The number one highest growth-limiting factor in Swedish forests is nitrogen, because of that fertilization often gives a significant growth increase, wherever you are in Sweden. Specific leaf area (SLA) can be used as a standard measurement of how much resources a tre has to use to build up light absorbing leaf area of needles/leaves. Since there is a strong linear relationship between tree growth and leaf area, there should also be a clear correlation between each leaf area of single trees and its diameter, basal area and volume growth (Xiao, 2005).The datamaterial for the study was collected at the forest estate, Toftaholm, near Ljungby in Kronoberg County (57 ° 0´N; 14 ° 3`E). Data were collected from birches growing in both in fertilized and unfertilized young stands of Birch during the growing season of 2018. The biomass sampling occured in May, July and August. At each occasion, samples were taken from 40 birches (a total of 120 samples were collected).The average value of SLA for all samples on the fertilized treatment was 17.33 m² / kg and 16.41 m² / kg for the non-fertilized treatment (Figure 4). The significance analysis obtained a p-value of 0.019 (Table 2), which confirms that there is a significant difference between the fertilized and the unfertilized treatment.In the significance analysis, it could be concluded that with a 95% probability, there is a significant difference between the comparison of all samples from the fertilized (G) and non-fertilized (OG) treatment.

This study compared the effects of nitrogen sources on the available inorganic soil nitrogen, nitrogen movement, nitrogen losses, and wheat yields when nitrogen fertilizers were applied to soil planted to drylond winter wheat at the Blue Creek Experimental Station in northern Utah. In the fall 1973 soil samplings, the fertilizers producing the largest mineral nitrogen contents in the 0-30 em soil depths were ammonium nitrate >ammonium sulfate > S-cooted urea, when they were broadcast at the practical rate of 56 kg N/ha. There was no increase in the mineral nitrogen at the deeper depths in the fall or at any depth in the following spring. Statistically, the three nitrogen sources did not increase grain yield significantly but did increase grain protein content and nitrogen content in grain. Ammonium nitrate and potassium bromide at the rates of 400 kg N and 200 kg Br/ha were broadcast to soil planted to winter wheat in October 1974. Nitrate-nitrogen and bromide distribution patterns in the soil profile looked alike in May 1975. These showed that their movements were similar. Considerable nitrate-nitrogen (35 percent of the added nitrogen) had moved down below the 120 em depth. The highest nitrate-nitrogen concentrations were found at the 45 to 90 em depth . There seems to be evidence that nitrate-nitrogen and bromide had moved deeper than the 150 em depth. Ammonia- nitrogen losses from nitrogen fertilized soils were conducted in the laboratory. Ammonium sulfate, ammonium nitrate, or urea applied to the soil surface lost ammonia-nitrogen differently. From noncalcareous soil, the ammonia-nitrogen loss was greatest from urea. From calcareous soil or soils receiving carbonates or high soil pH by the addition of sodium hydroxide solution, the greatest losses were from ammonium sulfate. High losses were favored by high temperatures and longer periods of moist soil. The total amounts of water lost from the soil was not closely related to the total ammonia-nitrogen loss during two weeks. No loss of ammonia-nitrogen occurred when nitrogen fertilizers were applied at a 2.5 em depth or deeper. The ammonia-nitrogen losses were also greatly reduced when nitrogen fertilizers applied to the soil surface was followed by irrigation or heavy rainfall. In the field, the higher temperatures increased the ammonia-nitrogen losses from ammonium sulfate, ammonium nitrate, and urea when applied to both a noncalcareous and a calcareous soil . However, the loss from calcareous soil was reduced by irrigation following fertilizer application. No ammonia-nitrogen was observed when ammonium sulfate was applied at a 2. 5 em soil depth, despite of the high soil temperature during the day time in moist soil. Rapid drying of the moist soil surface quickly reduced the losses per day.

Thesis (Ph.D.)--University of Delaware, 2007. / Principal faculty advisors: Patricia A. Martin-DeLeon and Deni S. Galileo, Dept. of Biological Sciences. Includes bibliographical references.

Thesis (M.S.)--University of Delaware, 2006. / Principal faculty advisor: Wallace G. Pill, Dept. of Plant & Soil Sciences. Includes bibliographical references.

