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The effect of legume cover crops grown in an olive orchard on soil microbial activity

Pereira, Ermelinda; Arrobas, Margarida; Ferreira, I.Q.; Rodrigues, M.A.
Fonte: International Legume Society Publicador: International Legume Society
Tipo: Conferência ou Objeto de Conferência
ENG
Relevância na Pesquisa
36.04%
Microbial biomass and soil respiration are major indicators of the soil biological fertility which can be affected by soil management practices. The aim of this study was the evaluation of the effect of three ground-cover treatments, imposed to an olive orchard, on soil microbial biomass and activity. The ground-cover treatments were: Natural vegetation (Nat veg); Natural vegetation fertilized with 60 kg N ha-1 (Nat veg +N); and a mixture of eleven sdf-reseed.ing annual legumes (Legumes) grown as a cover crop. The experiment was carried out in a rainfed olive orchard located in Mirandela, NE Portugal. Three years after the experimental set-up had been installed, random samples of soil were collected in two depths, 0-10 cm and 10-20 cm. The microbial biomass C (Cmic) was determined by the fumigation-extraction method; the basal respiration (BR) as the rate of C02 eyolved in a 7 days soil incubation at 25 oc; and soil organic C (Corg) by the Walkley-Black method. The Cmic:Corg ratio and the metabolic quotient (qCOz.), defined as the respiration rate per unit of biomass, were thereafter estimated. The values of Cmic and BR were significandy higher under the Legumes treatment in comparison with Nat veg +N and Nat veg. It seems that Legumes increased the C stored in the soil and promoted soil microbial activity...

Produção e decomposição de coberturas vegetais de inverno e sua influência na infestação  e fitossociologia de plantas daninhas; Production and decomposition of winter cover crops and their influence in the infestation and phytosociology of weeds

Marcolini, Livia Weyand
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 07/08/2009 PT
Relevância na Pesquisa
36.04%
Além dos aspectos relacionados à proteção do solo, as coberturas vegetais, vivas ou mortas, também contribuem para a redução da infestação de plantas daninhas no período da entressafra. Com o objetivo de analisar o potencial de espécies utilizadas como coberturas vegetais de inverno no manejo de plantas daninhas, conduziram-se dois ensaios em áreas pertencentes ao Departamento de produção Vegetal da ESALQ/USP, em Piracicaba SP, durante o ano de 2008. As espécies usadas como culturas de cobertura foram: Raphanus sativus L. (nabo forrageiro), Helianthus annuus L. (girassol), Avena strigosa Schreb (aveia preta), Avena bysantina L. (aveia amarela), Vicia sativa L. (ervilhaca) e Sorghum bicolor L. Moench (sorgo forrageiro), sendo que esta última espécie não foi utilizada em um dos ensaios. Realizaram-se nos dois ensaios estudos fitossociológicos, avaliações referentes à quantificação de massa seca produzida pelas coberturas, identificação e levantamento de plantas daninhas e avaliação da taxa de decomposição das coberturas. As comunidades de plantas daninhas apresentaram modificações em sua composição florística de acordo com o tipo de cobertura utilizado. D. horizontalis foi a principal espécie no primeiro ensaio...

Época de aplicação da primeira dose de nitrogênio em cobertura em milho e espécies antecessoras de cobertura de inverno; Timing of first side-dressed nitrogen application in maize as affected by antecedent winter cover species

