Bosman was hurt when he crashed into an advertising hoarding while fielding during a match against neighbouring Zimbabwe last month, and doctors have recommended he rest for six weeks.
Selection convenor Joubert Strydom said Nel's inclusion would strengthen the bowling line-up, which was looking "a bit under-done."
Nel will join the Proteas training camp in Potchefstroom as soon as possible to enable him to participate fully in the preparation phase.
"We are well stocked in the top three batting department with five players -- Graeme Smith, Herschelle Gibbs, AB de Villiers, Goolam Bodi and JP Duminy -- all technically equipped to deal with the new ball and having the expansive strokeplay to force the pace where necessary," said Strydom.
Norman Arendse, the president of CSA, said while the board aimed at having seven players of colour in the squad, this was not a quota.
"Quotas are set in stone while targets are something to strive for. The selectors have convinced me that there are logical and rational cricket reasons for opting for Nel," he said.
"These included an examination of strike rates, economy rates, number of wickets taken and the like of the leading candidates."