Traditional methods of oocyte selection for in vitro studies have proven inefficient with respect to achieving a level of predictability for competency. In this study, a novel method of oocyte selection was implemented that identified a relationship between oocyte morphological parameters (as defined by a ratio of a shape factor (SF) to average fluorescence intensity (AFI) and AFI, followed by in vitro fertilization (IVF) and in vitro culture (IVC) using the Well of Well (WOW) method to evaluate oocyte competency. Specifically, we used non-cytotoxic fluorescent molecular probes and multiphoton microscopy to non-invasively characterize spatial localization and functional activity of mitochondria, mitochondrial membrane potential (Δψm), and intracellular calcium activity ([Ca2+]i) using rhodamine 123, JC-1 and Fluo-4, AM, respectively in bovine and canine in vitro matured (IVM) oocytes. Comparison of morphological grading with fluorescence intensity yielded similar trends between all grades of oocytes for both species with no visually obvious, distinct characteristic staining that would permit classification of each oocyte as a specific morphological grade. Our studies confirmed that oocyte mitochondria were homogeneously distributed but primarily localized to the peri- and sub-cortical regions of the oocyte at MII stage for both species. Further, heterogeneously polarized mitochondria were localized to the peri- and sub- cortical regions of the oocyte for both species. In bovine oocytes labeled with Fluo-4, AM, levels of [Ca2+]i were either unremarkable, or very low and limited to the peri-cortical areas, just beneath the oolema. For canine MII stage oocytes, levels of [Ca2+]i were within the same range of AFI as bovine. Ranges of fluorescence intensity compatible for optimal embryo development for bovine and optimal fertilization for canine oocytes were 30-300 and 20-35, and 20-30 and 20-25.5 for rhodamine 123 and Fluo-4, AM, respectively. The optimal range for bovine oocytes imaged with JC-1 was 1.25-2.25 and <6 for canine.

Chlorine is one of most common element on earth and it is essential in every living organism, but can also cause problems in the environment. Chlorine can exist both as inorganic (Clin) and organically bound (Clorg). Earlier was the common opinion that Clorg only occurs from anthropogenic sources, but the last years, research has shown that chlorine is a part of the biogeochemical cycle and Clorg also can have natural sources. Many chlorinated substances are poisonous, so the fact that they have a natural source created attention. Fertilizations with nitrogen in forest areas have shown unexpected consequences, such as an increase leakage of nitrogen to ground and surface water. Clear-cutting is a disturbance on the ecosystem and the environment is sensitive for disturbances. Because of the fact that both chlorine and fertilization can be environmental problems and that clear-cutting is a big disturbance in the nature, this study will investigate if there are changes of organic chlorine (Clorg) in soil water after clear-cutting and if fertilization with nitrogen has any influence on the concentration of Clorg. This study was made in a forest area in Värmland, Sweden (Hagfors). Chemical analyses were made in the laboratory though measuring AOX (absorbable organic halogens). The result of this study showed that clear-cutting probably has some effect on the Clorg concentration and that nitrogen doesn’t have any influence.

Prozessmodelle zur Ermittlung von Humusumsatz und Nährstoffdynamik des Bodens erfordern umfangreiche Eingangsdaten und konnten bisher nur im wissenschaftlichen Bereich eingesetzt werden. Der Bericht beschreibt eine stark vereinfachte Variante eines Prozessmodells, das auch mit reduzierter Datengrundlage genutzt werden kann. Das Modell CANDY Carbon Balance (CCB) berücksichtigt Standorteffekte und besitzt einen Bezug zum Kohlenstoff und zum Stickstoff im Boden. Unter Nutzung von Schlagkarteiaufzeichnungen kann das Modell auf Schlag- und Regionsebene die Humusreproduktion und die N-Mineralisation in chronologischer Abfolge berechnen. Dadurch werden Informationen zur Kontrolle und Lenkung der Bodenfruchtbarkeit und der Nährstoffeffizienz sowie zur Verbesserung der Düngebedarfsermittlung gewonnen. Das Modell ist für die Landwirtschaftsberatung und -verwaltung des konventionellen und ökologischen Ackerbaus geeignet.

