Meandering rivers and associated vegetation communities are highly dynamic systems that interact through various geomorphic and successional processes. However, much is still unknown about these interactions. Studies that focus on system integration rather than examining fluvial-related and vegetation dynamics individually will benefit science and the management of river systems. Tree communities in riparian areas, although consisting mainly of bottomland hardwood species, can be very diverse. Diversity has been linked to environmental influences such as meander migration, and changes in elevation and soil texture. This study focused on a single meander bend of the lower Trinity River in southeast Texas. The purpose of this research was to examine interactions between soil texture variation and the establishment and succession of riparian tree communities, as such interactions contribute to the formation of complex riparian landscapes. A bend-scale approach was utilized to provide a detailed study of vegetation pattern and of soil texture resulting from sedimentation processes, to examine for any relationships between them. Aerial imagery was used to assist in interpreting patterns of vegetation succession. The field portion of the study collected species and size class data on trees and soil samples for textural analysis. These data were analyzed separately to understand variations in tree communities and soils, but also together, to determine any relationships between soil texture and what tree communities are able to establish. Mean annual flow data from gauges upstream and downstream of the site were analyzed for changes in flow following dam construction upstream, as river regulation could potentially alter the vegetation establishment regime. Results showed five distinct communities or zones of vegetation. Soils on the site were strongly skewed toward finer sands and high silt and clay content. Zone locations and community structure were not directly related to soil texture; however, given species had clear relationships of relative density or dominance with specific soil textures. No changes in flow were noted between pre- and post- dam construction periods, indicating that the riparian system at this site may operate under near-natural conditions. Further studies in species-soil texture interactions, and for rare and invasive species in particular, may prove beneficial in improving understanding of the complex functioning of riparian systems and in providing valuable information for their management and restoration.

Made available in DSpace on 2014-06-11T19:31:37Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-12-03Bitstream added on 2014-06-13T21:02:57Z : No. of bitstreams: 1 benini_lc_dr_botfca.pdf: 1063271 bytes, checksum: ac62bd61becd308d39b1c058ea679181 (MD5) / Este trabalho tem por objetivo principal apresentar o desenvolvimento de um sistema inteligente, utilizando a Teoria Fuzzy, para estimar valores aproximados da densidade do solo a partir de medidas diretas (campo) sem a necessidade de ensaios laboratoriais e, consequentemente, identificar a compactação do solo por meio destes valores estimados. A densidade do solo é um dos principais parâmetros utilizado para a identificação do grau de compactação do solo, e está relacionada com outros parâmetros tais como a resistência à penetração do solo, o teor de água e a textura do solo. Para o desenvolvimento do trabalho foram considerados três parâmetros do solo: a resistência à penetração representado pelo índice de cone (em kPa), o teor de água dado pela umidade do solo (em porcentagem, %), e a textura dada pela quantidade de argila presente no solo (em porcentagem, %). Foram, ainda, considerados solos preparados (passagem de arado, de grade, de escarificador, e outros) e solos não preparados (nenhum tipo de preparado ou em solo de plantio direto). Segundo a porcentagem de argila no solo, estes foram divididos em solo tipo I (teor de argila menor que 30%), solo tipo II (teor de argila entre 30% e 50%), solo tipo III (teor de argila maior que 50%) para o solo não preparado, e solo tipo I (teor de argila menor que 30%) e solo tipo III (teor de argila maior que 50%) para o solo preparado. O modelo matemático proposto para determinar as estimativas da densidade do solo foi desenvolvido com base em dados experimentais representados pelas três características do solo: índice de cone, umidade e argila. Utilizando os dados experimentais os modelos foram identificados por meio de um algoritmo neuro-fuzzy, em função da resistência à penetração, teor de