ALBERT

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: 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: 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: 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: A recent study has suggested that sweetgum (Liquidamberstyraciflua L.) differs from other species in that its marked response to mycorrhizae is not due to improved nutrient uptake. To investigate this possibility, sweetgum seedlings were grown in a 1:1:1 mix of peat, sand, and sandy loam treated factorially with: (i) 0, 50, or 500 ppm P; (ii) 0 or 5 ppm Cu; (iii) 0 or 8 ppm Zn, and (iv) Glomusfasciculatus Gerdemann and Trappe or no mycorrhizal inoculum. After 5 months' growth in the greenhouse, nonmycorrhizal seedlings receiving 500 ppm P were growing at the same rate as P-fertilized mycorrhizal seedlings and foliar P concentrations were higher in the mycorrhizal treatments. Mycorrhizae also alleviated a minor copper deficiency which occurred at the high level of P in the nonmycorrhizal treatments. The benefit of mycorrhizae to sweetgum is therefore a typical nutrient response, which may have been overlooked in previous work with this species by use of too narrow a range of phosphorus levels.

Description: The branch morphology and the distribution of leaves and specific leaf weight were determined within the crown of 5- and 6-year-old Populus 'Tristis No. 1' (P. tristis Fisch. × P. balsamifera L.) trees grown in northern Wisconsin under short-rotation, intensive culture at 1.2- and 0.6-m square spacings, respectively. The relationship of leaf area to aboveground biomass productivity was also evaluated for the same trees. The first-order branches within the trees exhibited acrotony and were predominantly long shoots. No branching higher than third-order was observed. Leaf size and specific leaf weight were greatest on the current terminal shoot and decreased from the upper portion of the crown to the base. When the 6-year-old trees were divided into eight 1-m vertical strata, over 80% of the total number of leaves and total leaf area was in three middle strata (4–7 m), and most of the 1-m strata contained leaf area attached to two or more height growth increments. Leaves attached to branches on a single height growth increment of the 6-year-old trees occurred in up to four 1-m vertical strata. Long shoots comprised 53% of total leaf area in the 5-year-old trees and 66% in the 6-year-old trees, short shoots the remainder. Ninety-five percent of the long shoots in the 6-year-old trees were in the three uppermost vertical strata (5–8 m), and 95% of the short shoots were in the lowermost leaf-containing vertical strata (3–6 m). Long-shoot leaves had higher specific leaf weights than short-shoot leaves attached to branches on the same height growth increment. Leaf-area indices (LAI) were 7.6 and 8.8 m2•m−2 for the 5- and 6-year-old stands, respectively. Leaf area per tree was linearly related to the aboveground biomass of the tree. The linear regression line for the relationship between leaf area and D2H (diameter2 × height) for the 6-year-old trees in the study was statistically different from that of the 5-year-old-trees. The data presented suggest that this relationship may serve as a useful quantitative index of crown closure in poplar stands. The results also suggest some crown morphological criteria useful for selection and breeding of improved poplar trees for short-rotation intensive culture.

Description: Tests with 4-month-old loblolly pine (Pinustaeda L.) seedlings grown in the greenhouse show decreased short-root formation when grown in soil treated with the root-inhibiting herbicides trifluralin and napropamide. However, short-root development of treated seedlings did not differ from controls after 7 months. Percentage of bifurcate roots of 7-month-old seedlings was increased by napropamide but they were not significantly affected by trifluralin. The herbicide bifenox did not affect short-root development of 4- or 7-month-old seedlings. Percentage of bifurcate roots was increased initially with bifenox but was not affected after 7 months. The systemic fungicide triadimefon decreased both short-root development and the percentage of bifurcate roots of 7-month-old seedlings.

Description: Seven surface and eight subsurface acid soils, sampled from six Canadian provinces, were cropped to barley in a greenhouse experiment. The soils were limed at determined rates to produce the following soil conditions: I, soluble Al to 8 ppm; II, exchangeable Al to 2 meq/100 g soil; III, base saturation to 60%; and IV, full base saturation. The adjustments were not as precise as intended, but they did provide means for finding relations between soil acidity measurements and barley yield response to lime. Both a 5-day equilibration method and a rapid method for soil analysis showed that soluble Al and percent base saturation correlated better with barley yields than did exchangeable Al and pH. The 5-day equilibration method gave the better correlations, with soluble Al, percent base saturation, exchangeable Al and pH accounting for 68, 73, 40 and 39% of the variation in barley yields, respectively. Although this study indicated that soluble Al and percent base saturation gave equally good predictions of Al-sensitive crops to liming, the soluble Al measurement is simpler and, therefore, more suitable for general diagnostic purposes.

Description: The microbial potential for denitrification and the effects of sulfur anions on this process were assessed in five Alberta soils. The denitrification potential of the various soils was ranked as follows: Black 〉 Dark Brown 〉 Brown [Formula: see text] Gray Luvisol [Formula: see text] Solodized Solonetz. The rate of denitrification in any soil was dependent on the chemical characteristics of that soil and the availability of a suitable carbon substrate for the denitrifying microorganisms. Denitrification was stimulated in three of the last four soils by adding 300 μg glucose-C/g of soil. Addition of 100 or 500 μg SO42−-S/g of soil had little or no effect on the rate of denitrification. In contrast, soils with added Na2SO3, Na2S2O3, and Na2S had reduced rates of denitrification and nitrite accumulated. The data suggest that microbial reduction of these sulfur anions to S2− occurred, and that S2− blocked the terminal steps of the enzyme pathway for denitrification, resulting in the accumulation of NO2−. The inhibition of denitrification by the sulfur anions could be overcome by adding 900 μg glucose-C/g of soil.

Description: In a greenhouse bioassay of soils from the central Oregon Cascades, Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) seedlings had the most total and ectomycorrhizal root tips when grown in soil from an unburned clear-cut and the least when grown in soil from (i) a 20-year-old plantation that had been clear-cut and burned in the late 1950's and (ii) one old-growth forest. Tip formation was intermediate in soil from a second old-growth forest, a recently burned clear-cut, and a 40-year-old natural burn. Root weights followed the same trend, but top weights did not differ among the various soils. Ectomycorrhizal and total root tips of western hemlock (Tsugaheterophylla (Raf.) Sarg.) were lowest in soils from the plantation and recently burned clear-cut. Unlike Douglas-fir, western hemlock's tip production was not greater in the unburned clear-cut than in the old-growth forest soils. In this species, both top and root weights varied according to soil, with the largest seedlings produced in soil from the unburned clear-cut. With both species, there was a significant interaction between ectomycorrhizal type and soil type. Cenococcumgeophilum Fr. predominated on western hemlock and was reduced in soils from the burned clear-cut and plantation. In comparison with the mean for all soils, ectomycorrhizal types that predominated on Douglas-fir were enhanced in the unburned clear-cut soil and reduced in one old-growth soil, an effect apparently related to litter leachate.