Local authorities also said Friday that three soldiers who had stopped the vehicle for inspection were lightly wounded in Thursday's attack in the town of Dicle, near Diyarbakir, the largest city in the Kurdish-dominated southeast.
Turkish officials believe rebels placed the bomb in the truck, which was delivering bread to the base, without the driver's knowledge.
Initial reports immediately after the blast said it occurred before the vehicle reached the military outpost, but authorities on Friday confirmed that the explosion took place at the base entrance.
The attack appeared to represent a new tactic by the rebels, who normally use roadside bombs to hit military convoys. The rebels also appear to be targeting civilians who do business with the military in Kurdish areas.
Guerrilla fighters also recently raked a delivery vehicle with automatic weapons fire near Diyarbakir, killing one civilian.
Fighting between Kurdish rebels and the Turkish military has claimed 37,000 lives since 1984, when the autonomy-seeking rebels took up arms.
In the latest reported violence, Turkish troops killed one Kurdish guerrilla in an overnight clash near the town of Dargecit in southeastern Mardin province, authorities said Friday.
US President Joe Biden and Iraqi Prime Minister Mustafa Al Qadimi signed an agreement on July 26 to formally end the USA's military presence in the country by the end of the year