Strieder, Mércio Luíz; Silva, Paulo Regis Ferreira da; Anghinoni, Ibanor; Meurer, Egon Jose; Rambo, Lisandro; Endrigo, Paulo César
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: application/pdf
POR
Relevância na Pesquisa
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Atualmente, os critérios utilizados no Sul do Brasil para definição da dose de nitrogênio (N) a ser aplicada no milho são o teor de matéria orgânica no solo, a expectativa de rendimento da cultura e as características da cultura antecessora. Embora apresente alta relação carbono:nitrogênio (C/N), a aveia preta é a espécie de cobertura de solo de inverno mais utilizada como antecessora às culturas comerciais de verão. Essa característica pode resultar em imobilização do N do solo, deficiência de N na planta de milho e redução no rendimento de grãos. Embora na determinação da dose a ser aplicada sejam consideradas as espécies antecessoras, os avanços quanto à melhor época para aplicar N em cobertura em milho foram pequenos. Com o objetivo de avaliar a época mais adequada para aplicação da primeira dose de N em cobertura no milho cultivado em sucessão a espécies de inverno com distintas relações C/N, um experimento foi realizado em vasos em casa de vegetação em Porto Alegre-RS. Utilizaram-se colunas de solo não deformado, classificado como Argissolo Vermelho distrófico típico. Os tratamentos constaram de quatro sistemas de coberturas de solo de inverno (aveia preta, ervilhaca comum, nabo forrageiro e pousio) e três formas de manejo de N em cobertura (com aplicação de N nos estádios V3 ou V5 e sem aplicação de N em cobertura). O delineamento experimental foi o completamente casualizado...

Parâmetros relacionados com a erosão hídrica sob taxa constante da enxurada, em diferentes métodos de preparo do solo; Water-erosion related parameters under steady runoff-rate for different soil tillage methods

Bertol, Ildegardis; Mello, Eloy Lemos de; Cogo, Neroli Pedro; Vidal Vázquez, Eva; Paz González, Antônio
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: application/pdf
POR
Relevância na Pesquisa
36.13%
O preparo do solo altera as suas condições físicas de superfície e subsuperfície e, conseqüentemente, influencia os valores dos fatores que se relacionam com a erosão hídrica. Considerando estes aspectos, realizou-se um experimento de erosão em campo, sob a ação de chuva simulada, entre outubro de 1999 e maio de 2000, na região do Planalto Sul Catarinense, tendo por objetivo a avaliação de alguns fatores relacionados com a erosão hídrica do solo na condição de equilíbrio do escoamento superficial, em três métodos de preparo do solo. No estudo, utilizou-se Nitossolo Háplico alumínico de textura argilosa, apresentando, no local do experimento, 0,14 m m-1 de declividade. Os tratamentos avaliados foram: (a) preparo reduzido (escarificação + gradagem); (b) preparo convencional tradicional (aração + duas gradagens), e (c) preparo convencional alterado (aração + duas gradagens + duas rastelagens), os dois primeiros em solo continuamente cultivado e o último em solo mantido continuamente sem cultivo (tratamento-testemunha). Os tratamentos foram caracterizados em termos de rugosidade ao acaso e cobertura superficiais do solo, as quais foram avaliadas imediatamente antes e depois do preparo, no dia anterior à aplicação da chuva simulada. O teste de chuva foi realizado por ocasião da semeadura da soja...

Bermuda grass sod production as related to nitrogen rates

Lima, Claudinei Paulo de; Backes, Clarice; Villas Bôas, Roberto Lyra; Oliveira, Mauricio Roberto de; Kiihl, Tammy Aparecida Manabe; Freitag, Elisa Eni
Fonte: Sociedade Brasileira de Ciência do Solo Publicador: Sociedade Brasileira de Ciência do Solo
Tipo: Artigo de Revista Científica Formato: 371-378
ENG
Relevância na Pesquisa
35.95%
O N é o nutriente que proporciona as maiores respostas no crescimento das gramas, e a adubação nitrogenada adequada pode proporcionar a formação do tapete com boa qualidade em menor tempo. Neste trabalho, objetivou-se avaliar a influência da adubação nitrogenada na produção e qualidade de tapetes de grama-bermuda. O experimento foi instalado e conduzido em área de produção comercial de grama, localizada na cidade de Capela do Alto, SP. A grama utilizada foi a Cynodon dactylon (Pers) L., conhecida como grama-bermuda. O delineamento experimental utilizado foi o de blocos casualizados, com cinco tratamentos e quatro repetições. Os tratamentos foram constituídos por cinco doses de N: 0, 150, 300, 450 e 600 kg ha-1. O aumento das doses de N aumentou a taxa de cobertura do solo pela gramabermuda, reduzindo o tempo para formação do tapete. O máximo acúmulo de matéria seca de rizomas + estolões + raízes foi proporcionado pela dose de 354 kg ha-1 de N, e a resistência dos tapetes, pela dose de 365 kg ha-1 de N. Doses de N entre 354 e 365 kg ha-1, aumentaram a resistência dos tapetes e, com isso, a capacidade deles serem manuseados após a colheita, podendo promover assim maior rendimento da área.; Of all nutrients...

