What is the ruling on seeking sustenance and success by performing a ritual with soil mixed with salt from the doorstep of a house or from a place where there are fruitful trees, placing it in a pouch, reciting the verse, "And I said, 'Ask forgiveness of your Lord. Indeed, He is ever Forgiving. He will send [rain from] the sky upon you in [continual] showers,'" and then performing ghusl (ritual bath) or wudu (ablution) with it after three nights? Is this considered magic or sorcery?

The blessing mentioned in the question is an innovation (bid'ah) and a means to shirk (polytheism), and it is not among the legislated forms of blessing. This is based on the saying of the Messenger of Allah, peace and blessings be upon him: "Whoever introduces into this matter of ours that which is not from it, then it is rejected." This form of blessing does not escalate to the level of major shirk (al-shirk al-akbar) that expels one from the fold of Islam, unless the one who performs it believes that the dust and salt themselves bring him sustenance and success.