The Legislature of Alabama shall appropriate during each of its regular sessions, or during such other sessions as conditions may require, a sufficient sum of money, based upon estimates and recommendations of the Adjutant General and approved by the Governor, for the purpose of defraying the expenses of the Military Department in carrying out the provisions of this chapter, and such other expenses connected with the organization, maintenance, support, upkeep, administration, armament, training, and discipline of the National Guard of Alabama and such other expenses of a general or special nature, as may be to the interest and benefit of the National Guard, as the Governor may approve. Any appropriations made by law for payment of salaries or other expenses of any agency of the state which shall be merged or consolidated with or made a part or subdivision of the Military Department, shall be merged with and become a part of the appropriations for "other salaries" and "other expenses" of the Military Department. The Governor shall prescribe necessary rules and regulations governing the manner and method of disbursing moneys authorized by this section to be appropriated, and all expenses authorized to be contracted shall be certified to and verified by affidavit, with itemized vouchers and orders attached. Any portion of any item of any regular appropriation for the support of the Military Department and National Guard which is unexpended and unobligated after the expiration of the eleventh month of any fiscal year shall be available for use in taking care of any expenses of operating the Military Department and the Armory Commission of Alabama for which the regular appropriation shall be insufficient for that fiscal year.