Nitrogen is a gas, he was Probably using ammonium nitrate (a fertilizer) and fuel oil (Anfo) It can't be set off with a blasting cap or det-cord. It needs a much bigger booster. We used hand mix the ammonium nitrate prills with fuel oil for small shots (blasting quantity measurement was by 'hard hat full'', poured into a plastic supermarket bag), and used a quarter stick of 40% straight on a length of 'B' line tied into the detcord trunk. The detcord trunk was then set off by a single cap, that inturn would set off the string of charges.. Using a tractor mounted fence post digger every couple of feet, we would put in one of these bags in the ground about two feet deep, and tie it in.. This was handy and cheap for blowing small drainage ditches.. One case of 40% has about 104 sticks in it, so we would get over 400 boosters for 400 charges, and anfo itself is real cheap..