Aderson Soares de Andrade Júnior

Uso e qualidade da água subterrânea para irrigação no semi-árido piauiense

The semi-arid region in the State of Piaui, Brazil, is characterized by low rain fall and high evapotranspiration. However, the groundwater reserves make possible the economic development by underground hydrogeology characteristics, which allow extractions of high water flow with good quality, in most of the cases. However, some wells reached formations that have low discharge and water with high salt concentration, which if used for irrigation may cause salinization and sodification. The main goal of this work was to characterize the different uses and quality of groundwater in a part of the semi-arid area of Piaui, with a view to its use for irrigation. Samples were collected in 225 wells distributed spatially in the area, in which the following variables were analyzed: electrical conductivity, Na, Ca, Mg, SAR, CO3, HCO3, Cl and SO4. Regarding water use, the domestic use prevailed (53.61%), followed by irrigation (21.17%), with the following irrigation methods: drip irrigation (14.03%); microsprinkler (3.83%); conventional sprinkler (16.11%); gun sprinkler and traveler irrigation machine (13.66%); surface irrigation (16.76%) and other handmade methods (35.52%). The maps of classes of use risk irrigation generated from groundwater quality showed the occurrence of sub-areas with the following classes: no restriction, moderate restriction and severe restriction.

Níveis de irrigação na cultura do feijão caupi

This work was carried out to evaluate the effect of irrigation depth on yield and production components of cowpea (Vigna unguiculata L. Walp) under soil and climatic conditions of the Coastal Tablelands in the State of Piaui - Brazil. The trial was conducted at the Embrapa Meio-Norte Experimental Area, in Parnaiba, in a sandy soil, during the period from August to October, 1998. Irrigation depths were applied through a sprinkler line source system. The treatments were constituted by combination of four depths of irrigation (449.1; 428.6; 317.1 and 194.4 mm) and two cowpea cultivars (BR 17 Gurgueia and BR 14 Mulato) arranged in a completely randomized block design in split-plot and five replications. Significant effects (p<0.05) of depth of irrigation and cultivar interaction with respect to number of pods per plant (NPP) and grain yield (GY) were observed. The highest NPP (25.6) and maximum GY (2,809 kg ha-1) for the BR 17 Gurgueia cultivar was obtained with the irrigation depth of 449.1 mm. The maximum NPP (15.0) and GY (2,103.4 kg ha-1) for the BR 14 Mulato cultivar were obtained with the irrigation depth of 363.5 and 389.9 mm, respectively.

Calibration of a capacitance probe in a Paleudult

ABSTRACT: The use of capacitance sensors is one of the methods used to quantitatively measuresoil water contents (θ, m 3 m -3 ). Sensors provide readings at desired depths and time intervals. Acapacitance probe (Diviner 2000) was calibrated for a Rhodic Paleudult from the Piaui State, Brazil. Sixaccess tubes were installed in a 5 × 2 m grid arrangement. Three moisture levels (saturated, moist anddry) were used in two replications. Probe readings and soil samplings to determine θ were made at 0.1m depth intervals down to a depth of 1.0 m. A power calibration equation was developed for eachdepth as well as for the entire soil profile (Root Mean Square Error = 0.014, R 2 = 0.93) for a θ range of0.068 to 0.264 m 3 m -3 . A separate calibration for each depth improves the correlation coefficient andminimizes RMSE. Site-specific calibration improves the accuracy for soil water monitoring.Key words: FDR probe, sensor, irrigation, soil water content CALIBRACAO DE UMA SONDA DE CAPACITÂNCIAEM UM ARGISSOLO

Climate variations in greenhouse cultivated with gerbera and relationship with external conditions

Black meshes used in greenhouses provide shade to plants, affecting photosynthesis and presenting certain properties that change the microclimatic conditions in these environments. The objective of this study was to evaluate the variation in climate elements in greenhouse cultivated with gerbera (Gerbera jamesonii, Vr. Rambo) in relation to external conditions and the reference evapotranspiration (ETo) at Teresina, State of Piaui, Brazil. The measurements were obtained from July to October 2007 by an automatic data acquisition system installed inside and outside the greenhouse. The global solar radiation, evapotranspiration, precipitation, temperature, relative humidity, and wind speed were estimated. The results showed that major effect of the shading occurred on the mean air temperature during the 120 days, making it higher than the external environment. Inside the greenhouse, mean values of relative air humidity, reference evapotranspiracao, global solar radiation and wind speed were lower compared to those outside the greenhouse.

