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: 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: 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 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: 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: 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: 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: 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: 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: 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 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: 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: 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: 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: 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: 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: 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: 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: Anomalous behavior of soil temperatures at Ste. Anne de Bellevue, affecting long-term statistics, appears to have been rectified by replacement of the sensors. The primary symptom of the malfunction was an apparent precipitous cooling under melting snow; the long-term effect was an apparent cooling trend of about 0.5 °C∙yr−1.

Description: Various concentrations of paraquat, atrazine, simazine, linuron, diuron, and paraquat in combinations with each including simazine + diuron, and terbacil alone, did not inhibit lytic activity of four bacteriophages of Agrobacterium radiobacter, three bacteriophages of Rhizobium meliloti, three bacteriophages of R. trifolii, or two bacteriophages of Streptomyces chrysomallus. Generally, the herbicides had no effect on the neutralization of radiobacterphage PR-1001 with its homologous antiserum, the length of the latent period, the percent adsorption or the average burst size. In contrast, paraquat concentrations from 20 to 400 μg∙mL−1 gradually reduced the adsorption from 38 to 21% and the average burst size from 67 to 9 in the PR-1001:R-1001 phage: host system. The same concentrations, however, showed no effect on the particle attachment or the length of the latent period.

Description: The nutrients NH4+, NO3−, Ca2+, Mg2+ and K+ in leachates from immediately below the forest floor and from the mineral horizons at 10- and 30-cm depths were monitored with tension lysimeter plates held at 10 ± 1.0 kPa. Experimental plot treatments were thinning, fertilizing with nitrogenous fertilizers (448 kg N∙ha−1), and both. Concentrations (mg∙L−1) of these nutrients in the forest floor leachates increased immediately following nitrogen fertilization, but returned to near those of untreated levels about 5–10 mo later. Concentrations fluctuated at 10- and 30-cm depths in the mineral horizons. With urea fertilization, the increases in concentrations of nutrients were primarily associated with the forest floor. Nitrate concentration of 200 mg N∙L−1 in the forest floor leachate 5 mo after urea fertilization compared to 0.1–0.5 mg N∙L−1 of the untreated, indicated that nitrification had taken place. With ammonium nitrate fertilization, substantially higher concentrations of NO3−, Ca2+, Mg2+, and K+ were detected at 10- and 30-cm depths compared with urea fertilization. Thinning, when combined with urea fertilization, enhanced the movement of nutrients to greater depth in the soil profile. On a unit area basis (kg∙ha−1) the leaching of nutrients from soil horizons could be overestimated by the tension lysimeter plate method, as these plates do not only draw soil water from directly above.

Description: Replicated analyses for each of five levels of total cation concentration showed that exchangeable sodium ratio (ESR) and sodium adsorption ratio (SAR) were linearly related by equations of the form ESR = a + b (SAR). The coefficient, b, decreased from 0.0163 to 0.0085 as total cation concentration increased from 39 to 1057 meq/L, showing that the equilibrium of exchange, as measured by ESR and SAR, is strongly affected by total cation concentration of the soil solution. A regression line, previously published by the U.S. Salinity Laboratory Staff, lies between the regression lines for 39 and 110 meq/L. Exchangeable sodium ratio can be inferred from SAR alone as long as SAR is not larger than about 20. However, the error of estimate for ESR is shown to increase with increasing SAR and total cation concentration unless the effect of total cation concentration is taken into account. This is an important factor to be considered when high-salt solutions are used to reclaim sodic soils.

Description: A shallow subsurface drainage system effectively controlled a high water table and reduced salinity in an irrigated soil near Magrath, Alberta. Plastic corrugated tubing was installed in 1976 at depths of 1.1–1.5 m and spacings of 15 and 30 m in a moderately saline soil. During the irrigation period, the water table rose to within 0.3 m of the surface but was lowered to pre-irrigation levels within 48 h. The water table was maintained at, or below, the depth of the drains between irrigations. The 15- and 30-m spacings of the drain lines were equally effective in providing water table control in this lacustrine soil which was underlain by a coarse sand and gravel layer. Salinity levels were decreased substantially only within the surface 0.3-m soil depth. Quality of the drainage effluent remained constant throughout the growing season with only small dilution effects detected during irrigations. Barley yields increased to 3900 kg/ha in 1978, 2 yr following drainage of this saline soil which had been out of crop production for 20 yr.

