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Impact of viruses on prokaryotic communities and greenhouse gas emissions in agricultural soils
No full textViruses are abundant and ubiquitous in soil, but their importance in modulating greenhouse gas (GHG) emissions in terrestrial ecosystems remains largely unknown. Here, various loads of viral communities are introduced into paddy soils with different fertilization histories via a reciprocal transplant approach to study the role of viruses in regulating greenhouse gas emissions and prokaryotic communities. The results showed that the addition of viruses has a strong impact on methane (CH₄) and nitrous oxide (N₂) emissions and, to a minor extent, carbon dioxide (CO₂) emissions, along with dissolved carbon and nitrogen pools, depending on soil fertilization history. The addition of a high viral load resulted in a decrease in microbial biomass carbon (MBC) by 31.4%, with changes in the relative abundance of 16.6% of dominant amplicon sequence variants (ASVs) in comparison to control treatments. More specifically, large effects of viral pressure are observed on some specific microbial communities with decreased relative abundance of prokaryotes that dissimilate sulfur compounds and increased relative abundance of Nanoarchaea. Structural equation modeling further highlighted the differential direct and indirect effects of viruses on CO₂, N₂, and CH₄ emissions. These findings underpin the understanding of the complex microbe-virus interactions and advance current knowledge on soil virus ecology
Updated groundwater redox and depth to water models for New Zealand with reduced uncertainty
No full textUnderstanding hydrogeochemical heterogeneity, associated with natural nitrate attenuation, is an integral part of implementing integrated land and water management on a regional or national scale. Redox conditions are a key indicator of naturally occurring denitrification in the groundwater environment, and often used to inform spatial planning and targeted regulation
“It all depends on what you value”: value hierarchies as barriers to native biodiversity on dairy farms
No full textGlobally, agriculture is a dominant land use, with approximately 40% of the Earth's ice-free land managed by farmers and herders (Landis, 2017). Pastoral farming accounts for approximately half of Aotearoa's (New Zealand) land area, which also contains over 25% of the country's remaining native vegetation – the highest proportion outside of public conservation land (Norton and Pannell, 2018). When natural habitats are cleared for agriculture, most native biodiversity is lost (Letourneau and Bothwell, 2008; MacLeod et al., 2022). Habitat loss and fragmentation are compounded by the impacts of chemical inputs, invasive species and climate change on what little native biodiversity remains in agricultural landscapes (Emmerson et al., 2016). There are increasing calls to incorporate native biodiversity into farming systems (Dominati et al., 2019; Garibaldi et al., 2021; Kremen et al., 2012) in order to:
a) Increase the land area dedicated to native biodiversity so as to halt its decline,
b) Provide ecosystem services necessary for the sustainable functioning of agricultural systems, and
c) Grow a conservation ethic among landowners by fostering affective bonds between people and nature through daily encounters with native species
Book Review: Tom Cochrane, The Aesthetic Value of the World, Oxford University Press, 2021, pp. 240, £55 (hardback), 9780192848819
No full textModern media, particularly the Internet, have made it harder than ever to deny that the world is, in a large part, a place of misery and suffering. The war in Ukraine, the recent Turkish earthquake, and the seemingly unending sequence of mass shootings in the United States, are the headline grabbing examples of such suffering. But for billions surely, life comprises not just drudgery, but a precarious and pained existence. Given this, ‘What’, Tom Cochrane asks, ‘can prevent us from falling into nihilism and despair?