Simulação da precipitação diária para Parnaíba e Teresina, PI, em planilha eletrônica

Os estudos envolvendo precipitacao pluviometrica sao bastante dificultados devido ao fato das series historicas disponiveis serem, na maioria dos casos, muito pequenas para efetua-los. Desta forma, faz-se necessario dispor de uma tecnica de simulacao estocastica que possibilite a geracao de valores diarios de precipitacao, utilizando-se uma planilha eletronica. No Estado do Piaui, estudos com esse objetivo sao inexistentes, razao por que este trabalho tem o objetivo de simular a precipitacao pluviometrica diaria para as regioes de Parnaiba e Teresina, PI, atraves de uma planilha eletronica. O processo de simulacao se baseou no metodo de Monte Carlo. A ocorrencia da precipitacao foi determinada atraves da cadeia de Markov, enquanto a sua magnitude foi estimada pelas funcoes de distribuicao de probabilidades gama e empirica. O modelo utilizado proporcionou estimativas com excelente precisao e exatidao, fato comprovado pelos resultados satisfatorios quanto aos indices de desempenho estatisticos.

Estratégias ótimas de irrigação do feijão‑caupi para produção de grãos verdes

The objective of this work was to determine optimal strategies of irrigation for cowpea (Vigna unguiculata) for the production of green bean, with water as the limiting yield factor and different values for the price of the product. The experiment was carried out at Embrapa Meio‑Norte, in Teresina, PI, Brazil, from September to November 2009. Five irrigation depths, established based on fractions of reference evapotranspiration (25, 50, 75, 100, and 125% of ETo), and the BRS Guariba and BRS Paraguacu cowpea cultivars were evaluated. Irrigation was done with a conventional fixed sprinkling system. The experimental design was a randomized complete block with four replicates, in a split‑plot arrangement (cultivars). The irrigation depths from 290 to 325 mm (108 to 130% of ETo) (BRS Paraguacu) and from 325 to 363 mm (130 to 153% of ETo) (BRS Guariba) maximize the liquid income, considering the price range of the product from US

Cultivation of gerbera irrigated with treated domestic effluents

0.75 to 2.00 kg‑1, for the cultivar BRS Paraguacu, and from US

Evapotranspiração de referência mensal para o Estado do Piauí

0.50 to 2.00 kg‑1, for BRS Guariba. The cultivar BRS Guariba shows better economic performance than BRS Paraguacu.

Water storage in a Plinthaqualf cultivated with sugarcane under straw levels

This paper evaluates the nutritional impact on growth, production and quality variables of gerbera crop when fertigated with treated domestic effluents. An experiment was carried out in greenhouse at the Embrapa Meio-Norte in Teresina, in the State of Piaui, Brazil, from July to October 2007. A completely randomized experimental design with five treatments and five replications was adopted. The treatments investigated were T1 - 100% of water and nutritional requirements of crop were met with chemical fertigation (N e K2 O); T2 - 25% volume of water through fertigation and 75% treated wastewater effluents (TWE); T3: 50% volume of water through fertigation and 50% TWE; T4: 75% volume of water with fertigation and 25% TWE; and T5 - 100% volume of water supplied through TWE. Leaf growth and plant development were favored by the application of 50% fertigation and 50% TWE (T3). As for commercial requirements, the best results for number of flowers were obtained with T4. However, concerning quality, T2 produced flowers in July and August with longer stems, but in the months of September and October, no treatment achieved this standard due to high temperature and low relative humidity of the air in the region.

Estudo da oferta e comercialização de melão na CEASA-PI (1991-1996)

The objective of this work was to estimate the mean monthly reference evapotranspiration (ETo) for Piaui State, Brazil. The ETo estimates were performed by the Thornthwaites (1948) empirical method, based on estimated mean air temperature equations developed by Lima & Ribeiro (1998). The ETo was estimated for 222 municipalites of Piaui State. The values were arranged in a spatial distribution and grouped in classes with 25 mm interval. Maps of monthly ETo were prepared. The monthly ETo values ranged from 55.4 to 212.0 mm, showing large evapotranspiration variation among the several regions of Piaui State. Lower monthly ETo values were obtained for the period of February to July, while the higher values were observed for September to December. The spatial distribution of the monthly ETo values occurred as a function of the spatial variation of the monthly mean air temperature in the different regions of Piaui State.