José Romualdo de Sousa Lima

Métodos de estimativa da evapotranspiração de referência diária para a microrregião de Garanhuns, PE

For high frequency irrigation management, based on climate data, it is desirable to estimate reference evapotranspiration at small time steps. This work aimed at to evaluate the performance of daily reference evapotranspiration estimated by the following methods: FAO-24 Radiation, Priestley-Taylor, Hargreaves-Samani, Camargo-71 and Blaney-Criddle, for Garanhuns-PE micro-region, having FAO Penman-Monteith method as standard. Considering the mean absolute error (MAE), among other statistics, it was verified that the best performance was obtained by the Priestley-Taylor method. Regarding the methods applicable when only temperature data are available, the Hargreaves-Samani showed the best performance, having been calibrated based on the minimization of the MAE.

Energy balance and evapotranspiration in cowpea under rainfed conditions

The objective of this study was to assess the energy balance components (net radiation, latent heat flux, sensible heat flux and soil heat flux), evapotranspiration (ET) and water use efficiency (WUE) of cowpea grown under rainfed conditions. The experiment was conducted in a 4 ha area in the CCA, UFPB, belonging to the Municipality of Areia, PB (6 o 58 S, 35 o 41 W and 620 m) during the period from July, 22 2003 to October, 17 2003. To determine th e energy balance components and ET, it was used the Bowen ratio method, and for that, the area was instrumented with a micrometeorological tower containing sensors for measuring air temperature and relative humidity at two levels above the canopy of cowpea. Measurements of net and global radiation, soil heat flux and rainfall were also made. The average value of the net radiation was 79% of the global solar radiation (Rn/Rg), in which 65% appeared as latent heat flux (LE/Rn), 23% as sensible heat flux (H/Rn) and 12% as soil heat flux (G/Rn). The total and average values for actual evapotranspiration were 330.7 mm and 3.8 mm day -1 , respectively. The production of cowpea was only 206.0 kg ha -1 with low WUE (0.06 kg m -3 ), which occurred probably due to water deficit at reproductive stage.

Varabilidade temporal da precipitação pluvial: nível de nitrogênio no solo e produtividade de cultivares de girassol

With the aim of analyzing the effects caused by temporal variability of rains over sunflower (Helianthus annuus L.) tillage income and development in function of nitrogen fertilization and cultivars, experiments with sunflower tillage were performed in Alagoinha-PB in the years of 1995,1996,1998 in the municipal district of Esperanca-PB in 1998. In this occasion four levels of nitrogen were verified (0, 30, 60 and 90kg.ha-1), two cultivars (one precocious and another late) in blocks at random with four repetitions. Beyond these experiments, some data about pluvial precipitation were analyzed. During the performance of the experiments we analyzed the tillage phenological stages, biomass accumulation and income and its components. In relation to the results, was verified in Alagoinha-PB an annual average rains of this period (1981 - 1999) around 1.018,6mm. The sunflower vegetative and reproductive stages have changed according to the distribution of rains during the tillage cycle. The adopted treatment answers for tillage over the analyzed variations were depending on the distribution of rains during the tillage development stages. There was also a big variation in the tillage answers in relation to the nitrogen levels and in the cultivars in function of weather.

Balanço hídrico da cultura da mamona sob condições de sequeiro

The study of water balance components is essential to understand the dynamics of soil water, providing subsidies to agricultural management and optimization of water use. The objective of this study was to determine the water balance components in a soil cultivated with castor bean under rainfed conditions. An experiment was installed in a 4 ha area in the Centro de Ciencias Agrarias, UFPB, in the municipality of Areia, Paraiba state (6o 58 S, 35o 41 W e 620 m), a rain gauge and three plots contained an access tube for neutron probe measurements, up to the depth of 1.60 m, and a set of eight tensiometers at depths of 0.10, 0.20, 0.30, 0.40, 0.60, 0.80, 1.20 and 1.60 m. Infiltration tests were performed on soil surface and 0.20, 0.40, 0.60 and 0.80 m depth for the determination of the saturated hydraulic conductivity of soil. It was verified that the evapotranspiration of castor bean followed the variations of rainfall with the mean and total values of 2.43 mm d-1 and 342.5 mm, respectively. The variation of soil moisture storage change followed the variations in rainfall and the flux of water crossing the last soil layer (capillarity rise or drainage) had very small values.

Land cover changes and greenhouse gas emissions in two different soil covers in the Brazilian Caatinga

The Caatinga biome covers an area of 844,453km(2) and has enormous endemic biodiversity, with unique characteristics that make it an exclusive Brazilian biome. It falls within the earths tropical zone and is one of the several important ecoregions of Brazil. This biome undergoes natural lengthy periods of drought that cause losses in crop and livestock productivity, having a severe impact on the population. Due to the vulnerability of this ecosystem to climate change, livestock has emerged as the main livelihood of the rural population, being the precursor of the replacement of native vegetation by grazing areas. This study aimed to measure GHG emissions from two different soil covers: native forest (Caatinga) and pasture in the municipality of São João, Pernambuco State, in the years 2013 and 2014. GHG measurements were taken by using static chamber techniques in both soil covers. According to a previous search, so far, this is the first study measuring GHG emissions using the static chamber in the Caatinga biome. N2O emissions ranged from -1.0 to 4.2mgm(-2)d(-1) and -1.22 to 3.4mgm(-2)d(-1) in the pasture and Caatinga, respectively, and they did not significantly differ from each other. Emissions were significantly higher during dry seasons. Carbon dioxide ranged from -1.1 to 14.1 and 1.2 to 15.8gm(-2)d(-1) in the pasture and Caatinga, respectively. CO2 emissions were higher in the Caatinga in 2013, and they were significantly influenced by soil temperature, showing an inverse relation. Methane emission ranged from 6.6 to 6.8 and -6.0 to 4.8mgm(-2)d(-1) in the pasture and Caatinga, respectively, and was significantly higher only in the Caatinga in the rainy season of 2014. Soil gas fluxes seemed to be influenced by climatic and edaphic conditions as well as by soil cover in the Caatinga biome.

