The reactions of the other alkali metals with nitrogen would not release enough lattice energy and would thus be endothermic, so they do not form nitrides at standard conditions.
ðə ɹɪˈækʃənz ʌvðɪ ˈʌðɚɹ ˈælkəlˌaɪ mˈɛɾəlz wɪð nˈaɪtɹədʒən wʊd nˌɑːt ɹᵻlˈiːs ɪnˈʌf lˈæɾɪs ˈɛnɚdʒi ænd wʊd ðˈʌs biː ˌɛndoʊθˈɜːmɪk, sˌoʊ ðeɪ duːnˌɑːt fˈɔːɹm nˈaɪtɹaɪdz æt stˈændɚd kəndˈɪʃənz.