoil reserves of sulphate sulphur (SO4-S) for barley (Hordeum vulgare) and rapeseed (Brassica napus). Two types of experiments were conducted. In the field-plot studies, barley was grown on dryland soils low in surface SO4-S but underlain by subsoil high in SO4-S. Neither elemental nor SO4 forms of S significantly increased barley yields in a series of 10 experiments on those soils. The comparisons were made at three levels of N fertilizers. In a series of lysimeter studies, three successive crops were grown in soil low in inorganic S (2.0 μg SO4-S∙g−1), or soil supplemented with 25 μg 35SO4-S∙g−1 soil at specified depths in the lysimeters. Barley was adequately supplied with S from SO4-S at a depth of 54–72 cm. It obtained 55% of its S from a high SO4-S (25 μg∙g−1) layer of soil at that depth, although 40 days growth were required before the S was effectively utilized. Five times as much S was taken up by the barley when the entire soil received an additional 25 μg SO4-S∙g−1 as when only the 54- to 72-cm depth was supplemented; however, the yields were unaffected. Most of the excess S was retained in the straw. Rapeseed took up an increasing amount of SO4-S as the proportion of the lysimeters that initially contained SO4-S was increased. Rapeseed was also able to utilize SO4-S from a depth of 54–72 cm. Rapeseed showed deficiency symptoms when most of the added and soil reserves of S had been depleted by previous crops; its growth habit became indeterminate and seeds did not develop. Although total dry matter yield was not greatly affected, seed yield was markedly reduced in S-deficient rapeseed. Rapeseed took up 10 times as much S as did barley when the S supply was just adequate for seed production. Although rapeseed had a much higher S requirement than barley, both crops were adequately supplied by subsoil reserves of SO4-S under the field and controlled environment conditions studied. The studies suggest that fertilizer recommendations should be based on soil analysis to a depth of at least 60 cm. Key words: Sulphur fertilizer, sulphates, 35S, barley, rapeseed, nutrient uptake

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

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

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

Description: A descriptive system is outlined for characterizing, in thin sections, the micromorphology of organic soils and organic layers. In each thin section, distinct regions of morphology, fabric zones, can be recognized. Each fabric zone may be composed of various combinations of organic constituents. These constituents are designated as basic morphologic units and four main types are defined: particulate material, granular units, discrete compound particles, and massive-appearing fabric. The fabric zone and basic morphologic units can be coded in a fabric description symbol of the following simple general form [Fabric Unit]1 …[Fabric Unit]n, where [Fabric Unit] represents a particular fabric zone and its basic morphologic units. For example, [PpGa] [Ma] is a fabric description symbol indicating that two fabric zones are identified in the thin section. The first [PpBa] is the dominant fabric zone in the thin section (areal proportion) and is composed of two basic morphologic units, mainly recognizable plant fragments, Pp, and a lesser occurrence of amorphous granular material, Ga. The second fabric unit [Ma] indicates a fabric zone composed of one basic morphologic unit: amorphous massive-appearing fabric, Ma. The system is applied to the micromorphological characterization of a Typic Mesisol from Keswick, Ontario. Key words: Microcorphology, organic soils, descriptive method, characterization

Description: This study evaluated the relative responses of alfalfa (Medicago sativa L.), peanuts (Arachis hypogaea L.), and soybeans [Glycine max (Merr.)] on two calcareous Ontario soils. The B-horizon of a Pontypool sand (Typic Psammentic Hapludalf) and the Ap-horizon of a Plainfield Fine Sand (Typic Udipsamment) were each cropped to all three species in the greenhouse. Thirty-six treatments comprised factorial combinations of three rates (0, 0.25 and 1.00 μg/g) of B, two rates (0 and 25 μg/g) of Mn, the two soils, and the three crops with three replications. Plants were clipped at soil level at flowering stage, oven-dried to constant weight, and analyzed for nutrient content. Boron and Mn additions significantly increased concentrations of these elements in plant tissue. Boron uptake was significantly higher on the coarser-textured Pontypool soil and toxicity significantly reduced soybean yields on this soil, but alfalfa and peanut yields were unaffected. Peanuts appeared least sensitive to B toxicity and Mn deficiency. Soybeans were most sensitive to B toxicity and alfalfa most sensitive to Mn deficiency. The differences in tolerance to B seem attributable to the relative abilities of the three species to withstand high B concentrations in plant tissue rather than to differences in uptake. Differential susceptibility to Mn deficiency on the other hand seems attributable to relative efficiencies of the crops to extract Mn from Mn-deficient soils. Soil organic matter may have had some ameliorative effect on B toxicity. Yield and nutrient uptake were not significantly affected by B × Mn interactions.

Description: Soil samples contaminated in the laboratory with a NaCl solution were leached with water after various amendments had been added. With no amendments added, percolation rates were reduced more on a light-textured Dark Brown Chernozemic A than on a medium-textured Black Chernozemic A. Undisturbed B horizon cores showed a smaller decrease in percolation rate than the A horizons, but natural gypsum or carbonates were of no benefit in maintaining percolation through the unamended contaminated subsoils. Percolation generally increased as more Ca-amendment was added to the contaminated A horizons, but rate of (surface-applied) amendment had no effect on the percolation through the B horizon cores. Gypsum mixed into the contaminated soil was much more effective than gypsum applied on the surface; adding NH4NO3 to the gypsum had no effect. The efficiency of incorporated amendments decreased in the order: gypsum 〉 MgSO4 〉 Ca(NO3)2. Surface-applied Ca(NO3)2 was a better amendment than mixed-in Ca(NO3)2. Caching losses decreased in the order: Cl 〉 Na 〉 Mg 〉 Ca 〉 K. Initial losses of Cl, Na, Mg and Ca were faster than expected from the rule of thumb that one pore volume of water reduces the salt content by about one-half. Subsequently, losses were much slower than in the rule of thumb as most of the remaining cations are in exchangeable form.

