Pinus contorta growth in northern Sweden as affected by soil scarification

The aim of this study was to quantify the effects of different soil scarification methods on tree growth. Soil scarification influenced stem volume and stem biomass yield of lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.) in a 17-year-old field trial in boreal Sweden. Soil scarification (disc trenching, mounding and ploughing) resulted in an average stem volume yield of 3.1 and 34.2 m³ ha^–1 on the poor and intermediate sites, respectively, while corresponding values for no soil scarification were 0.9 and 16.7 m³ ha^–1. In comparison to no scarification, ploughing increased volume yields by 500% on the poor site and by 200% on the intermediate sites. The ranking according to stem volume yield was ploughing > disc trenching = mounding no soil scarification. Averaged over the two sites, the mean annual increment of stem biomass was 219% and 145% higher (in d.w., 0.26 kg and 0.34 kg per sample tree) after ploughing compared with no soil scarification, for the average and dominant sample trees, respectively. Although not significant, the increased growth rate after soil scarification decreased the average stem basic wood density of the sample trees with 1.6% and 5.3%, at the poor and intermediate sites, respectively. In conclusion, soil scarification significantly increased the 17-year stem volume yield compared with no scarification. The results also indicate that the difference in stem biomass yield between ploughing and the other methods, especially no soil scarification, will increase even more in the near future.     

Immunisation of mice against neosporosis with recombinant NcSRS2 iscoms

The coccidian parasite Neospora caninum is an intracellular protozoan, causing abortion in cattle in many countries around the world. In this study, the protective potential of the major N. caninum surface antigen NcSRS2, expressed in Escherichia coli and formulated into immunostimulating complexes (iscoms), was investigated in an experimental mouse model. The recombinant protein was specially designed for binding to iscoms via biotin-streptavidin interaction. Two groups of 10 BALB/c mice were immunised twice, on days 0 and 28 with iscoms containing either the recombinant NcSRS2 (NcSRS2 iscoms) or similar iscoms with NcSRS2 substituted by an unrelated recombinant malaria peptide (M5) as a control (M5 iscoms). A third group of 10 age-matched BALB/c mice served as an uninfected control group. Immunisation with recombinant NcSRS2 iscoms resulted in production of substantial antibody titres against N. caninum antigen, while the mice immunised with M5 iscoms produced only very low levels of antibodies reacting with N. caninum antigen. After challenge infection with N. caninum tachyzoites on day 69, mice immunised with NcSRS2 iscoms showed only mild and transient symptoms, whereas the group immunised with M5 iscoms showed clinical symptoms until the end of the experiment at 31 days post inoculation. A competitive PCR assay detecting Nc5-repeats was applied to evaluate the level of parasite DNA in the brain. The amount of Nc5-repeats in the group vaccinated with NcSRS2 iscoms was significantly lower than in the control group given M5 iscoms. In conclusion, it was found that the recombinant NcSRS2 iscoms induced specific antibodies to native NcSRS2 and immunity sufficient to reduce the proliferation of N. caninum in the brains of immunised mice.     

Laminar growth of ultrathin metal films on metal oxides: Co on hydroxylated alpha-Al2O3(0001)

Metals deposited in vacuum on metal oxides such as alumina normally grow as three-dimensional clusters because of weak adatom-substrate interactions. This tendency hinders our ability to form interfaces of ultrathin, laminar metal films on oxides for use in microelectronics and other technologies where nanostructural control is desired. We present experimental and theoretical results showing that room temperature Co deposition on fully hydroxylated clean sapphire (alpha-Al2O3) produces a surface chemical reaction that leads to laminar growth, despite a large mismatch in lattice constants. This process should be applicable to a wide range of metals and metal oxides.     

Comparative studies of radionuclides from global fallout and local sources in ground level air and sewage sludge

The presence of activation products in the environment released to the air from a nuclear power station has been studied in sewage sludge and ground level air. The measured time variation of the ⁶⁰,Co concentration in sludge and ground level air was found to be in good agreement with the reported variation in release rate to the air from the power station when the prevalent wind direction is taken into account. The ratio between the ⁷,Be normalized concentration in sludge and ground level air was studied and was found to be about 1 for radionuclides due to global fallout but less than 2 · 10^?3, for ⁶⁰,Co. Our conclusion is that ⁶⁰,Co spreads from a local source (a nuclear power station) and to a considerable degree is dry deposited on the ground and then washed off by rain.     

