Comparison between The Measured and Predicted moisture contents as affected By Some Soil Improvements

Abstract

Predicted equation were used for best fitting between measured and calculated moisture contents of two soils texture located at Ninevah governorate under the effect of soil improvements . Soil samples were sieved by 2 mm sieves and saturated to measure the soil moisture characteristic curve of 10, 33,100, 200,400, 600,800,1000 and 1500 Kpa. By using both pressure plates and membrane and pressure compared its value by using predicted equations. Results indicated that the values of both Θs and Θr were highest of P3O0 treatment for the clay texture compared with the loamy texture soil.The values of m, n and α of VanGenuchetn equation. for the first location were lower than the second to location and the value of n was higher than both m and α.The value of a of Van&Mua was higher than bmfor the first location than the second one.The value of a of Van&Bur equal to a value of Van&Mua .while b and bˉ were variable and b was lower than bˉ for both locations. The values of a, c and hr were higher for P3O2 treatment of Fred &Xing .compared with the lower values of P0O0 for both location, On the other hand,the a value of Pere&Fred was equal to the same value of both Van&Mua and Van&Bur and the b value equal to Van&Bur and c value was variable and similar to m values of VanGenuchetn .Best fitting between the measured and calculated values at higher suction by Fredlund & Xing equation for both location and at lower suction by (VanGenuchetn, Van&Mua, Van&Bur and Pere&Fred ). Equation VanGenuchetn gave best first to the measured value at 33 Kpa for the second location.while equation Van & Bur gave best first at 100-400 Kpa for both location and Pere&Fred at 33 Kpa for first location.