Produção de tapetes de grama Santo Agostinho submetida a doses de nitrogênio

Grava de Godoy, Leandro Jose; Villas Boas, Roberto Lyra; Backes, Clarice
Fonte: Universidade Estadual de Londrina (UEL) Publicador: Universidade Estadual de Londrina (UEL)
Tipo: Artigo de Revista Científica Formato: 1703-1716
POR
Relevância na Pesquisa
45.97%
Nitrogen is the nutrient that provides the greatest turfgrass growth responses and the adequate nitrogen fertilization can provide sod formation in less time and firm to be handled after harvest. This study aimed to evaluate the effect of nitrogen levels in the formation of St. Augustinegrass sod. The experiment was conducted in a sod production farm in Itapetininga, SP. The experimental design was a randomized blocks with four replications. The treatments consisted of five N doses: 0, 150, 300, 450 and 600 kg ha(-1), split into three applications. Increased levels of nitrogen affected the soil cover rate by the St. Augustinegrass reducing the time for sod formation. The leaf N concentration and intensity of green grass were influenced by nitrogen doses, and with the rate of green coverage rate (GCR) of soil, can be used to assist in the recommendation of N doses. Rate of 430 kg ha(-1) of N provided the production of St. Augustinegrass sod resistant the harvest and transport, within ten months.

Aplicação e efeito residual do lodo de esgoto em sistemas de produção de tapetes de grama esmeralda

Backes, Clarice
Fonte: Universidade Estadual Paulista (UNESP) Publicador: Universidade Estadual Paulista (UNESP)
Tipo: Tese de Doutorado Formato: ix, 152 f.: il. color., gráfs, tabs.
POR
Relevância na Pesquisa
45.87%
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Pós-graduação em Agronomia (Horticultura) - FCA; A disposição final de lodo de esgoto no solo representa não somente um sistema apropriado, mas também a oportunidade para o manejo dos mesmos com o mínimo de efeito sobre o ambiente podendo gerar benefícios químicos e físicos ao solo. O trabalho teve como objetivo avaliar doses de lodo de esgoto e o efeito residual na produção e qualidade de tapetes de grama esmeralda bem como as alterações químicas desse solo. Os experimentos foram instalados e conduzidos em uma propriedade de grama, localizada na cidade de Itapetininga - SP. A cultura utilizada foi a grama Zoysia japonica Steud. conhecida como grama esmeralda. O delineamento experimental utilizado foi o de blocos ao acaso em parcelas subdivididas, com quatro repetições, sendo as parcelas principais constituídas por dois sistemas de manejo (com e sem o uso de um escarificador superficial “estrelinha”, utilizado para romper uma camada superficial compactada). e as subparcelas de cinco doses de lodo (0, 10, 20, 30 e 40 Mg ha-1, base seca), mais um tratamento com adubação química...

