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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
141

Effects of hydro-meteorological variables, soil physical properties, topography and land use on unsaturated zone soil moisture in Siloam Village, South Africa

Nndwammbi, E. M. 10 February 2016 (has links)
MESCH / Department of Hydrology and Water Resources
142

Uso de resíduo da extração de celulose e o impacto em solo de cerrado cultivado com eucalipto e espécie arbórea nativa /

Arruda, Otton Garcia de. January 2012 (has links)
Orientador: Marlene Cristina Alves / Banca: Francisco Maximino Fernandes / Banca: Rafael Montanari / Resumo: Com a produção de papel e celulose as indústrias do setor têm gerado diariamente grandes quantidades de resíduos sólidos e efluentes, constituindo-se em uma grande preocupação ambiental e econômica. No intuito de retornar com estes subprodutos de forma sustentável à natureza, esse trabalho teve como objetivo testar a eficácia de um resíduo orgânico advindo da indústria de papel e celulose quanto a sua influência sobre os atributos químicos e físicos do solo e desenvolvimento de plantas arbóreas. O experimento foi implantado em um Latossolo Vermelho distrófico no município de Selvíria, MS. O delineamento experimental foi em blocos ao acaso, onde se avaliou o clone Eucalyptus spp. e a espécie nativa Mabea fistulifera com cinco tratamentos: sem adubação (controle), adubação mineral, 10 t ha -1, 15 t ha-1 e 20 t ha-1 do resíduo celulósico. Nas camadas de solo de 0-0,05; 0,05-0,10; 0,10-0,20 e 0,20-0,40 m avaliaram-se os atributos químicos: MO, pH, P, K, Ca, Mg, H + Al, Al e calculou-se a SB, CTC e V%; e os atributos físicos: macroporosidade, microporosidade, porosidade total, densidade do solo, estabilidade de agregados em água, resistência do solo à penetração e infiltração de água. Para as características dendrométricas das plantas foram avaliados: altura média de plantas, diâmetro do caule na superfície do solo (DSS) e diâmetro médio das copas (DMC) trimensalmente, até os 21 meses. Para a cultura do eucalipto, também foram determinados o diâmetro a altura do peito (DAP), o volume de madeira e o incremento médio anual do volume de madeira aos 21 meses. Os resultados foram analisados aplicando-se a comparação entre médias, contrastes e análise de regressão. Concluiu-se que o uso de resíduo celulósico influenciou os atributos do solo estudado, principalmente nas camadas superficiais do solo... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: A large amount of solid waste and effluents have been daily generated by industries due to the cellulose and paper production, becoming a major environmental and economic concern. In order to return with these by-products in a sustainable way to nature, the aim of this study was to test the effectiveness of an organic waste from cellulose and paper industry as its influence on soil chemical attributes and development of eucalyptus plants. The experiment was implanted in an Oxisol in the city of Selvíria, MS, Brazil. A randomized block design was used, which evaluated Eucalyptus spp. and and the native species Mabea fistulifera with five treatments: no fertilization (control), mineral fertilizers, 10 t ha -1, 15 t ha-1 and 20 t ha-1 of cellulosic residue. In the soil layers of 0-0,05; 0,05-0,10; 0,10 - 0,20 and 0,20 - 0,40 m, were evaluated: organic matter, pH, P, K, Ca, Mg, H+AL, Al and calculated the sum of bases, CEC and base saturation, and physical attributes: macroporosity, microporosity, total porosity, bulk density, aggregate stability in water, soil resistance to penetration and water infiltration. For the plants dendrometric characteristics were evaluated: plant height, stem diameter at the soil surface and diameter of the crown quarterly, up to 21 months. For the cultivation of eucalyptus the diameter at breast height, the volume of wood and the average of the annual increment of timber volume were also determined. The results were analyzed by comparison of means, contrasts and regression analysis. In conclusion, the use of cellulosic waste influence the soil characteristics studied mainly in the surface layers of soil (0-0,10 m), negatively macroporosity and infiltration of water to the cultivation of eucalyptus and stabilit y of aggregates M. fistulifera. For the chemical increased the contents of Ca, Mg, SB and CEC of the soil for eucalyptus... (Complete abstract click electronic acces / Mestre
143

Soil health as influenced by the integration of cover crops and poultry litter in north-central Mississippi

