conscription does not exist
Nigeria has no military conscription and has never had since achieving independence.  
There is, however, another form of conscription for all university graduates. They are required to perform a 12-months' civilian service, working outside their state of origin in community projects, social programmes, public health, agriculture and sports. This service has no link with the armed forces. 
Recruitment into the professional armed forces is on a voluntary basis. The minimum legal recruitment age is 18.  
Apparently there is no standard or basic educational requirement to be allowed to enlist in the Nigerian armed forces as a private, corporal or sergeant. But there are stringent physical requirements. Despite the fact that examinations are required before being promoted to the rank of sergeant, there are sergeants within the military who are illiterate. 
A 1987 source states that the minimal educational qualification for recruits is the West African School Certificate. Also recruits have to come from every one of the 302 local government areas to safeguard a national identity. In 1987 there were over 20,000 applicants for the 1,760 available places in the armed forces. 
2 Conscientious objection
There is no known legal provisions for conscientious objection.
No information available.
Conscription existed when Nigeria was under British colonial rule and there were provisions for conscientious objection. During the Second World War at least 18 COs were given CO status in Nigeria. 
6 Annual statistics
The armed forces comprise about 77,000 troops - that is, 0.07 percent of the population. Approximately 12,000 of them are stationed in the ECOMOG peacekeeping forces in Liberia and Sierra Leone. 
 Prasad, D., T. Smythe 1968. Conscription: a world survey, compulsory military service and resistance to it. War Resisters' International, London.  Williams, D. 1987. Nigeria: military strength. ANB/BIA, West Africa, UK, 21 December 1987.  IRBDC 1994. Telephone interview with staff member of defence section of the Embassy of Nigeria, Washington DC; and with a professor of political science, University of Texas, Austin. 26 September 1994.  Gouault, J. 1995. Service National, quelle options? Serie POUR Avec. GREP Editions/UNESCO, Paris.  UN Commission on Human Rights 1997. The question of conscientious objection to military service, report of the Secretary-General prepared pursuant to Commission resolution 1995/83. United Nations, Geneva.  Institute for Strategic Studies 1997. Military Balance 1997/98. ISS, London, UK.