Spilled fertiliser caused minor traffic delays on State Highway Three North of Whanganui Monday morning.
Red dust covered much of the road after a truck's trailer overturned on a straight stretch of road, five km north of Maxwell, shortly after 8am.
The driver was not hurt and the truck remained upright.
Police said the cause of the accident was not known at this state.
A nearby farmer said she heard "screeching" followed by a bang.
"I could see lots of traffic stopping to help," she said.
There were minor delays as traffic was stopped and allowed to pass one lane at a time.
Road machinery was brought in to sweep the highway of what police at the scene said was fertiliser.
The truck's trailer would be removed later in the morning, police said.
The crash was the second in five days and follows a horror collision along SH3 near Makirikiri Road, South of Whanganui, on Thursday when two trucks collided.
The cab of one truck was knocked from its chassis and came to rest several metres along the road in what a witness described as a crumpled ball of steel.
The driver climbed free of the wreckage with only minor injuries.
Location
(see link below to earlier story)