Acharya N.G. Ranga Agricultural University

You need to write EAMCET exam after your class 12th.
Then, according to your rank and marks obtained, for your reserved category, you may obtain a seat in the college.

You have to score above 80% marks in B.Sc final exam or above average 72.5% marks in whole Bachelor program.

You need to opt for AP EAMCET to get admission in Acharya N.G. Ranga Agricultural University for B.Tech in agricultural engineering
Details below :
https://www.shiksha.com/b-tech/course/b-tech-in-agricultural-engineering-acharya-n-g-ranga-agricultural-university-rajendra-nagar-hyderabad-85923
https://www.shiksha.com/university/jawaharlal-nehru-technological-university-kakinada/exams/ap-eamcet

Yes, you can change the course from CS to B.Tech Agri Technology. You will have to go through a process which includes the written test and selection as students do after their class 12th.
Best of luck.

Qualification for admission into PG Program:
B.H.Sc./B.Sc. (Home Science) of 4 years duration.
Qualifying entrance exam for admission into M.Sc programs is conducted by Acharya N.G. Ranga Agricultural University on its own. The entrance examination consists of different sections, aiming to test the aptitude of the candidate in regard to knowledge of the subject, as well as general knowledge and current affairs. Regards.

Check this link to know about the eligibility criteria of various programmes offered by Acharya N.G. Ranga Agricultural University
http://www.angrau.ac.in/AdmissionsIndia.php#PG
B.Sc (Ag./Hort.) or B.Tech (Ag.Engg.) or BV.Sc & AH / B.F.Sc. / B.H.Sc. (H.Sc.) B.Tech (Dairying) B.Tech (Food Processing & Technology) / B.Tech /B.Sc (Food Science & Technology) / B.Sc(CA&BM) / B.Sc (Farm Science) / B.Tech (Biochemistry) of 4 years duration.