Characterization of the movement of spray drift past a shelterbelt

Pesticide use is an important component of the agricultural industry. Pesticides are typically applied to crops as a droplet spray, and these droplets are susceptible to off-target movement due to wind, which is called spray drift. It has recently been recognized that shelterbelts may protect vulnerable downwind areas from spray drift. There is a need to characterize the movement of spray drift past a shelterbelt to better understand the extent of this protection and the variables which affect it. The variables investigated in this research may be classified as meteorological conditions, spray application settings, and shelterbelt properties.This research investigated the movement of spray drift past a 5 m tall carragana/chokecherry shelterbelt. Spray was applied using a conventional sprayer that travelled on a path that was upwind and parallel to the shelterbelt. A tracer substance was mixed into the spray solution, and the deposition and airborne concentration of drift was measured using a variety of collectors placed at perpendicular distances up- and downwind of a shelterbelt. The mass of drift deposit on the collectors was determined using spectrofluoremetry and standard solutions.When the spray swath was a distance of 3H (where H is the height of the shelterbelt) upwind of the shelterbelt, it was found that the ground deposition of drift at a distance of 0.5H downwind of the shelterbelt was reduced by approximately 74%, compared to the drift deposit at 0.5H upwind. The reduction over the same downwind distances was 29% in the open field setting. The airborne drift cloud was attenuated by the shelterbelt and the airborne concentration of drift exiting the shelterbelt was reduced by approximately 85% of the entering drift. The airborne drift concentration profile indicated that there was a greater proportion of drift travelling over the top of the shelterbelt rather than passing through the shelterbelt, with the peak concentration occurring at approximately 1.2H.Qualitative and multiple linear regression analyses were used to determine the significance of a number of meteorological and controlled variables on the deposition of drift. It was found that the mass of drift deposited downwind of the shelterbelt increased with a higher wind speed, higher temperature, and lower relative humidity. For the range of meteorological conditions sampled, the effect of wind direction and atmospheric stability were found to be insignificant. Finer spray qualities and higher shelterbelt optical porosity produced greater airborne drift and deposition downwind of the shelterbelt. With increasing upwind sprayer distance, the mass of drift deposited within the shelterbelt decreased

Identifying and reversing ecological barriers to successful farmland revegetation specific to tubestock planting and direct seeding in northern New South Wales