Description: Soil pH variation was examined in British Columbia apple orchards. Soil pH tended to increase as distance from the tree trunk and depth from the soil surface increased. However, pH variation from tree to tree was frequently significant both for widely separated trees in orchards where pH was expected to be variable and for adjacent trees in orchards expected to have uniform soil pH. To represent orchard blocks adequately, emphasis should, therefore, be placed upon collecting samples from many rather than a few trees. Nonetheless, the possibility of decreased soil pH near trees can not be ignored in sampling individual trees.

Description: Investigations of soils at the Ellerslie Agricultural Research Station and adjacent areas in the Lake Edmonton Plain revealed pedoturbations ranging from 5 to 20% of the area. Turbated soils exhibited a bowl-shaped pattern with Ah horizons, frequently mixed down to a depth of 2 m or more and often extended over an area up to 7.5 m in diameter. Configurations of turbated A and B horizon materials were numerous and varied with no fixed pattern. Consistency was much more mellow than adjacent undisturbed material. Undistrubed soil had a thin eluviated horizon below the Ah and numerous argillans were evident in the B horizon. Such features were evident only in microfabrics of disturbed soils. There were no strongly contrasting analytical attributes between disturbed and undisturbed soils. 14C dating suggests a burial date for lower Ahu material at approximately 2500–3000 yr B.P. Mixing was attributed to floral turbation caused by tree-throw.

Description: The numbers and weights of earthworms were measured in the top 20 cm of soil in a long-term monoculture corn (Zea mays L.) experiment involving different tillage treatments. There was a marked seasonal trend in earthworm concentrations, with number and weight of worms being higher in spring and autumn than in summer. Spring tillage reduced earthworm numbers; however, the incorporation of surface residues per se had no effect.

Description: Replicate soil samples (2–20) from the A, B and C horizons of 41 pedons were collected to measure within-pedon variability of particle size distribution, organic matter content, calcium carbonate equivalent and pH. Variability in soil properties was examined in relation to the mode of origin of the soil material, soil horizonation and soil drainage. Variance in particle size distribution was significantly influenced by mode of deposition as well as by soil horizons, while soil drainage had no significant influence on the variation in particle size distribution. Variance in calcium carbonate equivalent and organic matter content was not influenced by soil drainage or mode of deposition. The number of replicate samples required for statistically reliable evaluation of a pedon at given confidence limits was determined for the soil properties studied. The results of these calculations indicate the need for up to five replicate samples to achieve satisfactory levels of accuracy at the 95% confidence level for some of the soil properties studied.

Description: A study was undertaken to characterize the spatial relation between agriculture and the soil resource in Canada. Cluster analysis was used to develop crop groups, using data from a large, computerized soils, climate and census data base. The crop groups were interpreted spatially and relative to soil Great Groups. Good spatial grouping was found with land-based agricultural activities such as crop type, crop acreage profiles and extent of cultivation. Poor association was found with livestock and amount of off-farm work. The study demonstrates the regional specialization in Canadian agriculture, and shows that particular physical environments are best suited to certain kinds of agriculture.

Description: Recommendations of N, P and K fertilization presently made for vegetable production in Quebec need to be verified through local field studies. To this end field trials were made on 11 soils located in the Montreal, Nicolet and Quebec-Portneuf areas, through the year 1978–1980. Fertilization increased green pea yields in seven trials out of 16; most of these increases were caused by phosphorus applications. Similar results were obtained with snap beans, except that this crop tended to require a somewhat greater quantity of applied N. Fertilizer requirements of these crops were obtained by fitting Mitscherlich or polynomial equations to field data. Accordingly 15–30 kg N/ha seem to be required by green peas and snap beans, respectively, to obtain optimum yields. Modification of present soil test norms is suggested for phosphorus and potassium fertilization. For these crops the suggested rates are 20, 40 and over 60 kg P/ha for soils with high, moderate or low levels of available P and the minimum rate of 20 kg K/ha for every level of K except for the low level which would require about 40 kg K/ha for green peas.

