Southern Ontario Soils Research Articles

Ground penetrating radar use in three contrasting soil textures in southern Ontario

Abstract Ground penetrating radar (GPR) is a non-invasive, geophysical tool that can be used for the identification of clandestine graves. GPR operates by detecting density differences in soil by the transmission of high frequency electromagnetic waves from an antenna. Domestic pig ( Sus scrofa domesticus ) carcasses were clothed in 100% cotton t-shirts and 50% cotton/50% polyester briefs, and buried at a consistent depth at three field sites of contrasting soil texture (silty clay loam, fine sand and fine sandy loam) in southern Ontario. GPR was used to detect and monitor the graves for a period of 14 months post-burial. Analysis of collected data revealed that GPR had applicability in the identification of clandestine graves in silty clay loam and fine sandy loam soils, but was not suitable for detection in the fine sandy soil studied. The results of this research have applicability within forensic investigations involving decomposing remains by aiding in the location of clandestine graves in loam soils in southern Ontario through the use of GPR.

Crop performance on soils receiving annual papermill biosolid amendments with and without supplementary nitrogen

Nitrogen availability is often a limiting factor for optimum crop growth on agricultural soils amended with papermill biosolids (PB). The objective of our study was to evaluate the effect on corn (Zea mays L.) and soybean (Glycine max L.) production of adding supplementary nitrogen fertilizer to soils amended with increasing rates of PB. Papermill biosolids were applied annually on four agricultural soils in southern Ontario, Canada. Treatments included three rates of PB (50, 100, and 150 Mg ha-1), combined with four levels of nitrogen fertilizer [crop recommended [CR], [CR] + 0.5 kg N Mg-1 PB, [CR] + 1.0 kg N Mg-1 PB, and [CR] + 1.5 kg N Mg-1 PB]. In addition, non-amended plots were also established receiving either (a) zero PB and zero nitrogen fertilizer or (b) zero PB and [CR] nitrogen fertilizer only. All the plots received the same treatment combinations, i.e., PB × N, each year for the duration of the study. In corn, [CR] nitrogen fertilizer was insufficient to satisfy plant growth and PB decomposition requirements. Supplementary nitrogen fertilizer at a rate of 1.0 kg N Mg-1 PB was generally required to maintain or increase corn grain production relative to the control plots receiving the [CR] nitrogen fertilizer only. Corn grain yield increases ranged from 1000 to 6000 kg ha-1 relative to the control at some of the research sites. The optimum rate of supplementary nitrogen fertilizer varied by soil texture (location) and year. In contrast, production of soybean did not require high supplementary nitrogen fertilizer, or in some cases any, in order to maintain or increase yields at most locations. Our study shows that nitrogen fertility management had a greater impact on yields in production systems planted to corn than soybeans while receiving annual PB amendments. No residual effects on corn yield or corn grain protein content were observed after PB amendments were stopped.Key words: Papermill biosolids, carbon:nitrogen ratio, corn, soybean, nitrogen fertilizer

Response to annual applications of de-inked papermill biosolids by field earthworms on three agricultural soils

Papermill biosolids (PB) have been used as soil conditioners on agricultural soils, to reclaim mining soils, and to rehabilitate old landfill sites. Earthworm population responses to a de-inked PB were measured on three agricultural soils in southern Ontario, Canada. Four rates of PB, 0, 50, 100, and 150 Mg ha −1, were applied annually for 3 years. In addition, plots receiving the PB treatments were planted to corn ( Zea mays L.) and soybean ( Glycine max L.). Earthworm populations prior to PB applications ranged from 9 to 22 individuals m −2 on the sandy loam and loam soils. Linear increases in earthworm populations were observed ranging from approximately 153 to 280 individuals m −2 after 3 years of PB amendments. On the clay loam soil, initial fall earthworm populations were about 124 individuals m −2 which increased to 482 individuals m −2 after 2 years of PB applications. Earthworm population increases to PB amendments were evident after 2–3 years at the sites measured.