Revegetation in agricultural regions across the globe has intensified over past decades in an effort to reverse widespread land degradation and conserve natural ecosystems and the biodiversity they contain. Biodiversity is essential for the physical, economic, social and cultural dimensions of human well-being, but agricultural intensification has resulted in the loss of millions of hectares of forests and natural vegetation globally. In Australia, a brief, but intense history of land clearing has resulted in the loss of 50% of forest ecosystems, with over 80% of eucalypt-dominated woodlands and forests having been altered by human endeavour. The situation on the Northern Tablelands of New South Wales reflects land clearing practices throughout the country with an estimated loss of tree cover of 50% to date. Although land clearing has eased in the past decade, tree decline continues due to recurrent episodes of rural dieback. To address this problem, substantial efforts have been made by revegetation organisations, practitioners and landholders to re-establish native trees in the region, but plantings often fail. This research was conducted to identify and reverse ecological barriers preventing the success of revegetation in temperate upland pastures. The work focused on tubestock plantings and direct seeding. The first study was conducted to determine if existing native shelterbelts can be evaluated in terms of survival and growth to identify the environmental stresses influencing planted eucalypt establishment and growth on the Northern Tablelands. Most ‘on-ground’ revegetation is designed and implemented with no thought given to follow-up scientific monitoring. Monitoring is important not only to justify the large amounts of public funding directed into revegetation activities, but also because it demonstrates whether targets have been achieved, and provides opportunities to learn from and improve upon past failures. Six-year old shelterbelt plantings consisting of Eucalyptus nitens, E. pauciflora and E. viminalis were examined to identify potential biotic and abiotic stresses influencing tree performance. Topographic position, altitude, slope, temperature, soil type, soil moisture and weed control were measured and modelled in relation to tree survival and growth (height). The information theoretic approach was used to select the best-fitting model from a set of competing models. Poor weed control and subzero temperatures were identified as the predominant stresses affecting eucalypt survival during the monitoring period. Subzero temperatures also significantly influenced tree growth. Given these results, the second study compared the performance of five native tree and shrub species grown in tall Corflute® tree guards and milk cartons at three landscape positions (lower slope, mid slope and upper slope) in an open temperate pasture. Seedlings in tall guards survived better than seedlings in milk cartons at mid and upper-slope landscape positions. Height was also greater for seedlings in tall guards than milk cartons at all landscape positions. Eucalypts in particular benefited from tall guards, with height growth up to three times greater than in milk cartons. Tall guards increased the temperature surrounding seedlings inside the guards, extending the growing period. Next, the efficacy of direct seeding as a revegetation technique was investigated. Prior to conducting this investigation, three trial sites were established and monitored for 3–6 months at Bingara, Ben Lomond and Invergowrie. Recruitment and subsequent establishment was so poor that the trials were considered a failure. This study compared the effects of three sowing methods (KB seeder, modified Chatfield planter and hand sowing) and three bulking materials (rice, chicken crumble and smoked vermiculite) on the recruitment of direct-seeded acacias and eucalypts. Recruitment was highest with the KB seeder followed by the Chatfield seeder and hand-sown methods. There were no significant differences in recruitment among bulking materials. Eucalypt recruitment was low compared to the recruitment of acacias. Recruitment peaked in mid May (8 weeks post-sowing) for acacias and in early July (15 weeks post-sowing) for eucalypts, but declined markedly for both genera during the reminder of the study. Some seedling losses were incurred following the first heavy frost, but most were attributed to an invasion of rat’s tail fescue (Vulpia myuros) in late winter, and waterlogging in the lower areas of the site due to above-average rainfall between May and August. Based on the results of the previous study two subsequent investigations were designed and implemented. To address the problem of weed invasion in direct-seeded revegetation, the effect of eight herbicide oversprays on the survival of 11 native tree and shrub species was examined. Seedling survival was assessed at 1, 2, 7 and 8 weeks post-spraying. Survival was greatest in seedlings treated with imazethapyr and isoxaflutole, and least in seedlings treated with diflufenican and glyphosate. There were also significant differences in survival between species, with Dodonaea viscosa, Acacia pendula and Senna artemisioides exhibiting the highest tolerance to the greatest range of herbicides, and Atriplex nummularia, Casuarina cristata and Einadia nutans exhibiting the lowest tolerance. Species varied in their tolerance of different herbicides, due to the selective nature of the different modes of action of the active ingredients and their differential uptake, translocation and metabolism between species. To address the problem of poor eucalypt recruitment, the effects of three seed-coating treatments (coated seed, seed coated with MycoApply® and uncoated seed), four watering regimes (30 mL per day, 30 mL per 3 days, 30 mL per 5 days and no water), and two seed-sowing methods (surface-sown vs buried beneath a 5-mm vermiculite layer) on eucalypt germination and early establishment were examined. Coating the seed with microbial inoculants as well as daily watering significantly increased germination. The interaction between sowing method nested within coating treatment and watering regime was significant. Soil moisture was essential for eucalypt germination and MycoApply® appeared to enhance water capture during the critical early post-germination phase when desiccation was most likely. When soil moisture was limited, seed burial beneath vermiculite was important because it increased seed-soil contact, providing better access to soil moisture, but only in seed coated with microbial inoculants. Seed-coating treatments did not benefit seedling growth (height) because soil moisture was not limiting. The final study examined the effects of four weed-control treatments (scalping, glyphosate, sugar and glyphosate, and sawdust and glyphosate) on the recruitment of native grasses and weed suppression. Recruitment of native grass was significantly higher in scalped plots compared to other treatments. The most effective weed- control treatments were scalping and the combinations of sugar and sawdust with glyphosate. Scalping and carbon (sugar and sawdust) addition controlled weeds by depleting weed seed banks, and alleviating soil nutrient enrichment. In combination with glyphosate application, which removed above-ground biomass, these techniques were effective strategies for combatting competitive invasive weeds. A summary of the main findings, study limitations and recommendations for future research were presented in the final chapter