Re-assessing groundwater-surface water exchange in gravel-bed rivers
No full textThe aim of this presentation is to re-assess the concepts of surface water-groundwater interaction in gravel-bed river settings. The simple concepts and definitions familiar to us have been inherited from studies conducted in relatively passive river environments oversees (e.g. Winter et al. 1998, Brunner et al. 2009). For gravel bed rivers, a re-assessment is required to understand how existing definitions apply to a river environment which has an appreciable riverbed reservoir
Obstacles facing the development of forensic accounting curricula within the Australian universities: Exploring perspectives of practitioners and educators
No full textForensic accounting education has become an increasingly significant issue in recent years. In Australia, universities have acknowledged the industry’s growing relevance, and there have been attempts to address gaps in the provision of forensic accounting education. Despite these efforts, forensic accounting education is frequently omitted in university programs. This paper seeks to identify the obstacles that influence the transformation of forensic accounting knowledge into university programs. To do so, this study explores the perspectives of two groups: forensic accounting practitioners and university academics. Simi-structured interviews were conducted with the two groups to gather their perception. The findings show that the interdisciplinary nature of forensic accounting, the educator's relevant experience, and some other factors (e.g. university timetabling, calendar, venue arrangements, lack of forensic accounting instructional material, and professional and educational accreditations) are all obstacles facing the development process of forensic accounting. It is recommended for schools that do not have the required resources or are facing many obstacles in integrating forensic accounting education to offer an introductory elective course in the curriculum or utilize appropriately qualified guest speakers. The findings in this qualitative study could help educators in the development process of forensic accounting curricula
Reimagining innovation through Indigenous Agricultural Knowledge (IAK): Indigenous innovations and climate crisis resilience in the Pacific
No full textThis paper examines Indigenous innovation using self-determination for climate resilience within Indigenous communities in the Pacific. Given the Pacific context, communities are vulnerable to the climate crisis, but have adopted climate-resilient strategies and practices. A Pacific research methodological framing and qualitative ethnographic-case study approach was used for the study, which included discussion of some Indigenous enterprises and communitydriven development projects in Fiji. Talanoa method was used to collect data. Three themes unfolded from the three case studies in Fiji: the adoption of Indigenous Agricultural Knowledge as part of their operating model, practical contributions by the enterprises and community-driven projects in response to climate-induced disasters and aiding collective community resilience and well-being through their operations. Indigenous peoples are intimately and holistically connected to their vanua (resources, people and culture) reflected by their environment-related contributions and practices. The paper contributes toward understanding Indigenous innovation centred on indigenous peoples' socio-cultural and spiritual value systems. These are reflected in business operations and community-driven development projects that consider ecological limits and build collective resilience to the climate crisis
Global lake health in the anthropocene: Societal implications and treatment strategies
No full textThe world's 1.4 million lakes (≥10 ha) provide many ecosystem services that are essential for human well‐being; however, only if their health status is good. Here, we reviewed common lake health issues and classified them using a simple human health‐based approach to outline that lakes are living systems that are in need of oxygen, clean water and a balanced energy and nutrient supply. The main reason for adopting some of the human health terminology for the lake health classification is to increase the awareness and understanding of global lake health issues. We show that lakes are exposed to various anthropogenic stressors which can result in many lake health issues, ranging from thermal, circulatory, respiratory, nutritional and metabolic issues to infections and poisoning. Of particular concern for human well‐being is the widespread lake drying, which is a severe circulatory issue with many cascading effects on lake health. We estimated that ∼115,000 lakes evaporate twice as much water as they gain from direct precipitation, making them vulnerable to potential drying if inflowing waters follow the drying trend, putting more than 153 million people at risk who live in close vicinity to those lakes. Where lake health issues remain untreated, essential ecosystem services will decline or even vanish, posing a threat to the well‐being of millions of people. We recommend coordinated multisectoral and multidisciplinary prevention and treatment strategies, which need to include a follow‐up of the progress and an assessment of the resilience of lakes to intensifying threats. Priority should be given to implementing sewage water treatment, mitigating climate change, counteracting introductions of non‐native species to lakes and decreasing uncontrolled anthropogenic releases of chemicals into the hydro‐, bio‐, and atmosphere
The development of terrestrial ecosystems emerging after glacier retreat
No full textThe global retreat of glaciers is dramatically altering mountain and high-latitude landscapes, with new ecosystems developing from apparently barren substrates¹⁻⁴. The study of these emerging ecosystems is critical to understanding how climate change interacts with microhabitat and biotic communities and determines the future of ice-free terrains¹’⁵. Here, using a comprehensive characterization of ecosystems (soil properties, microclimate, productivity and biodiversity by environmental DNA metabarcoding6) across 46 proglacial landscapes worldwide, we found that all the environmental properties change with time since glaciers retreated, and that temperature modulates the accumulation of soil nutrients. The richness of bacteria, fungi, plants and animals increases with time since deglaciation, but their temporal patterns differ. Microorganisms colonized most rapidly in the first decades after glacier retreat, whereas most macroorganisms took longer. Increased habitat suitability, growing complexity of biotic interactions and temporal colonization all contribute to the increase in biodiversity over time. These processes also modify community composition for all the groups of organisms. Plant communities show positive links with all other biodiversity components and have a key role in ecosystem development. These unifying patterns provide new insights into the early dynamics of deglaciated terrains and highlight the need for integrated surveillance of their multiple environmental properties
Metabolisable protein supply and diurnal rumen nitrogen management and use in beef steers grazing fodder beet : A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Lincoln University
No full textThe winter feeding period in New Zealand presents a significant challenge for beef farmers to provide adequate feed for stock to maintain live weight (LWT) gains. The recent development of the fodder beet (Beta vulgaris subsp vulgaris L.) grazing system has enabled high LWT gains over this period. Commercial beef finishing operations have repeatedly reported ~1kg LWT gain per day, with dietary CP of <13%, and high sucrose and water content. Experiments were developed to investigate rumen and plasma nitrogen use and movement in the fodder beet diet, to better understand the mechanisms enabling high daily LWT gains.
