How can Agri Engineer become Civil engineer?

Dear Editor,
I would like to bring to notice of the Student union leaders, unemployed civil engineering students and the department concern in framing recruitment rules.
My first question is how can an Agriculture engineer graduate become a Civil Engineer or How can a Civil Engineer graduate become an Agriculture Engineer? Agriculture and Civil Engineering are two totally different fields of engineering.
Agriculture Engineers study about agriculture tools and machineries whereas civil engineer studies about constructions of roads, buildings and bridges, waste management and water supplies.
I have given examination two times for the post of Assistant Engineer (Civil), recent being in June. The Arunachal Pradesh Public Service Commission has conducted the examination. In their advertisement for the post of Civil Engineer, they have mentioned that agriculture engineer graduates are also eligible for the post of civil engineer for the Rural Works Department and Water Resource Department.
I can accept that Water Resource department takes agriculture projects like construction of irrigation canals and bunds. But we all are very much aware that Rural works Department is also a client department like PWD in Construction of Roads, Bridges and Buildings. Now how can a student who studied farms technique, its tools and machinery, all of a sudden construct road and bridges?
A Civil Engineer Graduate