Wind Shielding Analysis for Cold Regions Using Experimental and Numerical Techniques

The thesis presents a systematic experimental and numerical study on the interactions among porous fence, airflow, and windblown snowdrifts, a knowledge that will contribute to optimize the performance of porous wind shielding system in Cold Regions. A comprehensive review of the concepts, theories, techniques, and key findings associated with the research work has been undertaken. The key technical parameters influencing fence performance have been systematically studied by means of wind tunnel experimental investigations and Computational Fluid Dynamics (CFD) simulations. The study has found that porosity is the most influential structural parameter affecting the performance of porous fences in many aspects. Fence height stands a significant positive position in terms of its performance. It was found that fence performance is not sensitive to the changes of approaching atmospheric airflow velocity. Nevertheless, a bottom gap can improve snow fence trap efficiency. All of those findings agree with most of the findings of other researchers, which affirms that the research methodology adopted in this research is sound. Physical experimental work was performed to assess the reliability and credibility of the numerical models. Those models have been intentionally simplified, which made them easier to construct and quicker to obtain numerical solutions at a lower computational cost. Furthermore, the numerical models demonstrate the level of competence acquired through this research that is implemented in the optimisation of fence design. Special attention has been paid to the issues where elaborate research work has not been systematically reached in the open literature, this includes areas such as the effects of arrangement of porous holes, fence surface shear, and directions of wind load with respect to the fence, etc. Correlation between the reattachment length, the shelter distance, and the creation and distribution of fence surface shear is reported, to the author’s knowledge, for the first time in the open literature. General guidelines for the design of shelters based on porous fences have been established through this study. For example, the desirable size of hole range should be identified beforehand, and porous holes with sharp angular corners should usually be avoided in the fence design. It is recommended to place the fence within an angle of 30° to the wind load, where the effective shelter distance can be estimated in a linearized equation, and the normal drag coefficient can be described as a function of cos2θ. Optimal design of the arrangement of porous holes will maximize the fence performance, especially when the close fence environment is of concern. Although the definition of fence effective zone is still vague in the research field, the key factors influencing the fence effective zone have been investigated by evaluating the reduction of wind velocity leeward of the fence in this thesis. It is found that the fence effective zone is not sensitive to the change of approaching airflow velocity, and that increasing fence height will increase the physical size of the fence effective zone, but not in a proportional manner. It is also concluded that fence effective zone will be significantly reduced when the non-normal wind load is inclined at an angle greater than 30° to the fence. The effective zone increases effectively when the fence porosity is optimal. In contrast to the majority of published research work, the transient snow transport model presented in this work considers the snow transport rate as a whole without distinguishing the rate in saltation and suspension layer. The numerical study indicated that the position of the snow crest is mainly determined by the fence height, while porosity and bottom gap mainly affect the downwind deposition length. The optimal porosity for snow fences is in the range of 0.4 to 0.5, which is greater than the one for wind fences, which lies in the range from 0.25 to 0.35. Two snow crests have been observed leeward the fence at the onset of snow deposition, when the fence was placed without a bottom gap to the snow ground. This finding has not been encountered in any of the reported research work. Wind tunnel simulations of snowdrift around the fences have marginally under-predicted the sizes of snow deposition. The numerical predictions were quantitatively and qualitatively in good agreement with the field observations. This incompetence of wind tunnel experiments on porous fences implies that numerical modelling can play a more important role in snow fence research

Guidance and tool to support farmers in taking aware decisions on Ecological Focus Areas : Final report for Project JRC/IPR/2014/H.4/0022/NC

