It takes mere seconds to compact a soil, but years or even decades for it to recover. Biological activities by plant roots and soil organisms (earthworms) as well as physical effects like drying out and rewetting phases, and freezing-thawing cycles are vital for natural regeneration. Exactly how recovery happens is being investigated in a long-term field trial. For this, an observational infrastructure with hundreds of soil probes – the Soil Structure Observatory (SSO) – was set up in 2014 together with ETH Zurich. After the initial compaction event, a fallow, a permanent grassland and a crop rotation with and without tillage were set up. This allows to analyse e.g. the influence of plants and tillage on recovery.
Milkers frequently suffer from musculoskeletal disorders, especially in the area of the shoulders and arms. Agroscope therefore investigated whether appropriate working heights can reduce workload in the milking parlour. For this, the angle of flexion of various joints during milking was recorded in one experiment, whilst a second experiment recorded muscle contractions at three different heights. The study showed that although a lower working height in the milking parlour has no effect on forearms or upper arms, it significantly reduces strain on the shoulders.
Pick J. L., Kasper-Völkl C., Allegue H., Dingemanse N. J., Dochtermann N. A., Laskowski K. L., Lima M. R., Schielzeth H., Westneat D.F., Wright J., Araya-Ajoy Y. G.
Describing posterior distributions of variance components: Problems and the use of null distributions to aid interpretation.
Assessing the biological relevance of variance components estimated using MCMC-based mixed-effects models is not straightforward. Variance estimates are constrained to be greater than zero and their posterior distributions are often asymmetric. Different measures of central tendency for these distributions can therefore be very different, and credible intervals cannot overlap zero, making it difficult to assess the the size and statistical support for among-group variance. This is often done through visual inspection of the whole posterior distribution, and so relies on subjective decisions for interpretation. We use simulations to demonstrate the difficulties of summarising the posterior distributions of variance estimates from MCMC-based models. We compare commonly used summary statistics of posterior distributions of variance components showing that the posterior median is predominantly the least biased. We also describe different methods for generating null distributions (i.e. a distribution of effect sizes that would be obtained if there was no among-group variance) that can be used to aid in the interpretation of variance estimates. We further show how null distributions could be used to derive a p-value that provides complimentary information to the commonly presented measures of central tendency and uncertainty and also facilitates the implementation of power analyses within an MCMC framework.
On behalf of Micarna SA, Agroscope analysed the environmental impacts of beef, pork and poultry production. With beef production, feed intensity was crucial. In the case of pork and poultry production, the quantity of feed used per kg of meat had the greatest influence on environmental impacts. The use of European soya with its shorter transport distances had a positive effect.