Comparison of soil carbon and nitrogen stocks of adjacent dairy and drystock pastures

The largest terrestrial store of carbon (C) is in soil and research has shown that anthropogenic land use change and management practices can alter soil C stocks. A concern is that small losses of soil C can contribute to large increases in atmospheric CO2. Research has focused on identifying which land use conversions modify soil C dynamics and more recently, how management practices influence soil C stocks, with particular emphasis on croplands and forests but less on grazed pasture systems. The soil nitrogen (N) cycle has also been modified with increased N inputs, especially under agriculture where N fertilisers and N-fixing plants are used. About 33% of New Zealand’s total land area is used for grazing. A previous study observed that between the 1980s and 2000s soils on flat land under dairy farming had lost significant amounts of C and N, while soils under drystock farming on flat land had not. A conclusion drawn from the previous study was that a dairy farm was likely have a lower soil C stock than an adjacent drystock farm on the same soil, on flat land. The reasons for the reported soil C and N losses from dairy farm soils are not well understood and require further testing and verification using other approaches. The objectives of this thesis were to firstly, determine if there was a difference in soil C and N between adjacent dairy and drystock farms on the same soil and secondly, if differences were detected whether they were dependant on differences in farming intensity, as defined by stocking rate. A synthesis of recent literature showed that when differences in soil C have been observed under various grazing intensities, soil C was generally always lower under higher stocking rates. However, many of the grazing intensity studies were based in semi-arid regions and not particularly applicable to New Zealand’s pastoral grazing systems. I sampled 25 adjacent dairy and drystock farms (paired sites) on flat land in the Waikato Region to 0.6 m depth and analysed samples for C, N and soil dry bulk density by horizon. Sampling sites at each paired site were an average of 108 m apart and located on the same soil with a similar slope, aspect and topography. The estimated average stocking rate for dairy farms (24 ± 0.8 SU ha-¹) was higher (P<0.01) than drystock farms (14 ± 2.0 SU ha-¹). The mean soil C and N stocks for the whole soil profile (0–0.6 m) were 173.1 ± 12.4 t C ha-¹ and 18.5 ± 0.9 t N ha-¹ for the dairy farms and 182.7 ± 15.0 t C ha-¹ and 19.1 ± 5.7 t N ha-¹ for the drystock farms. The soil C and N stocks for the whole soil profile were not significantly different between dairy and drystock farms. However, when soil horizons were considered separately there was a significant difference in C stocks of the A horizon (P<0.05). The mean soil C in the A horizon under dairying was 94.7 ± 5.7 t C ha-¹ and 103.3 ± 6.1 t C ha-¹ under drystock, with dairy farms having an average of 8.6 ± 4.1 t C ha-¹ less than the drystock farms (P<0.05). No significant difference in soil N stock of the A horizons was detected. The increased variability of soil C and N with depth meant that the significant difference in soil C of the A horizon was not evident when the whole soil profile was considered. The A horizon thickness under dairy farming was shallower (P<0.05) and the soil dry bulk density was higher (P<0.05) than the drystock farms, indicating soil compaction. The total mass of soil sampled from the A horizons was similar for both types of grazing (0.14 ± 0.01 t m-²). Therefore, the significant difference in soil C of the A horizon was likely to be a consequence of land management rather than sampling different masses of soil. My result that dairy farms had less topsoil C than adjacent drystock farms aligned with the conclusion drawn from a previous study of New Zealand pastoral grazing systems. The result also supported the general trend of less soil C under higher stocking rates than lower stocking rates observed in the literature synthesis. Further work is required to understand what has driven the difference in topsoil C under dairy and drystock farming on flat land in New Zealand. Future research should include exploring how important stocking rates and the type of livestock being grazed are on soil C and N dynamics, as this may be useful information for future farming management decision making

The how and why of handgrip strength assessment

Introduction: Occupational therapists and physiotherapists routinely assess Hand grip Strength (HGS) to evaluate hand function. This study explored the experiences of clinicians who regularly assess and evaluate HGS including the testing protocol utilised, evaluation methods and the influence of various biological and functional factors. Method: This exploratory survey (n = 49) was distributed online to members of the Australian Hand Therapy Association. The questionnaire asked recipients to identify HGS testing protocols, evaluation methods, use of normative data, reasons for assessment and the influence of biological and functional factors on HGS. Demographic data was also collected. Results: Sixty-four percent of respondents were occupational therapists and 59% had over 10 years’ experience assessing HGS. The standardised American Society of Hand Therapists (ASHT) testing protocol was consistently adopted by only 67% of respondents . Variations in contraction time, scoring and evaluation methods were identified. Gender, age, employment and lifestyle were considered the functional and biological factors which influence HGS. Conclusion: This study details how and why occupational therapists and physiotherapists in Australia assess and evaluate HGS. Use of the ASHT testing protocol is not universal. Clinicians rely on the reason for assessment, clinical experience and practice context to determine how they assess and evaluate HGS

Manual competence in clumsy children.

