Important Characteristics Influencing the Cone Penetration Resistance in Virgin, Cultivated, and Sugarcane Land Uses in Some Khozestan Soils

The objectives of this study were to determine and compare the factors that influence cone penetration resistance (PR) under three land use types: virgin، under field crops، and sugarcane cultivated lands of Haft-Tapeh Agro-Industry، in Khozestan province. Accordingly، 80 soil samples from 0-40 and 40-80 cm were collected from each land use to establish regression equations predicting PR. Further، the possibility of using the slope of water retention curve at its inflection point (S index) to derive regression equations was investigated. In order to eliminate the effects of moisture content on the PR، measurements ​​were made at matric tension of 33 kPa. The results showed that variations of the factors affecting PR in virgin lands were more than those of sugarcane and arableones. In sugarcane and arable lands، PR values increased logarithmically with decrease in organic matter and mean weight diameter. Besides، S index was increased by reclamation of the virgin lands due to lowering of salinity and sodium-induced restrictions and improvement in organic matter content. Also، the results showed that at very low values of S index، PR depended on the compression forces and little change would occur with more reduction in organic matter content and mean weight diameter.