Upon the approval of the allotments provided for in this act by the Secretary of the Interior, he shall cause patents to issue therefor in the name of the allottees, which patents shall be of the legal effect, and declare that the United States does and will hold the land thus allotted, for the period of twenty-five years, in trust for the sole use and benefit of the Indian to whom such allotment shall have been made, or, in case of his decease, of his heirs according to the laws of the State or Territory where such land is located, and that at the expiration of said period the United States will convey the same by patent to said Indian, or his heirs as aforesaid, in fee, discharged of said trust and free of all charge or incumbrance whatsoever: Provided, That the President of the United States may in any case in his discretion extend the period. And if any conveyance shall be made of the lands set apart and allotted as herein provided, or any contract made touching the same, before the expiration of the time above mentioned, such conveyance or contract shall be absolutely null and void: Provided, That, subject to section 8(b) of the American Indian Probate Reform Act of 2004 (Public Law 108–374; 118 Stat. 1810), the rules of intestate succession under the Indian Land Consolidation Act (25 U.S.C. 2201 et seq.) (including a tribal probate code approved under that Act or regulations promulgated under that Act) shall apply to that land for which patents have been executed and delivered: And provided further, That at any time after lands have been allotted to all the Indians of any tribe as herein provided, or sooner if in the opinion of the President it shall be for the best interests of said tribe, it shall be lawful for the Secretary of the Interior to negotiate with such Indian tribe for the purchase and release by said tribe, in conformity with the treaty or statute under which such reservation is held, of such portions of its reservation not allotted as such tribe shall, from time to time, consent to sell, on such terms and conditions as shall be considered just and equitable between the United States and said tribe of Indians, which purchase shall not be complete until ratified by Congress, and the form and manner of executing such release shall also be prescribed by Congress: Provided, however, That all lands adapted to agriculture, with or without irrigation so sold or released to the United States by any Indian tribe shall be held by the United States for the sole purpose of securing homes to actual settlers and shall be disposed of by the United States to actual and bona fide settlers only in tracts not exceeding one hundred and sixty acres to any one person, on such terms as Congress shall prescribe, subject to grants which Congress may make in aid of education: And provided further, That no patents shall issue therefor except to the person so taking the same as and for a homestead, or his heirs, and after the expiration of five years’ occupancy thereof as such homestead; and any conveyance of said lands so taken as a homestead, or any contract touching the same, or lien thereon, created prior to the date of such patent, shall be null and void. And the sums agreed to be paid by the United States as purchase money for any portion of any such reservation shall be held in the Treasury of the United States for the sole use of the tribe or tribes of Indians; to whom such reservations belonged; and the same, with interest thereon at 3 per centum per annum, shall be at all times subject to appropriation by Congress for the education and civilization of such tribe or tribes of Indians or the members thereof. The patents aforesaid shall be recorded in the Bureau of Land Management, and afterwards delivered, free of charge, to the allottee entitled thereto. And if any religious society or other organization was occupying on February 8, 1887, any of the public lands to which this act is applicable, for religious or educational work among the Indians, the Secretary of the Interior is authorized to confirm such occupation to such society or organization, in quantity not exceeding one hundred and sixty acres in any one tract, so long as the same shall be so occupied, on such terms as he shall deem just; but nothing herein contained shall change or alter any claim of such society for religious or educational purposes heretofore granted by law. And in the employment of Indian police, or any other employees in the public service among any of the Indian tribes or bands affected by this act, and where Indians can perform the duties required, those Indians who have availed themselves of the provisions of this act and become citizens of the United States shall be preferred.