Description: Pollen profiles of Tsuga canadensis in a virgin and two cultivated areas of a bog revealed the bimodal distribution characterized by easily recognizable minima, thus establishing synchrony between specific layers of the three organic soil profiles. This knowledge allowed estimation of overall subsidence of the cultivated soils, and would facilitate comparisons between subsurface layers now determinable as synchronous. Such comparisons should help determine the extent and depth of temporal biochemical and physical changes in subsurface layers of cultivated organic soils.

Description: In 1979–1980, Ca, Mg, and K were measured in soil, leaf and fruit samples from 48 ’Starkrimson Red Delicious’ (Malus domestica Bork.) and 48 ’Summerland Red McIntosh’ (Malus domestica Bork.) apple trees located in 16 Okanagan orchards from Osoyoos to Vernon. The relationship Ca〉Mg〉K was generally found in the soils examined although, for nine sites, soil Mg content comprised from 5 to 10% of exchangeable bases while for 15 sites soil K exceeded 10% of exchangeable bases. The ’Delicious’ trees accumulated higher leaf Ca, Mg, and K and higher fruit Ca and K compared to ’McIntosh’ on a similar range of soils. A significant correlation between ’McIntosh’ leaf and soil Mg (expressed as a percent of exchangeable bases) was found in the 2 yr of the study. No direct positive plant-soil relationships were found for Ca or K. Significant negative correlations were measured in both years between soil Ca (expressed as a percent of bases) and leaf Mg for both cultivars, and between leaf Ca and K and between leaf K and Mg for ’Delicious.’ The results emphasized the importance of balanced orchard cation nutrition, particularly with respect to local soil Mg.

Description: Experiments were done to compare the cation exchange and soil solution chemistry characteristics of seven acid soils in the presence of chloride and sulfate ions. The pH of the soil suspensions and degree of base saturation of equilibrated soil samples in CaSO4 solutions were higher than those of CaCl2-equilibrated samples. A comparison of the soil solution chemistry of Al in the presence of Cl and SO4 ions showed significant differences in the distribution of aluminum ion species. Even though the total aluminum (AlT) was greater in CaSO4 suspensions than in corresponding CaCl2 suspensions, trivalent Al (Al3+) was much smaller in CaSO4 suspensions, e.g. 93.4% of aluminum was present as Al3+ in CaCl2 suspensions compared to 36.0% in CaSO4 suspensions. In CaSO4 suspensions, 60.0% of aluminum was present as monovalent AlSO+4, which was probably not as effective as trivalent Al in competing with basic cations in occupying exchange sites. This reveals that in SO4 systems, a substantial amount of Al (60%) was present in a form which could easily move in the soil profile or could leach out of the soil profile and thus to the aquatic environment.

Description: The effects of potassium fertilization on potatoes (Solanum tuberosum L.) grown on 40 experimental sites were related to tuber yields and soil test values. The data used in this work were gathered by seven research groups over a 25-yr period. Concentrations of exchangeable potassium (1 N NH4OAc, pH 7.0) in soils ranged from 28 to 462 kg K/ha. About 68% of the soils were classed as having a poor supply of available potassium, according to the criteria used until now in Quebec, because they contained less than 200 kg K/ha. A Mitscherlich exponential equation was fitted to the relationship between the percent of maximum yield and the concentration of available K in soils (R2 = 35.9%). The Cate-Nelson procedure was also used for ranking soils in three potassium fertility classes as indicated by their relative yields without K fertilization. The following classification of soil K levels was obtained: poor, soils containing less than 140 kg K/ha; intermediate, those containing between 141 and 300 kg K/ha; and sufficient, those containing more than 300 kg K/ha. The percent of maximum yield ranges obtained without K fertilization by these different soil fertility classes were: poor, from 34 to 98% with an average of 74%; intermediate, from 88 to 100% with an average of 95: and sufficient, from 93 to 100% with an average of 98%. The fertilization rates required to obtain or maintain maximum yields by these respective classes were 175, 130 and 80 kg K/ha. Potassium fertilization increased yields significantly on the soils that had a poor K supply only. Nonetheless, the average tuber yield indicated that a 5% increase in yield might be obtained with K fertilization on the intermediate soils and this increase would easily be profitable. Potassium fertilization of the soils classed sufficient would, however, only maintain soil fertility by supplying part of the K requirement of this crop.

