Resumo A chuva (P) e a evapotranspiração potencial (ETP) são variáveis climáticas relevantes para diferentes áreas do conhecimento, tais como: agricultura, manejo de bacias, previsões de tempo e drenagem urbana. O objetivo deste trabalho foi caracterizar os padrões de chuva e de ETP para o município de Goiânia, GO. Foram utilizados dados de 36 anos para chuva e de 21 anos para ETP. A precipitação foi de 1.494,66 mm, com tendência de redução a uma taxa de 3,7 mm ano-1. Observou-se que 99% das precipitações diárias são p ≤ 50 mm dia-1. Registraram-se 292 dias sem chuva e 72 dias chuvosos, com tendência de redução dos dias chuvosos e aumento de dias secos. A ETP foi de 1.380,57 mm, sendo a maior e a menor média registrada no 3° (139,02 mm) e 35° (55,36 mm) quinquídios. Há tendência de aumento na ETP (6,37 mm ano-1). Registrou-se excedente hídrico de 607 mm ano-1 e déficit 471 mm ano-1. ETR/ETP <0,8 entre os meses de abril e outubro. Frequências predominantes de P e ETP foram de 38% ( P > X ¯ ) e 31% ( E T P > X ¯ ), com periodicidades 4,0 (P) e 3,2 (ETP) anos. Observou-se r = 0,68 entre a temperatura média do ar e as taxas de desmatamento.

Abstract Rainfall (P) and potential evapotranspiration (ETP) are climatic variables relevant to different areas of knowledge, such as: agriculture, watershed management, weather forecasts and urban drainage. The aim of this work was to characterize the rainfall and ETP patterns for the Goiânia, GO city. Data of 36 years for rainfall and 21 years for ETP were used. The precipitation was 1,494.66 mm, with a trend of reduction at a rate of 3.7 mm year-1. It was observed that 99% of the daily precipitations are p ≤ 50 mm day-1. We recorded 292 days without rain and 72 rainy days, with a tendency to reduce rainy days and increase dry days. The ETP was 1,380.57 mm, with the highest and the lowest mean recorded in the 3rd (139.02 mm) and 35th (55.36 mm) quinquides. There is a tendency to increase in ETP (6.37 mm year-1). A water surplus of 607 mm year-1 and a deficit of 471 mm year-1 were recorded. ETR/ETP <0.8 between the months of April and October. Predominant frequencies of P and ETP were 38% ( P > X ¯ ) and 31% ( E T P > X ¯ ), with periodicities 4.0 (P) and 3.2 (ETP) years. Correlation of 0.68 between the mean air temperature and Goiás deforestation rates was observed.

ABSTRACT Plinthite and petroplinthite occur frequently in Brazilian soils, but there is little information on the behavior of these materials. The aim of the present study was to assess the effect of different drying periods on the hardening and stability of plinthic materials of soils in the floodplain of the Araguaia River and the João Leite stream in Goiás. Soil samples were collected, with the aid of 0.10 m high and 0.15 m diameter PVC cylinders, directly from the plinthic horizons of five profiles of Plintossolos Argilúvicos (Plinthosols). Plinthite and soil matrix subsamples were obtained from these samples. Homogeneous petroplinthite samples were collected from the concretionary horizon of a Plintossolo Pétrico (Plinthosol) profile, and these were separated into subsamples with the aid of a rock hammer. All subsamples were dried in two manners: air drying and drying in a forced ventilation oven for 10, 20, 40, 80, and 160 days. Compressive strength and degree of stability were assessed. The results show a considerable variety of responses to the compressive force applied to the plinthite and petroplinthite samples in the same horizon and among the different profiles examined.

ABSTRACT Although ferruginous materials occur frequently in soils of tropical regions, information about the reversal of the hardening process of these materials is scarce. This study assessed the influence of different chemical treatments and periods of immersion on the reversibility of the hardening process of plinthite and petroplinthite in soils of the Araguaia River plain. Soil samples were collected from the plinthic horizons in 0.10 m high and 0.15 m diameter PVC cylinders and divided into subsamples with a rock hammer. Homogeneous petroplinthite samples were also collected and broken into subsamples with a rock hammer. The plinthite and petroplinthite subsamples were subjected to five immersion treatments: distilled water, calcium carbonate solution, sodium hydroxide solution, sodium hydroxide solution + sodium hexametaphosphate, and acidic solution. The subsamples were immersed for 20, 40, 80, and 160 days. The dispersion and stability degrees and compressive strength in these subsamples were assessed. The wet aggregate stability test indicated no impact on the structural stability of plinthite and petroplinthite subsamples subjected to the treatment with different chemical agents, demonstrating the non-reversibility of the hardening process of these materials of the Araguaia River floodplain, under the studied conditions.

RESUMO: Objetivou-se com este estudo avaliar diferentes materiais para ensacamento a campo quanto às alterações físico-químicas causadas em frutos de meloeiro Cantaloupe. O estudo foi conduzido em ambiente protegido localizado na cidade de Goiânia, Goiás. O experimento foi composto por cinco tratamentos, referentes ao ensacamento de frutos de meloeiro Cantaloupe com quatro materiais (papel jornal, papel Kraft, TNT e polietileno) e um tratamento controle, sem ensacamento, dispostos em blocos casualizados, com cinco repetições, representadas por uma planta com um fruto cada. Os frutos foram avaliados quanto às características físico-químicas. Também foi contabilizado o número de dias desde o ensacamento até a colheita e observados os aspectos visuais dos frutos. Verificou-se que os materiais influenciaram as características relativas ao acúmulo de sólidos solúveis e espessura do halo verde da polpa, o intervalo de tempo entre o ensacamento e a colheita e os aspectos visuais dos frutos. Recomenda-se o ensacamento de melões Cantaloupe com a utilização do TNT ou a não utilização da técnica, em condições semelhantes às do estudo. Em complemento, não é recomendada a utilização do polietileno para o ensacamento dos frutos, uma vez que esse material tem efeito deletério sobre as características essenciais à comercialização.

ABSTRACT: The objective of this study was to evaluate different materials for field bagging with respect to the physicochemical changes caused in cantaloupe melon fruits. The study was conducted in a protected environment in the city of Goiânia, Goiás in Brazil. The experiment consisted of five treatments, with bagging of cantaloupe melon fruits with four materials (newspaper, Kraft paper, NWF, and polyethylene) and a control treatment without bagging, in a randomized block design with five replications of one plant with a fruit each. Fruits were evaluated for physicochemical characteristics. Number of days from bagging to harvest was also recorded and visual aspects of the fruit were observed. The materials as well as the time interval between the bagging and harvest affect physicochemical characteristics such as accumulation of soluble solids and thickness of the green pulp halo and visual aspects of the fruit. This study recommends bagging cantaloupe melons using white non-woven fabric or to not use the technique at all, under the conditions similar to those used in the study. In addition, using polyethylene for the bagging of fruit is not recommended, because this material has a deleterious effect on the characteristics essential for commercialization of melons.