528. As to improvements which the lessee has made voluntarily, without being bound to do so, the lessor has the option of either keeping them, upon paying what they cost or their actual value, or permitting the lessee, if the latter can do so with advantage to himself or herself and without deteriorating the land, to remove them at his or her own expense; otherwise, in each case, they belong, without indemnification, to the lessor, who may, nevertheless, compel the lessee to remove them, in conformity with the provisions of article 372.