Measuring salinity using electromagnetic sensors for sustainable management of rice fields in the Ebro River Basin, NE Spain

Red rice (Oryza saliva L.) is a common weed in rice fields throughout the world. In the area studied, two sub-areas of 23 and 47 ha of saline soils in a semi-arid region in NE Spain, rice has been grown for more than 15 years under flooding conditions as part of the process of soil reclamation. Both sub-areas were split into 14 and 25 crop fields, respectively. Since implementing crop rotations is an effective and sustainable practice in fighting red rice and other weeds, the objective of this study was to determine the suitability of the use of all electromagnetic sensor to delimit the distribution of soil salinity in the area, so that areas with lower salinity Could be identified for implementation of alternative crops. A simple calibration was made between readings from the sensor and the actual soil electrical conductivity (EC(e)), calculated as the average EC(e) of a saturation extract of soil samples from three depth intervals. Salinity was then measured in the points of a 25 x 50 In plot and the average salinity was calculated for each particular field. Coordinates of each point in the plot were obtained with the help of GPS, and a salinity map of each area was plotted. The Study showed how the use of the average salinity of each field, as obtained from the readings of the electromagnetic sensor, is a useful, quick and suitable tool. This allowed the establishment of four different management areas in which different strategies could be followed in order to introduce new crops, in rotation as a sustainable practice, in fighting red rice, and as a step forward in the process of soil reclamation.