Description: Three fields which received a heavy application of digested sewage sludge were studied over a 6-yr period to determine the accumulation, movement and losses of nitrate. The soils were fine textured and predominantly poorly drained. After an initial fallow year, the fields were cropped to cereals. Very high nitrate concentrations were found near the soil surface for several years. Downward movement of nitrate was very slow. There was a continuous loss of nitrate over the study period; this was attributed to denitrification. Laboratory experiments using 15N were conducted to determine the rate of denitrification and the soil conditions that were favorable to the reaction. The denitrification intensity of the soil profile decreased with depth, but was still appreciable at the greatest depth. When oxygen diffusion in the soil was slow and oxygen demand was high, denitrification occurred within a few centimetres of the soil surface or an air-filled pore. Poorly drained soils promote denitrification and offer some protection against the risk of nitrate pollution of groundwater.

Description: The use of sewage sludge on vegetable gardens is a public health concern. A growth chamber experiment was employed to investigate the effect of sewage sludge application on the copper, zinc, lead and cadmium content of lettuce, carrot and pea crops. No yield reduction or other toxicity symptoms were noted, although tissue levels of several metals were elevated. There were small increases in copper in the three vegetables, but zinc and cadmium increased considerably with sludge application. The higher Zn levels present no problem, but the higher Cd levels are undesirable. Cadmium uptake by vegetables and the increased dietary intake of Cd should be considered when sewage sludge is used on vegetable gardens.

Description: Two beach ridge soils are described from the area west of Winisk, Ontario, in the Hudson Bay Lowland. These soils, although frozen, are podzolic and incipient-podzolic. The occurrence of frozen podzols in the Lowland indicates vegetational and pedological changes related to regional paludification.

Description: The 1500-kPa pressure plate extraction procedure for estimating the wilting percentage was an unreliable predictor of water remaining in soil-peat mixes when plants wilted. Quantities of water remaining in the mixes when corn and sunflowers wilted increased as the percentage of peat increased reaching more than 1/3 of the volume of the medium in some of the mixes and in pure peat.

Description: Eight-month-old loblolly pine (Pinustaeda L.) seedlings were grown in a greenhouse nutrient sand culture for 110 days. Eight levels of nitrogen (1, 5, 10, 25, 50, 100, 250, and 400 ppm) were added to the nutrient solution. The effect of nitrogen level on growth and relationships between needle reflectance in the visible region and needle nitrogen and chlorophyll contents were determined. Maximum growth occurred with the 100-ppm nitrogen treatment. Needle nitrogen content was negatively correlated with needle reflectance. Nitrogen content of loblolly pine needles could be rapidly and accurately estimated from needle-reflectance measurements when all other elements were held at sufficient levels. The results suggest that reflectance measurements can also be used to detect changes or relative differences in chlorophyll content.

Description: Ammonia volatilization from organic (raw humus) horizons collected from an area in northern New Brunswick variously affected by SO2 (point source) pollution was studied under laboratory conditions. Samples were treated with urea at the rates of 0, 15, and 30 mg N per jar (0, 150, and 300 kg N ha−1) and incubated in closed dynamic systems for 14 days.The quantity of ammonia volatilized was proportional to the rate of urea application. While the quantities of ammonia given off from samples representing unaffected and moderately affected areas did not differ significantly, they were more than 20 times larger than the quantities volatilized from samples representing severely affected areas. The effect of SO2 pollution on ammonia volatilization was related to the original pH of the organic horizons before incubation. The reduced pH of the soil, owing to SO2 pollution, appeared to affect ammonia volatilization through the inhibitory effect of increased hydrogen ion concentration, and (or) by the ability of the acidic upper soil horizons to trap NH3 released in the lower horizons. The threshold pH at which ammonia volatilization is drastically reduced lies between 3.5 and 4.0.