Description: The Podzolic B horizon of the Calder series sampled in Quebec was incubated at field capacity for 2 yr in the presence of various amounts of P (0–1500 ppm). Total and available P measured after incubation ranged from 179 to 1627 ppm and from 26 to 489 ppm, respectively, following the different P additions. Charge properties were determined using 1 N NH4OAc at pH 4.8 and 7.0, potentiometric titration and ion adsorption techniques. The CEC of the sample measured at pH 4.8 varied from 7.2 to 11.4 meq/100 g, while at pH 7.0 it ranged from 9.1 to 16.3 meq/100 g following the 0- to 1500-ppm P additions. This increase in negative charges was attributed to the progressive lowering of the pHzpc (from 4.30 to 3.35 in NaCl) determined by potentiometric titrations of the P-treated samples and as a result of specific P adsorption. Ion adsorption in 0.01 N NaCl showed a gradual increase in Na+ adsorbed as a function of pH and amount of P added while an opposite trend was observed for Cl− as a function of pH. P added did not seem to change the amount of Cl− adsorbed or compete for adsorption sites; this would rather demonstrate the specificity of these sites for anion adsorption.

Description: The effects of different tillage methods (normal, chiselling and deep plowing) on chemical characteristics and reclamation of a Duagh, Black Solonetz, soil were evaluated separately and in combination with chemical amendments of lime and gypsum. It was found that within the tillage treatments, deep plowing was the most effective in reducing exchangeable sodium percentage, sodium adsorption ratios and alkalinity potential in most soil layers. Also, deep plowing changed the chemistry of the soil solution thereby improving plant nutrition conditions in the root zone. There was only one significant difference in exchangeable sodium percentage values within the chemical amendments under tillage treatments, namely for the Ap and Bnt horizons of the chiselling treatment where lime and gypsum lowered the ESP. This indicates that chiselling hastened the penetration of the amendments. However, the amended values were not markedly lower than the ESP for the normal tillage treatment without chemical amendments.

Description: We, as well as others, have observed that nitrous oxide (N2O) fluxes increased markedly during soil thaw in early spring. This phenomenon was examined further by determining nitrous oxide concentrations in the soil profile and N2O fluxes from the soil surface during the winter-spring period and evaluating physical release and microbial production of N2O on thawing of frozen soil cores in the laboratory. In mid-winter, soil profile N2O concentrations were close to ambient and surface N2O fluxes were low. At thawing, high N2O concentrations (ranging from 1082 to 2066 mg∙m−3) were found at 10–30 cm in the soil profiles of a coniferous forest, and in manure- and straw-treated plots. Concurrently, N2O flux increased markedly and reached some of the highest values observed during the entire season. When thawing was complete, soil profile N2O concentrations and N2O flux declined. Soil cores were taken from frozen soil, warmed in the laboratory, and N2O release measured. Nitrous oxide was released on warming, and cores treated with CHCl3 had a slower release rate. The results indicate that some of the N2O flux occurring at thawing is due in part to physical release of N2O, and that additional N2O is likely produced by denitrification. Key words: Nitrous oxide, denitrification, frozen soils, nitrogen loss

Description: Twenty-one topsoils, with texture varying from sandy loam to clay and organic matter content ranging from 1.6 to 11.9%, were submitted to compaction and settling at different moisture contents where dry bulk density was determined. Under compaction, the density curve went through a maximum while a minimum was observed in the case of settling. Optimum moisture contents corresponding to these two characteristic densities were almost the same. The most important physical properties affecting soil behavior under compaction and settling were found to be water retention properties at low matric potential which themselves depended primarily on organic matter content. Samples submitted to compaction had saturated hydraulic conductivities less than 1 cm/h, while after settling, Ksat measurements ranged from 0.8 to 234 cm/h. Organic matter played an important role in reducing the effects of compaction, and moisture content alone was not sufficient to predict the best conditions for workability in the fields.

Description: Yield of corn on Brookston clay increased 0.45 t∙ha−1∙yr−1 as distance from subsurface drain was reduced by 2 m (2.5 vs. 0.5 m). Yield increases associated with this drain-spacing interval were significant [Formula: see text] in eight of the individual years 1971–1980. While drain spacing affected yield and plant height, it had little effect on plant leaf percent NPK, soil porosity and compaction. Variation in soil measurements appeared to be primarily due to climate and rotation. Analysis of the yield data suggests that the effects of soil drainage, crop rotation and use of fertilizer are primarily additive, and that each of these practices is essential to achieving high yields of corn on southwestern Ontario clay soils. The response of rotation corn to applied fertilizer was lower than that of continuous corn, indicating that adjustment of N application in accordance with cropping history of soil may be cost effective.

Description: The effect of phosphorus fertilization on potato yields (Solanum tuberosum L.) was studied on 24 experimental sites varying from 44 to 1000 kg/ha of soil test P. The respective relative yields (yield with P fertilizer/maximum yield with P fertilizer x 100) varied from 20.3 to 100%. The Mitscherlich equation was used to relate relative yields to soil test P. According to their soil test value, the soils were partitioned in three classes by the Cate-Nelson method to establish poor (300 kg/ha of available P or less), medium (301–400 kg/ha P) and rich 401 kg/ha P or more) soil fertility classes. It was found that 94 kg/ha fertilizer P was necessary for maximum yields with an increase of 10% or greater on poor soils. On medium and rich soils, the requirement was 50 kg P/ha for a yield increase of 1–10%. Below a 1% increase, the P application should be lowered. At high rates diammonium phosphate (DAP) has been found to give tuber yield equal to those of superphosphates. On the other hand, at low rates, DAP application was more effective. DAP induced a higher mid-season P concentration in the petiole tissue Acidification by superphosphates increased aluminum, iron and manganese availability in the soil and reduced P solubility in the band area, in contrast to DAP. Key words: Potato, soil test phosphorus, source of phosphorus fertilizer, phosphorus fertilization, superphosphate, ammonium phosphate

