Tatiane Bagatini

Perdas de água, solo, matéria orgânica e nutriente por erosão hídrica na cultura do milho implantada em área de campo nativo, influenciadas por métodos de preparo do solo e tipos de adubação

Despite the available knowledge on erosion of cultivated lands, there are situations of soil use and management that need more detailed studies. Based on that, this research work was accomplished with the objective of evaluating soil erosion by rainfall from an area of native pasture cropped with corn (Zea mays L.), under reduced-tillage and no-tillage, and mineral (chemical fertilizer containing N and P) and organic (poultry litter) fertilization. The study was developed in the field, at the Agriculture Experimental Station of the Federal University of Rio Grande do Sul (EEA/UFRGS), RS, Brazil, in the summer of 2006/2007, by applying simulated rainfall on an Ultisol having sandy loam texture in the surface layer and 0.13 m m-1 average slope steepness. Two erosion tests in the research, were performed, each one of them at the constant 64.0 mm h-1 rainfall intensity and for 1.5 h duration, by using the rotating boom rainfall simulator. The first test was performed soon after treatments establishment, at corn seeding, and the second one 75 days later, at corn tasseling. Soil and plant attributes were evaluated in the experimental plots and those of water erosion in the surface runoff. It was observed that the crop growth and the erosion losses were influenced by the studied treatments. Corn grew better in reduced-tillage, regardless of fertilization type. Soil loss occurred only in reduced-tillage and in the first erosion test, in very small amount, regardless of the fertilization type. Water, organic matter, and nutrients losses occurred in all treatments and erosion tests, in variable amounts, generally being higher in no-tillage and in the first erosion test. The pH of the runoff varied little and no trends in treatments and erosion tests were observed, whereas electric conductivity and mean concentrations of organic matter and nutrients varied widely and clear trends could be observed. This latter aspect repeated with the accumulated total amounts of organic matter and nutrients lost by erosion. The highest accumulated total amounts of nutrients lost by erosion were observed for K in both organic and mineral fertilization, for P in mineral fertilization, and for N in both organic and mineral fertilization, in this decreasing order of values and all under no-tillage. Accumulated total amounts of nutrients lost by erosion lower than the ones just mentioned, but still significant, were observed for K in practically all other treatments and for N under reduced-tillage with organic fertilization.

Perdas de solo e água por erosão hídrica após mudança no tipo de uso da terra, em dois métodos de preparo do solo e dois tipos de adubação

A mudanca no tipo de uso da terra, se nao devidamente planejada e conduzida, podera resultar em solos com capacidade produtiva diminuida e com propensao a erosao aumentada, o que ira diminuir o rendimento das culturas e prejudicar a conservacao do solo e da agua. Esta pesquisa teve como objetivo avaliar a erosao hidrica pluvial do solo em area originalmente de campo nativo, nos seus segundo e terceiro anos de cultivo com culturas anuais em fileira (respectivamente, feijao-miudo - Vigna unguiculata - e sorgo - Sorghum bicolor), nos metodos de preparo do solo reduzido (escarificacao) e sem preparo (semeadura direta) e nos tipos de adubacao mineral (fertilizante NPK) e orgânica (cama de aviario), alem de uma condicao sem adubacao (tratamento testemunha). O estudo foi desenvolvido em campo, na EEA/UFRGS, em Eldorado do Sul (RS), nos veroes de 2007/2008 e 2008/ 2009. Usou-se chuva simulada e um Argissolo Vermelho distrofico tipico com textura franco-arenosa na camada superficial e declividade media de 0,13 m m- 1. Realizaram-se dois testes de erosao em cada ciclo cultural: o primeiro, logo apos o preparo do solo e a semeadura das culturas; e o segundo, cerca de 90 dias mais tarde (estadio fenologico de enchimento de legumes, no caso do feijao-miudo, e de maturacao, no do sorgo). As chuvas foram aplicadas com o simulador de bracos rotativos, na intensidade planejada de 64 mm h-1 e com duracao de 1,5 h cada uma. Os resultados evidenciaram que a mudanca no tipo de uso da terra, excluida a condicao sem adubacao, nao ocasionou perdas relevantes de solo e agua por erosao hidrica. A mobilizacao do solo pela escarificacao, na maior parte dos casos, favoreceu a infiltracao e a retencao superficial da agua da chuva e, em decorrencia, reduziu a enxurrada, ao mesmo tempo em que satisfatoriamente controlou a erosao. Por sua vez, a ausencia de mobilizacao do solo na semeadura direta, tambem na maior parte dos casos, induziu a formacao de maior enxurrada, porem controlou melhor a erosao. Comparadas a condicao sem adubacao, a adubacao mineral e a adubacao orgânica contribuiram para reduzir a enxurrada e a erosao nos dois metodos de preparo do solo investigados, sem diferencas definidas entre elas em qualquer um destes ultimos.

