Transport of volatile chlorinated hydrocarbons in unsaturated aggregated media

Transport of volatile hydrocarbons in soils is largely controlled by interactions of vapours with the liquid and solid phase. Sorption on solids of gaseous or dissolved compounds may be important. Since the contact time between a chemical and a specific sorption site can be rather short, kinetic or mass-transfer resistance effects may be relevant. An existing mathematical model describing advection and diffusion in the gas phase and diffusional transport from the gaseous phase into an intra-aggregate water phase is modified to include linear kinetic sorption on gas-solid and water-solid interfaces. The model accounts for kinetic mass transfer between all three phases in a soil. The solution of the Laplace-transformed equations is inverted numerically. We performed transient column experiments with 1,1,2-Trichloroethane, Trichloroethylene, and Tetrachloroethylene using air-dry solid and water-saturated porous glass beads. The breakthrough curves were calculated based on independently estimated parameters. The model calculations agree well with experimental data. The different transport behaviour of the three compounds in our system primarily depends on Henry's constants.     

Assessment of seafood processing wastes as alternative sources of Selenium in plant production

Abstract

In some parts of the world, the soil selenium (Se) content is too low to ensure the Se level recommended for human or animal consumption in the crops produced. In order to secure a desired concentration of Se in crops, Se has been applied as mineral fertilizer to agricultural fields. Since only a minor part of the inorganic Se applied is utilized by plants and small increases in Se concentrations in, e.g., drinking water, may be toxic, the method is somewhat controversial. As an alternative to Se-enriched mineral fertilizer, different seafood-processing wastes have been examined as a source for Se in crop production. Both in greenhouse pot experiments and field trials the Se in seafood waste was not plant-available during the first growing season. There was no significant difference between the Se concentration in wheat growing in soil without added Se and in soil receiving Se from seafood waste in amounts ranging from 0.9 to 9 g ha^?1. Neither was any residual effect of Se in seafood waste seen during a second year growth period. Thus, seafood-processing waste cannot be regarded as a potential source of Se in crop production. Possible mobilization of formerly applied Se, as seafood-processing waste or Se enriched mineral fertilizer due to changes in soil redox conditions were examined in a leaching experiment. The mobility of formerly applied Se was generally very low, but the results indicated that under permanently wet soil conditions leaching of Se may occur in plant dormant periods in soils with low organic matter content and high pH.     

Food Waste Products in Diets for Growing-finishing Pigs: Effect on Growth Performance,Carcass Characteristics and Meat Quality

With high variation in environmental conditions, especially during the extensive grazing season, genotype by environment interaction is potentially important to lamb production in Norway. Using breed as an indicator of genotype, the interaction between breed and environment, i.e. production level of farm and year calculated as solutions of a random farm*year variable, on 52 farms keeping both long-tailed Dala and short-tailed Spæl during 1989–98 was studied. The dataset included 48,946 Dala lambs and 38,299 Spæl lambs. The breed by environment interaction affected lamb autumn weights, and though Dala lambs were always heavier, the difference was substantially smaller at lower than at higher production levels: 1 kg increase in production level was related to Dala lambs’ weights increasing 0.09 kg more than the Spæl lambs’ weights. The results indicate that breed by environment interaction may be of importance, and potential bias in the data and need for further research is discussed.     

Comparison of variance components for test-day electrical conductivity of milk and test-day somatic cell score for first lactation cows in an experimental herd

In recent decades, electrical conductivity (EC) has been introduced as an indicator of mastitis, and genetic selection based on this trait may be possible. In this study, genetic parameters for test-day EC and test-day somatic cell score (SCS) were compared. Data were collected from a Danish experimental herd, including daily records of EC and SCS from 265 first lactation cows. Different genetic models were tested, and a random regression animal model with a 4th order Legendre polynomial for the permanent environmental effect for both traits, a 1st order Legendre polynomial for the additive genetic effect of EC and a 2nd order Legendre polynomial for the additive genetic effect of SCS, gave the best fit. The patterns of the curves were similar for both permanent environmental and additive genetic variance for the two traits. Heritability estimates ranged from 0.05 to 0.12, and from 0.01 to 0.09, for EC and SCS, respectively. The estimate of genetic correlation between the traits was high, and ranged from 0.86 to 0.98. Based on these results, EC could be a potential indicator trait in a breeding programme where selection for increased mastitis resistance is included.     

Random within-herd variation in financial performance and time to financial steady-state following management changes in dairy herd

Abstract

The manager of a dairy herd and the affiliated consultants constantly need to judge whether financial performance of the production system is satisfactory and whether financial performance relates to real (systematic) effects of changes in management. This is no easy task because the dairy herd is a very complex system. Thus, it is difficult to obtain empirical data that allows a valid estimation of the random (within-herd) variation in financial performance corrected for management changes. Thus, simulation seems to be the only option. This study suggests that much caution must be recommended when claming effect of changes in herd management because the link between management changes (cause) and effect (measured as improvement of gross margin per cow year) is extensively blurred by a large within-herd variation in available real life accounting data and differences between herds in time to steady state following management changes.     

