Cycling of nutrients, such as Carbon (C) and Nitrogen (N), is one of the most important soil functions and is strongly related to the composition of the soil microbial community. However, soil is increasingly under environmental pressures that threaten its ecological functions and sustainability. To maintain soil functional sustainability, it is important to understand how soil withstands environmental stresses (subsequently referred to as resistance) and recovers from stresses (subsequently referred to as resilience). This study focused on the resistance and resilience of C and N processes and the underpinning microbial communities to a persistent Cu stress or a transient heat stress. The main advances and novel findings of this thesis are: (1) C mineralization is more resistant and resilient than ammonia oxidation and denitrification, and thus the combination of C and N processes are more informative than measuring a single process to interpret the overall resistance and resilience; (2) microbial composition and microbial physiological evolution play important roles in affecting resistance and resilience; (3) soil physico-chemical properties (e.g. organic matter, soil water and soil pH) are critically important in conferring resistance and resilience. The outcome of this study advances the understanding of the mechanisms of soil resistance and resilience of C and N cycling to environmental changes. The results generated here are an essential step for improving soil sustainability and promoting agricultural productivity under future environmental challenges.

No description available.

Typescript. / Digitized by Kansas Correctional Industries

As Charles Darwin first noted in 1881, earthworms through their burrowing and casting activities, play an important role in the creation and maintenance of soil structure. Burrowing activity leads to the reorganisation of voids and creation of macropores within the soil. This has implications for aeration and the flow properties of water through soils. Casting activity affects the structural stability of soil through the stabilisation of aggregates. The overall aim of this research project has been to investigate the effects of earthworm activity and diversity on void space and aggregation in an upland soil. This research has been carried out as part of NERC's Thematic Programme on Soil Biodiversity. The field site was located on the Macaulay Land Use Research Institute's experimental farm at Sourhope in the Scottish Borders. Three experiments were designed to investigate the impact of earthworms on soil fabric, with each experiment representing an increased level of system complexity. The simplest experiment took place in a controlled environment and used an artificial soil and different earthworm treatments. The second level of system complexity used soil from Sourhope which had its structure removed, and then earthworm and liming treatments applied. The most complex experiment also used Sourhope soil and liming and earthworm treatments, except in this case the soil was undisturbed. The effects of earthworms and liming on void space were characterised using saturated hydraulic conductivity to measure macroporosity, and image analysis to quantify total porosity and void size distribution. Aggregation was assessed through aggregate stability and point counts of earthworm excremental features. The effect of earthworm inoculation in the simplest experiment led to the reorganisation of voids through increased abundance of voids > 2 mm2 in area, and decreases in the proportion of voids with an area < 2 mm2. No significant effects were observed on aggregate stability. The effect of liming in the experiment using disturbed soil was to increased abundance of voids > 2 mm2. No significant effects were observed on aggregation due to either liming or earthworm inoculation. In the most complex experiment, neither liming nor earthworm inoculation led to changes in void space or aggregation, except for an increase in saturated hydraulic conductivity and therefore macroporosity due to earthworm inoculation. The overall conclusions from this research were that as system complexity increased, then the effects of the treatments on void space and aggregation became more difficult to isolate. Nevertheless, it was clear that liming significantly affected void space through increased abundance of earthworms. Out of the two treatments applied to the Sourhope soil, liming had the strongest effect on both earthworm abundance and void space.

Thesis (M. Sc.)--Carleton University, 1992. / Also available in electronic format on the Internet.

No description available.