543 Effect of Calcium and Sulfur on Yield of Late-storage Cabbage

Soil and crop management practices suggest the possibility of sulfur deficiency for cole crops in Southern Ontario. A 3-year study was conducted to evaluate rates of calcium and sulfur on yield of `Huron' late-storage cabbage. Treatments were based on CaSO4 applied at 0, 1000, 2000, and 3000 kg·ha–1 `Novacal' (Ca 27%, S 19%, Mg 2.5%, Dolomex Inc., Portage-du-Fort, Quebec, Canada), a granulated gypsum product. Potassium sulfate and calcium nitrate were used as elemental controls. Potassium and nitrogen levels were balanced with potassium chloride and ammonium nitrate. Phosphorous applications were based on soil analysis. All treatments were applied pre-plant incorporated. This trial was repeated on sand and loam soils typical of soil used for cabbage production in southern Ontario. Applications of sulfur increased yield of cabbage on sand and clay, although the optimum rate varied from year to year. Medium and high rates produced the highest yield in the first year, while low rates were more effective in the second and third seasons. Response of cabbage to calcium varied from year to year. Medium and high rates of calcium increased yield on sand, but had no effect on clay in the first year. Calcium had no effect on yield on either soil type in the second year. However, in the third year, low rates of calcium produced the highest yield on both sand and clay. Although there were no visual symptoms of deficiency, applications of sulfur, and to a lesser extent calcium, increased yield indicating that a `hidden hunger' for these elements may exist on some soils in southern Ontario.

Tillage effects on the dynamics of total and corn-residue-derived soil organic matter in two southern Ontario soils

Agricultural management practices affect the dynamics of soil organic matter (SOM) by influencing the amount of plant residues returned to the soil and rate of residue and SOM decomposition. Total organic C and δ13C of soil were measured in two field experiments involving corn cropping to determine the effect of tillage practices on SOM dynamics. Minimum tillage (MT) and no tillage (NT) had no significant impact on the soil C compared with conventional tillage (CT) in the 0- to 50-cm soil depth sampled at both sites. Continuous corn under MT and CT for 29 yr in a silt loam soil sequestered 61–65 g m−2 yr−1 of corn-derived C (C4-C), and it accounted for 25–26% of the total C in the 0- to 50-cm depth. In a sandy loam soil cropped to corn for 6 yr, SOM contained 10 and 8.4% C4-C under CT and NT, respectively. Reduced tillage practices altered the distribution of C4-C in soil, causing the surface (0–5 cm) soil of reduced tillage (MT and NT) plots to have higher amounts of C4-C compared to CT. Tillage practices did not affect the turnover of C3-C in soil. Key words: Soil organic matter, 13C natural abundance, tillage practices

Industrial organic compounds in selected Canadian soils

Studies were conducted to determine the concentrations of a large number of industrial organic compounds in selected Canadian agricultural soils and to assess the potential for land application of municipal sludges to cause significant polynuclear aromatic hydrocarbon (PAH), organochlorine pesticide (OC) and polychlorinated biphenyl (PCB) contamination of agricultural land. Twenty-four Agriculture and Agri-Food Canada, Soil Quality Evaluation Program (SQEP) benchmark soils and six intensively cropped southern Ontario soils exhibited similar small concentrations of a few base-neutral and acid (BN&A) extractable industrial organic compounds (seldom >1 mg kg−1 dry wt), PCBs (<200 μg kg−1 dry wt) and organophosphorus pesticides (OPs). Fonofos, the only OP detected, was observed at concentrations <100 μg kg−1 dry wt. Neutral and phenoxy acid herbicide analyses for 13 soils (seven SQEP and six intensively cropped) indicated infrequent detection of these compounds. There was no detection of carbamate herbicides. In most soils, only trace amounts (<10 μg kg−1 dry wt) of OCs were observed but in one intensively cropped soil, DDT exceeded 70 mg kg−1 dw. A greater incidence of compounds such as alpha chlordane, dieldrin, aldrin and DDT in intensively cropped than in other soils is assumed to reflect increased use of these compounds for intensive crop production. Soils treated with sludge according to recommended practice exhibited minor increases in PAH, OC and PCB concentrations. There is no risk to human health or the environment from industrial organic conpounds, except possibly DDT, in Canadian agricultural soils that have received no sludge or from PAHs, OCs and PCBs in soils that have received southern Ontario sludges according to recommended practice. Key words: Municipal sludge, industrial organic compounds, organic contaminants, agricultural sustainability, soil

