Section 15, insofar as it is material provides: "(1) The Collector shall give notice,by the publication in the Official Gazette and in such other manner as may be prescribed, requiring every person, whose total agricultural income during the previous year exceeded the maximum amount which is not chargeable to agricultural income tax to furnish to such assessing authority and within such period, not being less than thirty days, as may be specified in the notice, a return in the prescribed form and verified in the prescribed manner, setting forth his total agricultural income during the previous year (2) (3) In the case of any person whose total agricultural income is, in the opinion of the assessing authority, such amount as to render such person liable to payment of agricultural income tax in any year, he may serve in that year a notice in the prescribed form requiring such person to furnish within such period, not being less than thirty days as may be specified in the notice, a return in the prescribed form and verified in the prescribed manner setting forth his total agricultural income during the previous year 165 Section 16 sets out the procedure of assessment by the assessing authority, and against the order of assessment by the assessing authority, an appeal lies under section 21 to the Commissioner.