The dipole performance is largely defined by the height of the antenna. The performance of the vertical is defined largely defined by the ground conductivity and the radials. We can also say that the height of the antenna has some affect on performance as well due to the decoupling from the ground losses at the higher heights. If you look on the EZNEC, you can change the definition of the ground conductivity and see how this factor can make a lot of difference in the vertical performance. It won't change much on the horizontal performance per a given height. A salt water ground definition is best and sandy soil is worst. For the same take off angle, it is possible to see a difference of 4dB difference between a rich pasture soil and a sandy dry soil. That is a large difference.