Changes in the forms and distribution of soil phosphorus due to long-term corn production

Long-term fertilizer-P application affects soil-P distribution and forms. These effects must be characterized to use fertilizer P most efficiently. In three southern Ontario soils of varying texture, we determined changes in soil organic P (Po) and inorganic P (Pi) caused by fertilizer P application (0–90 kg broadcast P ha−1 yr−1 during 10 yr of corn production. Soil P was characterized by (1) annual measurement of 0.5 M NaHCO3-extractable P (Olsen-P) and (2) sequential extraction from soil taken at the beginning of the experiment and after receiving 0 to 90 kg broadcast P ha−1 yr−1 for 10 yr. Fertilizer P increased Olsen-P concentrations in all soils. The increases were proportional to the cumulative amount of P applied. Based on all three soils, 16 kg P ha−1 was required to increase Olsen-P concentrations by 1 mg L−1 soil. After 10 yr of 90 kg broadcast P ha−1 yr−1, labile Pi fractions (resin P and NaHCO3 P) were increased, as was NaOH-extractable Pi in all soils. On the most P-deficient soil (Conestogo SiL), where corn grain yields were increased by fertilizer P, P fertilization also increased HCl-Pi, residual P (H2O2-H2SO4 extractable P) and labile Po (NaHCO3-Po and NaOH-Po). A P balance was calculated, which accounted for additions to, removals from, and changes in the total P status of the 0–20 cm layer. When no broadcast P was applied, there was an unaccounted-for input (possibly from the subsoil), of 20.9 kg P ha−1 yr−1 on the Conestogo SiL. When 90 kg broadcast P ha−1 yr−1 was applied to the Fox SL, the coarsest soil studied, there was a deficit of 30.9 kg P ha−1 yr−1 and elevated Olsen-P concentrations in the 25–36 cm depth, suggesting downward movement on fertilizer P. It appears that subsoil P was involved in the P cycle of these two soils. Key words: Continuous corn, P fertilization, sequential extraction, organic phosphorus, inorganic phosphorus, labile phosphorus, subsoil P, leaching

Evaluation of strip tillage systems for corn production in Ontario

Strip tillage, which involves cultivation of a narrow strip in the row area, has the potential advantages of providing a suitable seedbed for corn ( Zea mays L.) production with minimum energy expenditures, while leaving surface residues in the interrow area to reduce soil erosion. A study was conducted where three rotary tillage implements (Howard Rotaspike, Howard Rotavator, and Lely Roterra, The Lely Corporation, Suffolk, UK) and a former interrow cultivator were modified to cultivate a strip 25 cm wide in the row area. These strip tillage implements were compared with fall moldboard plow, fall chisel plow, and no-till tillage systems for 3 years of continuous corn production on sandy loam, silt loam, and clay loam soils in southern Ontario. The strip tillage treatments left significantly higher amounts of surface residue than either the moldboard plow or the chisel plow and thus provided potential soil conservation benefits. The moldboard plow system resulted in a greater proportion of fine aggregates in the seedbed than strip tillage, and strip tillage generally had more fine aggregates than no-till. Plant growth with strip tillage tended to be delayed compared with the moldboard plow treatment on all three soils. Average strip tillage yields were 10.3 and 12% lower than the moldboard plow treatments for the silt loam and clay loam soils, respectively. On the clay loam soil, differences were not significant between the strip tillage and chisel plow or no-till treatments. On the sandy loam soil, average strip tillage yields were significantly lower than the moldboard plow treatment in 1 year out of 3, equal to chisel plow in all 3 years, and higher than no-till in 2 years out of 3. Among the strip tillage treatments, the Howard Rotaspike and Howard Rotavator often resulted in finer seedbeds, better plant growth, and higher yields than the Lely Roterra and strip-till cultivator. The Howard strip tillage implements tended to compare most favorably with the moldboard plow tillage system.