água e textura do solo, onde se pode analisar a densidade do solo para os distintos valores das variáveis de entradas... / The present work aims to develop a intelligent system using fuzzy theory in order to estimate approximate values for the soil density taking in account direct measurements (in loco) disregarding laboratorial essays and, consequently, to identify the compactation of the soil through those estimated values. The soil density is one of the main parameters used to identify the soil compactation level, and it is also related to other parameters such as resistance to the soil penetration, water content and soil texture. Three soil parameters were considered for the development of this work: resistance to the soil penetration represented by the cone index (in kPa), the water content given by the soil humidity (percentage, %), and the texture given by the quantity of clay present in the soil (percentage, %). Also, prepared soils were considered (plough step, grid, disk harrow, and others) as well as non prepared soils (no kind of soil preparation or direct planted soil). According to the percentage of clay in the soil, they were classified as soil type I (clay content less than 30%), soil type II (clay content between 30% and 50%), soil type III (clay content higher than 50%) for the case of non prepared soil. For the case of prepared soil it was considered only soils type I (clay content less than 30%) and type III (clay content higher than 50%). The mathematical model considered to estimate the soil density was developed on the basis of given experimental data having the three soil characteristics: Cone index, humidity and clay content. Using the experimental data the models were identified by means of a neuro-fuzzy algorithm in function of the resistance to the penetration, water content and soil texture, through which one can analyze the soil density for different values of the model entrance variables. The experimental data and the estimated ones by the model...(Complete abstract click electronic access below)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The traditional soil analysis many techniques are used in order to determine the physical and chemical properties of the soil. The radiometry appears as a promising alternative technique in the analysis of soil properties. This technique has demonstrated great potential for identification and quantification of certain properties of the soil. It is a non-destructive and non-polluting tool, with the ability to collect data on large spatial dimensions with relative speed. The radiometry may in cases be simpler than the traditional analysis of the soil and on various occasions, more accurately. The main objective of this study was to determine pedotransfer functions to soil properties based on radiometric data. It was observed that the heterogeneity of the soil decreases the accuracy of the models, however it was possible to construct prediction functions for the content of sand, silt, clay and soil organic matter from the radiometry with a level of prediction models acceptable. Considering that, in the prediction of soil properties using radiometry, there is no reagents spending and less resource invested beyond the analysis time shorter than the traditional analysis, the results were promising. / Na análise tradicional do solo muitas técnicas são utilizadas na tentativa de determinar suas propriedades físicas e químicas. A radiometria aparece como uma técnica alternativa e promissora na análise de propriedades do solo. Essa técnica tem demonstrado grande potencial na identificação e quantificação de determinadas propriedades do solo. Trata-se, de uma ferramenta não destrutiva, não poluidora, com capacidade de coleta de dados em grandes dimensões espaciais com relativa velocidade. A radiometria pode, em muitos casos, ser mais simples do que a análise tradicional do solo e em várias ocasiões, mais precisa. O principal objetivo desse trabalho foi determinar funções de pedotransferência para as propriedades do solo tendo como base os dados da radiometria. Observou-se que a heterogeneidade do solo diminui a precisão dos modelos, porém foi possível construir funções de predição para o teor de argila, areia, silte e matéria orgânica do solo a partir da radiometria com um nível de predição dos modelos aceitável. Considerando que, na predição das propriedades do solo utilizando a radiometria, não há gastos com reagentes e menos recursos investidos além do tempo de análise menor que a análise tradicional, os resultados apresentados foram promissores.

