We extend the contingent valuation (CV) method to test three differing conceptions of individuals' preferences as either (i) a-priori well-formed or readily divined and revealed through a single dichotomous choice question (as per the NOAA CV guidelines [K. Arrow, R. Solow, P.R. Portney, E.E. Leamer, R. Radner, H. Schuman, Report of the NOAA panel on contingent valuation, Fed. Reg. 58 (1993) 4601-4614]); (ii) learned or 'discovered' through a process of repetition and experience [J.A. (2003) 73-105]. Findings reject both the first and last of these conceptions in favour of a model in which preferences converge towards standard expectations through a process of repetition and learning. In doing so, we show that such a 'learning design CV' method overturns the 'stylised facts' of bias and anchoring within the double bound dichotomous choice elicitation format. r

A laboratory study evaluated the effect of rate (0, 100, 250, 500, 750 or 1000 mg ⁄ kg) and mode of application of the urease inhibitor N-(n-butyl) thiophosphoric triamide (nBTPT) (coating the urea granule, adding to the urea melt or adding to urea ammonium nitrate (UAN) solutions) on NH 3 volatilization from urea, at three temperatures (5, 15 and 25°C), with four contrasting soil types. Daily ammonia loss was measured for up to 21 days after surface N application, using ventilated soil enclosures. Ammonia loss from unamended urea varied with soil type and temperature and ranged from 8.2 to 31.9% of the N applied. nBTPT was highly effective in lowering NH 3 volatilization from urea and in delaying the time of maximum rate of loss. The average % inhibition over all soils, temperatures and formulations was 61.2, 69.9, 74.2, 79.2 and 79.8% for the 100, 250, 500, 750 or 1000 mg ⁄ kg nBTPT concentration, respectively. The % inhibition with nBTPT was lower at 15°C compared with at 5 or 25°C and was lower in UAN solutions than in granular products. There was little difference between the melted and coated granular products in lowering NH 3 loss or in soil N transformations. The stability of nBTPT in urea products was dependent on its mode of application and on the storage temperature. Incorporating nBTPT in the urea melt produced a more homogeneous product with superior stability than coating the urea granule.

Bovine tuberculosis (bTB) is a zoonotic disease which is endemic in Northern Ireland. As it has proven difficult to eradicate this disease, partly due to a wildlife reservoir being present in the European badger (Meles meles), a case-control study was conducted in a high incidence area in 2010-2011. The aim was to identify risk factors for bTB breakdown relating to cattle and badgers, and to assess the adoption of bTB related biosecurity measures on farms. Face-to-face questionnaires with farmers and surveys of badger setts and farm boundaries were conducted on 117 farms with a recent bTB breakdown (cases) and 75 farms without a recent breakdown (controls). On logistic regression at univariable and multivariable levels, significant risk factors associated with being a case herd included having an accessible badger sett within the farm boundaries in a field grazed in the last year (odds ratio, OR, 4.14; 95% confidence interval, CI, 1.79, 9.55), observation of live badgers (OR 4.14; 95% CI 1.79, 9.55), purchase of beef cattle (OR 4.60; 95% CI 1.61, 13.13), use of contractors to spread slurry (OR 2.83; 95% CI 1.24, 6.49), feeding meal on top of silage (OR 3.55; 95% CI 1.53, 8.23) and feeding magnesium supplement (OR = 3.77; 95% CI 1.39, 10.17). The majority of setts within the farm boundary were stated to be accessible by cattle (77.1%; 95% CI 71.2, 83.0%) and 66.8% (95% CI 63.8, 69.7%) of farm boundaries provided opportunities for nose-to-nose contact between cattle. Adoption of bTB related biosecurity measures, especially with regards to purchasing cattle and badger-related measures, was lower than measures related to disinfection and washing.

