Soil physical characteristics have main role for plant growing and product efficiency. Soil physical measurement is necessary to correct management and exploitation of soil and best operation. Soil moisture content and its porosity are important physical factors to growing plants. Soil with appropriate moisture and porosity, obtain better conditions for plant growing. To predict soil moisture and its porosity the methods with advantages and disadvantages were recommended. Ultrasonic nondestructive tests have high ability for estimate soil physical characteristics, because ultrasonic waves need a medium for transmission. Ultrasonic tests used in agricultural products in different frequencies, but used in soil rarely. In the present study, the characteristics of transmission ultrasonic waves in the soil sample with two transducers (transmitter and receiver) in two frequencies, 75 kHz and 125 kHz, and two levels of voltage 900V p-p and 1800V p-p were investigated. To estimate soil moisture content and porosity the velocity and attenuation of waves was measured. Soil samples in three levels of porosity 55%, 47%, and 40% and three soil textures clay, clay loam, and sandy loam in many levels of soil moisture was used. Soil moisture content based on the dry weight was used from high plastic limit and continued to a constant ratio in the oven. Moisture range was 30%-12% for clay, 24.5%-7% for clay loam, and 19%-6% d.b. for sandy loam soil. Soil sample rings had 69 mm in diameter and 20 mm in thickness. Soil samples fixed in a holder and the transducers was put in its two sides. Soil samples included two transducers were put in the oven at 55 and at each 15 minute intervals the velocity and attenuation of ultrasonic waves and the weight of control sample were
