Earthworm populations in conventional/organic arable-based systems and their contribution to soil fertility OF0117T

The project aimed to characterise earthworm population dynamics and behaviour under rotational cropping, comparing organic and conventional systems. Benefits arising from earthworm activity in terms of soil fertility were also assessed. Although some difficulties were encountered with details of the work, these problems did not affect the overall reliability of research findings and the broad aims were achieved. Earthworm populations, casting and burrowing, and selected soil or cast properties (microbial biomass, available P and K, organic content and aggregate stability) were monitored on three pairs of matched organic-conventional farms over a two year period. Farm pairs represented a gradation from stockless to ley-arable systems. The survey was extended in the final year to include a further four farm pairs sampled on a single occasion. Population data indicated the marked beneficial effect of leys within rotations and their key role in maintaining high earthworm densities in organic systems. Although there were some indications of species differences between systems, patterns of variation were essentially similar for the biomass and abundance of the total population and of individual species. Tillage did not appear to have a large or persistent effect on earthworms. Populations increased under leys, approaching the size and species composition of permanent pasture after 3-4 years. There were, however, examples where low populations of earthworms failed to respond to favourable ley management. Much of the beneficial effect of leys was dissipated after one year of cereal cropping. There was some evidence of increased surface burrowing in organic compared with conventional systems, a feature explained partly by higher densities of the more shallow dwelling species and partly by higher levels of activity for a given population density. Efforts to relate burrowing activity to water infiltration were only partially successful, the technique used being ineffective on cereals or recent leys. Earthworm casts had higher organic and nutrient contents, microbial biomass and aggregate stability than underlying soil. These differences tended, if anything, to be greater in conventional compared with organic systems. A high proportion of the variation in earthworm populations could be accounted for by soil and agronomic factors within individual sites. However, the importance and direction of individual factors varied between sites. Given the benefits arising from large and active populations, for soil fertility and within the larger agricultural ecosystem, there are sound reasons for encouraging systems of farming which favour earthworms. Organic farming is one such system, although including or increasing the proportion of leys in rotations may achieve many of the benefits associated with organic husbandry. Within organic rotations, the key role of leys, their management and break up, is clear. The need for further work is indicated in several areas including: • minimum populations require to deliver soil/environmental benefits and to ensure sustainable use of soil resources; • system differences in earthworm impacts on nutrient cycling; • agronomic options within organic farming as they affect populations; • interactions with other soil organism

Soil stabilisation for DNA metabarcoding of plants and fungi. Implications for sampling at remote locations or via third-parties

Storage of soil samples prior to metagenomic analysis presents a problem. If field sites are remote or if samples are collected by third parties, transport to analytical laboratories may take several days or even weeks. The bulk of such samples and requirement for later homogenisation precludes the convenient use of a stabilisation buffer, so samples are usually cooled or frozen during transit. There has been limited testing of the most appropriate storage methods for later study of soil organisms by eDNA approaches. Here we tested a range of storage methods on two contrasting soils, comparing these methods to the control of freezing at -80 °C, followed by freeze-drying. To our knowledge, this is the first study to examine the effect of storage conditions on eukaryote DNA in soil, including both viable organisms (fungi) and DNA contained within dying/dead tissues (plants). For fungi, the best storage regimes (closest to the control) were storage at 4 °C (for up to 14 d) or active air-drying at room temperature. The worst treatments involved initial freezing, followed by thawing which led to significant later spoilage. The key spoilage organisms were identified as Metarhizium carneum and Mortierella spp., with a general increase in saprotrophic fungi and reduced abundances of mycorrhizal/biotrophic fungi. Plant data showed a similar pattern, but with greater variability in community structure, especially in the freeze-thaw treatments, probably due to stochastic variation in substrates for fungal decomposition, algal proliferation and some seed germination. In the absence of freeze drying facilities, samples should be shipped refrigerated, but not frozen if there is any risk of thawing

CBS domains form energy-sensing modules whose binding of adenosine ligands is disrupted by disease mutations

CBS domains are defined as sequence motifs that occur in several different proteins in all kingdoms of life. Although thought to be regulatory, their exact functions have been unknown. However, their importance was underlined by findings that mutations in conserved residues within them cause a variety of human hereditary diseases, including (with the gene mutated in parentheses): Wolff-Parkinson-White syndrome (γ2 subunit of AMP-activated protein kinase); retinitis pigmentosa (IMP dehydrogenase-1); congenital myotonia, idiopathic generalized epilepsy, hypercalciuric nephrolithiasis, and classic Bartter syndrome (CLC chloride channel family members); and homocystinuria (cystathionine β-synthase). AMP-activated protein kinase is a sensor of cellular energy status that is activated by AMP and inhibited by ATP, but the location of the regulatory nucleotide-binding sites (which are prime targets for drugs to treat obesity and diabetes) was not characterized. We now show that tandem pairs of CBS domains from AMP-activated protein kinase, IMP dehydrogenase-2, the chloride channel CLC2, and cystathionine β-synthase bind AMP, ATP, or S-adenosyl methionine,while mutations that cause hereditary diseases impair this binding. This shows that tandem pairs of CBS domains act, in most cases, as sensors of cellular energy status and, as such, represent a newly identified class of binding domain for adenosine derivatives

A new emphasis on root traits for perennial grass and legume varieties with environmental and ecological benefits

Grasslands cover a significant proportion of the agricultural land within the UK and across the EU, providing a relatively cheap source of feed for ruminants and supporting the production of meat, wool and milk from grazing animals. Delivering efficient animal production from grassland systems has traditionally been the primary focus of grassland‐based research. But there is increasing recognition of the ecological and environmental benefits of these grassland systems and the importance of the interaction between their component plants and a host of other biological organisms in the soil and in adjoining habitats. Many of the ecological and environmental benefits provided by grasslands emanate from the interactions between the roots of plant species and the soil in which they grow. We review current knowledge on the role of grassland ecosystems in delivering ecological and environmental benefits. We will consider how improved grassland can deliver these benefits, and the potential opportunities for plant breeding to improve specific traits that will enhance these benefits whilst maintaining forage production for livestock consumption. Opportunities for exploiting new plant breeding approaches, including high throughput phenotyping, and for introducing traits from closely related species are discussed