All payments made under the provisions of this article, except pay and allowances for active service of the state, shall be paid out of the military fund. All pay and allowances and other expenses incurred in active service of the state shall be paid out of any moneys in the treasury not otherwise appropriated. The military fund shall be disbursed on warrant of the Adjutant General, properly drawn and in such manner as the Governor may order, or as may be required by law, but no warrant for funds signed by him shall be honored by the Auditor until such Adjutant General shall have executed and filed such bond as may be required by the Governor. Payments shall be made on proper vouchers, which vouchers shall show the authority under which the expenditures are made, contain an itemized statement of the transactions, and be filed for record in the office of the Adjutant General. All claims for services rendered or material furnished shall be approved by the officer ordering the work or material, and shall be over his certificate to the effect that the amount is just and reasonable, and that it has not been previously paid. No expenditures shall be made by any officer until an estimate of the amount and a statement of the necessity therefor shall have been laid before the Adjutant General and his approval received.