What is the ruling regarding money found in an empty plot of land near workshops, where its owner could not be identified, and it is difficult to return to the place where it was found, and is it permissible to donate a portion of it and keep the rest, or must the entire amount be donated?

The money you found is considered a 'Luqatah' (found object), and you must announce it for a year in the village where you found it, without mentioning its amount. If someone comes and accurately describes the money, you must hand it over to them. You should not tell the owners of nearby shops the amount of the money. If a full year passes and no one claims it, you may utilize it, on the condition that you return it to its owner whenever they appear, based on the saying of the Prophet, peace and blessings be upon him: "Remember its strap and its container, then announce it for a year. If it is not claimed, then spend it, and let it be a trust with you. If its owner comes one day, then hand it over to him." You can also give it as charity after the year, and if its owner is found, they can choose between the reward of the charity or having you compensate them. It is not permissible to dispose of it before the year has passed. If you are far away, your friend can announce the money in their location.