Corn development and crop yield response to ridge-planting systems on a poorly drained soil in southwestern Ontario

Minimum-tillage systems have the advantage of reducing soil erosion as well as decreasing the amount of time and fuel necessary for land preparation. However, no-till and chisel plowing have resulted in decreased corn ( Zea mays L.) yields compared with moldboard plowing on poorly drained southern Ontario soils. Ridge planting was proposed as a more feasible option than other minimum-tillage systems on these soils. An experiment was conducted from 1983 to 1985 to examine various ridge-planting alternatives in comparison with no-till and moldboard-plow tillage systems for corn and soybeans ( Glycine max Merill). The ridge-planting treatments included no-till planting on the ridge top, removal of the ridge top while planting, rototilling the ridges, and chopping the corn stalks in the previous fall. Corn seedlings in the ridge-planting treatments emerged quicker than those in the no-till treatment, but slightly slower than those in the moldboard-plow treatment. Measurements of corn plant development and maturation showed little difference between ridge planting and moldboard plowing. Corn grain yield response to the tillage systems was not consistent over the 3 years. In 1984, corn grain yields were 8.02, 6.71 and 6.05 Mg ha −1 for the moldboard-plow, ridge-planting and no-till treatments, respectively. In 1985, the moldboard plow and most of the ridge-planting treatments were not significantly different, and no-till outyielded all other treatments. Over the 3 years of the experiment, soybean yields averaged 2.45, 2.39 and 1.79 Mg ha −1 for moldboard plowing, ridge planting and no-till, respectively. Among the ridge-planting treatments, rototilling the ridge top tended to produce better corn plant growth, lower ear moisture at harvest and higher grain yields than other ridge-planting treatments. Chopping the corn stalks the previous fall resulted in better corn growth and higher yields than not chopping. Results from this study indicate that a reduced-tillage system of ridge planting with tops rototilled could produce corn and soybean yields comparable to the conventional moldboard-plow tillage system on poorly drained soils.

STUDIES ON THE POTASSIUM-SUPPLYING CAPACITIES OF SOUTHERN ONTARIO SOILS. III. MEASUREMENT OF AVAILABLE K

This study was conducted to determine which of eight different extractants best described the K-supplying capacities of nine southern Ontario soils. The total amount of K extracted by eight crops of alfalfa grown in the greenhouse was related to soil K by regression techniques. The following procedures extracted increasingly higher average amounts of soil K: water; electro-ultrafiltration (EUF) at 20 °C (EUF-K-20) (37 μg K g−1); EUF at 80 °C (EUF-K-80) (83 μg K g−1); 2M NaCl (89 μg K g−1); 1M NH4OAc (131 μg K g−1); 0.1 M HNO3 (163 μg K g−1); seven sequential 7-min extractions with boiling 1 M HNO3 (Mactotal) (940 μg K g−1); and 0.2 M sodium tetra-phenyl boron (NaTPhB) (3248 μg K g−1). Of the eight extractants tested, the amount of K removed by EUF was the most closely associated to total K uptake; a multiple regression model with the logarithm of EUF-K-20 and the logarithm of EUF-K-80 as independent variables explained 97% of the total variation in K uptake. The K extracted by 2 M NaCl and by 0.1 M HNO3 also explained more variation in total K uptake (r2 = 0.86, and 0.92, respectively) than did 1 M NH4OAc (r2 = 0.61), which is currently used in the Ontario soil test program. The other extractants did not offer an improvement over NH4OAc, with the exception of the most soluble fraction of Mactotal (StepK). Extraction of soil K with electro-ultrafiltration may offer a more precise estimation of the K supplying capacities of southern Ontario soils than the currently used extractant. Key words: Electro-ultrafiltration, nonexchangeable K, ammonium acetate, soil test