Description: Cones were collected weekly from August 6 to October 2, 1979, from 10 Lake States provenances of jack pine (Pinusbanksiana Lamb.). We evaluated cone and seed characteristics (cone color, volume, fresh and dry weight, specific gravity, scale color, seed color, and embryo length) that can be used for field and laboratory determinations of seed ripeness, so that cones can be harvested before squirrels begin cutting them. Seeds were partially retained in cones picked in August and extracted by shaking. Final embryo length was attained 2 weeks before germination reached a maximum on September 10. The adaxial surface of the cone scales turned reddish brown and the seeds turned black 1 week before maximum germination was reached. Seed maturity coincided with the beginning of cone cutting by the squirrels.

Description: The mean number of pollen grains produced per pollen cone (P) ranged from 37 310 to 62 960 ([Formula: see text], SE = 1584) among eight seed-orchard clones of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) and correlated significantly (r = 0.87, p 

Description: This study investigated size and number of plots needed to precisely estimate tree mortality, mean dead basal area, mean dead volume, mean live basal area, and mean live volume in stands infested with the spruce budworm, Choristoneurafumiferana (Clemens).Depending on the parameter, precision of four different plot sizes (0.02, 0.04, 0.08, 0.40 ha) was examined. For most parameters the 0.04-ha plot appears to be approximately as precise as the larger plot sizes. Variables which affect the precision of the plot sizes are percent mortality, patchy distribution of the character of interest, and the variability associated with the population of interest. The precision of two, three, four, and five plots per stand was investigated. The coefficient of variation of the mean is reduced the greatest between two and three plots; subsequent reductions beyond three plots are not great. The number of plots needed based on sampling theory varied according to the parameter and the variability associated with the parameter. It was determined that the time involved in evaluating three 0.04-ha plots was approximately the same as needed to evaluate two 0.08-ha plots.

Description: Three conifer species, Pinnscontorta Dougl., Pinusflexilis James, and Piceaengelmannii Parry, were inoculated with the ectomycorrhizal fungi Pisolithustinctorius (Pers.) Coker & Couch, Suillusgranulatus (L. ex Fr.) Kuntze, and Cenococcumgeophilum Fr. These, plus noninoculated control seedlings, were grown in a greenhouse for 8 months to assess mycorrhizal formation and seedling response. For all conifer species, top height, diameter, and seedling total dry weight were greater in the S. granulatus and control ("wild" fungus) treatments as compared with P. tinctorius and C. geophilum.In the 2nd year of the study, greenhouse container-grown conifers with ectomycorrhizae formed by the above three fungi and an unknown fungus were planted under four fertilizer treatments on a high-elevation (3200 m) molybdenum tailing pond covered with deep mine waste rock.After 4 years in the field, height growth of the seedlings (all tree species combined) inoculated with S. granulatus were greater than seedlings inoculated with P. tinctorius, C. geophilum, or control ("wild" fungus). Through four growing seasons, a sewage sludge and wood-chip treatment resulted in greater height growth than the three treatments of combined inorganic N and P, P alone, and no fertilization. The combined survival for all species and all treatments was 58% after four growing seasons.

Description: Systematic thinning (alternate rows) was done in a 19-year-old Douglas-fir plantation. The principal microclimatic effect was to increase light at ground level (less than 1% in the unthinned versus 7.3% in the thinned stand) and also in the crowns (crown bases: 1% in the unthinned compared with 17.6% in the thinned stand). The other microclimatological parameters were less influenced.With reference to the water balance, the results indicate that thinning half the trees diminished the interception by only 13.1% (43.4% water intercepted in the unthinned versus 30.3% in the thinned stands). Indeed, the influence of the thinning on the actual evapotranspiration was relatively weak: the observed decrease was only 16.7% compared with the unthinned stand.The measurements also show that, as of the 1st year, the thinning increased the rate of tree growth substantially; the increase in basal area of the thinned stand was 101% of that of the unthinned stand. In other words, there was no production decrease the year of thinning.Essentially thinning benefits codominant trees. As a result of thinning, modifications to the crown cover became evident: the lower whorls of the tree crowns, remaining after the thinning, exhibited a greater mass of foliage compared with the unthinned stand owing to fewer old needles dropping.