The management of cover plant residues for cotton cropped in a no-tillage system

Furlani Júnior, Enes; Neves, Danilo De Carvalho; Santos, Marcio Lustosa; Ferrari, Samuel
Fonte: Editora da Universidade Estadual de Maringá (EDUEM) Publicador: Editora da Universidade Estadual de Maringá (EDUEM)
Tipo: Artigo de Revista Científica Formato: 371-376
ENG
Relevância na Pesquisa
35.95%
The cutting of plant residue in no-tillage systems under certain environmental conditions becomes necessary to adequately establish and grow crops. This study aims to assess the effect on the yield of different methods of managing millet plant residue in cotton plantations. The study was conducted during the agricultural years 2006/07 and 2007/08, and the treatments included no-mechanical-treatment tillage and the use of a rotary shredder, crimper-roller, and mechanical disintegrator for millet plants before sowing the cotton. Evaluations were performed for the residue fragmentation, emergence speed, percent of soil cover during the cycle and yield of the cotton crop. The emergence speed was faster in the management with the rotary shredder. In 2006/07, the no-tillage treatment showed a rate of loss for soil cover that was 46 percent greater than the disintegrator treatment. The rotary shredder and the disintegrator yielded greater soil coverage during the cultivation cycle, and the yield was highly correlated with the soil cover at 75 days after emergence. The management of the millet residue affected the cotton plants for the two-year study period.; O manejo dos resíduos vegetais em sistema plantio direto em certas condições torna-se necessário para o bom estabelecimento e crescimento da cultura. Este estudo visa verificar o efeito de diferentes formas de manejo de resíduos vegetais de milheto na semeadura e produtividade do algodoeiro. Foi conduzido durante os anos agrícolas 2006/07 e 2007/08...

Wildfire selectivity for land cover type: does size matter ?

Barros, Ana M.G.; Pereira, J.M.C.
Fonte: Gil Bohrer, The Ohio State University, USA Publicador: Gil Bohrer, The Ohio State University, USA
Tipo: Artigo de Revista Científica
Publicado em //2014 ENG
Relevância na Pesquisa
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Previous research has shown that fires burn certain land cover types disproportionally to their abundance. We used quantile regression to study land cover proneness to fire as a function of fire size, under the hypothesis that they are inversely related, for all land cover types. Using five years of fire perimeters, we estimated conditional quantile functions for lower (avoidance) and upper (preference) quantiles of fire selectivity for five land cover types - annual crops, evergreen oak woodlands, eucalypt forests, pine forests and shrublands. The slope of significant regression quantiles describes the rate of change in fire selectivity (avoidance or preference) as a function of fire size. We used Monte-Carlo methods to randomly permutate fires in order to obtain a distribution of fire selectivity due to chance. This distribution was used to test the null hypotheses that 1) mean fire selectivity does not differ from that obtained by randomly relocating observed fire perimeters; 2) that land cover proneness to fire does not vary with fire size. Our results show that land cover proneness to fire is higher for shrublands and pine forests than for annual crops and evergreen oak woodlands. As fire size increases, selectivity decreases for all land cover types tested. Moreover...

Spatio-temporal land use/land cover changes analysis and monitoring in the Valencia Municipality, Spain

Yesserie, Addis Getnet
Fonte: Universidade Nova de Lisboa Publicador: Universidade Nova de Lisboa
Tipo: Dissertação de Mestrado
Publicado em 06/03/2009 ENG
Relevância na Pesquisa
35.97%
Dissertation submitted in partial fulfilment of the requirements for the Degree of Master of Science in Geospatial Technologies; Issues of land use/land cover changes and the direct or indirect relationships of these changes have drawn much attention in recent years. In the Mediterranean Spain, observed environmental changes influenced with dramatic urban growth and their likely changes can have extensive unforeseen ramification. Thus, the objectives of this research were to map and determine the nature, extent and rate of changes and to analyze the spatio-temporal land use/land cover change patterns and fragmentation that has occurred in Valencia Municipality. Multi-temporal Landsat MSS1976, TM1992 and ETM2001 images were acquired. Digital orthophotos, IKONOS images and existing Corine land cover maps were used as reference. More than 130 training samples were selected for classification of the Landsat images using supervised method parallelepiped-maximum likelihood algorithm in ERDAS Imagine 9.1, and land cover maps were generated and change detection analysis was performed.(...)

