Calibration of a capacitance probe in a Paleudult

• Autor(a) principal: Silva,Cláudio Ricardo da
• Data de Publicação: 2007
• Outros Autores: Andrade Júnior,Aderson Soares de, Alves Júnior,José, Souza,Antonio Barros de, Melo,Francisco de Brito, Coelho Filho,Maurício Antonio
• Tipo de documento: Relatório
• Idioma: eng
• Título da fonte: Scientia Agrícola (Online)
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162007000600012
• topic: FDR probe; sensor; irrigation; soil water content

The use of capacitance sensors is one of the methods used to quantitatively measure soil water contents (theta, m³ m-3). Sensors provide readings at desired depths and time intervals. A capacitance probe (Diviner 2000) was calibrated for a Rhodic Paleudult from the Piaui State, Brazil. Six access tubes were installed in a 5 × 2 m grid arrangement. Three moisture levels (saturated, moist and dry) were used in two replications. Probe readings and soil samplings to determine theta were made at 0.1 m depth intervals down to a depth of 1.0 m. A power calibration equation was developed for each depth as well as for the entire soil profile (Root Mean Square Error = 0.014, R² = 0.93) for a theta range of 0.068 to 0.264 m³m-3. A separate calibration for each depth improves the correlation coefficient and minimizes RMSE. Site-specific calibration improves the accuracy for soil water monitoring.