The Sefer Yetzirah only enumerates three elements ‘fire’, ‘water’ and ‘air’, even though in the Medrash, in the Zohar and in the Rambam they enumerate four elements: ‘fire’, ‘water’, ‘air’ and ‘earth’, because primarily there are three elements ‘fire’, ‘water’ and ‘air’ which themselves also include the element of ‘earth’. And the element of ‘earth’ is only revealed at a later stage within them.
An Illustrative Example
There is a well-known example that illustrates this; when one places a pot of ‘water’ to boil on the ‘fire’ and there is [room for] some ‘air’ in between it then builds up [a dust like earth particle which represents the] earth element which is submerged within. In his book, Pardes Rimonim (Portal 11, chapter 3), the 16th Century Tzfas Kabbalist the ‘Ramak’ (Rabbi Moshe Cordovero) presents an example that may explain why the element of earth is mentioned and "revealed" only later: water in a pot near fire, with the air in between. After the water is heated, bits of earth develop, which emerge as the element of earth. This parable is brought by the Tzemach Tzedek in Ohr Hatorah on Parshas Yisro from the Ramak (9:3:3 on Sefaria.org) if one was to allow the water in the pan to boil away and then to put more water into the pot and then let that boil away and continue doing that for a while there would be a build-up in the pot of a collection of earth particles. Like a dusty residue in the pot and that is from the particles which represent the earth particles. We see it as limescale or hardness in the water. So that together there is a blend and fusion between the three foundational elements: fire, air and water.
Similarly, it could be understood how the three strands of ‘Chessed’, ‘Gevurah’ and ‘Tiferes’ above also include everything within them and it is from them that Malchus is also eventually revealed. Therefore, from the Torah there are only three Brochos which bring abundance and added blessings from the supernal ‘Middos’ of ‘Chessed’, ‘Gevurah’ and ‘Tiferes’ and they all include Malchus within them. But afterwards the Sages of blessed memory added the fourth blessing of Sefiras Hamalchus alone and unadulterated.
