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Borges V.P.,Federal University of Campina Grande | de Oliveira A.S.,Nucleo de Engineering de Agua e Solo UFRB | Coelho Filho M.A.,Laboratorio Of Irrigacao E Fertirrigacao | da Silva T.S.M.,Laboratorio Of Irrigacao E Fertirrigacao | Pamponet B.M.,Nucleo de Engineering de Agua e Solo UFRB
Revista Brasileira de Engenharia Agricola e Ambiental | Year: 2010

Solar radiation at the earth's surface (R s) is one of the essential weather variables for several agro-environmental studies. In the absence of measured R s, it's possible to simulate them by models. Using three years of daily R s data (2004-2006) collected by an INMET (Brazilian Meteorological Service) automatic weather station installed in the municipality of Cruz das Almas, BA, three air temperature-based R s simulation models were evaluated. As a preliminary step, data quality was investigated and, when needed, adjustments were made based on clear sky solar radiation envelopes. The following models were evaluated: Hargreaves-Samani for both interior and coastal regions, Thornton-Running, and the Weiss model. Linear regression R 2, mean ratio (MR), mean absolute error (MAE), root mean square error (RMSE), and the index of agreement of Willmott (d W) were used for model performance evaluation against measured R s. The results recommended the coastal-region Hargreaves-Samani for prediction of R s in the Reconcavo of Bahia, Brazil, since it presented the MR value closest to 1.00 (1.01), the lowest MAE (2.54 MJ m -2 d -1), the lowest RMSE (3.13 MJ m -2 d -1), and the highest d W (0.90).

de Lourdes Silva de Lima R.,Rua Osvaldo Cruz | Severino L.S.,Rua Osvaldo Cruz | Severino L.S.,Texas Tech University | Gheyi H.R.,Nucleo de Engineering de Agua e Solo UFRB | And 2 more authors.
Revista Ciencia Agronomica | Year: 2011

The addition of phosphorous to the substrate for the production of seedlings promotes faster growth of both root and shoots, increases tolerance to environmental stress and diseases, and even improves the efficiency of nutrient and water use in several plant species. This experiment aimed to study the effect of the addition of simple superphosphate to the substrate on the growth and macronutrient levels in the contents of seedlings of Jatropha curcas. A substrate containing soil and urban-waste compost was modified by the addition of simple superphosphate in 0; 2.5; 5.0; 7.5; 10.0 and 12.5 kg m -3 amounts. The seedlings were evaluated 30 days after planting. Maximum growth of the Jatropha plants was observed for the simple superphosphate added in estimated amounts in the range of 5 to 8 kg m -3. The phosphorus fertilization especially favored the growth of leaf-area and roots, and promoted increase in contents of all macronutrient except calcium.

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