Hello Gagana!

Exact rank cannot be precisely predicted. Your KCET score is 90 marks (PCMB),  so your expected rank will be in range of 3501-4000 (PCMB). Although it is expected rank, actual rank may differ from it. You can get Bsc agriculture seat, although it depends on your PCB marks.

For further details regarding marks vs rank go through following link;
https://engineering.careers360.com/articles/kcet-marks-vs-rank

Below are  the cutoffs of some agriculture colleges for general category :-

College of agriculture ,GKVK Campus, Bangalore   -    1676

College of agriculture, VC Farm, Mandya                 -     2642

College of agriculture, Hassan                                   -      3301

College of agriculture, Navile, Shimoga                    -       3521

College of agriculture, Dharwad                                -        2607

College of agriculture, Vijayapur                                -        5443

College of agriculture, Haveri                                     -        4898

College of agriculture, Shahapur, Yadgiri                 -         6220

College of agriculture, Kalaburgi                                -         5076

Sericulture College, Chintamani , Chikkabalapur    -         4332

All the Best

Hope this helps!