Urban land cover change detection analysis and modeling spatio-temporal Growth dynamics using Remote Sensing and GIS Techniques: A case study of Dhaka, Bangladesh

Ahmed, Bayes
Fonte: Universidade Nova de Lisboa Publicador: Universidade Nova de Lisboa
Tipo: Dissertação de Mestrado
Publicado em 07/03/2011 ENG
Relevância na Pesquisa
36.01%
Dissertation submitted in partial fulfillment of the requirements for the Degree of Master of Science in Geospatial Technologies.; Dhaka, the capital of Bangladesh, has undergone radical changes in its physical form, not only in its vast territorial expansion, but also through internal physical transformations over the last decades. In the process of urbanization, the physical characteristic of Dhaka is gradually changing as open spaces have been transformed into building areas, low land and water bodies into reclaimed builtup lands etc. This new urban fabric should be analyzed to understand the changes that have led to its creation. The primary objective of this research is to predict and analyze the future urban growth of Dhaka City. Another objective is to quantify and investigate the characteristics of urban land cover changes (1989-2009) using the Landsat satellite images of 1989, 1999 and 2009. Dhaka City Corporation (DCC) and its surrounding impact areas have been selected as the study area. A fisher supervised classification method has been applied to prepare the base maps with five land cover classes. To observe the change detection, different spatial metrics have been used for quantitative analysis. Moreover, some postclassification change detection techniques have also been implemented. Then it is found that the ‘builtup area’ land cover type is increasing in high rate over the years. The major contributors to this change are ‘fallow land’ and ‘water body’ land cover types. In the next stage...

Analysis of urban land use and land cover changes: a case of study in Bahir Dar, Ethiopia

Sahalu, Atalel Getu
Fonte: Universidade Nova de Lisboa Publicador: Universidade Nova de Lisboa
Tipo: Dissertação de Mestrado
Publicado em 28/02/2014 ENG
Relevância na Pesquisa
36.04%
Dissertation submitted in partial fulfillment of the requirements for the Degree of Master of Science in Geospatial Technologies; The high rate of urbanization coupled with population growth has caused changes in land use and land cover in Bahir Dar, Ethiopia. Therefore, understanding and quantifying the spatio- temporal dynamics of urban land use and land cover changes and its driving factors is essential to put forward the right policies and monitoring mechanisms on urban growth for decision making. Thus, the objective of this study was to analyze land use and land cover changes in Bahir Dar area, Ethiopia by applying geospatial and land use change modeling tools. In order to achieve this, satellite data of Landsat TM for 1986 and ETM for 2001 and 2010 have been obtained and preprocessed using ArcGIS. The Maximum Liklihood Algorithm of Supervised Classification has been used to generate land use and land cover maps. For the accuracy of classified land use and land cover maps, a confusion matrix was used to derive overall accuracy and results were above the minimum and acceptable threshold level. The generated land cover maps have been run with Land Change Modeler for quantifying land use and land cover changes, to examine land use transitions between land cover classes...

Malaria entomological risk factors in relation to land cover in the Lower Caura River Basin, Venezuela

Rubio-Palis,Yasmin; Bevilacqua,Mariapia; Medina,Domingo Alberto; Moreno,Jorge Ernesto; Cárdenas,Lya; Sánchez,Víctor; Estrada,Yarys; Anaya,William; Martínez,Ángela
Fonte: Instituto Oswaldo Cruz, Ministério da Saúde Publicador: Instituto Oswaldo Cruz, Ministério da Saúde
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2013 EN
Relevância na Pesquisa
36.03%
To explore the effects of deforestation and resulting differences in vegetation and land cover on entomological parameters, such as anopheline species composition, abundance, biting rate, parity and entomological inoculation rate (EIR), three villages were selected in the Lower Caura River Basin, state of Bolívar, Venezuela. All-night mosquito collections were conducted between March 2008-January 2009 using CDC light traps and Mosquito Magnet(r) Liberty Plus. Human landing catches were performed between 06:00 pm-10:00 pm, when anophelines were most active. Four types of vegetation were identified. The Annual Parasite Index was not correlated with the type of vegetation. The least abundantly forested village had the highest anopheline abundance, biting rate and species diversity. Anopheles darlingi and Anopheles nuneztovari were the most abundant species and were collected in all three villages. Both species showed unique biting cycles. The more abundantly forested village of El Palmar reported the highest EIR. The results confirmed previous observations that the impacts of deforestation and resulting changes in vegetation cover on malaria transmission are complex and vary locally.