Farming has a significant role to play in the delivery of a number of desirable outcomes, including ecosystem services and biodiversity. Regardless of past agri-environmental policy and its intentions, there are still ongoing ecological problems that need attention, as demonstrated by the decline in populations of birds and mammals across the EU. The introduction of Ecological Focus Areas (EFAs) on the farm has potential to deliver tangible environmental improvements. However, it is also recognised that the extent of such improvements, and so the success of the policy, will ultimately depend on the specific EFA elements a farmer selects as well as the particular characteristics of the holding. To address this issue the JRC commissioned a project to develop a software tool to help farmers select EFA elements that can deliver the optimal environmental benefits considering the farms site specific characteristics and the pragmatic requirements of ensuring that the EFA solution overall are realistic in terms of farm management. There were four main tasks to the project: an extensive literature review; impact assessment; software development; and testing of the software application. This document constitutes the final report for this project (Ref. JRC/IPR/2014/H.4/0022/NC). It provides a description of the approach taken, a synthesis of the knowledge collated and a description of the outputs that have emerged, including the prototype software that has been developed. The literature review involved collating the scientific evidence that forms the foundation for the software tool. Over 350 papers, reports and guides which were collated and reviewed, resulting in synthesis provided herein, which is structured using the 19 individual EFA elements specified in the legislation. Although the synthesis itself was a valuable output from the project, it was not in a form that could be used to support the software tool. Thus the objective of the second task was to convert this knowledge into a form that could be utilised within the software. The impact assessment task analysed the knowledge synthesised in the first stage and converted it into a set of guidelines, criteria and rules that could be embedded in the core database that underpins the software. There were no established techniques available that could be used to undertake this task, so a bespoke approach had to be developed, albeit utilising established frameworks where possible. For example, the Common International Classification of Ecosystem Services (CICES) was used as the basis for the ecosystem service impact categories. A bespoke scoring system was developed, which although was relatively simple, distilled a lot of complex, and data intensive, parameters. The potential impact of each EFA feature on ecosystem services, biodiversity and management was determined. Then for each feature-impact, a set of parameters (and classes within those parameters) were determined, which affect the relative significance of the impact of that feature on the specified impact. For example, the parameter 'soil texture' with classes of: coarse, medium, medium-fine, fine, and very fine, will affect the impact on soil erosion, thus these classes were used to derive different impact scores (in combination with other parameters). In so doing, when the user of the EFA software describes their farm and features using such parameters, it is then possible to derive a potential impact score that is relevant for that farm. There were two approaches to the scoring of impacts: quantitative (using meta-modelling) and qualitative (using a risk factor approach). The quantitative approach was a more objective means to determine the scores, but it could only be undertaken for a few ecosystem service impacts (due to modelling limitations). Consequently, the majority of the scoring was done using the qualitative approach. Currently there are a total of 230 feature-impact combinations that have been created in the core the database. These are characterised using 138 different parameters containing 708 parameter classes. The software developed is known as the EFA calculator. It is a standalone Windows application that has been created using MS Visual Studio 2010 with the core database developed using MS Access. The software is freely available to download from the web (https://sitem.herts.ac.uk/aeru/efa/). The user downloads a setup file which then installs the application locally on the PC. The software has three key functions: to calculate the contribution of different farm features to meeting the 5% EFA target (including checking implementation rules); to calculate the potential impact of different features on ecosystem