Impact of ring-billed gull ( Larus delawarensis Ord.) foraging on earthworm populations of southwestern Ontario agricultural soils

Analysis of soil earthworm (Annelida: Lumbrcidae) populations in southwestern Ontario estimated mean earthworm density and biomass as 111 m −2 and 35 g m −2, respectively, for five cultivated sites. About 2 × 10 6 ha are ploughed annually each autumn in southern Ontario, exposing about 11% of resident earthworms, 37% of which were injured by ploughing. Many of the 700 000 ring-billed gulls ( Larus delawarensis Ord.) living adjacent to these cultivated fields in the Great Lakes Basin forage on the exposed earthworms immediately behind the plough, raising concern amongst growers that earthworm populations might be vulnerable to eradication by gull predation. When the huge renewable, dispersed and cryptic earthworm resource was compared with the much smaller food requirements of the Ontario gull flock, and with the relatively few days during the ploughing season that the flocks has to forage on the earthworm resource, it should be inferred that the current gull flocks poses no danger to earthworm populations in cultivated southern Ontario soils.

STUDIES ON THE POTASSIUM-SUPPLYING CAPACITIES OF SOUTHERN ONTARIO SOILS. I. FIELD AND GREENHOUSE EXPERIMENTS

The response of grain corn (Zea mays L.) to applied K was studied for 10 yr on three southern Ontario soils. On a Conestogo L, the most profitable rate of K application was 2.5 times higher than expected and the critical concentration of NH4OAc-K, above which no response occurred to either applied K or increasing NH4OAc-K concentrations, was higher (2 ×) than expected, based on 1 M NH4OAc-extractable K and interpretation by the Ontario Ministry of Agriculture and Food soil test. All soils fixed substantial quantities of applied K, but the amount fixed by the Conestogo L was not greater than that fixed by the other two soils. When no K was applied, corn removed less nonexchangeable K (NEK) from the Conestogo L than from the other two soils. A greenhouse experiment was conducted to determine if either the availability of NH4OAc-K or NEK to alfalfa (Medicago sativa L. 'Banner') was lower on highly responsive soils than on less responsive soils. By the end of the experiment, soils on which crops were very responsive to applied K (Guelph L, Conestogo L, and Teeswater SiL) had supplied less K to alfalfa than had soils (Brookston L and Fox SL) on which response to applied K in field trials was similar to that predicted by the soil test. Total K uptake was related to NEK uptake suggesting that differences in the K-supplying capacities of the soils were associated with the availability of NEK to alfalfa. It was concluded that the responses to higher rates of applied K than expected in field trials were due to lower uptake of NEK. The clay mineralogy of the soils was dominated by illite with lesser amounts of vermiculite. No appreciable differences in mineralogy were found between the two groups of soils and NEK uptake was not significantly related to the amount of clay nor to the illite content of the coarse clay and fine clay fractions. Key words: NH4OAc-K, nonexchangeable K, illite, vermiculite, alfalfa, corn

STUDIES ON THE POTASSIUM-SUPPLYING CAPACITIES OF SOUTHERN ONTARIO SOILS. II. NITRIC ACID EXTRACTION OF NONEXCHANGEABLE K AND ITS AVAILABILITY TO CROPS