Description: Long-term effects of air pollutants emitted in energy production were studied by analyzing pine needles (Pinussylvestris L.) from 1959–1979 corresponding to the natural fall. The needles originate in different parts of Finland between the latitudes 60 and 68° N. New procedures were introduced to apply the sensitive X-ray fluorescence (PIXE) method to elemental analysis of the needles. Concentrations were shown to be lower in northern Finland than in southern Finland. Several elemental concentrations follow an annual increase in the southern part of the country, but not in northern rural areas.

Description: To construct tree biomass tables it is customary to select the sample trees by cluster sampling and then to apply the classical least squares regression techniques under the assumption of simple random sampling. A modified linear regression procedure is proposed for which the assumption of simple random sampling is no longer required. The procedure can be used when (i) the regression of a biomass component on tree characteristics other than biomass can be approximated reasonably well by a linear function and (ii) the number of sample clusters is sufficiently large. Applied to two large cluster samples of trees, where the cluster size is approximately equal to five trees, and compared with the classical linear regression approach, the modified procedure results in biomass tables which arc essentially the same. The confidence intervals, however, are quite different. The classical least squares regression method results in intervals which, on the average, are about 60% as large as those calculated by the modified procedure.

Description: This paper describes a prediction model adopted by the Department of Energy and Resources of Quebec to (i) update temporary sample plots and (ii) project into the future the state of permanent sample plots in Quebec forests. Predicting the growth of a forest species means predicting the state of this species in time. Three basic characteristics mark the state of a species in a given year: number of trees, their total basal area, and their total volume. To date, in Quebec, normal or empirical yield tables have been used to predict the state of some species in ideal or real growth conditions, but these yield tables apply only to pure or almost pure even-aged stands. The prediction model for hardwood and softwood species presented in this paper serves the same purpose as the yield tables; however, it differs from the yield tables in that it can predict the state of each hardwood or softwood species found in pure or mixed, even- or uneven-aged stands. The prediction model was validated for 19 species found in a pilot territory located in the Basse-Gatincau (southwestern Quebec). The paper terminates with a discussion on the limitation of the prediction model and the conditions for its use.

Description: A 29-year record of seedfall in thinned and unthinned portions of a Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) stand, spanning ages 39 through 68, reveals annual seed production from no seeds to about 3 million per hectare. For the nine largest crops, annual seedfall in the best seed-producing thinning treatment included at least 100 000 filled seed per hectare. The first of these nine crops was in 1950; the other eight occurred at 1- to 4-year intervals beginning with 1959. For the nine largest crops, the proportion of seeds filled averaged 45% and ranged from 30 to 54%. Typically, about two-thirds of the seed fell by mid-December; but for two of the three largest crops, time of seed shedding was greatly delayed. Thinning substantially increased the number of seeds produced in some years following thinning but the effect was not lasting. There was little or no effect of thinning on the proportion of seed filled or timing of seed dissemination.

Description: Yearly applications of N, P, and K fertilizer for a 6-year period to a young, postfire aspen forest, resulted in substantial increases in tree growth primarily in response to nitrogen. The main effect of N was to increase, by at least a factor of two, the stand leaf area index, and bole and total aboveground tree mass. Improved nitrogen nutrition appeared to reduce the efficiency of production per unit of nitrogen incorporated into tree crowns.

Description: Studies in the specific density and caloric level per unit volume of trunk wood of three deciduous tree species of differing successional positions support the thesis that tree wood properties are related to the differing successional positions of trees. White birch, (Betulapapyrifera Marsh.), black cherry (Prunusserotina Ehrh.), and sugar maple (Acersaccharum Marsh.) were chosen as being characteristic of early, middle and late stages in forest succession. Wood cores were taken for these species from three different stands in southern Ontario and specific density, calorie value, and caloric level per unit volume were determined.Sugar maple had a higher specific density and caloric value than black cherry or white birch but only small differences were evident between black cherry and white birch. Specific density was found to be the least variable measure, but caloric level per unit volume was also useful, although less accurate. These latter estimates proved to be indicative of the successional positions of the three species.

