It happened near Caruthers around 2 p.m. on Friday. The Fresno County Sheriff's Office says a tractor spraying fertilizer on an almond orchard made a U-turn and sprayed a mist on a Caruthers Unified school bus.
Investigators told Action News some of the windows on the bus were open but the fertilizer was not hazardous.
15 students were on the bus. Deputies say the fertilizer was organic and made up of fish parts and kelp.
The Fresno County Sheriff's Office says one student was taken to Children's Hospital as a precaution because the student is asthmatic.