Made available in DSpace on 2014-06-11T19:29:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2004-07-15Bitstream added on 2014-06-13T18:59:26Z : No. of bitstreams: 1 kitamura_ae_me_ilha.pdf: 2042410 bytes, checksum: 4aa141418d1268c6856d0ede3f60bf61 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / O conhecimento dos atributos do solo, principalmente aqueles relacionados com sua distribuição granulométrica, tem grande influência na produtividade vegetal. No ano agrícola de 2002/2003 foram analisados atributos da planta e do solo: produtividade de grãos do feijoeiro (PG), produtividade de palha (PP), teor de argila (ARG), de silte (SIL) e de areia (ARE) de um Latossolo Vermelho Distroférrico sob plantio direto, do Campus Experimental da Faculdade de Engenharia/UNESP (Ilha Solteira/SP - Brasil: latitude 20°18 S; longitude 52°39 W). O objetivo foi analisar a variabilidade dos atributos pesquisados, de forma a caracterizar suas dependências espaciais, e as correlações, linear e espacial, entre eles. Foi instalada uma malha experimental para a coleta dos dados estabelecida com espaçamento de 10 x 10 m, contendo 135 pontos amostrais distribuídos numa área de 8000 m2. A variabilidade dos dados foi baixa para a ARG, média para o SIL e ARE, e alta para a PP e PG. A maioria apresentou moderada dependência espacial, com alcances entre 19,8 m (SIL) e 103,1 m (ARE), e de 29,8 m para a PG. Foi observada uma evidente correlação espacial entre todos os que apresentaram, dois a dois, os maiores coeficientes de correlação. Entretanto, entre aqueles que apresentaram os menores, os dados sugeriram, em alguns casos, haver uma moderada correlação espacial. / The knowledge of the soil attributes, mainly those related with its particle-size diameter, has great influence on the vegetal productivity. In the agricultural year of 2002/2003 attributes of the plant and soil had been analyzed: grain productivity of common bean (GP), straw productivity (SP), clay content (CL), silt (SI) and of sand (SA) of a Red Latosol under no-tillage, pertainning to Experimental Station of Faculdade de Engenharia/UNESP (Ilha Solteira/SP - Brazil: 20º18' Latitude S; 52º39' Longitude W). The objective was to analyze the variability of the researched attributes to characterize its spatial dependences. Also, to study the correlations, linear and spatial, between them. An experimental grid for the collection of the data was installed, established with distance of 10 x 10 m, contends 135 points shows in an area of 8000 m2. The data variability was low for the CL, medium for the SI and SA, and high for SP and GP. The majority then presented moderate spatial dependence, with ranges between 19.8 m (SI) and 103.1 m (SA), and of 29.8 m for the GP. An evident spatial correlation was observed between all the ones that had presented, two to two, the biggest correlation coefficients. However, between the ones minors, the data had suggested, in some cases, to have an moderate spatial correlation.

Made available in DSpace on 2016-01-26T18:56:25Z (GMT). No. of bitstreams: 1 ERNI_DISSERTACAO_25_06_2012[1].pdf: 835253 bytes, checksum: 22f9a507f3839f6e97a447c10101bb75 (MD5) Previous issue date: 2012-06-19 / This work aimed to evaluate the water in Typic Paleudult with loam layer (0-20 cm) under sandy loam loam layer (21-100 cm) in silvopastoral and pasture systems in Paranavaí, northwest of Paraná, Brazil. Twelve gravimetric determinations of water in the work were carried out in 2010 and 2011, from 24 to 33 months after planting grass with rank of double rows of eucalyptus (3 m x 2 m) spaced 21 m. Disturbed and undisturbed soil samples were collected in layers of 20 cm to a depth of 100 cm, 2.5, 5 and 10 m from the level terrace in silvopastoral systems with eucalyptus in rank of 8 to 11 m height (Eucalyptus grandis) and pasture (Cynodon nlemfuensis). Undisturbed soil samples were collected with three replicates to determine field capacity, wilting point and bulk density. The gravimetric water data were compared between the layers of the silvopastoral and pasture systems by test confidence interval of the mean (P<0.05). In silvopastoral system, water availability in the soil decreases to 2.5 m from the rank of eucalyptus and in the profile layer of sandy loam (21-80 cm) from the 10.0 m of eucalyptus rank. The availability of soil water in the surface layer increases with the distance of the loam layer (0-20 cm) equivalent to distance the height of the rank of eucalyptus. / O objetivo deste trabalho foi avaliar a água em um Argissolo Vermelho distrófico latossólico com camada de areia franca (0-20 cm) sobre camada franca-arenosa (21-100 cm), em sistemas silvipastoril e pastagem, em Paranavaí, noroeste do Paraná. Doze determinações de água gravimétrica no solo foram realizadas em 2010 e 2011, dos 24 a 33 meses após plantio de pastagem com renques de fileiras duplas de eucalipto (3 m x 2 m) espaçadas em 21 m. Amostras de solo deformadas e indeformadas foram coletadas em camadas de 20 cm até a profundidade de 100 cm, a 2,5; 5 e 10 m de terraços em nível nos sistemas silvipastoril com eucalipto em renque de 8 a 11 m de altura (Eucaliptus grandis) e pastagem (Cynodon nlemfuensis). Amostras de solo indeformadas foram coletadas com três repetições para determinar a capacidade de campo, ponto de murcha permanente e densidade do solo. Os dados de água gravimétrica foram comparados entre as camadas dos sistemas silvipastoril e pastagem pelo Teste t e intervalo de confiança da média (P<0.05). No sistema silvipastoril a disponibilidade de água no solo diminui a 2,5 m do renque de eucalipto e na camada subsuperficial de textura média (21-80 cm) a 5 m do renque de eucalipto. A disponibilidade de água no solo aumenta na camada superficial areia franca (0-20 cm) equivalente à distância da altura de 10,0 m do renque de eucalipto.