Neste trabalho apresenta-se o estudo geoarqueológico do sítio Sol de Campinas do Acre (SCA), sítio de estruturas monticulares localizado no sudoeste da Amazônia brasileira. Considerado pelo Registro Nacional de Sítios Arqueológicos como um geoglifo circular, atualmente é composto de 15 montículos com uma altura média de 3 metros. Os montes são dispostos de forma elíptica em torno de uma praça central, cobrindo aproximadamente 15.000 m². As datações de radiocarbono mostraram que o SCA foi construído após a maioria dos geoglifos na região. Especificamente, o montículo M11, estudado neste trabalho, revelou uma sucessão de eventos de ocupação entre os séculos XI e XVII As estruturas em terra são amplamente conhecidas na Amazônia desde os tempos antigos por causa de sua conspicuidade na paisagem (frequentemente interpretada como evidência de monumentalidade). Apesar da quantidade, extensão e diversidade de formas que essas estruturas podem adotar, pouco se sabe sobre o uso que tiveram nas comunidades responsáveis pela sua construção. Pesquisas recentes no sudoeste da Amazônia concebem a engenharia de terra como uma prática cultural dinâmica e duradoura que transformou a paisagem e estabeleceu redes regionais de comunicação. Apesar das estruturas em terra da Amazônia serem amplamente conhecidas, ainda existem poucos estudos geoarqueológicos que busquem compreender os processos de formação a partir do estudo de seu principal componente: os sedimentos. Os resultados do estudo micromorfológico do montículo M11 indicaram uma clara intencionalidade na escolha do material de construção. A matéria prima utilizada foi sempre o solo da região. Foi possível observar duas técnicas construtivas em diferentes momentos da história do montículo M11: a primeira foi utilizada na construção da base do montículo, com o uso de material argiloso e nódulos de ferro, possivelmente para oferecer maior resistência à estrutura; e a segunda utilizada nas camadas superiores, construídas com material de granulometria mais grossa (frações silte e areia), que indicam uma continuidade desta prática ao longo de diferentes gerações. A construção do montículo M11 segue uma engenharia que o permitiu permanecer na paisagem por pelo menos cinco séculos, com uma realidade climática de intensas chuvas, secas e recentemente atividades pecuárias. Os povos originários responsáveis pelas construções das estruturas em terra da Amazônia Ocidental não tinham variedade de materiais construtivos. A história geológica da região resultou em um cenário onde os recursos minerais eram restritos aos solos da região e sedimentos dos rios e igarapés. Os povos construtores foram capazes de conhecer e dominar os recursos criando variedades com seleção de misturas e técnicas para uso. / This dissertation presents the geoarchaeological study of one of the largest geoglyph sites in the southwest of the Brazilian Amazon: the Sol de Campinas do Acre site (SCA). Considered by the National Register of Archaeological Sites as a circular geoglyph, it is currently made of 15 mounds with an average height of 3 meters. The mounds are arranged elliptically around a central plaza covering approximately 15.000 m². Radiocarbon datings showed that SCA was built after most geoglyph sites in the region. Specifically Mound 11, studied in this work, revealed a succession of occupation events between the 11th and 17th centuries. Earthen mound complexes have been widely known in the Amazon since ancient times because of their conspicuousness in the landscape (often interpreted as evidence of monumentality). Despite the quantity, extent, and diversity of forms that earthen mounds can adopt, little is known about their use in the communities responsible for their construction. Recent research in the southwest Amazon conceives earth engineering as a dynamic, enduring cultural practice that transformed the landscape and established regional communication networks. Although widely known, there are still few geoarchaeological studies on the Amazonian earthen mounds seeking to understand the formation processes of the structures from the study of its main component: sediments. The results of the micromorphological study of Mound 11 at SCA have indicated a clear intentionality in the choice for construction material. The soil around the archaeological site was always used as raw material. Two construction techniques were identified in different moments of the mound\'s history: the base of the mound, where material with clay and iron nodules was utilized, possibly to offer more resistance to the structure; and the upper layers, constructed with coarser material (silt and sand), indicating the continuity of this building practice across different generations. Construction of mound M11 followed an engineering that allowed it to remain stable in the landscape for at least five centuries in a climatic context of intense rain, droughts and recent livestock farming. The indigenous peoples responsible for the construction of the earthen mounds of Western Amazonia faced a scarcity of construction materials. The geological history of the region resulted in a scenario where mineral resources were restricted to the local soils and the sediments near rivers and streams. Mound builders knew and controlled the resources by creating varieties with selection of mixtures and techniques.

Thesis (Ph. D.)--Carleton University, 1996. / Also available in electronic format on the Internet.

Thesis (Ph.D.) - University of Queensland, 2005. / Includes bibliography.

Ever since the development of farming humans have been implicitly linked with the landscape. Influences include the manipulation of natural environments by woodland clearance, field developments and animal husbandry. Development can also be determined by the identification and distribution of soils developed and modified by the addition of organic and inorganic components. Anthropogenic or amended soils have been identified in many forms across north west Europe that retain distinctive physical and chemical indications of historical agrarian and settlement history. This thesis researched the on-site distribution of anthropogenic and amended soils across different landuse areas and identified and quantified a range of black carbonised particles in order to investigate their role in the soils ability to retain high elemental concentrations of manuring and elements associated with domestic activity and industrial processes. Three sites in contrasting environments were chosen for analysis; in Fair Isle, the Netherlands and Ireland on the basis of an excellent agararian and settlement history and previous analysis of anthropogenic soils. The fieldwork results showed extremly deep plaggen soils in the Netherlands but considerably shallower horizons of amended arable soils on Fair Isle and in Ireland contrary to previous analysis. There was however, clear evidence of a reduction in anthropogenic and amended soils with increased distance from the farm centres as a result of less manuring. The soil pH, organic matter, particle size, magnetic susceptibility and bulk elemental analysis results showed unexpected increases in the amended soils of Fair Isle and Ireland and reflected a similar manuring process. In the Netherlands the deep plaggen soils had very low results reflecting modern arable farming. The micromorphology results illustrated distinctive characteristics associated with localised manuring techniques. On Fair Isle and in Ireland the main organic manuring material was peat and burnt peat, whereas in the Netherlands the plaggen soils were predominantly composed of meadowland and heathland turf. At all three sites there was a large number of black carbonised and black amorphous inclusions and point counting and image analysis results showed a decrease with depth and distance from settlement nucleii mirroring the fieldwork observations. The elemental analysis conducted has proved to be an extremly useful tool for the identification of various forms of black carbon and for identifying the provenance of high elemental concentrations. The oxygen:carbon ratios confirmed the origins of organic components used in the development of the amended and anthropogenic soils and the elemental analysis showed that at each site over 80% of visually unidentifiable amorphous black carbon particles were heavily decomposed carbonised inclusions. Overall the elemental concentrations within the black carbonised particles was very low but this reflected the elemental results found in the bulk soils and the inclusions contained higher concentrations of P, Ca, K, Fe and Al and considerably lower concentrations of elements associated with domestic activity or industry Zn, Cu, Ba, Cr, As and Pb.