Control of radiation-induced emesis with promethazine, cimetidine, thiethylperazine, or naloxone

Promethazine (2 mg/kg), cimetidine (4 mg/kg), thiethylperazine (0.86 mg/kg), and naloxone (0.08 mg/kg) were each evaluated for their ability to increase the threshold of radiation-induced emesis in the dog. Each dog was fed a can of dog food (ca 0.4 kg) and then injected IM with the appropriate drug 1 hour before being irradiated by a 60Co teletherapy unit. The total radiation dose given an individual dog was determined by an up-and-down exposure schedule. Dogs were then observed continuously for 10 hours while the number, time of onset, and duration of each emetic episode were monitored. The dose of radiation causing emesis in 50% (ED50 +/- SEM) of control dogs was 170 +/- 38.5 rad. The ED50 +/- SEM was increased to 402 +/- 18.6 rad by promethazine, to 331 +/- 27.3 rad by cimetidine, and to 320 +/- 38.5 rad by thiethylperazine. This increased tolerance was significant at P less than 0.05 for each drug. The ED50 for naloxone was 262.5 +/- 92.9 rad, which was not a statistically significant increase in threshold.     

Calculation of radionuclide ground deposition by means of measurements on sewage sludge

The concentrations of various radionuclides have been measured in the incoming water, the outgoing water and the sludge from the sewage treatment plant serving the town of Lund in southern Sweden. The mean residence time for the water in the plant is 1 to 2 days, whereas for the sludge it is 3 to 4 weeks. Variations in the residence time, which may influence the efficiency of the plant, are related to the season of the year and the load on the plant. Measurements show that for ⁷Be, ⁵¹Cr, ¹³⁴Cs, and ¹³⁷Cs between 37 and 56% of the incoming activity leaves the plant with the sludge. For ¹⁰⁶Ru and ¹³¹I these figures lie between 6 and 14%. The deposition of ⁷Be has been measured at Lund and the relation between the deposition on the ground (Bq m^?2) and the activity concentration in the sludge (Bq kg^?1 dry weight) has been studied and found to by relatively constant at ?(0.8 ±0.2) kg m^?2. In measurements on sewage sludge, the detection limit for deposition of ⁷Be on the ground is around 16 Bq m^?2.     

A simplified protocol for molecular identification of Eimeria species in field samples

This study aimed to find a fast, sensitive and efficient protocol for molecular identification of chicken Eimeria spp. in field samples. Various methods for each of the three steps of the protocol were evaluated: oocyst wall rupturing methods, DNA extraction methods, and identification of species-specific DNA sequences by PCR. We then compared and evaluated five complete protocols. Three series of oocyst suspensions of known number of oocysts from Eimeria mitis, Eimeria praecox, Eimeria maxima and Eimeria tenella were prepared and ground using glass beads or mini-pestle. DNA was extracted from ruptured oocysts using commercial systems (GeneReleaser, Qiagen Stoolkit and Prepman) or phenol-chloroform DNA extraction, followed by identification of species-specific ITS-1 sequences by optimised single species PCR assays. The Stoolkit and Prepman protocols showed insufficient repeatability, and the former was also expensive and relatively time-consuming. In contrast, both the GeneReleaser protocol and phenol-chloroform protocols were robust and sensitive, detecting less than 0.4 oocysts of each species per PCR. Finally, we evaluated our new protocol on 68 coccidia positive field samples. Our data suggests that rupturing the oocysts by mini-pestle grinding, preparing the DNA with GeneReleaser, followed by optimised single species PCR assays, makes a robust and sensitive procedure for identifying chicken Eimeria species in field samples. Importantly, it also provides minimal hands-on-time in the pre-PCR process, lower contamination risk and no handling of toxic chemicals.     