Description: The change in the extractability of soil phosphorus (P) in response to temperature was examined in 12 Manitoba soils. These soils varied in carbonate and P contents. The soil P was labelled with 32P to facilitate measurements. Sodium bicarbonate extractions, anion exchange resin extractions, P desorption curves and short-term plant uptake using wheat were used to measure P extractability. An increase in soil temperature increased the extractability of P. This was apparent for P extracted by NaHCO3 only in soils low in P. The P extracted by resin appeared to respond similarly but was quite variable. Effects of temperature on the desorption curve parameters were significant only in soils high in P. The latter may reflect the detection limits for P using the desorption curve extraction system. Plant uptake was closely correlated to root growth. Both increased markedly as temperature increased. However, in certain soils the increase in P uptake due to temperature was far greater than the corresponding increase in root growth. The estimates of the labile pool accessed by plants increased as temperature increased. The principle hypothesis, that the effect of temperature on P extractability changed from soil to soil, was confirmed. The only controlling soil factor that could be identified was the basic soil P content. Key words: Temperature, soil phosphorus, carbonated, non-carbonated, plant uptake, wheat

Description: The NH4+-N concentration at the point of anhydrous ammonia injection of 19 Saskatchewan soils ranged from 200 to 800 μg/g. More than 90% of the NH4+-N was retained in a zone 5 cm in diameter from the injection point. Increasing the application rate generally increased the NH4+-N concentration in the retention zone.

Description: Acidification of two soils was measured in an experiment in which fertilizer and CaCO3 treatments were applied in various combinations. The highest rate of fertilizer used, which included N at 139 kg/ha, decreased the pH in 4–5 yr in unlimed Donnelly (Gray Luvisol) and Josephine (Eluviated Gleysol) soils by 0.43 and 0.18 units, respectively. The fertilizer increased the soluble Al content in both soils. Yields of barley (Hordeum vulgare L.) were greatly increased by the fertilizer and lime treatments. However, by the fourth crop on the Josephine soil, fertilizer failed to give a yield increase in the absence of lime; this was apparently due to declining soil pH and increasing soluble Al. In another experiment, loss of lime was measured over an 8-yr period in six soils that had been limed with Ca(OH)2 to pH 6.5–7.0. The average loss of lime from the soils was equivalent to 495 kg of CaCO3/ha annually. This was accompanied by a decline in pH of 0.48 unit in the 8 yr. Liming caused substantial increases to subsoil pH for three of the soils. Despite the decline in surface soil pH, increases in yields of barley from liming were sustained over the 8-yr period. The implication of these findings to soil fertility practices in the Peace River region are discussed.

Description: Differences between analyses of washed and unwashed filbert leaves were found for N, P, Mg, S, B, Mn, Zn and Cu but not for K and Ca. The contamination was attributed primarily to particulates since washing reduced average leaf weight measurements. The magnitude of the contamination varied among orchards and between years. It was concluded that washing leaves is essential for both micro- and macronutrient considerations. Key words: Filberts, leaf washing, macronutrients, micronutrients, contamination

Description: not available

Description: The effects of soil and solution pH and Na:Ca ratio in solution on the exchangeable Na, Ca, and (Na + Ca) of a Na-saturated Dark Brown Chernozemic soil were studied. At soil pH 9.0, the exchangeable Na, Ca, and (Na + Ca) were 14.5, 25.4, and 21.8% greater than at soil pH 6.0. Solution pH (6.0–9.0) had small but statistically significant effects on the amount of Na and Ca adsorbed by the soil. The logarithm of exchangeable sodium percentage (ESP) was related to the Na fraction in the solution by a polynomial equation, log ESP = 0.93 [Na/(Na + Ca)]2 + 0.16 [Na/(Na + Ca)] + 0.82. Not only is replacement of exchangeable Na with Ca important in the reclamation of this soil, should it become sodic and have a high pH, but also lowering of its surface charge, through lowering of its pH, would be an important factor in its reclamation. It appears impractical to reduce soil pH by applying acidified irrigation water. Acidic amendments such as gypsum and sulfur may be more suitable. Key words: Cation exchange, solution pH, soil pH

Description: Surface samples of five Quebec soils (St. Bernard, Ormstown, Howick, Dalhousie and Bearbrook) were selected to represent typical agricultural soils with a range of parent material. Soil minerals were fractionated by size into five separates and examined using X-ray diffraction (XRD) techniques and chemical analyses. In nearly all cases the non-clay separates (250–2.0 μm) contained feldspars, amphiboles and quartz as dominant minerals with only small amounts of layer silicates. Feldspars, amphiboles and quartz were also relatively abundant in the clay separates. The layer silicates in the clay separates consisted mainly of mica, chlorite and vermiculite. The soils had similar mineral suites, considered indicative of a low degree of weathering. Considering the mineral composition and the low degree of weathering, it is proposed that primary K-bearing minerals, including K-feldspars, are important sources of K in these soils. Key words: K release, particle size, soil mineralogy

Description: Leaf tissue nutrient concentrations measured over 3 years in 17 filbert orchards showed consistent correlations between N/S, Cu/S, Zn/Cu, Ca/K, Mg/K and Mg/Ca. Optimum concentrations of 1.44% Ca, 0.27% Mg, 0.14% S, 8.8 ppm Cu, and 19.5 ppm Zn were calculated using regression equations of the various correlations and optimum values of N and K (2.2% N and 0.8% K) reported in the literature. Correlations between leaf and soil nutrient concentrations were observed but they were not consistent over the 2 years and all depths (0–15, 15–30, 30–60 cm) of soil samples taken. Average leaf weight measurements were sufficiently consistent within orchards to allow detection of orchard to orchard differences. Several nutrients appeared to affect or be affected by average leaf weight. Average leaf weights appear to have potential as a biologically important measurement but the significance has yet to be derived. Key words: Filberts, macronutrients, micronutrients, optimum leaf concentrations, leaf weights

Description: In this review, the fate of herbicides in Canadian field soils and their effects on soil fertility are discussed. Pertinent data are summarized for field persistence studies involving single and repeated annual applications, for the movement of herbicides in and from the soil, for the incorporation of metabolites into soil colloids, and for their effects on soil microflora and fauna.

