How much farm lang is there in total? To seed crops on 4 acres you would have to know that 1 acre is equal to 43,560 sq ft, so that multiplied by how many acres there are would be 174,240 sq ft, so $0.05 multiplied by the amount of sq ft in four acres would be $8,712 to seed four acres for crops. The other half we would have to know how many acres you are seeding for grass.