Simultaneous monitoring of soil water content and salinity with
a low-cost capacitance-resistance probe
C. Grosso
Mario Gulich Institute, National Agency of Spatial Activities (CONAE), Córdoba, Argentina
G. Manoli
Institute of Environmental Engineering, ETH Zurich, Switzerland
M. Martello, I. Piccoli, F. Morari
Dept. of Agronomy, Food, Natural Resources, Animals and Environment, University of Padova, Legnaro, Italy
Y. H. Chemin
Harvesting, Silicon Valley, CA, USA
D. H. Pons
INTA EEA Manfredi, Córdoba, Argentina
P. Teatini
Dept. of Civil, Environmental and Architectural Engineering,
University of Padova, Padova, Italy
ABSTRACT
The surface energy balance algorithm for land (SEBAL) has been successfully applied
to estimate evapotranspiration (ET) and yield at different spatial scales. However, ET and yield
patterns have never been investigated under highly heterogeneous conditions. We applied SEBAL
in a salt-affected and water-stressed maize field located at the margin of the Venice Lagoon, Italy,
using Landsat images. SEBAL results were compared with estimates of evapotranspiration by the
Food and Agriculture Organization (FAO) method (ETc) and three-dimensional soil-plant simulations.
The biomass production routine in SEBAL was then tested using spatially distributed crop yield
measurements and the outcomes of a soil-plant numerical model. The results show good agreement
between SEBAL evapotranspiration and ETc. Instantaneous ET simulated by SEBAL is also consistent
with the soil-plant model results (R2 = 0.7047 for 2011 and R2 = 0.6689 for 2012). Conversely,
yield predictions (6.4 t/ha in 2011 and 3.47 t/ha in 2012) are in good agreement with observations
(8.64 t/ha and 3.86 t/ha, respectively) only in 2012 and the comparison with soil-plant simulations
(8.69 t/ha and 5.49 t/ha) is poor. In general, SEBAL underestimates land productivity in contrast to
the soil-plant model that overestimates yield in dry years. SEBAL provides accurate predictions under
stress conditions due to the fact that it does not require knowledge of the soil/root characteristics.