Made available in DSpace on 2016-07-18T17:51:09Z (GMT). No. of bitstreams: 1 ERNI_DISSERTACAO_25_06_2012[1].pdf: 835253 bytes, checksum: 22f9a507f3839f6e97a447c10101bb75 (MD5) Previous issue date: 2012-06-19 / This work aimed to evaluate the water in Typic Paleudult with loam layer (0-20 cm) under sandy loam loam layer (21-100 cm) in silvopastoral and pasture systems in Paranavaí, northwest of Paraná, Brazil. Twelve gravimetric determinations of water in the work were carried out in 2010 and 2011, from 24 to 33 months after planting grass with rank of double rows of eucalyptus (3 m x 2 m) spaced 21 m. Disturbed and undisturbed soil samples were collected in layers of 20 cm to a depth of 100 cm, 2.5, 5 and 10 m from the level terrace in silvopastoral systems with eucalyptus in rank of 8 to 11 m height (Eucalyptus grandis) and pasture (Cynodon nlemfuensis). Undisturbed soil samples were collected with three replicates to determine field capacity, wilting point and bulk density. The gravimetric water data were compared between the layers of the silvopastoral and pasture systems by test confidence interval of the mean (P<0.05). In silvopastoral system, water availability in the soil decreases to 2.5 m from the rank of eucalyptus and in the profile layer of sandy loam (21-80 cm) from the 10.0 m of eucalyptus rank. The availability of soil water in the surface layer increases with the distance of the loam layer (0-20 cm) equivalent to distance the height of the rank of eucalyptus. / O objetivo deste trabalho foi avaliar a água em um Argissolo Vermelho distrófico latossólico com camada de areia franca (0-20 cm) sobre camada franca-arenosa (21-100 cm), em sistemas silvipastoril e pastagem, em Paranavaí, noroeste do Paraná. Doze determinações de água gravimétrica no solo foram realizadas em 2010 e 2011, dos 24 a 33 meses após plantio de pastagem com renques de fileiras duplas de eucalipto (3 m x 2 m) espaçadas em 21 m. Amostras de solo deformadas e indeformadas foram coletadas em camadas de 20 cm até a profundidade de 100 cm, a 2,5; 5 e 10 m de terraços em nível nos sistemas silvipastoril com eucalipto em renque de 8 a 11 m de altura (Eucaliptus grandis) e pastagem (Cynodon nlemfuensis). Amostras de solo indeformadas foram coletadas com três repetições para determinar a capacidade de campo, ponto de murcha permanente e densidade do solo. Os dados de água gravimétrica foram comparados entre as camadas dos sistemas silvipastoril e pastagem pelo Teste t e intervalo de confiança da média (P<0.05). No sistema silvipastoril a disponibilidade de água no solo diminui a 2,5 m do renque de eucalipto e na camada subsuperficial de textura média (21-80 cm) a 5 m do renque de eucalipto. A disponibilidade de água no solo aumenta na camada superficial areia franca (0-20 cm) equivalente à distância da altura de 10,0 m do renque de eucalipto.