A previous study showed that large differences in K uptake by alfalfa (Medicago sativa L.) grown in the greenhouse occurred on soils which had similar ammonium-acetate-extractable K (NH4OAc-K) concentrations at seeding. Differences in total K uptake appeared to be closely related to the uptake of nonexchangeable K (NEK). The objective of this study was to determine what fractions or forms of NEK in the soils were responsible for the large differences in total K uptake noted in the greenhouse experiment. The total amount of NEK extracted in seven sequential extractions with boiling 1 M HNO3 (Mactotal) varied widely among soils and was significantly related to the total amount of K (r = 0.69; P < 0.05) and NEK (r = 0.75; P < 0.05) taken up by eight crops of alfalfa. Mactotal was separated into two fractions of differing solubility and the most soluble fraction, StepK, was highly correlated with NEK uptake (r = 0.85; P < 0.01) and total K uptake (r = 0.86; P < 0.01). The least soluble fraction, CRK, was not significantly correlated with either NEK or total K uptake. A multiple regression equation with NH4OAc-K and StepK as independent variables explained 86% of the variation in total K uptake among soils. The coarse clay fraction (0.2–2.0 μm) was the main source of NEK taken up by alfalfa. It was concluded that differences in the K-supplying capacity of southern Ontario soils were due not only to differences in NH4OAc-K concentrations but also to the amount of the StepK fraction of NEK present in the soils. The quantity of StepK present appeared, from a field experiment, to be influenced by the amount of fertilizer applied over a period of years. If a simple method of measuring StepK can be found, soil tests for plant available K in Ontario soils might be greatly improved. Key words: HNO3 extractable K, nonexchangeable K, NH4OAc-K, alfalfa, coarse clay, fine clay

Concentration of cadmium in Coturnix quail fed earthworms.

Earthworms (Lumbriscus terrestris), collected from soils in southern Ontario, Canada, that had no previous history of cadmium application, contained 3 ppm cadmium. They were fed to Coturnix quail as 60% dry weight of their diet for 63 d to examine the extent of deposition of native cadmium. Cadmium in kidney, liver, and excreta was greatly elevated above that of birds fed a control diet without worms. No increase in the level of cadmium in eggs was found. The factors affecting the association of cadmium in soils and worms and their assimilation and possible toxic effects in foraging birds are discussed.

Chemical pools of cadmium, nickel and zinc in polluted soils and some preliminary indications of their availability to plants

SummaryThis study was conducted to determine the chemical distribution and plant availability of Cd, Zn and Ni in eight metal‐polluted soils in southern Ontario, Canada. There were altogether 30 different soil samples because two of the soils had received various sewage sludge treatments. The soils were sequentially extracted with 1 m ammonium acetate to remove soluble plus exchangeable metals, with 0.125 m Cu(II) acetate to remove complexed metals, and with 1 m HNO3 to dissolve chemisorbed or occluded metals and precipitates such as oxides and carbonates. Expressed as a percentage of the metal soextracted, exchangeable Cd and Zn and Ni; complexed Cd and Zn>Ni and Ni>Zn>Cd in the acid‐soluble pool. With a few exceptions (soils with high organic matter content or low pH) at least 50 per cent of the extracted metal was in the acid‐soluble pool. The percentage of metal complexed was significantly correlated with organic matter content. The percentage of metal in the acid‐soluble fraction was significantly correlated with soil pH. Preliminary findings based on the results with two soils suggested that for Cd and Zn plant availability was correlated with the concentrations of exchangeable, complexed or acid‐soluble pools of Cd and Zn.

BROWN HEART IN RUTABAGAS GROWN ON SOUTHERN ONTARIO SOILS

Brown heart sometimes occurs in rutabagas (Brassica napobrassica Mill.) grown on some southern Ontario soils even though a recommended quantity of B fertilizer has been applied. Fourteen field experiments were conducted on growers' fields over a 4-yr period to determine the cause of this phenomenon. Brown heart occurred when the hot-water-soluble B content of the soil decreased below approximately 1.3 ppm although there were a few exceptions. An application of 4.5 kg B/ha as borax did not completely overcome the brown-heart condition in a majority of the experiments. The B concentration in the third or fourth leaf from the centre of the whorl was not related to brown-heart incidence. However, it was found that a B concentration of less than 18 ppm in the roots was generally associated with brown-heart incidence. Although there was no clear relationship between the Ca/B ratio in the leaf blades and brown-heart incidence, there was an increase in brown-heart incidence as the Ca/B ratio in the roots increased above 170. In three experiments, an application of 224 kg Na/ha as NaCl significantly increased brown-heart incidence, whereas in a fourth experiment there was a significant decrease. There was some evidence that the Na may slightly decrease the B concentration. Also the Ca concentration increased as the Na concentration increased in rutabaga tissues thereby affecting the Ca/B ratio and possibly brown-heart incidence. There was also evidence that, in the root tissues, the Ca/B ratio was inversely related to the K concentration. It was concluded that the effectiveness of B in decreasing brown-heart incidence was related to the Ca concentration in rutabaga plants.

