Soil compaction effects on soil bulk density and penetration resistance and growth of spring barley (Hordeum vulgare L.)

Abstract

The weight of the tractor is not the only factor affecting soil compaction. Soil-management practices, such as the use of fertilizers and pesticides, also affect soil properties through an increased number of overriding. The aim of the current study was to investigate compaction effects on soil physical properties, such as dry bulk density and penetration resistance, and the growth of spring barley (Hordeum vulgare L.) as a monoculture. The five-year experiment was conducted on the Estonian University of Life Sciences’ research field at Eerika, near Tartu in 2001–2005. The soil of the experimental site is sandy loam Stagnic Luvisol. The treatments included were no compaction, one pass, three passes, and six passes. All passes were track-by-track. Measurements of soil and plant were made in the earing phase of barley and measurements of yield in the maturity phase of barley. The compaction treatment was conducted using an MTZ-82 tractor (total weight 4.84 Mg). Neither fertilizers nor herbicides were used. 5 years after compaction distinguishable subsoil and topsoil compaction was detected. Soil deformation increases with the number of passes; in the case of six passes soil bulk density increased by 0.15 Mg m^?3 and penetration resistance by 3 MPa. However, there were no significant differences in the soil bulk density and penetration resistance between treatments compacted with one and three passes. The effect of compaction on soil bulk density was higher when the soil was compacted under wet conditions. Compaction decreased the quantity of barley shoots, their phytomass, and grain yield by more than 80%. In the second year of the experiment the dry weight of above ground biomass decreased by almost three times and shoots’ density by 1.5 times, compared with the first year results. In the third year of the experiment the biomass, plant density, and grain yield of barley were stabilized and no further decreases were detected in the following two experimental years. The results from the experiment revealed that even a low weight tractor can induce subsoil compaction and a high decrease of plant productivity by repeated passes over time.     

Versuche mit Herbiziden in Waid Isatis tinctoria L. in Thüringen

Between 2002 and 2006 seven experiments with different herbicides were carried out in woad in two Thuringian experimental stations. The objective of these tests was to get the required data for the approval procedure according to the regulations of §§?18?a and?b PflSchG. The tests showed the applicability of some herbicides for the weed control in woad. Because of the possible use of woad for pharmaceutical purposes in the future investigations with dried leaves and roots of woad were carried out with the objective of getting data of the residues of active compounds in the plant materials. The results of the tests have shown that the maximum residue level for some active compounds can be exceeded. At the current situation of woad cultivation further herbicide tests in this crop are not intended.     

Phosphorus supply and cycling at long-term forest monitoring sites in Germany

In this study, the supply and input–output balances of phosphorus (P) were investigated for a 10-year-period at 85 long-term monitoring sites in German forest ecosystems under the European Level II programme. These sites encompass 23 European beech (Fagus sylvatica L.) stands, 9 oak stands comprised of common oak (Quercus robur L.) and/or sessile oak (Quercus petraea Liebl.), 20 Scots pine (Pinus sylvestris L.) and 33 Norway spruce (Picea abies H.Karst.) stands. We quantified P concentrations in needles and leaves, P inputs from the atmosphere, P outputs through leaching and harvesting, and total P in the soil and humus layers. The P concentrations in European beech leaves from two sites (>1 mg P g⁻¹ dry weight), and in Norway spruce needles from four sites (>1.2 mg P g⁻¹ dry weight), were deficient over several years. In contrast, the oak and Scots pine sites were well supplied with P. When P removal through harvesting was disregarded, P balances were positive or stable (median 0.21 kg P ha⁻¹ a⁻¹). With harvesting, balances were mostly negative (median −0.35 kg P ha⁻¹ a⁻¹), with long-term P removal from the forest ecosystems.     