services, biodiversity and management; and to steer farmers towards features which offer the greatest potential benefits (with respect to minimising burdens and maximising benefits). As with any tool that attempts to make an assessment of potential environmental impacts the knowledge it is attempting to capture and communicate is inherently complex, which works against the criterion of designing a 'simple to use' to tool. To overcome this issue, the design philosophy from the outset was to provide the user with options to customise the tool to the level of detail they require. Therefore the user can decide to have 'basic' settings, or activate more advanced options to increase the level of detail to a level they desire. Using the basic settings the software only displays the necessary detail to undertake the core function of calculating the 5% EFA target. The impact assessment is still undertaken in the background, but the user is not presented with the detailed data input that is used to increase the accuracy of the impact assessment. In the advanced mode the user can obtain more accurate assessment of impacts, but this requires more data to be entered. The software has undergone two phases of testing: functionality testing and testing with hypothetical farm data. The first phase has been an ongoing task and involves checking for faults, errors and bugs; validity testing; usability (ease of use, support and help, interpretation and readability); testing of the installation routine; and performance and stability tests. The second phase was split into two parts and involved setting up hypothetical farm data to run through the software. The first part used simple case study farms to test all EFA elements activated in each Member State (32 in total including regions) to ensure all combinations functioned correctly. The second part involved creating 25 detailed scenarios, based on real locations, in 16 Member States. As well as providing a test of the software, the detailed scenarios also generated some interesting findings, in particular that for the majority of the 25 farms, their existing features would not be enough to reach the 5% EFA target, and thus they would need to create new features on the farm. There is little doubt that this was an ambitious project to undertake in a relatively short period of time. A substantial amount of work has been undertaken and some practical outputs developed. However, it is important to acknowledge that the tool is a prototype, has strengths and weaknesses, and scope for development in the future. Firstly, there is scope to improve the knowledge base. Scientific understanding is continually growing and evolving and thus we need to acknowledge this evolution and ensure that it is reflected in the tools and information that are made available to farmers across the EU. In terms of ecosystem service impacts, there scope to make improvements with respect to understanding impacts on provision of water, biomass and energy; global climate regulation by reduction of greenhouse gas concentrations; flood protection and other cultural services. For biodiversity, this project has reinforced the need to find a common and/or established framework for assessing impacts on biodiversity, and within this project there scope for greater harmonisation across the different features with regard to impact categories used, albeit this is partly reflection of the inconsistencies in the scientific evidence. For management, difficulties were experienced in gaining evidence specifically on the management implications of EFA features. Assessments were largely confined to crude evaluations of the potential impact on labour. Consequently there is considerable scope for improvement for this impact category. The prototype EFA calculator software that has emerged from this project has scope to be developed in the future. Feedback from users will be important to steer any future developments and it would also be valuable to ground truth the tool, i.e. to see how well the outputs from the tool match up to what is observed on the ground. The tool has been designed for farmers and farm advisors to use, although the latter that are more likely to be the main users. It should also be acknowledged that in the long term, widespread adoption of this tool (and others of a similar nature) ideally needs to be achieved in cooperation with commercial software companies. Seamless integration with existing management activities and software applications will aid the process of integrating environmental issues into the decision making processes of agricultural businesses, thus increasing the scope for widespread improvements in environmental performance