Experiment 1 of Chapter 3 quantified the daily and diurnal (1, 3, 6 and 24-hour) dry matter (DM) and nitrogen intake of steers grazing industry standard fodder beet diets (90% fodder beet, 10% supplement), to match intakes with LWT gain of the steers, on a commercial farm. A single group of 69 steers (LWT 352kg) grazed fodder beet in situ for >120 days, with average LWT gain 1.0kg per day. Measured DM intakes and in sacco derived coefficients of rumen nitrogen disappearance were used to estimate metabolisable protein supply, compared with the estimated metabolisable protein demand, and then altered to reduce rumen nitrogen losses and increase bypass nitrogen, to provide new estimates of metabolisable protein supply. These data were used to model rumen nitrogen release across the diurnal period.
The diurnal DMI was non-uniform, and with a greater proportional intake of leaf and pasture components in the early grazing period. The diurnal nitrogen intake was then strongly non-uniform, with 47, 66 and 77% of daily nitrogen intake by 1, 3 and 6-hours. The feed nitrogen release was also strongly non-uniform, with 28% released in the first hour, then progressively declining to 24-hours. There was a 2.8kg WSC intake in the first 6-hours, and 0.97kg of WSC intake in the final 18-hours, with reduced nitrogen supply. It was concluded this diet was markedly asynchronous in rumen supply of energy and nitrogen. Despite a dietary CP content of 9.4%, the estimated metabolisable protein supply was adequate to meet the estimated metabolisable protein demand according to the AFRC feeding reference standard, but not for the NRC, for the observed LWT gain. Altering quickly degradable protein losses maximally from 0.8 to 0.95 increased the estimated metabolisable protein supply by 7%, and maximally altering undegraded dietary protein by 12%.
It was concluded that the non-uniform pattern of nitrogen intake and asynchronous supply of energy and nitrogen to the rumen did not significantly adversely reduce production in steers grazing this diet, as high LWT gains were observed. The strongly non-uniform rumen nitrogen release and high LWT gains suggested nitrogen recycling would be required. Finally, it was therefore concluded that there may be additional nitrogen management strategies in operation, as well as the traditional rumen and whole-animal nitrogen use in steers fed this diet, perhaps due to the novel characteristics of the diet, evidenced by the high LWT gains observed.
The strongly non-uniform, asynchronous intakes and high LWT gains observed in Experiment 1 led to the development of Experiment 2 in Chapter 4. This compared the DM and nitrogen intakes, LWT gains, rumen and plasma urea and ammonia concentrations, and plasma amino acids of steers on a fodder beet diet or a synchronous total mixed ration (TMR) on a commercial farm. A total of 938 steers in six mobs of ~150 steers, mobs grazed a diet of ad libitum fodder beet in situ or an ad libitum TMR. The diurnal DM and nitrogen intake of steers on the fodder beet and TMR diet treatments were measured at 1, 3, 6 and 24-hours, and rumen and plasma samples were obtained at two times during the grazing period. The LWT gains were similar (0.98kg per day; P>0.05) between treatment groups, despite the different dietary characteristics. The fodder beet diet treatment displayed a greater non-uniform pattern of DM and nitrogen intake than the TMR diet treatment (P<0.05), with 47 and 75% DMI, and 45 and 78% nitrogen intake, at 1 and 6-hours, respectively, and the TMR 20 and 45% DM and nitrogen intake at 1 and 6-hours, respectively.
The fodder beet diet treatment had lower mean rumen ammonia concentrations (86mg /L) and higher mean rumen urea concentrations (992mg /L) (P0.05) between the two diet treatments, with no apparent differences in glucogenic or ketogenic amino acid groups. While the TMR diet treatment estimated metabolisable protein supply was higher, both diet treatments supplied adequate metabolisable protein to meet demand despite the lower CP content of the fodder beet diet treatment (11.6 vs. 14.1%). It was concluded that there were important differences in rumen and whole-animal nitrogen use between the two diet treatments, despite the observed LWT gains being similar.