This thesis starts by addressing some complex issues\ud concerning the classification of children called 'Clumsy'. The\ud focus then turns more specifically to manual competence in\ud Clumsy children, which is investigated using both a\ud descriptive and an experimental approach. In both cases\ud performance on two different groups of manual tasks is\ud examined: drawing tasks and object manipulation tasks.\ud Within the descriptive approach, both cross-sectional and\ud longitudinal analyses are undertaken. Firstly, overall\ud differences in the performance between Clumsy children and\ud age-matched controls are described. More detailed examinations\ud are then made of different aspects of movement quality using\ud observation checklists. The main findings are that Clumsy\ud children perform more poorly than controls on simple manual\ud tasks. Their performance is worse, not only in terms of motor\ud control, but also in relation to spatial characteristics and\ud more global factors. It was also found that the movement\ud characteristics of Clumsy children vary at different ages and\ud that, although there are general improvements with age, the\ud motor aspects of performance seem resistant to change.\ud Within the experimental approach the role of vision in\ud performance is studied in two different ways. Using a\ud correlational approach, one study suggests that although\ud Clumsy children have visual perceptual deficits, it is not\ud clear how these are related to their motor difficulties. Using\ud a different methodology, another study involves the\ud manipulation of visual information to produce different\ud perceptual conditions. The main finding is that Clumsy\ud children (and particularly the younger ones) are affected more\ud by a lack of visual information than controls. It is suggested\ud that the role of vision in Clumsy children may differ at\ud different ages but that generally it seems that they depend\ud heavily on visual information and that they are poor at making\ud sense of kinaesthetic input

Accuracy and consistency of letter formation in children with Developmental Coordination Disorder: an exploratory study

Background: Handwriting difficulties are frequently mentioned in descriptions of Developmental Coordination Disorder (DCD). Recent studies have shown that children with DCD pause more and produce less text than typically developing (TD) peers. This temporal dysfluency indicates a lack of automaticity in handwriting production. One possible contributing factor is the accuracy and consistency of letter formation. The aim of this study was to gain a better understanding of handwriting dysfluency by examining the accuracy and consistency of letter production both within and across different writing tasks. Method: Twenty-eight 8-15 year-old children with DCD participated in the study, with 28 typically developing (TD) age and gender matched controls. They completed the alphabet writing and copy fast tasks from the Detailed Assessment of Speed of Handwriting on a digitising writing tablet. The accuracy and consistency of letter production were examined. Results & Discussion: The DCD group had a higher percentage of errors within their letterforms than TD peers. Letter production was also less consistent between tasks. Children with DCD appear to have difficulties with the ‘allograph’ (motor program) aspect of handwriting and may require explicit teaching of letter formation

When an object appears unexpectedly: foot placement during obstacle circumvention in children and adults with Developmental Coordination Disorder

Adjustments to locomotion to avoid an obstacle require a change to the usual pattern of foot placement, i.e. changes to step length and/or step width. Previous studies have demonstrated a difficulty in individuals with Developmental Coordination Disorder (DCD) in controlling stability while both stepping over and while circumventing an obstacle. In a previous study we have considered the way in which individuals with DCD prepare for the possibility of an obstacle appearing (Wilmut and Barnett, 2017). Using a parallel data set from this same task on the same individuals the aim of the current study was to investigate the exact nature of changes in foot placement during obstacle avoidance, as this was not clear from previous work. Children and adults aged from 7 to 34 years of age took part in the study. Forty-four met the criteria for a diagnosis of DCD and there were 44 typically developing (TD) age and gender matched controls. Participants walked at a comfortable pace down an 11m walkway; on 6 out of 36 trials a ‘gate’ closed across their pathway which required circumvention. These 6 ‘gate close’ trials were analysed for this study. The number and magnitude of step length and step width adjustments were similar across the DCD and TD groups, however, the younger children (7-11yrs) made a greater number of early adjustments compared to the older children and adults (12-34 years of age). In contrast the adults made a greater number of adjustments later in the movement compared to the children. In terms of foot placement adjustments a clear preference was seen across all participants to use adjustments which resulted in reducing step length, stepping away from the obstacle and a combination of these. Apart from subtle differences, the individuals with DCD make step placements to circumvent an obstacle in line with their peers. It is suggested that the choice of foot placement strategy in individuals with DCD, although in line with their peers, may not be optimal for their level of motor ability