The Olsen-P status of grazed grassland (Lolium perenne L.) swards in Northern Ireland was increased over a 5-yr period (March 2000 to February 2005) by applying different rates of P fertilizer (0, 10, 20, 40, or 80 kg P ha(-1) yr(-1)) to assess the relationship between soil P status and P losses in land drainage water and overland flow. Plots (0.2 ha) were hydrologically isolated and artificially drained to v-notch weirs, with flow proportional monitoring of drainage water and overland flow. Annually, the collectors for overland flow intercepted between 11 and 35% of the surplus rainfall. Single flow events accounted for up to 52% of the annual dissolved reactive phosphorus (DRP) load. The Olsen-P status of the soil influenced DRP and total phosphorus (TP) concentrations in land drainage water and overland flow. Annual TP loss was highly variable and ranged from 0.19 to 1.55 kg P ha(-1) yr(-1) for the plot receiving no P fertilizer and from 0.35 to 2.94 kg P ha(-1) yr(-1) for the plot receiving 80 kg P ha(-1) yr(-1). Despite the Olsen-P status in the soils ranging from 22 to 99 mg P kg(-1), after 5 yr of fertilizer P applications it was difficult to identify a clear Olsen-P concentration at which P losses increased. Any relationship was confounded by annual variability of hydrologic events and flows and by hydrologic differences between plots. Withholding P fertilizer for over 5 yr was not long enough to lower P losses or to have an adverse effect on herbage P concentrations.

As part of an initiative aimed at reducing the number of cattle deaths in Northern Ireland, a survey of bovine mortality on a stratified random sample of farms and veterinary practices was carried out during 1992. In the farm survey, over 3500 deaths were reported from 1069 farms, with a further 237 farms reporting no deaths during the year. The estimated numbers of deaths of suckler cows and dairy cows were 5997 and 4246, respectively, giving an estimated annual mortality rate of 2.36 per cent for suckler cows and 1.55 per cent for dairy cows. One third of the suckler cows and 19 per cent of the dairy cows were found dead with no previous signs of illness. In the cows in which clinical signs were observed and which received veterinary attention, hypomagnesaemia (20.3 per cent) was the main cause of death in suckler cows and coliform mastitis (12.3 per cent) was the single most important cause of death in dairy cows. Conditions associated with calving accounted for approximately 30 per cent of the deaths in both types of cow.

No abstract

The high nutrient content of poultry litter poses a threat to water quality if managed incorrectly during storage. The aim of this study was to evaluate the transfers of nutrients from four methods of poultry litter heaps storage on six arable sites located in Northern Ireland. The methods investigated were; covered heaps, covered heaps with runoff diversion trenches, enveloped heaps, and enveloped heap with runoff diversion trenches. Facilities were installed at each site to capture runoff from the area surrounding the heaps, while changes in nutrient concentration in the soil profile below the heaps were also monitored. Compared to the control plots the presence of the poultry litter heaps did not have a significant impact on the concentrations of total phosphorus (TP) in runoff. However, soil P had a significant positive impact (P = 0.02) on the TP concentrations measured in runoff from plots. There was a significant decrease (P \ 0.01) in NO 3 and NH 4 concentrations in runoff from poultry litter heaps plots. The presence of litter heaps had no impact on conductivity or biological oxygen demand. There was no change in soil P below the heaps however, there was a small increase in soil NO 3 concentration at 60-90 cm depth under heaps when compared with the control plots (P \ 0.05), which was likely due to elevated soil temperatures under the heaps causing an increase in nitrification. The results demonstrate that poultry litter stored in field heaps poses a minimal risk to water quality if managed carefully.

Phosphorus (P) inputs (wet deposition and fertilizer P) and outputs (animal product and drainflow) were studied on reseeded grazed grassland swards receiving different nitrogen (N) inputs (100-500 kg N ha À1 year À1 ) for 10 years (March 1989-February 1999, at an experimental site in Northern Ireland. All plots received the same maintenance application of P fertilizer (8.5 kg P ha À1 year À1 ) to meet grass requirements, to minimize the P surplus and to quantify the impact on P losses to land drainage water. The annual flow weighted mean total P concentrations in drainflow ranged from 187 to 273 mg P litre À1 and were well above the concentrations believed to trigger eutrophication. Annual total P lost to drainage water ranged from 0.28 to 1.73 kg P ha À1 , but was unaffected by N input. As the average annual P balance was zero, there was no significant change in total P in the top 15 cm of soil. However, there was a highly significant redistribution of P to the soil surface from the 10-15 cm depth, possibly as a result of root acquisition and earthworm activity. Total P in the top 5 cm of soil increased from 0.85 g kg À1 to 1.04 g kg À1 , over the 10 years of the study, despite there being no net P input. This P accumulation in the top few cm of soil is likely to exacerbate P losses in overland flow and make improvements in water quality difficult to achieve.