COMPARISON BETWEEN PROTON MAGNETIC RESONANCE SPECTROSCOPY FINDINGS IN DOGS WITH TICK‐BORNE ENCEPHALITIS AND CLINICALLY NORMAL DOGS

In vivo diagnosis of tick‐borne encephalitis is difficult due to high seroprevalence and rapid viral clearance, limiting detection of antibodies in blood and cerebrospinal fluid. Magnetic resonance imaging (MRI) characteristics of tick‐borne encephalitis have been reported, however MRI studies can also be negative despite the presence of neurologic signs. Magnetic resonance spectroscopy (¹H MRS) is an imaging method that provides additional information about the metabolic characteristics of brain tissues. The purpose of this retrospective cross‐sectional study was to describe brain metabolites using short echo time single‐voxel ¹H MRS in dogs with confirmed tick‐borne encephalitis and compare them with healthy dogs. Inclusion criteria for the affected dogs were neurological symptoms suggestive of tick‐borne encephalitis, previous endemic stay and tick‐bite, diagnostic quality brain MRI and ¹H MRS studies, and positive antibody titers or confirmation of tick‐borne encephalitis with necropsy. Control dogs were 10, clinically normal beagles that had been used in a previous study. A total of six affected dogs met inclusion criteria. All dogs affected with tick‐borne encephalitis had ¹H MRS metabolite concentration alterations versus control dogs. These changes included mild to moderate decreases in N‐acetyl aspartate and creatine peaks, and mild increases in glutamate/glutamine peaks. No lactate or lipid signal was detected in any dog. Myoinositol and choline signals did not differ between affected and control dogs. In conclusion, findings supported the use of ¹H MRS as an adjunctive imaging method for dogs with suspected tick‐borne encephalitis and inconclusive conventional MRI findings.     

Comparative measurements on ruminal pH-value in cattle

Subacute rumen acidosis (SARA) of ruminants is an important factor in terms of animal health, especially in high yielding cattle. In order to find an accurate method to determine the ruminal pH-value, three methods using eight rumen cannulated cattle were compared. An indwelling measuring unit (sensor) was used for continuous measurement of the ruminal pH-value. These results were compared to the pH-values of samplings via rumen fistula and to the results of samplings via oral stomach tube. Due to the different rations, mean pH-value of trial 1 (average of all methods) was 6.64 +/- 0.37 (hay ad lib., 2 kg concentrate/ animal) and 6.24 +/- 0.36 for trial 2 (75% maize silage, 1 kg hay, 2 kg soybean meal). In trial 1 no statistically significant differences between all methods could be observed. Under more acidic ruminal conditions of trial 2 all methods differed significantly (p < 0.05). In the lower pH-range of trial 2, a difference of 0.32 that data can be collected continuously. The sensor system was evaluated by a comparison with standardized pH-dilutions (pH 4, pH 7). The sensor system has proven to be an accurate and reliable instrument (r = 0.9984) and it represents an innovative system for answering scientific questions in terms of rumen physiology and rumen pathology.     

Sensitivity and specificity of fasting ammonia and serum bile acids in the diagnosis of portosystemic shunts in dogs and cats

Background: Portosystemic shunt (PSS) is the most common cause of hepatic encephalopathy in dogs and cats. Fasting ammonia and serum bile acids (SBA) are used to diagnose PSS, but their true sensitivity and specificity have not been fully evaluated, especially in cats. Objectives: The purpose of this study was to determine the diagnostic accuracy of fasting ammonia and SBA concentrations in the diagnosis of PSS in dogs and cats and to compare diagnostic accuracy between species. Methods: A retrospective analysis of data from 373 dogs and 85 cats presented to the clinic from 1996 to 2006 was carried out. Based on clinical, laboratory, and imaging findings, animals were grouped as having PSS, parenchymal hepatic disease, or extrahepatic disease. The sensitivity and specificity of ammonia and SBA concentrations for the diagnosis of PSS were calculated and receiver‐operating characteristic analysis was used to optimize cut‐offs. Results: Using the upper limit of laboratory reference intervals (ammonia, 59 μmol/L; SBA, 20 μmol/L), the sensitivity and specificity of ammonia was 85% and 86% in dogs, and 83% and 76% in cats, respectively. The sensitivity and specificity of SBA was 93% and 67% in dogs, and 100% and 71% in cats, respectively. Using optimal cut‐off points for ammonia (dogs, 57 μmol/L; cats, 94 μmol/L) the sensitivity and specificity was 91% and 84% in dogs and 83% and 86% in cats, respectively. Using optimal cut‐off points for SBA (dogs, 58 μmol/L; cats, 34 μmol/L) the sensitivity and specificity was 78% and 87% in dogs and 100% and 84% in cats. Conclusion: Increased fasting ammonia and SBA concentrations are accurate indicators of PSS. An improvement in diagnostic accuracy can be achieved by using defined optimal cut‐off points for the selective diagnosis of PSS.     

