"Minnesota Environmental Preservation Property Tax Law"; providing for a property tax basis on current instead of potential alternative or future use of certain properties; entitling real estate of a certain number of acres classified as residential or agricultural homestead property owned by noncorporate entities to valuation and tax deferment upon meeting certain specified criteria; providing for determination of value with reference to current use and value, requiring assessor exclusion of additional value resulting from potential alternative and future uses of the property and annual separate determinations of market value and tax; requiring and providing for annual application for tax deferment; subjecting property no longer qualifying to additional taxes; taxes imposed to be a lien against the property; providing for continuation of tax treatment upon sale of the property (ra)