Hello aspirant,

Yes you can pursue agriculture after your graduation.

To get admission in government agriculture college through all india quota you have to appear in ICAR-UG exam conducted by National testing agency (NTA) , BHU Under graduate test (BHU-UET) exam.Beside this every state agriculture University conduct their own exam for native students.

For further details about these exams go through following link;

http://university.careers360.com/articles/bhu-uet/amp

http://university.careers360.com/articles/icar-aieea/amp

You can also get direct admission in private agriculture colleges . Some private colleges for agriculture are as follow;

1. SRM University, Chennai

2. Lovely Professional University, Jalandhar

3. Chandigarh University, Chandigarh

4. Sharda University, Greater NOIDA

For further details about Colleges go through following link;
http://university.careers360.com/colleges/list-of-agricultural-science-universities-in-india


Hope this helps!!
All the best!!