Avaliação de cinco algoritmos de árvores de decisão e três tipos de modelos digitais de elevação para mapeamento digital de solos a nível semidetalhado na Bacia do Lageado Grande, RS, Brasil

O mapeamento digital de solos (MDS) tem como base a geracao de sistemas de informacoes que permitem estabelecer relacoes matematicas entre variaveis ambientais e solos e, dessa forma, predizer a distribuicao espacial das classes ou propriedades dos solos. Dentre as abordagens mais utilizadas, as arvores de decisao tem se destacado por apresentar bons resultados no MDS. Por outro lado, dada a disponibilidade de novas fontes de informacao sobre a elevacao, torna-se necessario o teste e avaliacao de modelos digitais de elevacao (MDE) quanto ao seu uso para o MDS. Este estudo testa cinco algoritmos de arvores de decisao (Simple Chart, Random Tree, REP Tree, BF Tree e J48) e tres MDE (Aster GDEM, SRTM e SRTM V3) para o MDS a nivel semidetalhado, em situacoes em que o principal fator diferenciador entre os tipos de solo e o relevo. O uso do MDE Aster GDEM e arvore de decisao com algoritmo J48, Simple Tree e BF Tree foram os que produziram modelos de arvore de decisao capazes de produzir mapas de solo com maior similaridade ao mapa de referencia.

Comparação do uso de modelos digitais de elevação em mapeamento digital de solos em Dois Irmãos, RS, Brasil

Os modelos digitais de elevacao (MDEs) sao fontes fundamentais para correlacionar a ocorrencia e distribuicao de solos com a paisagem pelo mapeamento digital de solos (MDS). A influencia dos tipos e das resolucoes dos MDEs na capacidade de predicao dos modelos preditores de classes de solo ainda e pouco estudada. Neste estudo, foram avaliados e comparados os efeitos de diferentes MDEs na predicao de ocorrencia de unidades de mapeamento de solo (UM). Foram correlacionados 12 atributos do terreno derivados de diferentes MDEs com a ocorrencia de UM. Os MDEs utilizados foram os oriundos dos projetos SRTM v4.1, ASTER GDEM v2, TOPODATA e Brasil em Relevo, e os MDEs gerados a partir de curvas de nivel na escala de 1:50.000, com resolucoes de 30 e 90 m. Os modelos preditores foram treinados por arvore de decisao (Simple Cart) com dados amostrados em 4.280 pontos aleatorios contendo informacoes dos solos extraidos de um mapa convencional de solos na escala 1:20.000 e 12 atributos do terreno derivados de seis MDEs com tamanhos de pixel de 30 e 90 m. A validacao dos modelos preditores de UM foi realizada com a totalidade dos dados da area. Os atributos do terreno que melhor explicaram a ocorrencia das UM foram elevacao, declividade, comprimento de fluxo e orientacao das vertentes. Os MDEs com tamanho de pixel de 30 m geraram correlacoes solo-paisagem menos acuradas. Os modelos preditores mais acurados e com maior numero de UM estimadas foram os gerados a partir dos MDEs com resolucao espacial de 90 m (SRTM v4.1 e CN90), sendo esses os MDEs mais indicados para o MDS, quando predominarem relevos plano e suave ondulado.

