Effect of burning alfalfa stubble for insect pest control on seed yield

Burning alfalfa (Medicago sativa (L.) stubble in the spring has been shown to be effective in reducing some insect pest populations. A study was conducted to detennine the long-tenn effect of this practice on seed yield. Plots were established at Lethbridge, Alberta, and burned in the spring or fall at various heights of plant growth from 1983 to 1989, with one half of each plot treated annually with insecticides when the pest insects were in their most vulnerable stage. Yields from burned treatments were not significantly different from unburned ones for the years 1983 to 1986, and 1988. In 1987, treatments burned in the fall had significantly higher yields than other treatments. Burning at 15-20 cm of growth significantly reduced yield compared to burning before spring growth. In 1989, yields from plots burned at 15-20 cm of growth were significantly lower than those burned every fall or spring. Insecticide treated plots had significantly higher yields in all years except 1983. Burning in the fall, or in the spring before growth, increased gross economic returns, but insecticide treatment gave the highest returns

A Comparison of Production and Soils in Modified Mixed Prairie Community

This study examined the effects of reseeding a Stipa-Agropyron- Bouteloua community to monocultures of crested wheatgrass (Agropyron cristatum (L.) Geartn.), Russian wild rye grass (Elymus junceus Fisch.), and wheat (Triticum aestivum L.) on above and below ground biomass and indicators of soil quality. Summer fallowed wheat produced 10817 kg ha-1 and 4090 kg ha-1 of above ground below ground biomass respectively whereas the native community produced 3191 kg ha-1 above ground and 13013 kg ha-1 of below ground biomass. However wheat, crested wheatgrass and Russian wildrye grass generally showed a lower biological index, phosphatase and dehydrogenase activity

Smoking and its effect on scar healing

Scar formation is influenced by several factors such as wound infection, tension, wound depth and anatomical localization. Hypertrophic scarring is often the result of an imbalance in the wound and scar healing process. The exact underlying pathophysiological mechanism remains unclear. Smoking has a higher risk of postoperative complications probably due to a diminished macrophage induction. Following our clinical impression that smokers without postoperative wound infections show esthetically better scars, we evaluated the scars after a reduction mammaplasty in smoking and nonsmoking patients in a prospective clinical trial. Between July 2006 and September 2007, 13 smokers and 30 non smokers with a reduction mammaplasty were included. They were recruited from Viecuri Medical Centre and Atrium Medical Centre in the Netherlands after written consent. Surgical data and data of the patients' condition were collected. Follow-up for erythema values of the scars was done with a colorimeter (The Minolta CR-300, Minolta Camera Co., Ltd., Osaka Japan) at 1, 3, 6 and 9 months postoperatively on four standardized postsurgical sites. ANOVA and Chi-square test were used for statistical analysis. In the smoking group, the scars were significantly less red compared to the nonsmoking group. No significant differences were found in BMI, resection weight and drain production between both groups. Although smoking is certainly not recommended as a preventive therapy to influence scar healing, this study confirms our assumption that smokers tend to have faster and less erythemateous scar healing to nonsmokers. Further research is needed to understand the mechanism of the effect of smoking on scars

Rhizosphere priming effects on soil carbon and nitrogen mineralization

Living roots and their rhizodeposits affect microbial activity and soil carbon (C) and nitrogen (N) mineralization. This so-called rhizosphere priming effect (RPE) has been increasingly recognized recently. However, the magnitude of the RPE and its driving mechanisms remain elusive. Here we investigated the RPE of two plant species (soybean and sunflower) grown in two soil types (a farm or a prairie soil) and sampled at two phenological stages (vegetative and mature stages) over an 88-day period in a greenhouse experiment. We measured soil C mineralization using a continuous 13C-labeling method, and quantified gross N mineralization with a 15N-pool dilution technique. We found that living roots significantly enhanced soil C mineralization, by 27-245%. This positive RPE on soil C mineralization did not vary between the two soils or the two phenological stages, but was significantly greater in sunflower compared to soybean. The magnitude of the RPE was positively correlated with rhizosphere respiration rate across all treatments, suggesting the variation of RPE among treatments was likely caused by variations in root activity and rhizodeposit quantity. Moreover, living roots stimulated gross N mineralization rate by 36-62% in five treatments, while they had no significant impact in the other three treatments. We also quantified soil microbial biomass and extracellular enzyme activity when plants were at the vegetative stage. Generally, living roots increased microbial biomass carbon by 0-28%, β-glucosidase activity by 19-56%, and oxidative enzyme activity by 0-46%. These results are consistent with the positive rhizosphere effect on soil C (45-79%) and N (10-52%) mineralization measured at the same period. We also found significant positive relationships between β-glucosidase activity and soil C mineralization rates and between oxidative enzyme activity and gross N mineralization rates across treatments. These relationships provide clear evidence for the microbial activation hypothesis of RPE. Our results demonstrate that root-soil-microbial interactions can stimulate soil C and N mineralization through rhizosphere effects. The relationships between the RPE and rhizosphere respiration rate and soil enzyme activity can be used for explicit representations of RPE in soil organic matter models. © 2014

