Exchangeable potassium and potassium balances in organic crop rotations on a coarse sand

Abstract. Crops on sandy soils (<5% clay) are exposed to K deficiency due to the small release and high leaching losses of K. Reliable tools are needed to improve the K management in cropping systems with limited K input, such as organic farming where import of nutrients are restricted according to the EC regulations. We investigated K balances and exchangeable K (K_exch) changes in an organic crop rotation experiment. Potassium leaching decreased from 42 kg ha⁻¹ in 1998/99 to 21 kg ha⁻¹ in 2000/01 as an average of a crop rotation (spring barley, grass-clover, winter wheat and pea/barley) with manure application and without catch crops. In the same period, spring K_exch decreased from 5.0 to 3.0 mg K 100 g soil⁻¹ (0–20 cm). The retention of the straw K left in the field after harvest increased with decreasing levels of K_exch. The cereal crops did not respond to K application but in the pea/barley mixture the pea yield increased by 46%. The concordance between measured K balances and changes in K_exch was weak. Exchangeable K is suitable as a tool for K management on a rotational basis, and a K_exch above 3 mg 100 g soil⁻¹ in the autumn should be avoided to minimize K leaching.     

Repeated administrations of adrenocorticotropic hormone during gestation in gilts: Effects on growth, behaviour and immune responses of their piglets

This study investigated whether repeated administrations of adrenocorticotropic hormone (ACTH) during mid or late gestation, a treatment which induces endogenous cortisol release, affect growth performance, early vitality, open-field behaviour and immune responses of neonatal pigs. Administrations of ACTH (100 IU per animal, Synacthen^® Depot) were given intramuscularly to gilts every second day either during mid (Day 49 until 75, Experiment 1) or late gestation (Day 85 until 107, Experiment 2). Control gilts received repeated injections of saline. The repeated ACTH stimulation of gilts during late gestation significantly reduced their daily weight gain during this period, but not when applied during mid gestation. Gestation length, number of born piglets and vitality measures of the newborn piglets, such as the rectal temperatures after birth and times elapsed between birth and first udder contact or milk uptake were not affected by the prenatal treatments. Administration of ACTH during late but not during mid gestation significantly increased the birth weights of piglets, and this difference in postnatal body weight was detectable until an age of 21 days. In addition, only the stimulation with ACTH during late gestation had an immunosuppressive effect on the lymphocyte proliferation of piglets 1 day after birth in response to the T-cell mitogen ConA and, in tendency, on the proliferation in response to the B-cell mitogen LPS. Twenty-four day old piglets from gilts treated during late gestation showed significantly more escape behaviour in an open-field than piglets from control litters. In conclusion, elevated maternal glucocorticoid levels during critical periods of prenatal development in pigs may affect prenatal growth, cell-mediated immunity and emotional reactivity in the neonatal piglets. The occurrence of these effects depends on the timing of increased maternal cortisol levels during gestation.     

Identification of Landscape Elements Related to Local Declines of a Boreal Grey-sided Vole Population

Several studies indicate a long-term decline in numbers of different species of voles in northern Fennoscandia. In boreal Sweden, the long-term decline is most pronounced in the grey-sided vole (Clethrionomys rufocanus). Altered forest landscape structure has been suggested as a possible cause of the decline. However, habitat responses of grey-sided voles at the landscape scale have never been studied. We analyzed such responses of this species in lowland forests in Västerbotten, northern Sweden. Cumulated spring densities representing 22 local time series from 1980–1999 were obtained by a landscape sampling design and were related to the surrounding landscape structure of 2.5×2.5 km plots centred on each of the 22 1-ha trapping plots. In accordance with general knowledge on local habitat preferences of grey-sided voles, our study supported the importance of habitat variables such as boulder fields and old-growth pine forest at the landscape scale. Densities were negatively related to clear cuts. Habitat associations were primarily those of landscape structure related to habitat fragmentation, distance between habitat patches and patch interspersion rather than habitat patch type quantity. Local densities of the grey-sided vole were positively and exponentially correlated with spatial contiguity (measured with the fragmentation index) of old-growth pine forest, indicating critical forest fragmentation thresholds. Our results indicate that altered land use might be involved in the long-term decline of the grey-sided vole in managed forest areas of Fennoscandia. We propose two further approaches to reveal and test responses of this species to changes in landscape structure.     