Evaluation of tropical legume cover crops for copper use efficiency.

FAGERIA, N. K.; BALIGAR, V. C.
Fonte: American Journal of Plant Sciences, v. 5, n. 9, p. 1236-1247, Apr. 2014. Publicador: American Journal of Plant Sciences, v. 5, n. 9, p. 1236-1247, Apr. 2014.
Tipo: Artigo em periódico indexado (ALICE)
EN
Relevância na Pesquisa
36.01%
Cover crops are important components of cropping systems due to their role in improving soil quality. Lack of adequate levels of soil micronutrients prevents the success of cover crops in highly weathered tropical soils. A greenhouse experiment was conducted with the objective to evaluate copper use efficiency of nine tropical legume cover crops. The copper levels used were 0, 5, 10 and 20 mg Cu kg−1 of soil. Shoot dry weight, maximum root length and root dry weight significantly increased in a quadratic fashion with increasing soil Cu levels in the range of 0 to 20 mg kg−1 soil. Cu x cover crops interactions for shoot dry weight, root dry weight, maximum root length and contribution of root to the total dry weight were significant, indicating different responses of cover crops with the variation in soil Cu levels. Overall, maximum shoot dry weight was obtained with the application of 13 mg Cu kg−1. Similarly, maximum root dry weight and maximum root length were obtained with the application of 12 and 14 mg Cu kg−1 of soil. Root dry weight and maximum root length were significantly and positively related to shoot dry weight, indicating that a vigorous root system is important for improving productivity of cover crops grown on Brazilian Oxisols...

Land Use /Land Cover Driven Surface Energy Balance and Convective Rainfall Change in South Florida

Kandel, Hari P
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica Formato: application/pdf
Relevância na Pesquisa
35.99%
Modification of land use/land cover in South Florida has posed a major challenge in the region’s eco-hydrology by shifting the surface-atmosphere water and energy balance. Although drainage and development in South Florida took place extensively between the mid- and late- 20th century, converting half of the original Everglades into agricultural and urban areas, urban expansion still accounts for a dominant mode of surface cover change in South Florida. Changes in surface cover directly affect the radiative, thermophysical and aerodynamic parameters which determine the absorption and partitioning of radiation into different components at the Earth surface. The alteration is responsible for changing the thermal structure of the surface and surface layer atmosphere, eventually modifying surface-induced convection. This dissertation is aimed at analyzing the extent and pattern of land cover change in South Florida and delineating the associated development of urban heat island (UHI), energy flux alteration, and convective rainfall modification using observed data, remotely sensed estimates, and modeled results. Urban land covers in South Florida are found to have increased by 10% from 1974 to 2011. Higher Landsat-derived land surface temperatures (LST) are observed in urban areas (LSTu-r =2.8°C) with satisfactory validation statistics for eastern stations (Nash-Sutcliffe coefficient =0.70 and R2 =0.79). Time series trends...