Construção de sentido nas narrativas de doentes crônicos

OBJECTIVE: Understand how chronically ill persons reframe life through their discursive practices. METHODS: Six interviews were selected from the original seventeen made with chronically ill persons from a public hospital in the metropolitan region of Porto Alegre. Recorded and transcribed interviews produced narratives concerning the existential situation in the face of disease, perspectives for the future, a comprehension of diagnosis and of therapy as well as the role of professionals for the reframing. Talks were divided in linguistic repertoires concerning diagnosis and therapy. RESULTS: In the first, the narratives of meaning are structured around cause of the disease from a genetic background (destiny) or due to the style of life (fault). In the repertoires about therapy, narratives of the self identity reconfiguration depend on the autonomy or heteronomy in relation to the physicians words as mediator of salvation, on perception of the body as a factor of relation, on the social representation of medication and on emotional situation. CONCLUSION: Self -satisfaction relies on finding the thread to bring together the elements of existence based on a new model permitting a new identity. The professional must be involved in the narratives of identity reconstruction enabling therapy to produce the expected effect and for the patient to feel as a participant of the process, assuming with autonomy the necessary changes in life.

Hidrogramas e sedimentogramas associados à erosão hídrica em solo cultivado com diferentes sequências culturais, com diferentes condições físicas na superfície

Detailed studies on hydrology and sediment production are of great value to enhance the understanding and control of the water erosion process, with a view to more continuous and effective soil and water conservation practices. The purpose of this study was to develop specific (for each treatment replication) hydrograms (instantaneous runoff discharge versus time) and sedimentograms (instantaneous sediment concentrations in the runoff and instantaneous soil loss rates versus time), associated with water erosion in a soil under different crop sequences (winter and summer grass and legume species in no-till, mono and intercropped), with different physical conditions on the surface (untilled, recently-chiseled, previously-chiseled, and recently-disked soil, in addition to the presence and absence of crust and of full, little, and no cover by crop residues). The study was conducted in the field, at an experimental station of the Federal University of Rio Grande do Sul (EEA/UFRGS), in Eldorado do Sul (RS), Brazil, under simulated rain on an Ultisol with a sandy clay loam texture in the surface layer and 0.115 m m-1 average slope steepness. In the beginning of the study the soil had a high degradation degree. The rains (six in total, one for each erosion test) were applied with a rotating-boom rainfall simulator, at the designed rainfall intensity of 64.0 mm h-1 (in this study the observed rainfall intensities were used, ranging from 59.1 mm h-1 to 74.6 mm h-1) and duration ranging from 1 to 3 hours (determined to reach the runoff equilibrium condition in all erosion tests). It was observed that the hydrograms and sedimentograms were generally coherent with the conditions under which they were developed. Therefore, in most erosion tests the hydrograms differed more from one another than in the crop sequence treatments, opposite to the sedimentograms. The untilled soil surfaces with low roughness and cover, in general, provided hydrograms and sedimentograms with shorter start-up period and greater magnitude, regardless of the presence or absence of crust and type of crop sequence. The recently-tilled soil surfaces and those with medium and great roughness, in general, provided hydrograms and sedimentograms with longer start-up period and smaller magnitude, practically regardless of cover and type of crop sequence. The runoff from soil surfaces with complete cover was diminished and erosion eliminated, regardless of tillage and type of crop sequence. For the crop sequence with teosinte, the hydrograms and sedimentograms showed longest start-up periods and smallest magnitudes, followed by the ones with corn+cowpea and pearl millet, which differed little from each other. The replications of the treatments provided values of instantaneous runoff discharges that seemed more similar to one another and were more regularly distributed in time than those for the corresponding instantaneous concentrations of sediment and instantaneous soil loss rates. The obtained data were valuable for a better understanding of the variation commonly observed in the results of water erosion research developed in the field.