Navegando por Autor "Bacchi, Osny O. S."

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Soil water extraction by roots and Kc for the coffee crop
(Departamento de Engenharia Agrícola - UFCG, 2009-05) Silva, Adriana L. da; Bruno, Isabeli P.; Reichardt, Klaus; Bacchi, Osny O. S.; Dourado-Neto, Durval; Favarin, José L.; Costa, Flávio M. P. da; Timm, Luis C.
Basic information for a rational soil-water management of the coffee crop is still insufficient, particularly under irrigated conditions. Of great importance for the estimation of water requirements of coffee crops are their root distribuition and evapotranspiration crop coefficients. This study compares soil water extraction by roots of coffee plants of the variety “Catuaí Vermelho” (IAC-44), grown in Piracicaba, SP, Brazil, 3 to 5 years old, with direct measurements of root dry matter, showing a good agreement between both approaches, and confirming that most of the root system is distributed in the top soil layer (0-0.3 m) and that less than 10% of the root system reaches depths greater than 1.0 m. Calculated evapotranspiration crop coefficients are in agreement with those found in the literature, with an average of 1.1, indepen- dent of shoot dry matter, plant height and leaf area index.
The 15N isotope to evaluate fertilizer nitrogen absorption efficiency by the coffee plant
(Academia Brasileira de Ciências, 2007) Fenilli, Tatiele A. B.; Reichart, Klaus; Bacchi, Osny O. S.; Trivelin, Paulo C. O.; Dourado-Neto, Durval
The use of the 15N label for agronomic research involving nitrogen (N) cycling and the fate of fertilizer-N is well established, however, in the case of long term experimentation with perennial crops like citrus, coffee and rubber tree, there are still shortcomings mainly due to large plant size, sampling procedures, detection levels and interferences on the system. This report tries to contribute methodologically to the design and development of 15N labeled fertilizer experiments, using as an example a coffee crop fertilized with 15N labeled ammonium sulfate, which was followed for two years. The N of the plant derived from the fertilizer was studied in the different parts of the coffee plant in order to evaluate its distribution within the plant and the agronomic efficiency of the fertilizer application practice. An enrichment of the fertilizer-N of the order of 2% 15N abundance was sufficient to study N absorption rates and to establish fertilizer-N balances after one and two years of coffee cropping. The main source of errors in the estimated values lies in the inherent variability among field replicates and not in the measurements of N contents and 15N enrichments of plant material by mass-spectrometry.