If we transport irrigation water in steam molecules, it will be more economical because it is frictionless. We can use the polar field to give them a path direction.
Adding to the previous answer, why would friction be an issue in most cases? Most irrigation systems are designed to be gravity-fed and the losses due to friction would, I would have thought, been a pretty small element of overall energy of transportation. As Tsanko Tsankov suggests, the energy cost of converting water to steam will significantly outweigh the benefits of transporting it by steam.
Another issue to bear in mind is that the steam will have to be condensed at the point of use and probably be brought down to near ambient temperature. This will also likely need a significant infrastructure to manage - cooling ponds at the very least - which again will add to costs. Given that this will probably need to be static to hold the volumes of water necessary for any irrigation scheme of any size and we are back to square one with the benefits of steam transportation.
I think clouds are already establishing a way of transportation of irrigation water around the globe. So, I may suggest to think of how we can move/transport the clouds to the regions/area that needs irrigation. Is not that a kind of real-time irrigation? Does it look realistic, indeed?
Since the water absorption process is mainly occurring in the roots, it’s complicated to infiltrate the steam in the soil where roots are because the soil must be under the dew point to achieve condensation. You must consider that the main reason of giving water to the plants is to keep the breathing and to control the temperature, over 25°C the photosynthetic process is less efficient in many crops in Mediterranean environments.
It's all a matter of energy and costs. I have not calculated the differences between the 2 options, but I can imagine the whole project to be far more expensive, even without taking into account friction matters, which occur eitherway.
If you do I can estimate your future losses of transfering water in steam formation, unless you get thermal water (steam under high pressure) very close to the planatation area.
The infrastructure must cost a fortune and the maintenance as well.
So, I would think twice and get 3 different visibilty studies, to calculate the overall costs, for the long run, properly.
For the sake of getting knowledge and providing a sustainable environment I will suggest your study to look on how to convert deserts into forests or otherwise change the micro-climate of the deserts so that it can start to rain in those area. This can be expensive but cost effective and need to be done once. This may include transportation of clouds as suggested above.
I suppose the cost of making steam and condensing the same to get water will be much more than that of using pipes. But I even find this useful for getting water from sea.