PC4/PCSK4 is the major Proprotein Convertase (PC) enzyme that plays a key role in mammalian fertilisation. It is detected in the acrosomal granules of round spermatids, acrosomal ridges of elongated spermatids and sperm plasma membrane overlying the acrosome with K-X-K/X-R as its preferred cleavage motif. Such motifs are present in male germ cell proteins ADAMs, proPACAP and proIGF-1/2 and these precursor proteins are processed most likely by PC4 during spermatogenesis, sperm maturation and sperm-egg interaction. For fertilization to occur, the mature sperm must penetrate the Zona Pelucida (ZP) and bind to the egg. Previously, PC4 null mouse sperm and wild type sperm treated with a specific PC4-inhibitor have shown to reduced abilities to penetrate the cumulus mass, bind to ZP and fertilize eggs. These findings suggest that sperm-PC4 plays an important role in fertilization and hence regulation of its activity is crucial for successful fertilization. But how PC4 activity is regulated in vivo is not yet clear. Recently, in epididymal fluid a serpin (serine protease inhibitor) called CRES has been described but the protease linked to this serpin in epididymis has not been identified. However in endocrine cells where CRES is also expressed, it inhibits PC2 enzyme. Thus based on localization and preliminary study, we propose that PC4 is the target enzyme for CRES in the reproductive tract. During sperm migration and storage in epididymis, sperm PC4 activity may be modulated by CRES so that premature sperm activation may not occur. Our data showed that CRES inhibits PC4 both in vitro (with IC50 in µM range) as well as ex vivo in human placenta trophoblast cell lines. Moreover CRES was found to be cleaved by PC4 suggesting a Serpin-Protease binding type of mechanism in the inhibition of protease activity. Taken together, we conclude that CRES regulates PC4 activity in reproductive tract crucial for mammalian fertilization.

Seit 1990 wird in Sachsen auf landwirtschaftlichen Dauertestflächen der Nitratgehalt im Frühjahr und im Herbst gemessen. Aus den gleichzeitig erhobenen Bewirtschaftungsdaten kann mit dem Modell REPRO der potenzielle Nitrataustrag unterhalb der durchwurzelbaren Bodenzone abgeschätzt werden. Im Ergebnis zeigt sich, dass weiterhin, vor allem in Trockengebieten in Nordsachsen, mit teilweise hohen Nitratkonzentrationen gerechnet werden muss. Die Düngungsauflagen in Wasserschutzgebieten bewirken sowohl geringere Stickstoffsalden als auch abnehmende Nitratgehalte im Boden. Auf ökologisch bewirtschafteten Flächen war die auswaschungsgefährdete Nitratmenge sehr gering.