Kovvuri, Nikitha Reddy 08 August 2023 (has links) (PDF)
Soil health-based agricultural management practices are widely promoted to improve soil structure, infiltration and reduce erosion. This study was conducted at two locations in North-Central Mississippi to evaluate the influence of different cover crop species and poultry litter on soil health that can impact crop production, climate change, and resilience. The results indicated that the cover crops showed a little effect on some soil health indicators compared to control treatment. However, in one location, rye, and a mixture of cover crops decreased bulk density and increased available water content and organic matter. The poultry litter had a positive effect on most soil physical and chemical health indicators. The cover crop species at Pontotoc decreased bulk density, increased field capacity, CEC, and total carbon. However, there was no significant effect of cover crops on most soil chemical health indicators, and soil responses may take more than five years for the changes to appear.
144

Evaluating soil health changes following cover crop and no-till integration into a soybean (Glycine max) cropping system in the Mississippi Alluvial Valley

Firth, Alexandra Gwin 13 May 2022 (has links)
The transition of natural landscapes to intensive agricultural uses has resulted in severe loss of soil organic carbon (SOC), increased CO₂ emissions, river depletion, and groundwater overdraft. Despite negative documented effects of agricultural land use (i.e., soil erosion, nutrient runoff) on critical natural resources (i.e., water, soil), food production must increase to meet the demands of a rising human population. Given the environmental and agricultural productivity concerns of intensely managed soils, it is critical to implement conservation practices that mitigate the negative effects of crop production and enhance environmental integrity. In the Mississippi Alluvial Valley (MAV) region of Mississippi, USA, the adoption of cover crop (CC) and no-tillage (NT) management practices has been low because of a lack of research specific to the regional nuances. Therefore, this study assessed the long-term soil physiochemical and biological responses from integrating CC and NT management to agricultural soils of the region. Research plots were established in a split-block design with two tillage treatments: NT and reduced tillage (RT) and three CC treatments: no cover (NC), rye (RY) and a rye+clover (RC) mix. Soil samples were taken during the growing season of 2019 and 2020. Bulk density was found to be significantly lower in NT plots and aggregate stability was greatest in plots with a single CC species. Moisture retention increased in NT.. Soil organic carbon was greater in NT and CC treatments and there was no difference in CO₂ flux. Bacterial abundance had a positive effect on SOC but a negative effect on CO₂. The rate of proportional change and pattern of variability in C pools suggested loss of SOC in reduced tillage (RT) treatments. Microbial abundance, functional genes and enzyme activity was greater in NT with CC, but diversity was greater in RT. No-tillage practices lower diversity and influence long-term community changes while CC practices enact a seasonal response to environmental conditions. I conclude that in heavy clay soils of the mid-South region of the MAV, RT with a CC is optimal for soil health traits associated with crop sustainability, however the management will still contribute to increased CO₂ emissions.
145

Modeling the Seasonality of Carbon, Evapotranspiration and Heat Processes for Cold Climate Conditions

Wu, Sihong January 2010 (has links)
The productivity of agricultural and forest ecosystems in regions at higher latitudes is to a large extent governed by low temperature and moisture conditions. Environmental conditions are acting both above- and below-ground and regulating carbon fluxes and evapotranspiration. However, the understanding of various feedbacks between vegetation and environmental conditions is still unclear. In this thesis, two studies were conducted to understand the physical and biological processes. In the first study, the aim was to simulate soil temperature and moisture dynamics in the bare soil with seasonal frost conditions in China. In the second study, the aims were to model seasonal courses of carbon and evapotranspiration and to examine the responses of photosynthesis, transpiration and respiration on environmental conditions in a boreal Scots pine ecosystem in Finland. In both studies the CoupModel was applied to simulate the dynamic responses of the systems. Both sites represented investigations from which a high number of measurements were available. To understand to what extent the data could be used to increase the understanding of the systems, the Generalized Likelihood Uncertainty Estimation (GLUE) was applied. The GLUE method was useful to reduce basic uncertainties with respect to parameter ranges, model structures and measurements. The strong interactions between soil temperature and moisture processes have indicated by a few behavioral models obtained when constrained by combined temperature and moisture criteria. Model performance on sensible and latent heat fluxes and net ecosystem exchange (NEE) also indicated the coupled processes within the system. Seasonal and diurnal courses were reproduced successfully with reduced parameter ranges. However, uncertainties on what is the most general regulation for transpiration and NEE are still unclear and need further systematic investigations. / QC 20101206
146

Assessing Soil-Water Status Via Albedo Measurement

Idso, Sherwood B., Reginato, Robert J. 20 April 1974 (has links)
From the Proceedings of the 1974 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 19-20, 1974, Flagstaff, Arizona / Reliable information on soil-water status is required in order to make accurate water balance studies of watersheds, to determine the survival probabilities of various types of vegetation between rainfalls in low rainfall areas, and to determine the susceptibility of the uppermost soil to wind erosion. Simple solarimeters may help to accomplish this objective. Bare soil albedo was a linear function of the water content of a very thin surface layer of soil, and albedo correlated well with water contents of thicker soil layers. In addition, albedo measurements could be used to delineate the 3 classical stages of soil drying. Albedo may also be used to differentiate between the initial potential rate phase of evaporation following an application of water, and the succeeding falling rate phase. Results of applying this technique to a field of Avondale clay loam indicate that 20% to 25% of the water applied by either irrigation or rain will be lost by stage 1 potential evaporation, independent of seasonal variations in evaporative demand. Presently the techniques developed are applicable only to bare soil surfaces.
147

Indicadores da qualidade do solo de propriedades em transição agroecológica. / Indicators of soil quality properties in agroecological transition.

