Prediction Soil Bulk Density and Moisture Constants Using Particle Size Distribution for Selected Libyan Calcareous Soils

The most developed Pedotransfer Functions (PTFs) for estimating the soil bulk density use data on soil texture and organic matter content  as independent variables, as well as  the majority published PTFs for predicting the soil moisture constants involved soil texture, bulk density, and organic matter  as independent variables. On a regional scale as in Libya where the organic matter content is spare, as a result of the prevailed climatic conditions, the parameterization of these equations will be difficult.  So, the objective of this work is studying the interrelations between soil texture and these parameters, and the possibility of access correlations for developing regression equations. For the purpose of estimating the bulk density and soil water constants from accessible routinely data such as soil texture as an independent variable, 46 soil samples were collected from Al Izzayat area ( Region of Al Jabal Al akhdar) as a training set , and 12 soil samples, as a test set from Mikilli area, which are characterized with the same environmental conditions  to the training area. The obtained PTFs equations are characterized with highly satisfied predicted coefficients of determinations (R2p). The validation of these derived equations was done successfully with calculated coefficients of determination (R2). The R2 values were 93.8 % for field capacity, 92.2 %for bulk density, 91.3% for permanent wilting point, and 71.7% for available water capacity. These variations were more related to sand and silt contents rather than clay content in the investigated samples.