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

Description: A method for calculating the fractions of water leached through the profile (leaching factor) in irrigated soils high in gypsum was developed. The method requires data on long-term changes in the salinity status of the soil profile, and is based on the principle that water moving through gypsum-rich soils becomes saturated with gypsum. The average total soluble salt content of two soils to a depth of 180 cm has decreased logarithmically since 1917. The average Ca content has decreased linearly at rates of 0.091 and 0.097 meq∙100 g−1∙yr−1 in a clay and clay loam soil, respectively. A leaching fraction 0.16, as obtained by our method, is similar to that calculated from a water balance procedure. However, the latter method required accurate information on the annual rate of irrigation and precipitation and consumptive water use by the crops grown. The results indicate that irrigation management at the two sites has provided sufficient leaching water to reduce the total soluble salts and to actually improve the suitability of the sites for crop production.

Description: Dynamics of woody material degradation were studied in the soils of six forest ecosystems of meridional Quebec. This comparative study was performed measuring weight losses of wood samples, buried for long periods of time in the different horizons of each soil studied. In all cases, degradation was much faster close to the soil surface; thus a more or less marked decreasing vertical gradient was observed in the activity for most of the soils studied. The lengths of time necessary for half decomposition (50%) were calculated for the samples buried in each station. For the hardwood forests, values of about 1.7, 2.8 and 2.3 yr were obtained for half decomposition in the Melanic Brunisol, the Sombric Brunisol and the Dystric Brunisol, respectively. A value of 4.6 yr was calculated for the Minimal Humo-Ferric Podzol of the mixed forest to reach half decomposition. Similarly about 35 and more than 40 yr would be necessary for half decomposition of the samples in the Orthic Ferro-Humic Podzol and the Ortstein Ferro-Humic Podzol of the two coniferous forests, respectively. The influence of major environmental factors, such as climate, soil and vegetation on the dynamics of microbial and faunal soil communities is discussed.

Description: The extent to which horizons can be differentiated from one another on the basis of chemical properties was examined. The horizons studied included F, H, Ah, Ae, Bhf and Bf and were taken from Podzolic soils developed on granodiorite-derived sediments in southwestern British Columbia. The determination of the degree to which the horizons form distinct groups in a multivariate context was performed using a grouping procedure based on the multivariate density equation. It was found that 63% of the observations were nearer to their own horizon centroid than to any of the other centroids. When horizon membership was altered in an attempt to form optimal groupings, the membership of 54% of the observations was unchanged. Considerable overlap was shown to exist between the F and H horizons and between the Ah and Bhf horizons. Otherwise the picture that emerges is one in which the horizons do not form distinct clusters, but do tend to fall into definite regions of the multivariate space.

Description: The 1981 Census of Agriculture statistics was used to estimate manure production from livestock activities in Quebec. Only 10 of the subdivisions (1%) were found to have an improved farmland base that was inadequate to meet the total manure stocking rate (TMSR) regulation (i.e. 0.3 ha per animal unit (AU) of production). There were two areas, one near Granby in the Yamaska River basin and another near the outlet of the Chaudiere River, where there was a substantial number of adjoining subdivisions with TMSRs above 2.0 AU∙ha−1. Analysis of soil survey data indicated a greater potential for groundwater contamination in the Chaudiere than in the Yamaska high-density subdivisions. However, about 15% of animal manure production in Quebec was on farms which did not meet the land base requirement. Hog waste constituted about 83% and poultry waste 13% of the manure produced on farms with inadequate improved land. Key words: Water pollution, animal waste, non-point sources, manure applications

Description: The potential of several field tests for differentiating podzolic B horizons from others was studied. The spodic horizon test involved determinations of 4 N KOH-extractable Al and the color of humic extracts. The 0.5% HCl-HF test and the acid oxalate test both involved a rating of the intensity of color of the extracts. For the samples tested, the HCl-HF test was the most promising on the basis of less dependence on correct sample weight, simplicity, and the best differentiation of the podzolic B horizons tested. For samples having borderline properties, however, such field tests might yield ambiguous results because sample weights and estimates of extract colors are not accurate. In most circumstances, sampling for laboratory analyses is recommended to resolve classification problems. Key words: Field test, podzolic B horizon, spodic horizon

Description: Humo-Ferric Podzols (Typic Cryorthods) developed on glacial till or glaciolacustrine deposits were sampled in the Chapleau-Foleyet area of northeastern Ontario. pHs of Ae horizons ranged from 3.30 to 4.20 and of C horizons from 4.40 to 4.85. Cation exchange capacities (CEC) of mineral soil horizons averaged 1.7 meq/100 g, whilst those of the forest humus (fibrimors) averaged 166 meq/100 g. The CECs of the Bf and BC horizons were highly pH-dependent, averaging 3.2 meq/100 g at pH 4 and 16.8 meq/100 g at pH 8. The pH-dependency of CEC in these horizons was believed to be due to Al-complexes with organic matter. Calculated elemental loss using Zr as an internal standard showed significant losses of Mg, Fe, Ca and Al from Ae (albic) horizons and gains of Fe and, to a lesser extent, gains of Al in Bf (spodic) horizons. The clay mineralogy of Ae horizons was dominated by a high-charge smectite and that of Bf and BC horizons by chlorite.

Description: The effect of fertilizer N on yield, protein content and symbiotic N2 fixation in faba beans (Vicia faba L.) was studied with nine field trials during 3 yr. Forage and seed yields of nodulated faba beans were infrequently and unpredictably affected by rate of application at seeding (up to 300 kg N/ha), type of application (34 and 67 kg N/ha surface-broadcast or placed with the seed), and time of application (at full bloom or at mid pod-fill). Protein content of faba bean forage material was variably affected by applied N; in one-half of the harvests conducted, at least one of the N application treatments resulted in significantly higher forage protein contents. No logical pattern or reason for the forage protein response was found. Seed protein content was unaffected by applied N up to 150 kg N/ha, but was significantly increased by 300 kg N/ha in two out of three trials. Maximum rate of dry matter accumulation and N uptake commenced at blooming and continued up to the mid pod-fill growth stage. In seven trials monitored, the proportion of faba bean shoot N derived by symbiotic N2 fixation was 54%, with values of five out of the seven trials ranging from 63 to 71%. This amounted to 54–111 kg N/ha. Applied N decreased faba bean symbiotic fixation at all trials but one where available soil N was very high and symbiotic N2 was not occurring.

