Numerical calculation of soil water potential in an irrigated ‘conference’ pear orchard

Irrigation in Belgian ‘Conference’ pear orchards is often managed by soil water potential (Ψsoil) sensors. The most widespread sensor among fruit growers in Belgium is the Watermark sensor (Irrometer Co., USA). To gain better insight into the use of the Watermark soil sensor for irrigation scheduling in pear orchards the water extraction pattern of the ‘Conference’ pear trees was acquired by a numerical calculation of Ψsoil in three experimental plots. A reasonable accordance between calculated and measured Ψsoil was observed with R2=0.56 and RMSE=13.4kPa over 1320 observations. Furthermore the sensitivity of the numerical calculation to the selected root distribution was shown. The Ψsoil calculation with the root distribution parameterized by site specific fine root length observations gave satisfactory results for all plots, in contrast to Ψsoil calculation based on other root distributions.