Jim Nelson played for Coach Kenneth Cleveland at Dimmitt High School, leading the team to the State semifinals three consecutive years.
Nelson led both the TIAA and NAIA District VIII in rebounding in 1991-92 with a 10.6 per game average, good for tenth in the nation. He also averaged 13.4 points and blocked 39 shots while earning first team All-Conference and All-District honors. He scored 25 points and pulled down 14 rebounds in a win at Huston-Tillotson. As a sophomore in 1990-91, he led the TIAA in rebounding with an 11.6 average and also averaged 10.6 points. He was a walk-on member of the Cowboys as a freshman, the last season HSU was a member of NCAA Division I. Nelson was a co-captain his junior and senior year.
Nelson's senior year ended with a conference championship, 23 wins and 6 losses which were an all-time school record for wins in basketball. Nelson was the leading rebounder with 322 rebounds which also led the conference. Nelson was also the conference leader with 51 blocked shots and was named All-Conference.
After graduating from Hardin-Simmons, Nelson received his graduate degree from Southwest Texas State in 1997. He was a research assistant at Colorado State University from 1998-2002 and spent four years as an Agronomist for the USDA-ARS in Raleigh, North Carolina. Since 2006 he has been a scientist at the University of Kentucky with a specialty in Plant Ecology. He has co-authored several books and numerous journal articles.