Relações entre atributos do solo e uso de água em arroz irrigado

• Autor(a) principal: Lorensi, Raquel Paula
• Data de Publicação: 2011
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional Manancial UFSM
• Texto Completo: http://repositorio.ufsm.br/handle/1/3594
• topic: Lavouras orizícolas; Gleissolos; Planossolos; Automonitoramento; Outorga; Rice farming; Gleissolos; Planossolos; Automonitoring; Grant; CNPQ::CIENCIAS AGRARIAS::ENGENHARIA AGRICOLA

The knowledge of the water volume used in rice farming is of fundamental importance for the solution related to water distribution problems between the multiple uses and the grant concession. In this way, the objective of this work was to quantify the water volume used in rice farming, through simplified methods of flow measurement in different soils classes, as subsidy to the administration of water resources and to relate it to soil attributes. The study was implanted in four municipal districts, producers of irrigated rice, of the State of Rio Grande do Sul: Cacequi, Cachoeira do Sul, Manoel Viana and Santa Maria, totaling seven areas with extensions between 0.66 to 30.1 ha. Were measured the flow and classified the soils of each area. The methodology of flow measurement consisted of the installation of simple hydraulic structures. The structures were installed in the irrigation channels and in some drainage ones. This methodology transforms the flow in volume through empiric equations. Later, the monitored volume was compared to real hydric balance volume to validation of flow measurement method (automonitoring). The characterization of the soil was accomplished through the profile description for obtaining the pedogenetic horizons. Later, physical analyses were accomplished, in laboratory, as the density (soil and particle), the porosity (macro, micro and total), the texture (clay, silte and sand), the hydraulic conductivity and the chemical analyses as soil pH, calcium, magnesium, aluminum, saturation (bases and aluminum). The rate of water infiltration into soil in the field was obtained through the double concentric rings infiltrometer. The soils classification was determined to the fourth categorical level adopted by the Brazilian System of Soil Classification (EMBRAPA, 2006). The results showed similarity comparing the automonitoring technique and the real hydric balance. Only two soil classes occurred: Planossolos end Gleissolos. The relation between the soil sandy layer thickness and water volume used in irrigation was directly proportional. Already the clay fraction and volume relationship was inversely proportional. Most of the areas showed high soil density and low total porosity. The saturated hydraulic conductivity was classified between very slow to slow. The areas that presented larger infiltration rates, in the beginning of the test, were: Cacequi (No Till) and Cachoeira do Sul (Conventional). In the first, due to the high concentration sand, and in the second, due to soil surface was turned over before the infiltration test. In this way, was concluded that the automonitoring technique was validated. The Manoel Viana area showed discrepant conflicting volume from the others. The quantification of water volume used depends almost exclusively of the soil class and only a few of the soil management system. An increase in clay content in the layer under the sand layer decreases the water volume in irrigation. The area that not showed B horizon had the greater volume. Soil density data, total porosity, the saturated hydraulic conductivity and infiltration rate did not have similar behavior in all evaluated areas.