Description: A study of plant uptake, incubation-extraction and acid hydrolysis was carried out on soil samples from a field study using 15N. The samples had varying proportions of residual fertilizer 15N (15Nex) as clay-fixed ammonium and organic N. Availability of 15Nex to plants was positively correlated with percent of 15Nex as clay-fixed ammonium, and negatively correlated with percent of 15Nex as organic N. A similar relationship was noted for recovery of 15Nex in acid hydrolysates. The relationship was reversed for recovery of 15Nex in aqueous extracts following incubation, although this may have been due to lack of removal of N by plant uptake or leaching, and limitation of microbial activity by lack of readily available carbon. This direct comparison of availability of residual fertilizer N as clay-fixed ammonium N and organic N demonstrates that fertilizer N, once incorporated into organic forms, is much less available to plants than fertilizer N in the form of clay-fixed ammonium.

Description: Experiments were conducted to determine the effect of Sea Crop (SC 16) and Ergostim on the yield and nutrient composition of a few crops. Studies conducted under greenhouse and field conditions showed that the yields of wheat (Triticum aestivum L.) and peas (Pisum sativum L.) were not affected by the addition of SC16. The nitrogen (N) and sulfur (S) concentrations of the two crops were not affected by SC 16, except in the control and SC 16 treatment only where the increases were likely due to a concentration effect, since these two treatments had lower yields. Boron (B) and molybdenum (Mo) concentrations in the plants were significantly affected by B and Mo applications, but not by SC 16. A greenhouse study showed that the yields of alfalfa (Medicago sativa L.) and wheat were not affected by the addition of Ergostim. The addition of Ergostim did not affect the N or S concentration of wheat or three cuts of alfalfa.

Description: The refractive index change caused by KCl diffusing from a cylinder into agar gel was found to distort a grid projected through it by laser light. By ray tracing and Fermat’s Principle it was shown that values of concentration of KCl at various times and distances were within experimental error of those calculated from the transient diffusion equation for diffusion from a cylindrical source. The diffusion equation was derived for the first time using Eyres’ method. Since the model and mechanism were confirmed as correct by experiment it was then possible to design a computer program to predict transient concentration gradients and hence concentration at any distance and time. The program has built into it flexibility to deal with such expected variables in soil as tortuosity, water content, etc., as well as different diffusion coefficients for different nutrients and also multiple sources. Such a program should be very valuable to fertilizer suppliers in designing timed release capsules and to those using them to obtain optimum nutrient concentrations in a volume of concern of soil.

Description: The formation and coexistence of four aluminum compounds, namely, gibbsite (Al(OH)3), boehmite (AlOOH), alumina (Al2O3) and alunite (NaAl3(OH)6(SO4)2) is reported under laboratory conditions. These solid phases were formed as hydrolytic products of aluminum sulphate solutions at room temperature. These results provide evidence that thermal conditions are not essential and not the only conditions under which boehmite and alumina are formed.

Description: The objectives of this work were to determine the effects of N-fertilizer sources, rates and fractionation on potato (Solanum tuberosum L.) yields, petiole-N content, defoliation and tuber specific gravity. To achieve these ends, urea and ammonium nitrate were side-dressed at 0, 70, 140 and 210 kg N/ha, by applying either all at planting or by fractionating the applications into half at planting and the other half a month later. The field experiments were carried out on eight sites consisting of six soil series. Nitrogen fertilization increased yields on all sites; the rate required for attaining maximum yields varied for 130 to 210 kg N/ha, according to the experimental site, with an average of 180 kg N/ha. Generally, both N-sources and fertilization methods had similar effects on yields defoliation, petiole N-content and tuber specific gravity. A 210-kg urea-N application at planting on the Lapointe loamy sand, however, decreased yields significantly. The importance of soil type, available water and total soil-N are discussed in relation to the quantities of fertilizer-N required to achieve maximum yields.

Description: Fertilizer tests using hard red spring wheat (Triticum aestivum L.) were conducted in the field from 1967 to 1979 on stubble and fallow land on the major soil types throughout southwestern Saskatchewan. The yield, percent nitrogen and phosphorus in the grain, kernel and volume weights of the grain were measured, and the responses of each of these characteristics to N and P fertilizer were determined. These responses were related to soil measurements of available H2O, NO3-N, NH4-N and sodium-bicarbonate-extractable P, which were taken at seeding time, at depths to 120 cm, and to the monthly rainfall during the growing season. On fallow, nitrogen rates higher than 15 kg N/ha gave little significant increase. The yield increase per kilogram of P applied decreased as the rate of application increased. On stubble, the yield increase per kilogram of N applied decreased for each additional increment of N added, down to 3.1 kg/ha yield increase per kilogram of nitrogen per hectare when the rate of application was increased from 45 to 60 kg N/ha. Regression analysis showed that the soil and the weather variables used accounted for only 20% of the variability in yield on fallow crops and for 40% on stubble crops. Nitrogen content of the grain was only increased by rates of 45 kg N/ha or greater. The P content of grain was decreased by both N and P fertilizer.

