Linking arable and livestock farms: Impact of grazing sheep on winter cereals and soil health

Given, in recent years, the UK has experienced a number of extreme weather events, and climate modellers are predicting these to occur more frequently in future, there is concern by some farmers in their ability to reliably provide sufficient homegrown forage for their ruminant livestock, especially over the winter period before grass fields are ready. There is also a desire by some arable farms to include livestock within their system in some way in order to try improving their soil health and in particular levels of residual nitrogen and organic matter through the act of animal manuring and urine deposition. These arable farmers do not necessarily want to change to a fully mixed farming system, or have overall responsibility for the animals involved. The grazing of winter cereals on arable farms by local shepherds / graziers has potential to provide a route to achieve this mutualistically beneficial relationship. This paper is based on a recent series of controlled field experiments and farmer led demonstrations in NE Scotland that have been used to test the hypothesis that the grazing of winter cereals can provide both a valuable late winter feed source for ruminants, as well as maintain acceptable grain and straw yields, while maintaining soil “health”. The overall aim was to assess a number of factors, including how crop establishment timing, grazing timing, intensity and stocking rate impacts on the performance of different winter cereals and the potential for economic and environmental benefits associated with this practice to be achieved.Results to date suggest that winter wheat, winter barley and winter oats can be grazed quite heavily, using either intensive grazing over a short period of time, or less intensive grazing over a longer period of time, without any clear negative impacts on a range of crop (including yield and quality) or soil factors. Analysis of the feed value of these crops at the time grazing has taken place, typically for between a few days and several weeks, within the period late November through to mid-March, has been consistently impressive. <br/

Growth dynamics of Phaeocystis antarctica-dominated plankton assemblages from the Ross Sea

Large-volume experiments were conducted using natural seawater assemblages collected in the southern Ross Sea during austral spring 1994 and summer 1995 to assess the carbon and nitrogen exchanges among phytoplankton, bacteria and dissolved organic carbon pools, and to compare the elemental partitioning in these experimental enclosures with those observed in situ. Large concentrations of particulate matter were produced in these enclosures, which were at all times dominated by the colonial haptophyte Phaeocystis antarctica. Particulate organic carbon concentrations exceeded 200 mu mol l(-1) at the end of the experiment. Bacterial carbon comprised only a small (%) fraction of the particulate carbon, but bacteria grew at 0.15 to 0.3 d(-1) and were not limited by bacteriovores. Nutrient levels decreased concomitantly with POC increases, and nitrate was reduced to undetectable levels. Dissolved organic carbon (DOC) levels remained low (less than 50 mu M) while nutrients were present, but increased dramatically (to more than 200 mu M) after nitrate was depleted. Growth rates calculated from changes in particulate matter concentrations were slightly below the predicted maximum based on temperature. Field studies, however, showed no depletion of nitrate, similar levels of particulate organic carbon to those found during exponential growth, low levels of DOG, and relatively low levels of bacterial biomass. It appears that P. antarctica in the Ross Sea does not produce large amounts of DOC during nutrient-replete growth; furthermore, because macronutrients are rarely, if ever, depleted where P. antarctica is dominant in the Ross Sea, it is likely that much of the carbon generated during its growth remains in the particulate pool

The DNA damage checkpoint pathway promotes extensive resection and nucleotide synthesis to facilitate homologous recombination repair and genome stability in fission yeast.