MSCAGR / Department of Soil Science / Soil hydraulic and hydraulic-related physical properties are key to soil productivity and these properties are widely studied. Nevertheless, their spatial variability is least understood. Two sites were selected for this study (University of Venda Experimental farm and Roodeplaat, Agricultural Research Council farm). The objectives of this study were to determine the spatial variability of soil water content, water infiltration and hydraulic conductivity on selected soils. Field measurements were done on a 20 m × 20 m. Soil hydraulic and hydraulic-related physical properties were studied at two depths, 0 – 0.2 m top soil and 0.2 – 0.4 m sub soil. The field was irrigated to saturation and let to drain freely for two days. The soil was quickly secured in water cans to avoid further loss of water by evaporation and taken to the laboratory for analysis. Data was analysed using ordinary kriging method in ArcMap® software version 10.4 to generate spatial variability maps and semi variograms. The University of Venda Experimental farm had lesser spatial variability with coefficient of variation ranging from 9.6 to 33.4%. The spatial variability of soil was very low confirmed by contour maps depicting slightly homogeneity. Whereas, the soil hydro-physical properties displayed greater spatial variability at Roodeplaat, Agricultural Research Council Experimental farm. The empirical variograms of spherical model fits were also assuming weak spatial dependence with a curve variogram. The coefficient of variation ranged from 10.5 to 51.9%. Therefore, the greater variability at Roodeplaat, Agricultural Research Council Experimental farm indicated that coarse soil texture under conventional tillage has a greater influence on the spatial variability of the soil hydro-physical properties. / NRF

No description available.

Thesis (MScAgric)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Soil texture, plant available water and fertilizer N would influence growth, biomass production and antimicrobial properties of locally used medicinal plants.This research was aimed at investigating how various soil textures (loamy sand, sandy loam and loam) with varying amounts of plant available water (PAW) and nitrogen fertilizer rates would influence the biomass production and antimicrobial properties of Mentha longifolia L. In this research, a two-way factorial experiment was used. It was produced by 3 X 3 factors, viz. three different soil textures (loam, sandy loam and loamy sand) and three levels of PAW in the first trial (0 %, 50 % and 90 % depletion of PAW) and three levels of N fertilizer rates in the second trial. The elemental fertilizers KNO3, K2SO4, KH2PO4, KCl Ca (NO3)2.2H2Oz, CaSO4.2H2O and Mg SO4.7H2O were used to prepare a nutrient solution for fertigation to meet 0Kg ha-1, 150Kg ha-1 and 250Kg ha-1 fertilizer N. This was replicated four times. The experiment was conducted in a tunnel. From the first trial the highest biomass production was obtained from 0% depletion of PAW treatments whereas 50% and 90% depletion of PAW matched each other at lower biomass productions. In terms of soil texture a higher biomass production was gained from loamy sand followed by loam and sandy loam. In the second trial similar influences of soil texture were evident and the significant biomass productions were highest, intermediate and low from 250Kg ha-1, 150Kg ha-1 and 0Kg ha-1 of fertilizer N, respectively. Accordingly, Mentha longifolia L revealed a minimal bacterial inhibition activity at 20g 100ml-1 against Staphylococcus aureus (gram positive bacteria) under Minimum Inhibitory Concentration assay–susceptibility test. It was therefore concluded that soil texture does influence biomass production. In a like manner, the PAW had a significant impact on the total biomass production. An increase in N fertilizer increased vegetative biomass production. Plant material obtained from Mentha longifolia L has antimicrobial properties. Medically the plant can be used to combat Staphylococcus aureus – a major and ubiquitous pathogen for humans. The significance of this study is thus that it will benefit and help the medical community and future research as the guide to sustainable production and utilization of Mentha longifolia L. / AFRIKAANSE OPSOMMING: Grondtekstuur, plant beskikbare water en kunsmis N sal plantegroei, biomassaproduksie en antimikrobiese-eienskappe van plaaslike medisinale plante affekteer. Die doel van die navorsing was om die effek van grondteksture, plant beskikbare water (PAW) en stikstof op die biomassaproduksie en antimikrobieseeienskappe van Mentha longifolia L. te bestudeer. 