Increased development in Canadas northern environments has increased the need for accurate methods to detect adverse impacts on tundra ecosystems. Ammonium nitrate is a common water pollutant associated with many industrial and municipal activities, including diamond mining, and is of special concern due to the toxicity of ammonia in aquatic systems. One solution to reduce exposure of sensitive aquatic systems to nitrogenous compounds is to atomize (atmospherically disperse in fine particles) contaminated water over the arctic tundra which will reduce N loading to surface water. However, the toxicity of ammonium nitrate to arctic soils is poorly understood. In this study I investigate the potential toxicity of ammonium nitrate solutions to arctic soil functions such as carbon mineralization, nitrification and plant growth, to determine concentrations that can be applied without causing significant inhibition to these processes. <p>Arctic ecosystems are based on a soil type termed a cryosol that has an underlying permafrost layer. Often these soils are subject to cryoturbation, a process which heaves and mixes the soil, bringing the mineral horizons to the surface. I hypothesized that phytotoxicity test results in arctic soils would be highly variable compared to other terrestrial ecosystems due to the cryoturbation process and subsequent range of soil characteristics. The variability associated with phytotoxicity tests was evaluated using Environment Canadas standardized plant toxicity test in three cryoturbated soils from Canadas arctic exposed to a reference toxicant, boric acid. The phytotoxicity of boric acid to northern wheatgrass (<i>Elymus lanceolatus </i>) in cryosols was much greater than commonly reported in other soils, with less than 150 ug boric acid g-1 soil needed to inhibit root and shoot growth by 20%. There was also large variability in the phytotoxicity test results, with coefficients of variation for 10 samples ranging from 160 to 79%. Due to this variability in cryoturbated arctic soils, more than 30 samples should be collected from each control and potentially impacted area to accurately assess contaminant effects, and ensure that false negatives of toxicant impacts in arctic soils are minimized. <p>To characterize the toxicity of ammonium nitrate I exposed a variety of arctic soils and a temperate soil to different concentrations of ammonium nitrate solution over a 90 day time period. Dose responses of carbon mineralization, nitrification and phytotoxicity test parameters were estimated for ammonium nitrate applications. In addition to direct toxicity, the effect of ammonium nitrate on ecosystem resistance was investigated by dosing nitrogen impacted soils with boric acid. Ammonium nitrate solutions had no effect on carbon mineralization activity, and affected nitrification rates in only one soil, a polar desert soil from Cornwallis Island. In contrast, ammonium nitrate applications (43 mmol N L-1 soil water) significantly impaired seedling emergence, root length and shoot length of northern wheatgrass. Concentrations of ammonium nitrate in soil water that inhibited plant parameters by 20% varied between 43 to 280 mmol N L-1 soil water, which corresponds with 2,100 to 15,801 mg L-1 in the application water. Arctic soils were more resistant to ammonium nitrate toxicity than the temperate soil under these study conditions. However, it is not clear if this represents a general trend for all polar soils, and because nitrogen is an essential macro-nutrient, nitrogenous toxicity should likely be considered a special case for soil toxicity. As soil concentrations could be maintained under inhibitory levels with continual application of low concentrations of ammonium nitrate over the growing season, atomization of wastewater contaminated with ammonium nitrate is a promising technology for mitigation of nitrogen pollution in polar environments. <p>Increased development in Canadas northern environments has increased the need for accurate methods to detect adverse impacts on tundra ecosystems. Ammonium nitrate is a common water pollutant associated with many industrial and municipal activities, including diamond mining, and is of special concern due to the toxicity of ammonia in aquatic systems. One solution to reduce exposure of sensitive aquatic systems to nitrogenous compounds is to atomize (atmospherically disperse in fine particles) contaminated water over the arctic tundra which will reduce N loading to surface water. However, the toxicity of ammonium nitrate to arctic soils is poorly understood. In this study I investigate the potential toxicity of ammonium nitrate solutions to arctic soil functions such as carbon mineralization, nitrification and plant growth, to determine concentrations that can be applied without causing significant inhibition to these processes. <p>Arctic ecosystems are based on a soil type termed a cryosol that has an underlying permafrost layer. Often these soils are subject to cryoturbation, a process which heaves and mixes the soil, bringing the mineral horizons to the surface. I hypothesized that phytotoxicity test results in arctic soils would be highly variable compared to other terrestrial ecosystems due to the cryoturbation process and subsequent range of soil characteristics. The variability associated with phytotoxicity tests was evaluated using Environment Canadas standardized plant toxicity test in three cryoturbated soils from Canadas arctic exposed to a reference toxicant, boric acid. The phytotoxicity of boric acid to northern wheatgrass (<i>Elymus lanceolatus </i>) in cryosols was much greater than commonly reported in other soils, with less than 150 ug boric acid g-1 soil needed to inhibit root and shoot growth by 20%. There was also large variability in the phytotoxicity test results, with coefficients of variation for 10 samples ranging from 160 to 79%. Due to this variability in cryoturbated arctic soils, more than 30 samples should be collected from each control and potentially impacted area to accurately assess contaminant effects, and ensure that false negatives of toxicant impacts in arctic soils are minimized. <p>To characterize the toxicity of ammonium nitrate I exposed a variety of arctic soils and a temperate soil to different concentrations of ammonium nitrate solution over a 90 day time period. Dose responses of carbon mineralization, nitrification and phytotoxicity test parameters were estimated for ammonium nitrate applications. In addition to direct toxicity, the effect of ammonium nitrate on ecosystem resistance was investigated by dosing nitrogen impacted soils with boric acid. Ammonium nitrate solutions had no effect on carbon mineralization activity, and affected nitrification rates in only one soil, a polar desert soil from Cornwallis Island. In contrast, ammonium nitrate applications (43 mmol N L-1 soil water) significantly impaired seedling emergence, root length and shoot length of northern wheatgrass. Concentrations of ammonium nitrate in soil water that inhibited plant parameters by 20% varied between 43 to 280 mmol N L-1 soil water, which corresponds with 2,100 to 15,801 mg L-1 in the application water. Arctic soils were more resistant to ammonium nitrate toxicity than the temperate soil under these study conditions. However, it is not clear if this represents a general trend for all polar soils, and because nitrogen is an essential macro-nutrient, nitrogenous toxicity should likely be considered a special case for soil toxicity. As soil concentrations could be maintained under inhibitory levels with continual application of low concentrations of ammonium nitrate over the growing season, atomization of wastewater contaminated with ammonium nitrate is a promising technology for mitigation of nitrogen pollution in polar environments.