The city of Selma, in addition to the taxes it is now authorized and empowered to levy and collect, shall levy and collect annually an additional tax of two-tenths of one per centum upon the value of the property therein as fixed for state taxation, to be applied exclusively to the maintenance of public schools therein, and shall levy and collect annually a further additional tax of one-tenth of one per centum upon the value of the property therein as fixed for state taxation, to be applied exclusively to public school buildings therein and improvements and repairs thereon, or to the payment of indebtedness contracted for the same by the city of Selma, or to the maintenance of public schools therein or to any one or more of these purposes; provided that these taxes shall be in lieu of all other city taxes now required to be levied or appropriated by the city of Selma for the support of schools or for school purposes.