'n Tweerigting-faktoriaal-eksperiment is gebruik deur drie verskillende grondteksture (leem, sanderige-leemgrond en leemsand) en drie vlakke van PAW in die eerste geval (0%, 50% en 90% uitputting van PAW) en drie vlakke van N-kunsmistoedienings in die tweede geval. Die basiese kunsmis KNO3, K2SO4, KH2PO4, KClCa(NO3)2.2H2Oz, CaSO4.2H2O en MgSO4.7H2O is gebruik in so „n mate dat 0Kg ha-1, 150kg ha-1 en 250 kg ha-1 Nas sproeibemesting toegedien is. Dit is vier keer herhaal. Die eksperiment is uitgevoer in 'n tonnel. Die hoogstebiomassaproduksie is van die eerste geval verkry van 0% uitputting van PAW behandelings, terwyl 50% en 90% uitputting van PAW ooreenstem met mekaar op laer biomassaproduksies. In terme van grondtekstuur is 'n hoër biomassaproduksie verkry in leemsand gevolg deur leem en sanderigeleem. In die tweede geval is soortgelyke invloede van grondtekstuur duidelik en die beduidende biomassaproduksies was die hoogste, intermediêre en laagste van 250 kg ha-1, 150kg ha-1 en 0Kg ha-1 van kunsmis N, onderskeidelik. Gevolglik, Mentha longifolia L onthul 'n minimale bakteriese inhibisie aktiwiteit op 20g 100ml-1 teen Staphylococcus aureus (gram positiewebakterieë) onder Minimum inhiberende konsentrasie assay-vatbaarheidtoets. Die gevolgtrekking is dus dat grondtekstuu biomassaproduksie beïnvloed. In 'n soortgelykewyse, het PAW 'n beduidende impak op die totale biomassaproduksie. 'n Toename in N-kunsmis verhoog vegetatiewe biomassaproduksie. Plantmateriaalverkry van Mentha longifolia L het antimikrobiale-eienskappe en kan as Die medisinale plante gebruik word om Staphylococcus aureus te bestry - 'n groot en alomteenwoordige patogeen in die mens. Die belangrikste bydrae van die navorsing is die bydra wat dit tot die mediesegemeenskap gemaak het. Die studie het ook riglyne gestel vir toekomstige navorsing vir volhoubare produksie van Mentha longifolia L. / NRF and DST for the funding of this study through the Seboka Project

To date, most studies on the effectiveness of geotextiles on soil erosion rates were conducted in laboratory experiments for &lt;1 h. Hence, at Hilton, East Shropshire, UK, this study investigated the effectiveness of palm-mat geotextiles (Borassus and Buriti mats) in reducing rainsplash erosion, runoff and soil loss and changing selected soil properties under field conditions over two years (January 2007-January 2009). Mat-cover effects on rainsplash erosion were studied in two sets on a loamy sand soil (0o slope). In both sets, six randomly-selected plots (each 1 m2) were completely matcovered and six were bare. Unlike Buriti mats, Borassus mat-cover on bare soil significantly (P&lt;0.001) decreased rainsplash erosion (by ~89%). Duplicate runoff plots (10 x 1 m on a 15o slope) had five treatments (bare, permanent grass, Borassus completely-cover, Borassus buffer strip and Buriti buffer strip). Using Borassus buffer strips (area coverage ~10%) on bare soil decreased runoff by ~71% (P&gt;0.05) and soil erosion by ~92% (P&lt;0.001). Borassus buffer strip, Buriti buffer strip and Borassus completely-covered plots had similar effects in decreasing runoff and soil loss. However, the longevity of Borassus mats was ~twice that of Buriti mats. Despite physical protection, runoff control and sediment entrapment, biomat buffer zones may considerably alter and protect flow direction by presenting barriers and creating several cross-drains. Except Borassus completely-covered plots, all plots had significant (P&lt;0.05) increases in topsoil (0-5 cm) bulk density and decreased aggregate stability. However, buffer strips were more effective in trapping fine particles than Borassus completely-covered plots. No treatments had significant (P&gt;0.05) effects on changes in pH, soil organic matter, total soil carbon or N. Plots with Borassus mats significantly (P&lt;0.05) increased total P and decreased total Ca. Treatments had no significant effects on changes in total S, Mg, Zn, Cu, Fe, Mn, Mo or Cl concentrations. Borassus buffer strips can effectively conserve soil and water and improve and maintain selected soil properties, with results similar to Borassus completely-covered plots. The mechanisms explaining the effectiveness of buffer zones require further studies under varied pedo-climatic conditions.