Comparative Nutrient Digestibility in Blue Foxes (Alopex lagopus) and Mink (Mustela vison) Fed Diets with Diverging Fat: Carbohydrate Ratios

Abstract

Nutrient digestibilities were evaluated in comparative experiments with blue foxes and mink by using six diets differing in fat:carbohydrate (F:C) ratios. In mink, apparent digestibilities of N and amino acids decreased with decreasing F:C ratio. N digestibility, and most amino acid digestibilities, were higher in blue foxes than in mink (P < 0.01). Fat digestibility in mink, but not in blue foxes, declined as the F:C ratio decreased (P < 0.05). Fat digestibility was higher in blue foxes than in mink (P < 0.05). Carbohydrate digestibility was not affected by the F:C ratio, but high levels of carbohydrates were digested more completely by foxes than by mink. The use of mink digestibility values in feed evaluations for blue foxes will consequently underestimate digestibility. Thus, to evaluate feed correctly, separate digestibility determinations should be made for mink and foxes.     

Pocket parks for people – A study of park design and use

The present study focuses on small urban public parks, specifically on how they should be designed to promote a potential for psychological restoration and on what activities people could imagine doing in such parks. Students from Oslo University College were presented with visual stimuli depicting 74 small urban parks. They were asked to assess how likely it was that they could rest and recover in the parks presented in the photos. In addition, the participants were asked to write down what park components contributed to high versus low ratings on restoration likelihood, and what types of activities they could imagine doing in the parks presented in the photos. The components and activities the participants mentioned were grouped into categories describing similar properties. The categories mentioned most frequently and giving high ratings on restoration likelihood represented natural categories such as: ‘a lot of grass’, ‘a lot of flowers/plants’ and ‘water features’. In contrast, the categories contributing to low ratings on restoration likelihood represented lack of vegetation or disturbance from the surroundings such as: ‘a lot of hard surfaces’, ‘a lot of traffic’ and ‘poorly shielded from the surroundings’. The activities mentioned as being typically performed in the types of parks presented in the photos were ‘relax and philosophize’, ‘read’ and ‘eat/drink’. Conclusions drawn from the study: Small urban parks should be designed with natural components, shielded from disturbing surroundings and furnished with some seating to promote opportunities for restorative experiences and to function as social meeting places.     

Nitrogen uptake,nitrate leaching and root development in winter‐grown wheat and fodder radish

Early seeding of winter wheat (Triticum aestivum L.) has been proposed as a means to reduce N leaching as an alternative to growing cover crops like fodder radish (Raphanus sativus L.). The objective of this study was to quantify the effect of winter wheat, seeded early and normally, and of fodder radish on N dynamics and root growth. Field experiments were carried out on a humid temperate sandy loam soil. Aboveground biomass and soil inorganic N were determined in late autumn; N uptake and grain yield of winter wheat were measured at harvest. Nitrate leaching was estimated from soil water samples taken at 1 m depth. Root growth was measured late autumn using the core break and root washing methods. Winter wheat root growth dynamics were followed during the growing season using the minirhizotron method. The 2013–2014 results showed that early seeding of wheat improved autumn growth and N uptake and reduced N leaching during the winter compared with the normal seeding time. Early‐seeded wheat (WW_early) was, however, not as efficient as fodder radish at reducing N leaching. Proper establishment of WW_early was a prerequisite for benefiting from early seeding, as indicated by the 2012–2013 results. Early seeding improved root growth throughout the 2013–2014 growing season compared with normal seeding time, but had no significant effect on crop grain yield. Our results indicate the potential of using early seeding as a tool to limit drought susceptibility and increase nutrient uptake from the subsoil.     

Tolerance to frost and ice encasement in cultivars of timothy and perennial ryegrass during winter

Ice encasement causes major winter damage in grasslands in coastal areas of Northern Scandinavia and may also affect grass performance in a future changing climate. Changes in ice‐encasement tolerance (LD50), frost tolerance (LT50) and water‐soluble carbohydrate (WSC) content were investigated in different cultivars of timothy and perennial ryegrass sampled at three sites with contrasting conditions. Timothy endured ice encasement for 40 d more than ryegrass (maximum LD50 63 vs. 20 d), and a cultivar originating from 69°N tolerated significantly longer periods in ice than a cultivar from 59°N. A similar relationship between cultivar origin and tolerance was observed for ryegrass. The higher LD50 in timothy compared with ryegrass seemed to be associated with a lower rate of change in WSC content during ice encasement, but no apparent relationship was found between WSC content at the start of encasement and plant survival in ice. A significant linear relationship was found between LD50 and LT50 of plants sampled in the field. A differing decline in frost tolerance during ice encasement for the species indicated that timothy is more resistant to dehardening under ice than ryegrass. This study contributes data and functional relationships needed to develop models of grass performance during winter.     

BIOECONOMICS OF CAPTURE-BASED AQUACULTURE OF COD (GADUS MORHUA)

This study formulates and parameterizes a bioeconomic model of capture-based aquaculture (CBA) of cod (Gadus morhua). The model is solved for the optimal harvest pattern and calculates economic profit and net present value for a model farm. The biological sub-model incorporates knowledge from interviews with existing farmers, research trials and existing cod aquaculture literature. Economic components are obtained from interviews and sales statistics from exporters. A farm of the modeled scale is likely to influence market prices, hence sales prices were estimated assuming a supply response based on the price elasticity. Taking into account the opportunity cost of selling the fish directly, NPV is found to be marginally positive. Sensitivity analysis revealed that profitability is sensitive to changes in several parameters. Hence, further research is valuable and care should be taken when considering investments in cod CBA.