Exploiting P in heavily P-dressed fields in Sweden

Phosphorus status of soils is regarded a component of soil fertility. This component can be influenced by cropping measures. In 1983 a number of Swedish fields with a high P status were identified. In all there were 17 fields chosen distributed over Sweden. On these fields P fertilizer experiments were started with the treatments 0, 15 and 30 kg P ha^-1 yr^-1.

In average of all experimental sites the starting P-AL value was 19.6 mg 100^-1g soil. Typically P-AL in Swedish arable soils are less than 10 mg, so the 19.6 average is a high value, pH varied from 5.1 to 7.3 with 46% of the sites having initial pH values less than 6.2. With no P applied the P-AL values decreased significantly with time. The slope of the regression line indicates that P-AL in the top soil decreased with 0.5 units year^-1. The decline was statistically significant at the 5% level. When 30 kg P year^-1 was applied the decline was insignificant. In the high pH range (≥ 6.2) the decline in P-AL was 0.67 units year^-1 compared with 0.18 in the low pH group. Measurement of the uptake and removal of P with harvest products was chosen as the best method to analyse the crop response with time. When the experiments were pH grouped and the effects in cereals were analysed a positive effect on the P uptake with time was found.     

Soil Organic C Development in Cereal and Ley Systems. Data from 20 Years Old Swedish Field Experiments

In four Swedish long-term field experiments in cereals and in four with mixed ley production the top soil organic C changes with time were investigated at different N levels. In the cereals treatments with all straw removed and all straw chopped and ploughed into the soil were compared. The experiments were started 20 years or more ago at 4 contrasting sites from south to north and they are still running. In the cereal system the C content decreased from 2.3 to 1.9% on average over the sites. The decline was the biggest where the initial content was the highest. Straw returned increased the C content with 0.1 percentage unit compared with straw removed. N also increased the C content in the cereal system but not in the ley system. The change with time was also insignificant in the ley part. Estimated rate constants for C decomposition varied from 0.1 to 1.66% yr m 1 in cereals. It decreased usually with increasing N level. When straw was returned at the high N level the rate constant also decreased. The rate constants corresponded to C break down of 610-740kg ha m 1 at the northernmost site and 250-270kg ha m 1 at the southernmost. With the assumed humification factor of 15% the gross supply of C was not high enough to maintain present C content at the northern site but at the southern site it was. In the ley systems steady state levels seemed almost to be established.     

Compatibility of the ammonium lactate (AL) and sodium bicarbonate (Olsen) methods for determining available phosphorus in Swedish soils

Abstract

Plant-available P was first extracted in soils 114 years ago and a number of different analytical methods have since been developed, but for good reasons none of these methods has been adopted as a standard for all soils. With increasing cooperation within research, there is a need to harmonise the interpretation of analytical data for fertiliser recommendations, research, and environmental control. This paper evaluates the compatibility of the Swedish standard ammonium lactate (P_AL) method and the widely used Olson's sodium bicarbonate (P_Ols) method in 82 topsoil samples taken from Swedish long-term soil fertility field trials. The P_AL-values were usually larger than P_Ols, with a mean P_AL/P_Ols quotient of 2.30±1.04 (0.67–6.58). The P_AL and P_Ols means and ranges were 126±89 (5–360) and 55.1±33 (3.1–122.8) mg P kg^?1 dry soil, respectively. Stepwise multiple linear regression analysis was used to evaluate the relationship between P_AL and P_Ols and how this relationship was affected by clay content, pH, and soil organic carbon content (SOC). After statistical transformation, it emerged that the square root of clay content (17.4%±13.82, range 1–54.4) and pH (6.45±0.54, range 5.5–7.7) significantly affected the relationship at partial R ²-values of 2 and 12%, respectively, while ln(SOC) (2.54%±1.21, range 1–6.03) did not, apparently due the narrow range. The regressions of predicted vs. measured values explained 95 and 94% of the variation in P_AL and P_Ols, respectively. The mean deviation of predicted compared with measured values was 21.3 and 8.3 mg P kg^?1 dry soil for P_AL and P_Ols, respectively, corresponding to 20 or 19% of the measured values. We conclude that a data set consisting of P_AL-values can be converted into P_Ols-values and vice versa with reasonably high accuracy when accounting for clay content and pH.