Experiment 3 in Chapter 5 was designed to investigate rumen nitrogen use and export across the diurnal period in fodder beet diets. A comparison of fodder beet and pasture feeding in treatment groups of eight pen-fed sheep (LWT: 34.1 and 39.3kg) with total urinary collection was used. Rumen nitrogen loss and microbial protein (MCP) outflow via sub-diurnal urinary nitrogen and purine excretion patterns were quantified. Measurements of total DMI and total urine production were undertaken at periods of 1, 3, 6 and 24-hours, to correspond with measurements conducted in Chapters 3 and 4. At 1 and 3-hours, the fodder beet diet treatment had 2-fold higher (P0.05), with 0.36 and 0.71g nitrogen excretion for the fodder beet diet treatment, and 0.23g and 0.47g nitrogen excretion for the pasture diet treatment. The urinary purine excretion was also similar between the two diet treatments at 1, 3 and 6-hours (P>0.05). The low DM content and heterogeneous nature of the fodder beet diet resulted in greater non-uniform diurnal intake of feed water for the fodder beet diet treatment. The feed water intake was ~3-fold and ~2-fold higher for the fodder beet diet treatment at 1 and 3-hours, respectively, and 48% higher for the fodder beet diet treatment at 6-hours (P=0.001, P=0.001, P=0.002). While urine production was higher for the fodder beet diet treatment at 1, 3 and 6-hours (P=0.001, P=0.004, P=0.017), this was not proportionate to the increase in feed water intake compared to the pasture diet treatment. From the comparatively greater water intake against urinary output in the early (1 and 3-hour) feeding period for the fodder beet diet treatment it was concluded that there was a net water retention, most likely an increased GIT volume as rumen digesta volume. It was concluded the proportionately lower rumen export of nitrogen in the fodder beet than the pasture diet treatment in the early (1 and 3-hour) period of the diurnal cycle to urinary nitrogen or to purines was likely due to greater nitrogen retention in the rumen in the early (1 and 3-hour) feeding period, and this may be a mechanism of nitrogen use and movement in the fodder beet diets that may explain the strong production observed with comparatively low CP content.
The results of Experiment 3 suggesting reduced rumen nitrogen export in the early feeding period and with this a net water retention were further examined in Chapter 6 in two experiments. Experiment 4a was designed to quantify the proportion of rumen nitrogen exported from the rumen, or recycled to the rumen, in ad libitum fodder beet fed steers, using infusions of isotopically labelled 15N15N urea to either the plasma or the rumen. Experiment 4b quantified the diurnal rumen volume fluctuations in fistulated rising-one-year-old beef steers fed fodder beet or pasture.
Four rising-one-year-old steers in metabolism crates (Experiment 4a) had feed intake measured and total faecal and urinary collection, in a 2 x 2 crossover experimental design. In each of two 76-hour periods separated by an 18-day washout, two steers were infused with the stable isotope of 15N15N urea into the rumen, and two steers were infused with 15N15N urea into the jugular and blood and rumen digesta samples were then obtained from steers at 4-hour intervals for 24-hours to determine abundance of 15N in rumen fluid and plasma, and also in daily urine and faeces. Experiment 4b used complete rumen evacuations every 16-hours for 48-hours to determine rumen digesta volume across the diurnal cycle (0, 8, 24-hours after feeding) in steers grazing ad libitum pasture or fodder beet. Diurnal rumen fluid abundance of 15N for the rumen infusion treatment displayed substantial diurnal variation (P0.05) at any measurement period throughout the diurnal cycle. Mean daily urinary excretion of 15N was 3701 for the rumen 15N infusion compared with 9842 for the jugular 15N infusion (P=0.004). The mean abundance of 15N in faeces was higher (P=0.037) for the rumen (238 δ15N ‰) than the jugular infusion (137 δ15N ‰) treatment. These results indicated low transfer of rumen nitrogen to the plasma, with little diurnal variation in this transfer, and that rumen import of nitrogen was more substantial, and greater at diurnal phases associated with higher rumen activity.
Experiment 4b demonstrated that rumen volume increases at 8-hours were greater in fodder beet fed steers, compared to pasture fed steers, and the rumen urea pool was significantly greater at 8 and 16-hours after feeding (P<0.05) for the fodder beet diet treatment, and the rumen ammonia pool significantly greater for the pasture diet treatment, across the entire diurnal cycle (P<0.05).
From the results of this series of experiments, it was concluded that, in addition to nitrogen recycling strategies previously described, rumen retention of nitrogen in the early post-prandial period, by these several mechanisms identified in this study, was a possible novel rumen nitrogen management approach which may have influenced the high LWT gains observed with this diet by reducing rumen nitrogen losses. The role of rumen adaptation to a diet of low CP and NDF, but high WSC and water content, in any rumen nitrogen management mechanism should be an important consideration in further research