Description: The concentrations of N, P, Ca, Mg, K, and Na are reported for leaf, twig, wood, bark, and root tissues for balsam fir (Abiesbalsamea (L.) Mill.) and heart-leaved paper birch (Betulapapyrifera var. cordifolia (Reg.) Fernald), the dominant tree species in subalpine forests of the Appalachian Mountains of northeastern United States. The N concentrations of birch leaves (2.79%) and especially current fir needles (2.48%) were high relative to comparable data in the literature. Ca and Mg concentrations of fir needles and birch leaves were relatively low, while the concentrations of P and K were typical. These chemical relationships generally, but not consistently, reflected the nutrient status of the forest floor and mineral soil in this environment. We believe that the foliar nitrogen values are partly a result of the chemical nature of the precipitation and cloud droplets impinging on these forests.

Description: Twenty fertilizer treatments of different rates and combinations of N, P, and K were established in young black cherry (Prunusserotina Ehrh.) stands that originated after clear-cutting in northwestern Pennsylvania, U.S.A. Height, diameter, and basal area growth rates and foliar nutrient composition were evaluated annually for 5 years thereafter. Nitrogen alone and P in combination with N produced large increases in height, diameter, and basal area growth. The addition of K to N + P treatments produced no additional response. Growth responses were largest during the first 2 years after fertilization, with increases in height and diameter lasting for 4 to 5 years. In year 1, maximum growth rates were reached with 112 kg N/ha and 49 kg P/ha, but 224 kg N/ha and 49 kg P/ha were necessary to sustain responses in following years. Both seedling and sapling stands responded to fertilization with similar absolute annual increases in height and diameter, though absolute basal area response of saplings exceeded that of seedlings owing to large differences in pretreatment diameters. Nitrogen fertilization increased average foliar N from 2.51 to 3.94% in year 1, but this concentration declined sharply thereafter and was at the control level by year 4. Phosphorus fertilization increased average foliar P from 0.12 to 0.21% in year 1, with further increases through year 5. Potassium fertilization increased average foliar K from 1.01 to 1.21% over the 5-year period, though there was considerable year-to-year variation.

Description: A probabilistic model is developed which relates stocking to degree of scarification and aerial seeding rate. Seed deposition patterns resulting from air turbulence and aircraft motion, as well as variability in seedbed distribution across a seeding chance, are shown to decrease potential stocking. The model is validated by comparison with experimental data on jack pine, using nonlinear regression. A set of equations is developed which enables selection of prescriptions for degree of scarification and seeding rates required to achieve desired stocking levels.

Description: Two isolates of an unidentified basidiomycete (UB) and two isolates of Echinodontiumtinctorium (ET), all from suppressed grand fir (Abiesgrandis (Doug.) Lindl.) in Oregon, were found to have an optimum growth temperature on malt agar medium of about 23 °C. In soil-block decay tests, conducted for 10 months at 23 °C. ET isolates caused average weight losses of 21.9 and 18.1%, while no decay was associated with UB. When UB was inoculated onto blocks precolonized with ET, it had a small negative effect upon the decay capacity of ET. However, when ET was inoculated onto blocks containing either living or dead (steam-sterilized) UB, no decay ensued. The UB isolates had apparently imparted a growth-inhibiting or fungitoxic material into the wood. As a result of this work, prior infection of twigs with UB is believed to inhibit or stop invasion of this infection court by ET.

Description: A heuristic, "unstructured" weight determination procedure was developed for harvest scheduling models in which goal programming algorithms are employed. Six noninferior solution sets that included four goals, total volume harvested, total discounted cash flow, total undiscounted cash flow, and total discounted costs, were generated using a complementary linear and goal programming approach. Representatives from a pulp and paper company (The Company) located in the southeastern United States ranked the solution sets from most to least preferred and provided a statement of why they ranked the sets the way they did. Additional noninferior solutions were generated to improve the achievement levels of the initial preferred solution. The procedure contributes to improved forest management decisions by providing the optimal harvest scheduling plan under each of the four goals individually and by providing goal achievement level trade offs under different weight structures. The procedure was well received and instructive to The Company representatives since it was easy to understand and required minimal analytic expertise and time on the part of the decision makers.

