Hello ,Dinesh 

For getting admission in a Bsc agriculture  is depend on your choice either you are intersted to take admission in privates college or in government colleges.some private colleges are take admission directly without any entrance test but these colleges are not well as like as government colleges .

For getting admission in goverment colleges like in BHU,BAU and many more.you have to give entrance test .most of the state takes its own exam for their own colleges,and different college takes their own exam seperately.you must constantly visit the all the colleges sites for getting update about admission.

ICRA is an entrance exam which is at level test.by this exam you will get admission in different popular colleges because every colleges have 15% reserve seats for ICRA.