DNA double-strand breaks (DSBs) can cause chromosomal rearrangements and extensive loss of heterozygosity (LOH), hallmarks of cancer cells. Yet, how such events are normally suppressed is unclear. Here we identify roles for the DNA damage checkpoint pathway in facilitating homologous recombination (HR) repair and suppressing extensive LOH and chromosomal rearrangements in response to a DSB. Accordingly, deletion of Rad3(ATR), Rad26ATRIP, Crb2(53BP1) or Cdc25 overexpression leads to reduced HR and increased break-induced chromosome loss and rearrangements. We find the DNA damage checkpoint pathway facilitates HR, in part, by promoting break-induced Cdt2-dependent nucleotide synthesis. We also identify additional roles for Rad17, the 9-1-1 complex and Chk1 activation in facilitating break-induced extensive resection and chromosome loss, thereby suppressing extensive LOH. Loss of Rad17 or the 9-1-1 complex results in a striking increase in break-induced isochromosome formation and very low levels of chromosome loss, suggesting the 9-1-1 complex acts as a nuclease processivity factor to facilitate extensive resection. Further, our data suggest redundant roles for Rad3ATR and Exo1 in facilitating extensive resection. We propose that the DNA damage checkpoint pathway coordinates resection and nucleotide synthesis, thereby promoting efficient HR repair and genome stability

Comparison of limb kinematics between collected and lengthened (medium/extended) trot in two groups of dressage horses on two different surfaces

Background: Dressage horses are often asked to work in lengthened paces during training and competition, but to date there is limited information about the biomechanics of dressage-specific paces. Preliminary work has shown increased fetlock extension in extended compared with collected paces, but further investigation of the kinematic differences between collected, medium and extended trot in dressage horses is warranted. Objectives: Investigation of the effect of collected versus medium/extended trot on limb kinematics of dressage horses. Study design: Prospective kinematic evaluation. Methods: Twenty clinically sound horses in active dressage training were used: Group 1) ten young horses (≤ 6 years) were assessed at collected and medium trot; Group 2) ten mature horses (≥9 years) were assessed at collected and extended trot. All horses were evaluated on two different surfaces. High-speed motion-capture (240Hz) was used to determine kinematic variables. Forelimb and hindlimb angles were measured at midstance. Descriptive statistics and mixed-effect multilevel-regression analyses were performed. Results: Speed and stride length were reduced and stride duration increased at collected compared with medium/extended trot. Lengthened trot (medium/extended trot) was associated with increased fetlock extension in both the forelimbs and hindlimbs in both groups of horses. Changes were greater in Group 2 compared with Group 1. Shoulder and carpus angles were associated with forelimb fetlock angle. Hock angle was not significantly influenced by pace. Surface had no effect on fetlock or hock angles. Main limitations: Only 2D motion analysis was carried out. Results may have been different in horses with more extreme gait characteristics. Conclusions: Medium/extended trot increases extension of the forelimb and the hindlimb fetlock joints compared with collected trot in both young and mature dressage horses, respectively

Soil health metrics reflect yields in long‑term cropping system experiments

Soil health metrics with strong links to ecological function and agricultural productivity are needed to ensure that future management of agricultural systems meets sustainability goals. While ecological metrics and crop yields are often considered separately from one another, our work sought to assess the links between the two in an agricultural context where productivity is a key consideration. Here, we investigated the value of soil health tests in terms of their relevance to agricultural management practices and crop yields at contrasting long term cropping systems experiments. One site was on a sandy loam Leptic Podzol and the other on a sandy clay loam Endostagnic Luvisol. Furthermore, the experiments had different management systems. One contained legume-supported rotations with different grass-clover ley durations and organic amendment usage, while the other compared a range of nutrient input options through fertiliser and organic amendments on the same rotation without ley periods. Metrics included field tests (earthworm counts and visual evaluation of soil structure scores) with laboratory analysis of soil structure, chemistry and biology. This analysis included bulk density, macroporosity, pH, available phosphorus, exchangeable potassium, soil organic matter and potentially mineralizable nitrogen. Using a novel combination of long-term experiments, management systems and distinctive soil types, we demonstrated that as well as providing nutrients, agricultural management which resulted in better soil organic matter, pH, potassium and bulk density was correlated with higher crop yields. The importance of ley duration and potentially mineralizable nitrogen to yield in legume-supported systems showed the impact of agricultural management on soil biology. In systems with applications of synthetic fertiliser, earthworm counts and visual evaluation of soil structure scores were correlated with higher yields. We concluded that agricultural management altered yields not just through direct supply of nutrients to crops, but also through the changes in soil health measured by simple metrics