Description: When pulped by the same schedule, barked white spruce (Piceaglauca (Moench.) Voss.) branch wood was comparable in pulp yield to the bole wood. Handsheet made of unbeaten branch pulp showed higher bulk and stretch, comparable tensile and burst strengths, and considerably lower tear strength than bole wood. In the case of beaten pulps, branch pulp gave comparable tensile strength and stretch and lower burst and tear strengths. Inclusion of bark in the cooking increased chemical consumption and degraded sheet cleanliness. Pulping of mixtures containing up to 20% branch wood reduced the tear, burst, and tensile strengths by about 10%). It appeared that the inclusion of branch wood in the furnish within the natural amount limit in kraft pulping would be feasible.

Description: Fish-eye pictures are often used to characterize forest canopies. The sky-obscuration factor (SOF), defined as the relative area of sky obscured by vegetational elements for a certain solid angle when observed from below, is evaluated by means of the interactive, computer-supported, diode-array scanner OSIRIS (now commercially available), with high geometric and photometric resolution. The SOF in each picture element is calculated by linear interpolation between the frequency peaks of completely covered and uncovered sky. This method gives good results when the two peaks show small skewness and limited width and are clearly separated. Compared with OSIRIS results (from nonideally exposed pictures), manual evaluation and radiation measurements gave a somewhat higher SOF, while precipitation–throughfall analysis agreed in the zenith-angle interval 0–10°. To facilitate and improve evaluation, a standardized photographic technique is recommended including usage of high contrast film, carefully controlled exposure, and identical development. An artificial horizon and north position indicated by lamps mounted within the depth of field of the fish-eye lens is also recommended.

Description: The coefficient of variation of forest stand volume can remain approximately constant over successive measurements. This consideration was exploited to provide an efficient estimator of the mean timber volume on the current occasion when sampling with partial replacement (SPR) on two occasions. For even-aged and normally distributed forest populations, the gains in precision were shown to be in the range of 8 to 200% when using the modified SPR estimator of the current mean volume.

Description: Photosynthetic characteristics and morphology of leaves of black walnut (Juglansnigra L.) seedlings grown under different types and degrees of shade were investigated by measuring insitu gross photosynthesis (Ps) and by microscopic study of leaf material. During the growing season of 1979, seedlings were subjected to artificial shading of two types: the first type simulated two overstory densities (leaf-area indices of 1 and 2) with corresponding proportions of sunflecks and total transmission of 50 and 21%, respectively, of incident photosynthetically active radiation (PAR, 400–700 nm); the second consisted of two densities of greenhouse shading screen which transmitted approximately 16 and 3% of incident PAR. From quantum efficiency values derived from Ps – quantum flux density response curves it was determined that the walnut seedlings adjusted photosynthetically to shade. Quantum efficiency increased as much as 44% with the densest shading. Light-saturated Ps did not appear to decline with increased shading if sunflecks were present, and it declined only 18% under complete shade that transmitted about 16% of incident PAR. Estimated daily photosynthesis per unit leaf area for black walnut growing under heavy and complete shade (3% of incident PAR) was nearly one-half that of the unshaded control. Shading resulted in plants that possessed leaves that were thinner, had less palisade mesophyll, had lower stomatal density, and had more chlorophyll per unit of leaf area. These data indicate that black walnut seedlings have the capacity for substantial photosynthesis under shade and may be more shade tolerant than silvicultural classifications suggest.

Description: The characteristics and short-term results of experimental prescribed fires in 2-year-old trembling aspen (Populustremuloides Michx.) logging slash in northern Minnesota have been described by D. A. Perala (1974. Can. J. For. Res. 4: 222–228). The associated burning conditions are expressed here in terms of the weather-dependent numerical fuel moisture codes and fire behavior indexes of the Canadian system of forest fire danger rating.