Quantifying the impact of rural land management on soil hydrology and catchment response

This thesis investigates several types of rural land management and the relationship with soil hydrology, local runoff and catchment response. There has been a clustering of extreme events over the last few decades which has encouraged debate amongst hydrologists that the frequency and magnitude of hydrological extremes are increasing. Land management changes are thought to have caused modifications to the hydrological cycle by altering the partitioning of rainfall into runoff. In England, farming is dominated by pastoral agriculture, with 40% of land cover classified as either improved or semi-natural grassland according to the Land Cover Map 2007. Nationalwide change to farming practices since the Second World War are thought to be responsible for high levels of soil compaction, longer slope lengths, increased runoff velocities and greater potential for connectivity, which may be responsible for an increase in flood risk at the catchment scale. However, there is a lack of physical evidence to support these theories. [Continues.

SITE-SPECIFIC CARBON STOCK ASSESSMENTS OF SHELTERBELT TREES IN SASKATCHEWAN

Climate change is threatening the entire planet, so collective efforts to mitigate it are crucial to our future. Planting trees is one of the easiest alternatives known to help sequester the carbon causing problem, yet this procedure is underutilized, especially in agricultural areas. This dissertation is an attempt to link the theoretical and practical issues regarding carbon stock assessments on a farm-level basis that could underpin policies aimed at mitigating climate change in rural areas. The goal of this study was to establish a method to retrieve past tree growth using increment cores, and to test if this information is reliable as input data to model carbon stocks on a farm-level basis. To do so, data was collected from shelterbelt grown trees of varying ages, species, and management conditions in farms across Saskatchewan, Canada, during the summers of 2018 and 2019. This dissertation presents many of the theoretical and historical aspects of shelterbelts in the early chapters, and then works towards finding practical solutions to some of the carbon modeling issues from shelterbelts in the later chapters. The first manuscript I developed discusses early shelterbelt history in Canada, and the environmental benefits that they have provided over the last century. I focus on the carbon sequestration potential from both above- and below-ground accrual, by examining the historical changes in the publication records on the subject through time. Contrasting shelterbelt effects on crops is also illustrated by comparing many studies from around the world, and how these effects change for different crops grown adjacent to shelterbelts. The many facets of carbon sequestration potential of shelterbelts were assessed by examining agroforestry studies from around the world. Conclusions drawn from this process are that shelterbelts represent a great potential for carbon sequestration and global warming mitigation. I argue that shelterbelts should therefore be more heavily applied to the existing agricultural land base, and discuss some potential policy changes that would assist in motivating more planting of trees to be implemented. Without a major change in policy, I argue that the full potential of carbon sequestration from shelterbelt systems will not occur. The goal of my second manuscript was to derive a precise and practical method to retrieve past tree growth using increment cores, and to better understand the associated error that came with such derivations. If accomplished, then shelterbelt carbon stock assessments could be improved, by allowing for a quicker and easier method of assessment. Factors such as the number of increment cores used, if a core reached the pith or the center of the tree, as well as species, age, and tree shape were assessed. Fifty-six combinations of these factors as well as their associated errors were processed, and the conclusion was that the more increment cores used reaching the pith, the better. The study also concludes that dendrochronologically derived increment core data, although not currently used for allometric purposes, is reliable as a mechanism to retrieve growth data (e.g., diameter at breast height, or basal area), which is commonly only measured in forestry operations from repeated visits and repeated measurements. In my last manuscript, the goal was to use data retrieved using the method described in my second manuscript, as input variables in the 3-PG model. This common forestry model was used to assess accuracy and how geographically specific fitting needs to be for the most precise estimates of past growth. It was found that using increment-core derived growth data yields a strong fitting, and that tree-level and site-specific fittings are more precise than the regional methods currently described in the literature. Both these results support that better carbon stock models could be made with this knowledge for two reasons. First, a greater database, i.e., ex-situ radial-growth data from tree-ring databanks, or in-situ obtained tree data, can be now considered for modeling purposes. Second, precise site-specific modeling can be used to calculate a farm-specific carbon footprint, which can ultimately be used as a tool to implement carbon incentivizing policies. The implications of being able to make a farm-based carbon stock model, is that it can support farm-specific carbon footprint calculations. This was the only theoretical-based factor remaining, a factor that precluded incentivization policies from being implemented by federal or provincial governments. Such policies could support a carbon market among farmers or/and a policy rewarding the carbon that many farmers are already sequestering. These policy/market changes would motivate shelterbelt tree planting, which would help the landowners, the agricultural sector, and most importantly, everyone, by assisting in the mitigation of global warming concerns.

An exploratory investigation of low-altitude aerial image acquisition for land surface studies

In the context of environmental monitoring and sustainable land management this thesis seeks to evaluate the application of low-altitude remote sensing from a DIY perspective in the lower Ashburton River catchment. It seeks to demonstrate that the innovative synergistic use of airborne digital videography and CIR (colour infrared) 35mm photography can provide near real-time photomapping at local levels. These technologies are relatively inexpensive, easy-to-use and have proven successful in other countries. Used together with Desktop software systems for image processing, measurement and spatial calibration one can fulfil many community based environmental monitoring and sustainable land use management tasks. The concept of sustainable land use also implies we have an understanding of the landscape processes past and present that have occurred in the region. This is assessed using historical documents so that we may better appreciate the pace of rapid transformation. The role of GPS technology for the georeferencing of selected images into a GIS system is evaluated. The potential adoption of environmental monitoring index systems developed in Australia and Canada is investigated which would rely partly on the proposals recommended in this study

Deserts and Desertification

A desert is an ecosystem in an arid zone in which sand dunes cover the land and sandstorms often occur. Although desert vegetation is sparse, it plays an important role in ecosystem structure and function. Desertification is one of the most severe environmental problems today. Land desertification can be controlled through many measures, such as eco-villages, eco-agriculture, biodiversity conservation, and the combination of engineering and biology. This edited volume provides new insights into the pattern of desert ecosystems and the progress of desertification control. It is a useful resource for researchers in ecology, forestry, and land desertification control