RUFINO, Sara Regina Miranda. 23 April 2018 (has links)
Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-04-23T15:55:11Z No. of bitstreams: 1 SARA REGINA MIRANDA RUFINO - TESE PPGEP 2014..pdf: 3286437 bytes, checksum: cfafef220e2b9de314c5df81f2286b36 (MD5) / Made available in DSpace on 2018-04-23T15:55:11Z (GMT). No. of bitstreams: 1 SARA REGINA MIRANDA RUFINO - TESE PPGEP 2014..pdf: 3286437 bytes, checksum: cfafef220e2b9de314c5df81f2286b36 (MD5) Previous issue date: 2014-08-28 / A agricultura familiar, com base agroecológica, tem estimulado mudanças significativas na vida de famílias de agricultores familiares, seja no manejo do solo, na relação com o meio ambiente, hábitos alimentares, segurança alimentar, ou mesmo autonomia produtiva. Nesta perspectiva, avaliar a qualidade do solo dentro de sistemas em transição agroecológica (convencional para agroecológico), pode proporcionar melhor compreensão sobre seus efeitos deste sistema de cultivo do solo. Na busca da sustentabilidade de sistemas agrícolas o uso de indicadores no monitoramento das condições do solo constitui-se numa importante ferramenta para a tomada de decisões na condução das produções. O objetivo deste trabalho foi comparar propriedades físicas, químicas, bioquímicas, microbiológicas e termogravimétricas de solos de mesorregiões do agreste da Paraíba em transição agroecológica. O presente estudo foi desenvolvido na Mesorregião do Agreste-Brejo da Paraíba. Foram coletados solos em propriedades de agricultores familiares sob sistema de cultivo agroecológico e convencional, os quais foram submetidos a diferentes indicadores de sustentabilidade do solo. Os indicadores químicos nitrogênio, matéria orgânica leve, carbono orgânico total e matéria orgânica, apresentaram maior correlação e sensibilidade quanto a sua utilização de indicadores da qualidade de solos em transição agroecológica. A termogravimetria apresentou potencialidade na identificação dos solos com relação ao teor de matéria orgânica de solo agrícola. / A family farm with agroecological base, has spurred significant changes in the lives of farming families, either in soil management in relation to the environment, eating habits, food security, or even productive autonomy. In this perspective, assessing soil quality within systems (for conventional agroecological) agroecological transition may provide better understanding of the effects of this system of cultivation. In search of the sustainability of agricultural systems, using indicators in the monitoring of soil conditions constitutes an important tool for decision making in the conduct of productions. The objective of this study was to compare physical, chemical, biochemical, microbiological and thermogravimetric soils of the rough mesoregions of Paraíba in agroecological transition properties. This study was developed in Meso - Heath of the Wasteland Paraíba. Soil samples were collected on properties of farmers in agro-ecological and conventional cropping system, which were subjected to different indicators of soil sustainability. Chemical indicators nitrogen, light organic matter, total organic carbon and organic matter showed higher correlation and sensitivity as the use of soil quality indicators in agro-ecological transition. Thermogravimetry showed potential in the identification of soils in relation to organic matter content of agricultural soil.
148

Posouzení kvality půdy zpracované klasickým způsobem ve vybrané lokalitě v Olomouckém kraji / Assessment of soil quality processed with conventional tillage in the selected site in the Olomouc region

Drlíková, Barbora January 2017 (has links)
Diploma thesis documents the problems of soil quality, which is assessed on the basis of physical, chemical or biological indicators of soil quality. The paper describes the various indicators, its methodology and evaluation. In the practical part evaluates the quality of soil cultivated with the traditional way - using plowing. The experimental area, where the samples were taken from the soil, lies in the Olomouc region in the municipality Šumvald. Evaluated were selected physical, chemical and physico-chemical properties of soil, e.g. particle size distribution, bulk density, porosity, air capacity, hydrolimits, pH, carbonates, humus content and salinity of the soil.
149

Impact of topsoil depth and amendment application on soil health and agronomic productivity in central Ohio

Moonilall, Nall Inshan January 2022 (has links)
No description available.

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