Cover crops for the sustainability of rainfed olive orchards

Bacelar, E.A.; Correia, C.M.; Santos, D.; Moutinho-Pereira, J.M.; Gonçalves, Berta; Brito, Carlos; Ferreira, H.; Rodrigues, M.A.
Fonte: NAGREF Publicador: NAGREF
Tipo: Conferência ou Objeto de Conferência
ENG
Relevância na Pesquisa
36.04%
Olive tree (Olea europaea L.) is present in large areas of mainland PortugaL predominantly in less-favored regions. In spite of the fact that irrigated areas are currently increasing, most of the olive orchards are still cultivated under rainfed conditions. The success of olive farming under rainfed conditions is mainly due to the high capacity of olive tree to develop anatomical, physiological and biochemical drought resistance mechanisms. Nevertheless, the productivity is low. We propose cover cropping to control soil erosion, improve soil quality and fertility of rainfed oli\'e orchards. Cover cropping is widespread in fruit farming in temperate climates and in irrigated olive orchards, where water is not a limiting resource. The effects of cover cropping were investigated on a 14-year-old olive orchard (Olea europaea L., c. Cobrançosa) with 240 trees ha-1, grown under rainfed conditions. The commercia! orchard was located in Mirandela, in the Northeast of Portugal (41 0 31' N; 7° 12' W). Four different soil management systems were compared: (i) development of natural vegetation, (ii) self-reseeding pasture species, such as subterranean clover and other annual legume species with short growing cycle grown as cover crop; (iii) white lupine cover crop; (iv) conventional tillage...

Forest cover monitoring in the Bara district (Nepal) with remote sensing and geographic information systems

Kandel, Chintamani
Fonte: Universidade Nova de Lisboa Publicador: Universidade Nova de Lisboa
Tipo: Dissertação de Mestrado
Publicado em 05/03/2009 ENG
Relevância na Pesquisa
36%
Dissertation submitted in partial fulfilment of the requirements for the Degree of Master of Science in Geospatial Technologies; This study uses Landsat Thematic Mapper of 1989, Enhanced Thematic Mapper of 1999 and 2005 imagery to evaluate forest cover dynamics during 1989-2005 in the Bara district, located in the Nepal's Central Terai region. The aim of the study is to analyse the extend and trend of forest cover dynamics, spatial pattern of forest and their driving forces. Forest cover change analysis was performed using object-oriented classification approach applying a standard nearest neighbour algorithm to classify the image in eCognition. The overall classification accuracies were 85.71% and 88.23% for the year 1999 and 2005 respectively. Initially, land cover maps for the year 1989, 1999, and 2005 were produced with seven land cover categories prevalent in study area. Classified images were further reclassified as forest and non-forest areas to analyse the forest cover dynamics effectively. Post-classification and times series analysis were carried out to detect the changes. Spatial metrics were computed for detecting the spatial pattern of forest. The classification showed that the amount of forest land decrease by 11.56% during 1989-2005. The result of the spatial metrics reveals that the forest area has been fragment and deforest with annual rate of 0.72%. The overall result demonstrates that forest area has experienced a significant shrinkage and mostly transferred into agricultural and bare land from 1989 to 2005. Expected change for the year 2021 was projected using Markov Chain Analysis (MCA). The MCA result showed that forest area including shrub will be decreased by 8.5% during 2005-21.

Manejo do Nitrogenio No Milho em Semeadura Direta em Sucessao a Especies de Cobertura de Solo No Inverno e em Dois Locais : efeito sobre o Rendimento de Graos; Nitrogen management in maize in no-till system in succession to inter cover crops in two locations. I - Effect on N Uptake