BALANÇO HÍDRICO EM NEOSSOLO REGOLÍTICO CULTIVADO COM BRAQUIÁRIA (Brachiaria decumbens Stapf)

Um dos principais fatores de producao para as culturas e a disponibilidade de agua no solo, de forma que a quantificacao das entradas e saidas dessa agua, por meio do metodo do balanco hidrico, pode ser um instrumento valioso para melhorar o manejo dado a ela. Desse modo, este trabalho teve como objetivo analisar os componentes do balanco hidrico (variacao do armazenamento de agua no solo, drenagem, ascensao capilar e evapotranspiracao) e o perfil do sistema radicular em Brachiaria decumbens, em nove meses do ano de 2011 (marco a novembro). Tambem foi avaliada a razao entre evapotranspiracao (ET) e evapotranspiracao de referencia (ETo). Esta pesquisa foi realizada na fazenda Riacho do Papagaio, em Sao Joao, na mesorregiao do Agreste do Estado de Pernambuco, onde foram instalados sensores automatizados para medicao da umidade volumetrica do solo nas profundidades de 0,10; 0,20; 0,30; e 0,40 m. A precipitacao pluvial foi monitorada por meio de um pluviografo automatizado instalado numa torre no centro da area. Para a determinacao da drenagem e da ascensao capilar, foram realizados ensaios de infiltracao para obtencao da condutividade hidraulica do solo, alem da determinacao da curva de retencao, em laboratorio. A ET foi obtida como termo residual da equacao do balanco hidrico e a ETo, pelo metodo de Penman-Monteith. O volume de controle utilizado para o balanco hidrico teve como limite superior a superficie do solo e como limite inferior a profundidade de 0,30 m. Tambem foi analisado o perfil do sistema radicular da braquiaria, mensalmente. Observou-se que os periodos com elevadas pluviosidades resultaram num maior armazenamento de agua no solo, em maiores valores de drenagem e de evapotranspiracao. O fluxo de agua no limite inferior (z = 0,30 m) do solo ocorreu somente no sentido descendente, sendo perdidos 103,14 mm de agua por drenagem, o que representa 24,12 % de toda a agua fornecida a cultura. A evapotranspiracao total da Brachiaria decumbens Stapf foi de 324,96 mm, com valor medio de 1,2 mm d-1. A pastagem sofreu estresse hidrico, em quase todo periodo experimental, tendo em vista os valores da relacao ET/ETo serem inferiores a 1. Os baixos valores da razao ET/ETo indicaram a necessidade de se realizar irrigacao para se diminuir o deficit hidrico. No entanto, em razao dos elevados valores de drenagem, recomendam-se praticas de manejo que aumentem a retencao de agua pelo solo.

Variabilidade espacial de propriedades hidrodinâmicas de um Neossolo Regolítico sob pastagem e caatinga

The hydrodynamic properties of soils under pasture and caatinga (native dry forest) are affected by several factors, mainly associated with spatial and temporal aspects, due to differing root characteristics or livestock trampling rates, but few results that evaluate the effect of the magnitude of these sources of variability in the hydrodynamic properties of soils have been reported in the literature. The objective of this study was to analyse the spatial variability of parameters of water retention (van Genuchten) and hydraulic conductivity (Brooks & Corey) curves, obtained with the Beerkan methodology based on simple infiltration experiments and soil texture data. These measures were obtained for two sampled areas: an area of pasture (Brachiaria decumbens) and another one of caatinga. The results showed that the use of pasture altered significantly the analysed properties of soil when compared to the ones with the soil under caatinga, and that the most significant changes were found in soil density and hydraulic conductivity. The geostatistic analysis identified the existence of spatial dependency of the studied attributes allowing the mapping of experimental areas.

Análise de risco e otimização de recursos hídricos e retorno financeiro em nível de fazenda

Este trabalho teve como objetivo analisar padroes de cultivo em uma propriedade rural, visando a otimizacao do uso de recursos hidricos e a maximizacao do retorno financeiro, para um estudo de caso no Agreste Meridional Pernambucano. O modelo de programacao linear com horizonte de planejamento de tres anos utilizado, foi implementado na planilha Microsoft® Excel. Este modelo visou a maximizacao do valor presente liquido total do empreendimento. Para a analise de risco foram utilizadas duas tecnicas complementares: a simulacao de risco, procedida com o programa @Risk, e a analise de sensibilidade. No primeiro padrao de cultivo, PC1, com restricao hidrica mensal para irrigacao de 8.500 m3, o maximo valor presente liquido total, VPLt , foi de R

Análise de Sensibilidade de Parâmetros do Modelo SWAT em uma Sub-bacia da Região Nordeste, Brasil (Sensitivity analysis of SWAT model parameters applied in a sub-basin of Northeast Region, Brazil)

8.771,10 (ha ano)-1; no segundo padrao de cultivo, PC2, com restricao hidrica mensal de 4.000 m3, o VPLt foi de R

Daytime Net Radiation on Cowpea and Castor Bean in the County of Areia-PB and Garanhuns-PE

8.228,77 (ha ano)-1. Na analise de risco, observou-se que os valores encontrados do VPLt foram positivos e proximos para os dois padroes de cultivo evidenciando a nao expectativa de fracasso financeiro, mas com consideravel reducao da demanda de agua para irrigacao para o PC2, indicando o potencial da metodologia aplicada a gestao de recursos hidricos na regiao.