"Hey bull, hey bull," Johnny Howell prods as he nudges the bull just before the gate opens and bull and rider charge into the arena. The bull jumps. Bucks. Twists. And the rider falls into the dirt and manure. The ride doesn't last eight seconds. But it doesn't matter. Not really. They're here to practice and to learn. Joe Clark moved to Washoe Valley in 1988 and started the Triple J Bull Riding livestock company. Now complete with an arena with outdoor lights, chutes and stands, Clark and his sons Johnny Howell, 35, and James Clark run the company, and …