Tree Breeding and Genetics of Exotic Conifers in Canada

The most commonly planted exotic conifers in Canada are Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) Norway spruce has its highest potential on acid soils in high precipitation areas where it is more productive than the local spruce and fir mixture. Extensive plantations of Norway spruce have not been established because of its susceptibility to attack by white pine weevil. A number of provenance experiments have been established, and selection and breeding for resistance to the white pine weevil appear promising.Scots pine has not been favoured for timber production in Canada mainly because most early seed imports came from poorly formed stands in western Germany. Rapid early growth and green foliage in early winter led to extensive cultivation of these German types for Christmas trees. A limited number of stands from Poland and White Russia, and nearly all the Scots pine from Estonia-Latvia (Riga Pine) are well formed and are recommended for timber production, but not for the growing of Christmas trees. On less fertile sites, Scots pine grows more rapidly than red pine but, at least in the first 20 years, it does not grow as well as jack pine. Selected provenances of Scots pine hold much promise in the prairie region and in the boreal forest.Other exotic spruces have not been widely planted in Canada so very little is known about their silvicultural potential and ecological amplitude. Combined species and provenance trials have been planted recently to remedy this situation. A hybrid between Serbian and black spruce growing at Chalk River, Ontario has grown more rapidly than either parental species. Other species hybrids have been made, but are not yet assessed.In an attempt to develop a hard pine of wider ecological amplitude than red pine, species hybrids have been made between Scots pine, Japanese red pine and varieties of Pinus nigra. These are promising on rich soils in southern Ontario and might be extended further to the north and to poorer acid soils by using selected provenances for the breeding work. Pitch pine has been successfully crossed with P. taeda and P. radiata in an attempt to improve the productivity and potential of pitch pine.

Teloschistes arcticus Zahlbr. Reaffirmed in the Canadian Arctic

The first occurrence of the hybrid sporophyte of Weissia muehlenbergiana x W. controversa is reported from Lambton County, Ontario. Hybrid sporophytes and both parents were present in large numbers. The characters of the hybrid are intermediate between those of the parent species. All the observed hybrids grew on gametophytes of W. muehlenbergiana. Weissia muehlenbergiana (Sw.) Reese & Lemmon and W. controversa Hedw. are both common on dry, poor, sandy soils in southern Ontario. An area in Lambton County near Thedfordc had been selected to search for Pottia davalliana, P. intermedia, and other bare-soil mosses because it formed an island of clay soil in an otherwise sandy area and because it was moist. Here, on April 20, 1966, growing intermingled with dense mats of fruiting W. muehlenbergiana and W. controversa, a third type of moss caught the eye because of its large, rounded, shining, red-bronze capsules. Upon sectioning, these capsules were found to have 16 small, variously distorted, papillose, red teeth under the prominent, bright red ridge at the annular region. These very much resembled the peristome teeth of some of the variants of W. controversa but were entirely enclosed (Fig. 8). Moreover, it soon became evident, upon examination of dozens of capsules, that W. muehlenbergiana provided the female parent for the new sporophyte, and that it was not uncommon for both the normal and the new-found sporophytes to occur on the same gametophyte (Fig. 2). The capsules were slightly smaller but of the same subglobose shape as those of W. muehlenbergiana (Figs. 2-3), and they shone as if varnished, like those of W. controversa. The seta usually measured more than 1 mm in length, and was thus intermediate between those of the presumptive parents. The operculum varied from erect to oblique. The line of dehiscence was well defined but nonfunctional (Fig. 6). 1 Millbrook, Ontario. This content downloaded from 207.46.13.109 on Sun, 24 Apr 2016 05:28:34 UTC All use subject to http://about.jstor.org/terms