Deconjugation and degradation of flavonol glycosides by pig cecal microbiota characterized by Fluorescence in situ hybridization (FISH)

As the bioavailability of flavonoids is influenced by intestinal metabolism, we have investigated the microbial deconjugation and degradation of several flavonols and flavonol glycosides using the pig cecum in vitro model system developed in our group. For this model system the microbiota was directly isolated from the cecal lumen of freshly slaughtered pigs. The characterization of the cecal microbiota by fluorescence in situ hybridization (FISH) with 16S rRNA-based oligonucleotide probes confirmed the suitability of the model system for studying intestinal metabolism by the human microbiota. We have investigated the microbial degradation of quercetin-3-O-beta-d-rutinoside 1, quercetin-3-O-beta-d-glucopyranoside 2, quercetin-4'-O-beta-d-glucopyranoside 3, quercetin-3-O-beta-d-galactopyranoside 4, quercetin-3- O-beta-d-rhamnopyranoside 5, quercetin-3- O-[alpha-l-dirhamnopyranosyl-(1-->2)-(1-->6)-beta-d-glucopyranoside 6, kaempferol-3-O-[alpha-l-dirhamnopyranosyl-(1-->2)-(1-->6)-beta-d-glucopyranoside 7, apigenin 8, apigenin-8- C-glucoside (vitexin) 9, and feruloyl-O-beta-d-glucopyranoside 10 (100 microM), representing flavonoids with different aglycones, sugar moieties, and types of glycosidic bonds. The degradation rate was monitored using HPLC-DAD. The flavonol O-glycosides under study were almost completely metabolized by the intestinal microbiota within 20 min and 4 h depending on the sugar moiety and the type of glycosidic bond. The degradation rates of the quercetin monoglycosides showed a clear dependency on the hydroxyl pattern of the sugar moiety. The degradation of 2 with all hydroxyl groups of the glucose in the equatorial position was the fastest. The intestinal metabolism of di- and trisaccharides was much slower compared to the monoglycosides. The structure of the aglycone has not much influence on the intestinal metabolism; however, the type of glycosidic bond ( C- or O-glycoside) has substantial influence on the degradation rate. The liberated aglycones were completely metabolized within 8 h. Phenolic compounds such as 3,4-dihydroxyphenylacetic acid 12, 4-hydroxyphenylacetic acid 13, and phloroglucinol 18 were detected by GC-MS as main degradation products.     

Influence of growth temperature on content, viscosity and relative molecular weight of water-soluble β-glucans in barley (Hordeum vulgare L.)

β-Glucan content and viscosity of water-soluble β-glucans have a considerable impact on the digestion of barley. Eight different 2-row barley (Hordeum vulgare L.) cultivars were grown in controlled environment chambers at five different temperatures until maturity. The samples were pearled, milled and analysed for their content of total, insoluble and soluble β-glucan. The water-soluble fraction was extracted at 37 °C, subjected to amylase treatment and freeze-dried. Water-soluble crude β-glucans were solubilised in distilled water, analysed for viscosity and their purity was checked by nuclear magnetic resonance. Molecular weights were profiled by size exclusion chromatography with RI detection. The content of total β-glucan varied from 4.0% to 7.4%, and was significantly affected by the growth temperature. An interaction between cultivar and growth temperature was observed for the total β-glucan content. The extractability was significantly affected by growth temperature, as there was recorded an increasing amount of water-soluble β-glucan with increasing growth temperature. Both the viscosity and the molecular weight of the water-soluble β-glucans increased with the growth temperature.