I am a Mashgiach Kashrut for a farmer growing vegetables for local Israeli consumption in greenhouses located 3-4 km south of Ashkelon along the coast. During Shmita, the farmer used the "Minutak" method of growing in pots, separated from the ground by a double layer of pastic. Now, after Shimita, the farmer is continuing to grow in pots above the ground. As Mashgiach taking Maaserot and Trumot, do I say the Bracha "...Lehafrish Maaserot and Trumot" or just the "Amera"? (the pots don’t have dirt but rather artificial peralite). Of course I will ask the Rabbanim giving the Hechsher but I want an opinion from zionist rabbis.
From what I have seen, Machon Hatorah VeHaaretz hold the opinion that one should tithe Trumot and Maasrot without a Bracha.