Recovery of Vegetative Cover and Soil Organic Matter During Revegetation of Abandoned Farmland in a Semiarid Climate

Much of the farmland in the Canadian Prairie region has been abandoned over the years and allowed to revert to weedy cover and eventually to grassland. While some of the changes in vegetation during plant succession have been documented, limited information is available on changes in soil characteristics. The purpose of this study was to assess the vegetative cover and soil transformation under similar semiarid climatic conditions with an annual precipitation of about 310 mm on 3 sites abandoned in 1925, 1927, and 1950 as compared to adjacent native range. Total C and N, water-stable aggregates between 1.0 and 5.0 mm, and polysaccharide content increased, while chelating resin-extractable C, humic acid/fulvic acid ratios, caloric content of the rootmass, and dehydrogenase activity decreased in the successional sequence. Nevertheless, more than 55 years will be required to allow soil to return to native range standards under moderate grazing by livestock. Revegetated range may have to be subjected to lighter grazing pressures than usual to allow the vegetation to continue to increase its rootmass and thus the soil chemical properties. A hypothesis to explain changes in root- and top-mass ratios with time on the basis of the quality of soil nitrogen has been advanced.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202

Effect of forty-four years of grazing on fescue grassland soils

A grazing study was initiated in the foothills of southwestern Alberta on the rough fescue grasslands (Festuca campestris (Rydb.) in 1949 comparing various grazing intensities. In 1992, soil samples were obtained from the Ah horizon of paddocks grazed at 1.2 (light), 2.4 (heavy), and 4.8 (very heavy) animal unit month ha-1 and from an ungrazed exclosure (control). The thickness of the Ah horizon of the control averaged 22 cm while that of the lightly, heavily and very heavily grazed paddocks averaged 18, 12, and 8 cm, respectively. Soil color changed from 10YR 2/1 (black) to 10YR 4/3 (dark brown to brown) in response to very heavy grazing. Grazing pressures decreased the mean-weight diameter of water-stable aggregates, total C and P, monosaccharide content and the galactose + mannose/xylose + arabinose ratio, while it increased bulk density, pH-CaCl2, and total N. The loss of P must be viewed with concern. Treatment effects on most soil parameters were most pronounced at the two heavier grazing pressures. Particularly, the heavy grazing pressure jeopardized the sustainability of the ecosystem by reducing fertility and water-holding capacity.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202

Productivity of Russian Wildrye and Crested Wheatgrass and Their Effect on Prairie Soils

Crested wheatgrass (Agropyron cristatum (L.) Gaertn.) and Russian wildrye (Elymus junceus Fisch.) are used extensively as seeded pastures in the Prairie Provinces of Canada. Rangeland plowed in 1954 was planted to the 2 grasses in 1955. Herbage was harvested over a 25-year period, root weights were determined in 1977, and soil samples were obtained in 1965 and 1978 from the 2 seeded pastures and from adjacent native rangeland from each of 3 replicates. Forage production from the seeded pastures was greatest 4 years after seeding. Averaged over all years, crested wheatgrass yielded 113% more and Russian wildrye yielded 47% more forage than did native rangeland. Total root weight in the surface 15-cm layer of soil was greater on the native rangeland pasture than on the seeded pastures. Soils from native range pastures generally contained more organic carbon, less sodium, and had lower pH and sodium adsorption ratios than the soils from Russian wildrye pastures seeded 10 and 23 years before the soils were sampled. The organic C and pH's of the soils obtained from crested wheatgrass pastures decreased during the 23-year period while those of soils from the native range did not change.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202

Water-extractable organic matter from plant litter and soil of rough fescue grassland

Little is known about the chemical composition of throughfall, or the water that falls through, and drips from, the grass canopy of Rough Fescue Grassland during the grazing season. Water-extractable C, N, organic acids, and monosoccharides from litter and from soil in the upper 2 cm of the Ah horizon collected at monthly intervals in 1988 were at Stavely, Alberta. Rough fescue (Festuca campestris Rydb.) were stocked at tither light (1.2 AUM/ha) or very heavy (4.8 AUM/ha) fixed rates for 39 years or were ungrazed in exclosures located within each field for an equal period of time. At the high grazing intensity, the soil and litter N was less water-extractable. The C/N ratios of the water-extractable organic matter from litter and soil averaged 11.2 and 2.3, respectively. Soil monosaccharides were essentially not water-extractable. The quality of the litter as reflected by the water-extractable constituents often differed over the season between fields. Observations at regular time intervals are essential. The effect of the quality of leachates of litter on soil was not predictable. The 3 major long-chain fatty acids identified, palmitic, stearic, and arachidic acids, from soil in grasslands that are in good condition because of the low grazing pressure, could well contribute to the resistance of those grasslands to the encroachment of invading species.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202