Argenta, Gilber; Silva, Paulo Regis Ferreira da; Rizzardi, Mauro Antonio; Baruffi, Marcos Joao; Lopes, Mara Cristina Barbosa
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: application/pdf
POR
Relevância na Pesquisa
36.05%
A permanência de restos culturais sobre a superfície do solo altera os processos de imobilização e mineralização, diminuindo a disponibilidade de nitrogênio para o milho, principalmente, em sucessão a gramíneas. O objetivo do trabalho foi o de avaliar, em dois ambientes, os efeitos de dose e época de aplicação de N no milho (0-0; 0-160; 30-13b e 60-100kg/ha, respectivamente, na semeadura e em cobertura), em sistema de semeadura direta, implantado em duas épocas após a dessecação (1 e aos 20 dias) de duas coberturas de solo no inverno (aveia' preta e ervilhaca comum) e da área em pousio invernal livre de plantas daninhas, sobre a absorção de N. Foram conduzidos dois experimentos com suplementação hídrica, sendo um em Eldorado do Sul e outro em Passo Fundo, no estado do Rio Grande do Sul, no ano agrícola 1996/97. Em Eldorado do Sul, a aplicação de N na semeadura foi benéfica, pois aumentou a absorção de N em relação ao tratamento com todo o N em cobertura, independentemente da cobertura de solo no inverno testada. Em Passo Fundo, somente no estádio de 3-4 folhas, houve vantagem da aplicação de N na semeadura em relação à aplicação total em cobertura sobre a absorção de N. Nos estádios de 6-7 folhas...

Cover crops for the sustainability of rainfed olive orchards

Bacelar, Eunice; Correia, Carlos; Santos, Dario; Moutinho-Pereira, José; Gonçalves, Berta; Brito, Cátia; Ferreira, Helena; Rodrigues, Ângelo
Fonte: Universidade de Trás-os-Montes e Alto Douro Publicador: Universidade de Trás-os-Montes e Alto Douro
Tipo: Conferência ou Objeto de Conferência
ENG
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Olive tree (Olea europaea L.) is present in large areas of mainland Portugal, predominantly in less-favored regions. In spite of the fact that irrigated areas are currently increasing, most of the olive orchards are still cultivated under rainfed conditions. The success of olive farming under rainfed conditions is mainly due to the high capacity of olive tree to develop anatomical, physiological and biochemical drought resistance mechanisms. Nevertheless, the productivity is low. We propose cover cropping to control soil erosion, improve soil quality and fertility of rainfed olive orchards. Cover cropping is widespread in fruit farming in temperate climates and in irrigated olive orchards, where water is not a limiting resource. The effects of cover cropping were investigated on a 14-year-old olive orchard (Olea europaea L., cv. Cobrançosa) with 240 trees ha-1, grown under rainfed conditions. The commercial orchard was located in Mirandela, in the Northeast of Portugal (41º 31' N; 7º 12' W). Four different soil management systems were compared: (i) development of natural vegetation, (ii) self-reseeding pasture species, such as subterranean clover and other annual legume species with short growing cycle grown as cover crop; (iii) white lupine cover crop; (iv) conventional tillage...

Soil drying rate and gas exchange of three Phaseolus vulgaris L. varieties

Aguirre-Medina,JF; Kohashi-Shibata,J; Cadena-Iñiguez,J; Avendaño-Arrazate,C
Fonte: Phyton (Buenos Aires) Publicador: Phyton (Buenos Aires)
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2008 EN
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Intermittent drought is the main limiting factor for bean production in Mexico. The root system of three bean varieties of different origin and tolerance to water stress was exposed to different drying soil rates. The synthetic varieties were: Pinto Villa (PV, water stress tolerant) and Bayo Madero (BM, water stress susceptible) both of mesoamerican origin and growth habit type III (climbing habit), and ICA Palmar (water stress tolerant) of Andean origin and growth habit type I (shrub). Treatments were three soil drying rates, which were achieved by stopping irrigation and either maintaining or removing the pot cover made with PVC tubes in a split root system. Gas exchange was studied during 32 h. Slow soil drying rate (with cover) generated a gradual decline in stomatal conductance and CO2 assimilation rate. In BM, the three dehydration levels significantly affected the response of the quantified variables. Despite water was available in the soil, plants remained with stomata closed. In PV and ICA Palmar, the most contrasting effects were achieved with intermediate and fast soil drying rates, even though there were differences in soil water availability; in PV, differences among treatments were not expressed. In ICA Palmar, soil water potential did not express the response in stomatal conductance. Both varieties showed high and low values in stomatal conductance. Leaflet temperature increased during the first two hours of sampling. ICA Palmar was the variety with less change in leaflet temperature...