A number of exams are there for admission to various agricultural courses in India. But you haven't mentioned the exam that you're asking for. Agricultural entrance exams like ICAR UG is one of the top exams where many students appear. Here I'm attaching a link where you can get study materials for Agricultural Entrance or Competitive exam. This is the e-learning portal on Agricultural Education by ICAR. You can get the study materials available in the link given below http://ecourses.icar.gov.in/ . NCERT Textbooks are mostly recommended by top educators for preparation of Agricultural Entrance Exam. Another books you can study- ICAR AIEEA UG Entrance exam guide, Bsc Agriculture entrance exam guide by Lalita Gaur. Also solve previous years' entrance exam papers for better understanding.