Determination of field capacity and permanent wilting point values for Fars province soils using capillary saturated water content, Karkanis method.
2009
Shahrokh Niya,Mohammad A`li | Nasr Ol-Lahi, Khandan | Ghiyasi, A`bd Ol-Motalleb
Field capacity and permanent wilting point are the important factors for irrigation scheduling. These parameters can be obtained from laboratory or field measurements, which are usually difficult and not costly. Previous studies show that these parameters could be related to the soil capillary saturated moisture and derive empirical estimator models. In the present study, more than 200 soil samples were collected in Fars province and used to test and calibrated the Karkanis formulas. The field capacity and permanent wilting point of the samples were measured by the pressure chamber method, and the capillary saturated moisture by the Karkanis method. Nonlinear regression was used to obtain the formulas relating field capacity and permanent wilting point to the percentage of soil particles and other soil parameters. Results show that the Karkanis method could have low performance and accuracy, comparing with the soil particle percentage. The combination of the soil particle percentage and Karkanis method may give the best results for estimation of field capacity and permanent wilting point.
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