Description: Concentrations of oxygen and carbon dioxide in the soil were measured periodically in disturbed and undisturbed Eriophorum vaginatum tussock tundra from 16 July to 21 Aug. 1979. The disturbed sites were in vehicle tracks, on plots cleared of vegetation, and on plots treated with urea, cornstarch, and artificially altered drainage. Vehicle tracks made in 1979 and the artificial impoundments did not significantly affect soil oxygen and carbon dioxide concentrations. The lowest soil oxygen concentration occurred in a 15-yr-old vehicle track and on the cleared plots. Urea and cornstarch temporarily reduced soil oxygen concentration and increased soil carbon dioxide levels. Tussocks were more poorly aerated than intertussock areas except in the old vehicle track. Soil oxygen concentration did not usually vary significantly between 5 and 15 cm, but dropped sharply at 25 cm. Oxygen diffusion coefficients calculated from an earlier study on soil oxygen flux and the current data on oxygen concentrations suggest that despite generally well-aerated conditions, anaerobic zones may occur frequently in tussock tundra soils.

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

Description: Ontario Soil Survey data for 278 soil series were interpreted to describe relationships between soil characteristics and the movement of water in saturated zones of the soil profile. Based on family particle size classes, groups of soil families, similar in profile and parent material, were formed. Groups were ordered in terms of increasing ability of soil to transmit water, as interpreted by Soil Conservation Service guidelines. The ordered groups were separated into two parts using the European concepts for surface water gley and groundwater gley soils. Six groups of surface water gley soils were differentiated in which surface water was interpreted as the principle source of saturation. Groundwater was interpreted to be the principle source of saturation for three groups of groundwater gley soils. Principles applied to grouping and ordering were augmented by data for soil texture and structure to develop a generalized profile description for each group. The generalized profile description was translated into a five symbol code by which the interpretation is applied to individual soil series within a group. The code is intended to enhance application of soil survey data to design of buried agricultural drainage systems. Key words: Soil physical characteristics, drainage characteristics, hydrologic soil groups, surface water Gleysols, groundwater Gleysols, pseudogleysols

Description: A study on the effect of time of sampling on filbert (Corylus avellana L.) leaf nutrient concentrations showed that from mid-August to mid-September N, P, K, Ca, Mg, Zn and Mn concentrations were relatively stable. This would be a suitable sampling time for diagnostic purposes. Boron was not consistently stable during this time and variability of B concentration at any one date was relatively high.

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

Description: The equilibration of acid soils, a Sombric Ferro-Humic Podzol (CSSC-2) from British Columbia, an Orthic Ferro-Humic Podzol (CSSC-19) from Quebec and two horizons of a Dystric Brunisol (SSD-330, SSD-331) from British Columbia, with CaSO4 solution demonstrated that SO4 ions reacted with components of these soils. These reactions increased soil pH, ion activity product (Al)(OH)3 and neutral salt extractable exchangeable cations. The increase in pH and ionic activity product (Al)(OH)3 were noticeable on a single equilibration; however, increase in neutral salt extractable cations was only observed after subsequent equilibrations. After three equilibrations, the sums of NaCl extractable cations were 6.56, 11.99, 5.62 and 4.31 meq/100 g for soil samples CSSC-2, CSSC-19, SSD-330 and SSD-331, respectively. The corresponding values for the unequilibrated soils were 5.20, 7.49, 4.30 and 2.50 meq/100 g. On further equilibration there was no increase in total extractable cations for sample CSSC-2; however, for the other three samples there were increases which became progressively smaller. The reaction of SO4 ions with aluminum hydroxy clay complexes seems to be the mechanism for the increase of negative sites. Key words: Cation exchange capacity, CaSO4, acid soils

Description: Soil samples, mainly from eastern and northern Canada, were extracted with sodium hydroxide-pyrophosphate and the centrifuged extracts were fractionated into humic acid, fulvic acid and the polyphenolic component of the fulvic acid fraction. Details of the extraction and fractionation procedure were altered systematically and the effects of these changes on amounts of carbon in the various fractions were studied. A tenfold increase in the ratio of soil to extracting solution resulted in a marked increase (nearly double in some cases) in the ratio of humic acid carbon to fulvic acid carbon (Ch/Cf). Increasing the centrifugal force from 1150 × g to 8200 × g had little effect on Ch, but decreased Cf values. Dissolving and reprecipitating humic acid resulted usually in a decrease in Ch/Cf. Different shaking speeds and times, and extraction under nitrogen rather than air had minor, if any, effects on the Ch/Cf ratios. Most of the podzolic B horizons tested could be distinguished from the other 60 horizons by the combination of C ext (extractable carbon), Ch/Cf and Ca/Cf (carbon content of the polyphenols component of the fulvic acid fraction/fulvic acid carbon).Extractable organic fractions have some promise as bases of soil classification criteria but their potential is limited at present. The procedures are time-consuming and exacting, and results are not comparable between laboratories. Rigorous standardization of methods and interlaboratory comparisons of data might lead to more useful criteria based on organic matter composition. Key words: Humic acid carbon, fulvic acid carbon, polyphenols carbon, extractable carbon, classification criteria

Description: The objective of this study was to determine changes in N dynamics in an Orthic Black Chernozem as a result of two tillage practices (conventional and zero tillage) using the variations in the natural 15N abundance of different soil-N fractions. After 14 yr, no significant differences in isotope composition of total soil-N between the two tillage practices could be found. However, changes were detected in the natural 15N abundance of the acid-hydrolyzable N and various organo-mineral size fractions which led to useful comparisons of the nature of N under the two systems. The N-content of the hydrolyzable-N fraction was similar at the 0- to 4- and 8- to 16-cm depth under both tillage practices, while it was significantly different at the 4- to 8-cm depth. The δa15N of this fraction was consistently higher than that of total soil N at all depths only under zero tillage. This was associated with the presence of more labile N compounds under zero tillage. No differences in the isotopic composition of the organomineral size fractions were found at the 0- to 4-cm depth. At the 4- to 8- and 8- to 16-cm depths, the δa15N values of the finer particle size fractions were higher under zero tillage than under conventional tillage. This indicates a more labile nature of the N associated with these size fractions under zero tillage. Key words: δa15N, conventional tillage, zero tillage, total N, acid-hydrolyzable fraction, particle size fractions

Description: Measurement of soil properties and field-crop yields on cropland traversed by the Sarnia-Montreal oil pipeline indicated that pipeline isntallation detrimentally affected both crop yields and soil physical-chemical properties in the first year after construction. After 5 yr, relative yields improved although reductions still persisted at most row-cropped sites. However, alfalfa yields at two sites appeared to be unaffected by pipeline construction. Soil mixing and compaction on the right-of-way were most prevalent on medium- to fine-textured soils. Compaction did not appear to be a problem at a coarse-textured site. Soil chemical data indicated that spoil (subsoil) materials from the trench were spread across the right-of-way at most sites. Diluted soil organic matter levels in the right-of-way adversely affected nitrogen status. Medium- to fine-textured right-of-way soils had reduced porosities and hydraulic conductivities, but increased strengths compared with undisturbed adjacent soils.

