effect of salinity on performance of smart sensors in determination of soil moisture content

the accuracy and effectiveness of precision agriculture is highly depending on accuracy and time analysis of the soil moisture conditions. monitoring of the soil water status is a proper method for optimizing the agricultural irrigation. automation irrigation, based on soil moisture measurement by smart sensors has the potential to provide maximum water use efficiency by maintaining soil moisture at optimum levels. the salinity of the soil solution has a great impact on sensibility of the smart sensors the soil moisture content is determined. therefore, in this study the performance of 4 smart sensors were compared to common methods in order to estimate the amount of soil water content under saline water at 30 and 60 cm depth from soil surface. the smart sensors used in this study were watermark 200ss-v, watermark 200ss, ics 9101 and ics9001 and the common methods which used to determining the soil moisture content were tensiometer, gypsum blocks, neutron meter and gravimeter method. the results showed that the watermark 200ss-v was introduced as a highest accurate method to determine the soil moisture content. among the conventional methods, the neutron meter showed a reasonable accuracy of soil moisture measurement. using the gypsum block and tensiometer were not the appropriate method for soil moisture measurement. the results indicated that the performance of watermark 200ss-v and tensiometer for measuring the soil moisture content under low soil moisture tension is better than in high soil tension condition.