Effects of grazing strategy on limiting nitrate leaching in grazed grass‐clover pastures on coarse sandy soil

Urinations of ruminants on grazed pastures increase the risk of nitrate leaching. The study investigated the effect of reducing the length of the grazing season on nitrate leaching from a coarse sandy, irrigated soil during 2006–2007 and 2007–2008. In both years, precipitation was above the long‐term mean. The experiment was initiated in a 4‐yr‐old grass‐clover sward in south Denmark. Three treatments were as follows grazing only (G), spring cut followed by grazing (CG) and both spring and autumn cuts with summer grazing (CGC). Nitrate leaching was calculated by extracting water isolates from 80 cm depth using ceramic suction cups. Because of considerable variation in measured nitrate concentrations, the 32 installed suction cups per treatment were insufficient to reveal differences between treatments. However, weighted nitrate leaching estimations for G, CG and CGC showed estimated mean nitrate N concentrations of 23, 19 and 13 mg/L for an estimated proportion area occupied by urine patches of 0.33, 0.26 and 0.16, respectively. Thus, N concentrations in G and CG exceeded the EU limit of 11.3 mg N/L. Under the prevailing conditions, the time of urination did not appear important. The estimated background leaching calculated from suction cups presumably not situated under urine patches resulted in mean nitrate N concentrations of 2.6 mg/L.     

Screening for periodontal disease in research dogs - a methodology study

Background

It has been shown that the prevalence of both clinical attachment loss (CAL) ≥1 mm and pocket probing depth (PPD) ≥4 mm is relatively high even in younger dogs, but also that only a minority of the dogs have such clinical signs of periodontal disease (PD) in more than a few teeth. Hence, a minority of dogs carry the major PD burden. These epidemiological features suggest that screening for PD in larger groups of dogs, allowing for rapid assessment of treatment planning, or for the selection of dogs with or without PD prior to be included in experimental trials, should be possible. CAL is the central variable in assessing PD extent and severity while PPD is the central variable used in treatment planning which make these two variables obvious in a screening protocol with the dual aim of disease identification and treatment planning. The main purpose of the present study in 98 laboratory Beagle dogs was to construct a fast, simple and accurate screening tool, which is highly sensitive for the identification of dogs with PD.

Results

Examination of the maxillary P4, P3, P2, I1 and C would, in this population, result in the identification of 85.5% of all dogs and 96% of all teeth positive for CAL ≥1 mm, and 58.9% of all dogs and 82.1% of all teeth positive for PD ≥4 mm.Examination of tooth pairs, all C’s, maxillary I2, M2 and the mandibular P4 would, in this population result in identification of 92.9% of all dogs and 97.3% of all teeth positive for PD ≥4 mm, and 65.5% of all dogs and 83.2% of all teeth positive for CAL ≥1 mm. The results presented here only pertain to the present study population.

Conclusions

This screening protocol is suitable for examination of larger groups of laboratory Beagle dogs for PD and our findings indicate that diseased dogs are identified with a high degree of sensitivity. Before this screening can be used in clinical practice, it has to be validated in breeds other than Beagle dogs and in populations with larger age variation.     

Factors (type,colour, density,and shape) determining the removal of marine plastic debris by seabirds from the South Pacific Ocean: Is there a pattern?

1. While floating near the sea surface plastic debris interacts with a number of external factors, including many different organisms. Seabirds have the most extensive documented history of interactions with plastics, through ingestion, entanglement, and nest construction.
2. In the present study, eight seabird species from the South Pacific Ocean were used as a proxy to determine potential patterns of removal of marine plastic debris, and three hypotheses were tested in relation to their feeding habits and nesting areas.
3. Plastics from abiotic compartments (Chilean continental coast, South Pacific Gyre, and Rapa Nui beaches) and biotic compartments (surface-feeding seabirds, diving seabirds, and nesting areas) were compared, according to their type, colour, shape, and density.
4. Continental beaches had a relatively wide range of colours and shapes, with many non-buoyant plastics. Samples from the South Pacific Gyre (SPG) and Rapa Nui (Easter Island) beaches comprised mainly hard, rounded, buoyant, and white/grey plastics.
5. These results indicate that the composition of floating plastics from terrestrial sources changes during transport with oceanic currents, reducing the proportion of prey-like plastics present in the subtropical gyres.
6. The stomach contents of surface-feeding and diving seabirds were dominated by hard, white/grey, and round plastic items, similar to plastics from the SPG, suggesting non-selective (accidental or secondary) ingestion.
7. Nesting areas had a more variable composition of brightly coloured plastics, suggesting a pattern of selective removal of plastics by seabirds, probably from oceanic sources.
8. The present study reveals extensive interactions of seabirds with plastics on a broader scale, which is highly relevant given that the impacts of plastics on seabirds are increasing worldwide, compromising their efficient conservation.

     

Forms and plant-availability of sulfur in cattle and pig slurry

The contribution of animal slurry to the supply of S to plants was studied. The total-S content of cattle and pig slurry was significantly correlated to DM and nitrogen content and was composed of sulfide, sulfate and C-bonded S. During 42 weeks of storage sulfate concentrations decreased and sulfide and C-bonded S concentrations increased. In a pot experiment plant-availability of S in slurry was found to be low, 5 to 7% of total-S.     

Methanol in Normal Human Breath

Free methanol has been detected and measured, by gas-liquid chromatography, in the breath of several normal, healthy humans. It is suggested that this is a metabolic product rather than the result of diet or intestinal bacterial decomposition although there seems to be no biochemical reason for its presence.