Description: A column study was conducted to determine the effects of soil texture, initial soil moisture content and timing of leaching on N removal from two irrigated soils of southern Alberta. Pelleted NH4NO3 fertilizer (0.639 g N per column = 336 kg∙ha−1) was applied to Lethbridge loam (Leth L) and Cavendish fine sandy loam (CV FSL) at three initial levels of soil moisture: air dry (AD), 0.5 field capacity (0.5 FC), and wet (W, 25 cm suction). Leaching began immediately after the fertilizer application or was delayed 1 wk. Water was applied in 1400-mL (7.6 cm depth) increments every 2nd day for a total of 33 600 mL (175 cm depth). The leachate was collected, measured, and analyzed for NH4-N and NO3-N. The soil was analyzed for N content before and after leaching. More N was leached from CV FSL (0.600 g) than from Leth L (0.521 g). Responses to initial soil moisture were similar for both soils; the NO3-N concentration peak followed the advancing wetting front more closely in the AD than in the W systems and leaching losses were greatest from the 0.5 FC treatment. Delayed leaching did not significantly affect the amount of N leached. N losses, other than from leaching, were greatest in the W and AD treatments, in the AD treatment these losses were attributed to volatilization and, in the W soils, to denitrification.

Description: Fertilizer trials which included ten treatments (N, P, K, Mg, B, Zn, and two limestone rates as soil amendments, a control plus an untreated pollenizer cultivar) were conducted on two commercial filbert (Corylus avellana L.) orchards in the coastal area of British Columbia. One of the sites had Daviana as the main cultivar and Duchilly as the pollenizer (Daviana trial), and the other had Duchilly as the main and Daviana as the pollenizer cultivar (Duchilly trial). The Daviana trial was conducted in 1974 and 1975, and the Duchilly trial from 1974 to 1976. There were no significant treatment effects on yield in either trial. There were limited treatment effects on leaf N, P, Ca and Mg concentrations which were assumed to have occurred because of adequate to abundant supplies of these nutrients in the soil. Leaf K concentration was increased by K application in the Duchilly trial and leaf Zn concentration was increased by Zn application in the Daviana trial. Both B and Mn in the leaves were affected by treatments in both trials. Leaf B concentration was increased readily by soil B application. Leaf Mn concentration was increased by N treatment and to a lesser extent by K treatment. Good positive correlations between soil extraction values and leaf concentrations for P, K and Mn suggest the former as a promising diagnostic method for fertilizer recommendations. This, however, was not true for Ca and Mg.

Description: The objective of this study was to determine conditional formation constants which are dependent on pH for Al-organic matter complexes. Potentiometric titrations of H-organic matter in the presence of 0, 0.004 and 0.01 M AlCl3 were carried out by the batch method. The conditional formation constants were calculated by simply relating the amount of complex formed to the amounts of unreacted metal and ligand. The addition of Al3+ resulted in displacement of the titration curves, indicating complex formation. The formation constants (log K′f) increased as the pH increased, illustrating the strong dependence of Al adsorption on pH. Values for log K′f ranged from 1.78 to 3.90 in this study.

Description: The persistence of the herbicide diclofop-methyl, methyl 2-(4-(2,4-dichlorophenoxy)) phenoxy)propionate, was measured in two soils under field conditions in southwestern Ontario. The hydrolysis of the herbicide ester to its corresponding acid, diclofop, 2-(4-(2,4-dichlorophenoxy)phenoxy)propionic acid, was slower at pH 5.5 than at higher pH but soil pH had no effect on subsequent degradation of diclofop or metabolites formed. After hydrolysis of the ester the acid degraded to 12–39% of the original concentration in 34 days and less than 14% of the applied herbicide, identified as diclofop, was recovered at the end of the growing season. During the course of the degradation small amounts of the metabolites 4-(2,4-dichlorophenoxy)phenol and 4-(2,4-dichlorophenoxy)phenetole were identified from their relative retention time (Rf) on silica gel plates along with traces of other nonidentified compounds. None of the identifiable products except diclofop was present at the last sampling date. Combustion of soils treated with 14C-diclofop-methyl revealed 26–32% of the radioactivity was not extracted at the end of the growing season. Key words: Hoegrass, diclofop degradation, soil residue, soil reaction, 14C-diclofop-methyl

Description: Cool soil temperature regimes with initial soil temperatures of 5 °C rising to 20 °C at the heading stage reduced the rate of growth of barley by approximately one-third compared to 15–25 °C but did not change the barley yield or the fate of the applied fertilizer N in the soil biomass, roots, or tops of the plant or that lost by denitrification. The primary isotope data, % Ndff or ’A’ values remained relatively constant irrespective of whether the straw was placed on the surface or mixed throughout the soil. In contrast, the nitrogen balance data verified that fertilizer N loss, presumably due to denitrification, was as high as 35% in certain treatments, and further that up to 40% of the added fertilizer N was immobilized where the straw was uniformly mixed in the soil. The nitrogen balance data were used to correct the original rate of fertilizer N application. When this was done, A values calculated on the basis of the revised rates of application showed that the amount of soil N which was denitrified or immobilized was approximately double that of the applied fertilizer N. Thus, it is possible where a N balance is included in an investigation to quantitatively assess the effect of management practices on available soil N. It is further concluded that differential immobilization or denitrification of the 15N fertilizer standard may invalidate yield-dependent isotope-derived data, such as dinitrogen fixation unless nitrogen balance data are available to permit the appropriate corrections to be made. Key words: Zero till, N-cycle, temperature, crop residues, barley

Description: Complete removal of organic matter from clay samples was achieved by oxygen plasma treatment. Little effect was subsequently observed on the extractability of Fe, while Al and Si were somewhat less soluble. X-ray diffraction patterns of the samples containing low amounts of amorphous material showed a better orientation of the particles and additional minerals were identified.

Description: For Chernozemic soils, published information on the aliphatic carboxylic acid fraction of the organic matter is scarce. Yet, geologically they are chemically stable and persist for long periods of time. The distribution of chloroform/methanol-extractable aliphatic carboxylic acids in five uncultivated and three cultivated Chernozemic soils and the roots of four grass species was, therefore, determined. Twenty-three organic acids (up to C30) were tentatively identified by high resolution gas chromatography-mass spectrometry. Hexanedioic acid and dioctyl phthalate were suspected of being contaminants. The relative proportions of aliphatic carboxylic acids varied for different soils. Tree invasions, overgrazing, and cultivation decreased the total aliphatic carboxylic acid content at the expense of the lower weight aliphatic carboxylic acids. Since the aliphatic carboxylic acids formed only a small portion of the total solvent-extractable organic matter and decreased after cultivation, the results do not explain the observation reported earlier that solvent-extractable organic matter of Chernozemic soils increased as a result of cultivation.

Description: Regression equations, developed to predict the water content at 1/3- and 15-atm tension for various soil Orders in Canada, were tested against a set of independent data with generally a good degree of success. Some of the discrepancies between predicted and observed values could be attributed to the mineralogical and/or textural distribution of the prediction vs. test data, but in other cases causes of inconsistency were unclear. The equations which were not tested, due to insufficient available test data, should be used with caution.

Description: Most of the soils studied are non-evolved. The other soils of the area that can be distinguished are calcareous brown soils, sierozems and erosion soils. The soils are low in organic matter. The carbonate, varying from 0.4 to 46.3%, tends to increase with depth. Horizon of accumulation of carbonate (in the sierozems) is found between 30 and 100 cm from the soil surface. Sulfate exceeds chlorine ions in the soil extract. The salinity does not exist in these soils. The exchange capacity varies from 4.7 to 29.4 meq/100 g of soil. The dominant clay mineral in some of these soils is vermiculite. In the forests of western Iran, Quercus persica and Quercus saii generally occupy calcareous, poor and rather deep soils, whereas Quercus infectoria is usually grown on the less calcareous, rich and deep soils.

Description: Dark Gray Luvisols developed from dune sand parent material near Devon, Alberta, have Ae horizons of unusually high chromas and dark values when moist, and B horizons with very hard massive structure when dry. Micromorphological examination shows the high chromas in the Ae reflect the presence of organic, and to a lesser extent, matrix coatings on f-members. Hardening results from development of chlamydic and plectic fabrics in the B, where clay bridges bind f-members together. The illuvial clays contributing to the fabric organization are, in part, derived from accretionary eolian deposits (containing minerals such as beidellite), in part from calcitic residua (largely non-expandable components), and in part from dislodgement of clay domains (rich in montmorillonite) inherent within the Ae horizon as a constituent of the original parent material. All are actively translocated down the solum.

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

Description: Total organic phosphorus, inositol phosphates and phosphatase activity of some selected Canadian and Ghanaian soils were compared. The lower organic phosphorus content of Ghanaian soils compared to the Canadian soils may be the result of either the faster rate of mineralization of organic phosphorus in the tropical Ghanaian soils or differences in the nature of organic residues returned to the soils. Wide variations in the amounts of inositol phosphate were observed in both groups of soils. The low activity of phosphatases in the Ghanaian soils may be due to the lower content of organic matter, a lower microbial biomass and consequently a lower phosphatase production. The effect of rotation and fertilizer application on the total organic P, inositol P and phosphatase activity indicated that alfalfa grown in rotation with corn and oats contributed significantly to the total soil organic phosphorus content with no apparent increase in inositol phosphate content. No consistent trends were observed in either the total amount of inositol phosphates or the proportion of the total phosphorus that existed as inositol phosphates for either the fertilized or unfertilized soils. The activity of phosphatase was generally higher in the corn-oat-alfalfa rotation than in the systems of corn-oat and continuous corn. Fertilization decreased the phosphatase activity in all cropping systems.

Description: Thirty-four samples from the Ap horizons of heavy-textured Orthic Humic Gleysols (Typic Haplaquolls) were sampled in southwestern Ontario. Surface areas of the soils ranged from 79–223 m2/g and multiple regression analysis indicated that the surface area of the clay fractions was 207 m2/g and that of the organic matter 805 m2/g. Approximately 74% of the variability in cation exchange capacity could be attributed to their clay and organic C contents at pH 4 and about 86% at pH 8. A value of 181 meq/100 g was calculated as the cation exchange capacity of organic matter at pH 4 and of 316 meq/100 g at pH 8. Mean cation exchange capacities at pH 4 were 20.3 meq/100 g and 31.6 meq/100 g at pH 8.

Description: A case study is presented to illustrate how factor analysis can be used to quantify probable causes of physical and chemical forest-floor variability. Twenty forest-floor variables were examined for a 30 × 30-m sampling plot located within a mature, naturally regenerated conifer stand. "Slough" (the degree of accumulation of decayed stumps, logs, branches, etc.), litter (hardwood- vs. softwood-type in terms of base-status) and insolation (degree of canopy closure) factors appeared to underlie the observed variability pattern. Factor identification was facilitated by the following variable association pattern: (i) total C with total Fe, Al, N, P, K; (ii) total C with LFH-mass and thickness; (iii) water-extractable P with 2 N potassium-chloride-extractable NH4-H; (iv) total and 1 N ammonium-acetate-extractable Ca with pH; and (v) ground cover vegetation density with forest floor moisture content and thickness. Key words: Forest floor, lateral variability, factor analysis